How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms

How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms Jiao Liu, Wen-Jing Liu, Yue Qiu, Hong-Mei Jiang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8431406/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objectives Mindfulness-based exercise has been shown to enhance affective responses to exercise, yet the momentary psychological mechanisms underlying these effects remain poorly understood. The present study examined how mindfulness during exercise shapes affective experience by focusing on dynamic, momentary psychological processes across a four-week intervention. Methods Physically inactive college students were randomly assigned to a mindfulness-based exercise condition, a distraction condition, or a control condition and completed 2–3 supervised exercise sessions per week for four weeks. Using an ecological momentary assessment (EMA)–informed design, immediate post-exercise affect and mindfulness-related psychological processes were assessed following each exercise session. Multilevel models decomposed within-person and between-person effects to examine concurrent associations between psychological processes and affect, moderation by intervention condition, and exploratory lagged effects across sessions. Results Session-specific fluctuations in acceptance, nonreaction, attention–awareness, and decentering were all positively associated with immediate post-exercise affect at the within-person level. Moderation analyses indicated that mindfulness-based exercise selectively strengthened the momentary association between nonreaction and affect, whereas other mechanisms showed comparable associations across conditions. Exploratory lagged analyses revealed no evidence that prior-session levels of acceptance or nonreaction predicted affective responses at subsequent sessions beyond concurrent effects. Conclusions These findings suggest that mindfulness influences affective experience during exercise primarily through dynamic, momentary psychological processes rather than sustained carry-over effects. By highlighting nonreactive engagement with internal experience as a key mechanism, the present study advances a process-based understanding of how mindfulness operates in exercise contexts and underscores the value of EMA approaches for capturing dynamic affective mechanisms. Mindfulness Exercise Affective responses Ecological momentary assessment Dynamic psychological mechanisms Nonreactivity Figures Figure 1 Introduction Mindfulness has emerged as a promising strategy for enhancing affective responses to exercise and supporting engagement in physical activity. Accumulating evidence indicates that integrating mindfulness into exercise produces small-to-moderate improvements in affective responses associated with exercise (Liu et al., 2026 ). Despite these promising findings, our understanding of why mindfulness enhances exercise-related affect remains limited, with little direct evidence clarifying the underlying psychological pathways. Mindfulness is commonly defined as the capacity to attend to present-moment experience with an attitude of openness, curiosity, and nonjudgment (Kabat-Zinn, 2003 ). Mindfulness during exercise has been conceptualized as a mode of experiential engagement in which individuals intentionally attend to bodily sensations, movements, and internal states as they unfold during physical activity, rather than evaluating, avoiding, or disengaging from these experiences (Bigliassi & Bertuzzi, 2020 ; Cox & Ullrich-French, 2021 ). From this perspective, mindfulness may alter how exercise is perceived and emotionally appraised, thereby shaping affective responses associated with physical activity. Exercise represents a unique affective context in which individuals are repeatedly exposed to salient bodily sensations, fluctuations in physiological arousal, and effort-related discomfort. Affective responses to exercise are therefore shaped not only by physical workload but also by how internal experiences are attended to, interpreted, and regulated in the moment (Ekkekakis et al., 2003; Ekkekakis et al., 2011 ). From this perspective, mindfulness may influence exercise-related affect by altering individuals’ momentary engagement with bodily and psychological experiences during physical activity. Drawing on contemporary models of mindfulness (Baer et al., 2006 ; Shapiro et al., 2006 ; Lindsay & Creswell, 2017 ) and affective models of exercise (Ekkekakis, 2003 ; Williams et al., 2008 ), the present study focused on four potential mindfulness-related processes that are particularly relevant in the exercise context: attention–awareness, decentering, nonreaction, and acceptance. These processes capture distinct yet complementary ways in which mindfulness may shape affective experience during and immediately following exercise. Attention–awareness, a foundational component of mindfulness, refers to sustained monitoring of present-moment internal and external experiences (Baer et al., 2006 ). In exercise contexts, attentional focus plays a critical role in shaping affective responses, as attending to bodily sensations versus disengaging from them can influence perceived exertion and pleasure (Gillman & Bryan, 2020 ). Prior research suggests that mindfulness training enhances awareness of bodily sensations, emotions, and thoughts, thereby strengthening top–down regulatory processes and emotional regulation (Chiesa et al., 2013 ; Ron-Grajales et al., 2021), and may reduce negative affect by improving internal attentional awareness (Wu et al., 2022). Accordingly, attention–awareness was hypothesized as a potential early-stage mechanism through which mindfulness may influence exercise-related affect. Acceptance reflects an open, nonjudgmental, and receptive stance toward ongoing experiences (Lindsay & Creswell, 2015 , 2017 ). By reducing experiential avoidance and altering individuals’ relationships with aversive internal states, acceptance enables continued engagement in goal-directed behavior despite discomfort, and is therefore conceptualized as a higher-order regulatory process supporting persistence in challenging activities and adaptive affective responses (Hayes et al., 2006 ; Lindsay & Creswell, 2017 ). This regulatory function may be particularly relevant in exercise contexts, where physical discomfort and effort-related sensations are inherent and unavoidable. Rather than attempting to suppress or evaluate these sensations, an accepting stance may allow individuals to remain engaged while experiencing exertion, thereby shaping affective responses as exercise unfolds (Hayes et al., 2006 ; Lindsay & Creswell, 2017 ; Bigliassi & Bertuzzi, 2020 ). Consistent with this view, prior research has linked mindfulness- and acceptance-related processes to both exercise adherence and affective experiences during physical activity (Ulmer et al., 2010 ). Importantly, acceptance is thought to develop gradually through repeated practice rather than emerging immediately, suggesting that it may operate as a later-emerging mechanism through which mindfulness during exercise influences affective responses over time. Decentering, also referred to as reperceiving, reflects the ability to adopt a distanced, observational perspective toward internal experiences (Shapiro et al., 2006 ; Bernstein et al., 2015 ). According to mindfulness-based coping models, mindfulness enhances cognitive flexibility and broadens awareness, allowing individuals to reinterpret bodily sensations and effort-related discomfort during exercise (Garland et al., 2019 ). In physically demanding contexts, decentering may reduce affective reactivity by weakening identification with discomfort-related thoughts and sensations. Thus, decentering was considered a hypothesized mechanism through which mindfulness may alter affective appraisals during exercise. Nonreaction refers to the tendency to refrain from automatic emotional or behavioral responses to internal experiences (Baer et al., 2006 ). In exercise settings, nonreaction may help interrupt habitual negative responses to exertion-related sensations, such as tension or breathlessness. Although prior work has not consistently demonstrated direct associations between nonjudgment and positive exercise-related affect (Liu et al., 2023 ), nonreaction may represent a more proximal and dynamically relevant process during exercise. Accordingly, nonreaction was included as an additional hypothesized mechanism. To better capture the present-centered nature of mindfulness and the immediate impact of momentary mindfulness-related processes on affective responses to exercise, the present study employed ecological momentary assessment (EMA) as its primary methodological approach to explore these hypothesized psychological mechanisms. EMA refers to the repeated, near real-time assessment of individuals’ experiences in their natural or semi-natural contexts, thereby reducing retrospective bias and enhancing ecological validity (Stone & Shiffman, 1994 ; Shiffman et al., 2008 ). In the present study, EMA was implemented in an event-contingent manner, with affective responses and mindfulness-related psychological processes assessed immediately following each exercise session across a 4-week intervention period. This design yielded repeated, session-specific observations nested within individuals, allowing for the examination of momentary fluctuations in psychological processes over the course of the intervention. The present study examined how mindfulness during exercise shapes affective responses by testing dynamic, momentary psychological mechanisms using an event-contingent EMA design embedded within a 4-week exercise intervention. We hypothesized that, at the within-person level, session-specific increases in attention–awareness, decentering, nonreaction, and acceptance would be associated with more positive immediate post-exercise affective responses, and that corresponding between-person differences in these processes would be associated with overall affective responses to exercise. We further hypothesized that these momentary process–affect associations would be stronger in the mindfulness condition than control conditions, reflecting a specific advantage of mindfulness-based exercise in shaping affective experience. Finally, exploratory lagged analyses were conducted to examine whether mindfulness-related processes exhibited carry-over effects across exercise sessions beyond concurrent associations. Method Participants Sample size determination Power estimation for linear mixed-effects models (LMMs), the primary analytic method employed in the present study, is complex and highly dependent on assumptions regarding fixed and random effects. Accordingly, a repeated-measures mixed factorial ANOVA was used to approximate the primary within–between interaction effects tested in the LMM, an approach commonly adopted in longitudinal research (Bolger & Laurenceau, 2013 ; Snijders & Bosker, 2012 ). In fully crossed designs, power estimates from repeated-measures ANOVA closely approximate those obtained from LMMs (Twisk, 2013 ). Power calculations were conducted using G*Power 3.1 (Faul et al., 2009 ), targeting the within–between interaction effect with α = .05 and 95% power. A medium effect size was assumed (Cohen’s f = .25), with three intervention conditions and eight repeated measurements, defined as post-exercise assessments collected across the planned exercise sessions during the 4-week intervention period. Under these assumptions, the required total sample size was estimated at approximately N = 30. To account for expected attrition and incomplete repeated measurements inherent in intensive longitudinal designs, a substantially larger sample than the minimum required was recruited, ensuring adequate power for the planned multilevel analyses. Recruitment and eligibility Participants were recruited via online advertisements posted on university-affiliated platforms and social media. Interested individuals completed an online screening survey that included the International Physical Activity Questionnaire (Craig et al., 2003). Consistent with guidelines from the World Health Organization and the American College of Sports Medicine, individuals were classified as having low physical activity levels if they reported engaging in less than 150 minutes of moderate-intensity physical activity per week or less than 75 minutes of vigorous-intensity physical activity per week. Only individuals meeting these criteria were eligible to participate. Participants were Asian college students recruited from a university population. Additional eligibility criteria included (a) current enrollment as a college student, (b) no self-reported history of psychiatric disorders, and (c) medical clearance for exercise as indicated by completion of the Physical Activity Readiness Questionnaire (PAR-Q; Shephard, 1988 ). Only individuals who met all eligibility criteria were enrolled in the study. Participants who completed the entire study protocol received monetary compensation of 80 RMB. Participants characteristics A total of 101 participants met the physical activity inclusion criteria and were enrolled in the study. Participants were randomly assigned to one of three intervention conditions. The intervention protocol required participants to attend two to three supervised exercise sessions per week over a four-week period, yielding a planned total of 8–12 sessions per participant. To ensure adequate exposure to the intervention, participants who completed fewer than eight exercise sessions were excluded from the final analyses. Based on this criterion, 10 participants were excluded due to insufficient session attendance, resulting in a final analytic sample of 91 participants. A flow diagram summarizing participant recruitment, eligibility screening, and inclusion in the final analyses is presented in Fig. 1 . ***Figure 1 *** Baseline demographic, physical, and psychological characteristics—including age, sex, education level, baseline physical activity, and baseline affective and psychological measures—did not differ significantly across intervention conditions (all p s > .12), indicating successful randomization and baseline equivalence among groups (Table 1 ). All participants provided written informed consent prior to participation, and the study protocol was approved by the institutional ethics committee. Table 1 Demographic and baseline psychological characteristics Variable Mindfulness ( n = 30) Distraction ( n = 31) Control ( n = 30) Test statistic p Age (years) 21.07 ± 1.95 20.61 ± 2.11 20.50 ± 2.33 F (2,88) = 0.73 0.485 Female, n (%) 25 (83.3%) 25 (80.6%) 27 (90.0%) χ² (2) = 0.94 0.626 Education level, n (%) χ² (2) = 0.84 0.657 Undergraduate 26 (86.7%) 27 (87.1%) 25 (83.3%) Graduate 4 (13.3%) 4 (12.9%) 4 (12.9%) HRR (bpm) 150.4 ± 7.6 149.1 ± 8.3 151.0 ± 7.9 F (2,88) = 0.41 0.665 Height (cm) 161.3 ± 6.2 162.7 ± 7.1 163.4 ± 6.8 F (2,88) = 0.62 0.539 Weight (kg) 54.7 ± 8.6 58.9 ± 11.4 60.1 ± 12.7 F (2,88) = 1.83 0.166 BMI (kg/m²) 20.61 ± 2.03 21.84 ± 4.96 22.43 ± 6.62 F (2,88) = 1.21 0.303 Exercise preference 2.34 ± 0.69 2.41 ± 0.74 2.29 ± 0.71 F (2,88) = 0.18 0.838 Exercise tolerance 3.62 ± 0.84 3.54 ± 0.88 3.67 ± 0.91 F (2,88) = 0.23 0.797 Trait mindfulness 3.70 ± 0.58 4.09 ± 0.65 3.74 ± 0.54 F (2,88) = 2.11 0.127 Exercise self-efficacy 2.06 ± 0.54 2.21 ± 0.59 2.14 ± 0.57 F (2,88) = 0.42 0.657 Rigorous PA (min/week) 3.67 ± 10.66 6.45 ± 16.44 5.00 ± 14.08 F (2, 88) = 0.30 0.739 Moderate PA (min/week) 53.3 ± 61.2 48.7 ± 55.8 51.0 ± 59.4 F (2,88) = 0.09 0.913 walking (min/week) 138.5 ± 166.7 142.1 ± 171.4 149.3 ± 180.2 F (2,88) = 0.03 0.973 Note. Values are mean ± SD unless otherwise indicated. Group differences were tested using one-way ANOVA for continuous variables and chi-square tests for categorical variables. HHR = heart rate reserve; 50%-65% HRR = ([HRmax − HRrest] × [55%–65%] + HRrest); BMI = body mass index; PA = physical activity. ***Table 1 *** Procedure After completion of baseline screening and eligibility assessment, participants were randomly assigned to one of three experimental conditions (mindfulness, distraction, control). Randomization was conducted at the individual level using a computer-generated random allocation sequence to ensure equal probability of assignment to each condition. Allocation was performed prior to the start of the intervention and was independent of participant characteristics. At the first exercise visit, prior to engaging in any exercise activities, participants provided written informed consent and completed baseline assessments, including a demographic questionnaire, measures of trait mindfulness, exercise intensity preference and tolerance, and exercise self-efficacy. Resting heart rate was also assessed at this time. Participants then completed their first supervised exercise session in accordance with their assigned experimental condition. Prior to each subsequent intervention week (with the exception of the first week), participants prepared an exercise schedule for the upcoming week. They attended the designated exercise location at their scheduled times and completed two to three supervised exercise sessions per week over the four-week intervention period, following the procedures specified for their assigned condition. Immediately following each exercise session, participants accessed an online survey via a QR code and completed momentary assessments of immediate post-exercise affective responses and mindfulness-related psychological processes. Exercise protocol The intervention phase lasted 4 weeks, during which participants completed 2–3 exercise sessions per week, with each session lasting 30 minutes (5 minutes of warm-up, 20 minutes of structured exercise, and 5 minutes of cool-down), consistent with prior exercise-based intervention protocols (Siqueira et al., 2016 ). All exercise sessions were conducted at the university fitness facility. Because all participants were classified as having low baseline physical activity levels, a progressive exercise intensity protocol was implemented across the intervention period to ensure safety and adherence. During Week 1, participants engaged in low-intensity walking; during Week 2, they performed moderate-intensity brisk walking; and during Weeks 3 and 4, they completed moderate-intensity running. Exercise intensity was prescribed using heart rate reserve (HRR), with low- and moderate-intensity exercise defined as 45%–55% and 55%–65% of HRR, respectively, in accordance with established exercise prescription guidelines (Garber et al., 2011 ). Intervention In the mindfulness condition, participants listened to guided mindfulness audio instructions throughout each exercise session. The audio, which matched the duration of the main exercise period (20 minutes), was designed to cultivate nonjudgmental attention to present-moment bodily sensations and experiential awareness during exercise and was delivered over neutral ambient instrumental background music. In the distraction condition, participants listened to a series of historical narratives delivered over the same type of neutral ambient instrumental background music, intended to direct attention away from bodily sensations and the exercise experience. Distraction was included as an active control condition because attentional diversion is a commonly used strategy in exercise contexts to enhance affective responses by shifting attention away from aversive bodily sensations (Brick et al., 2014 ; Hutchinson et al., 2015 ). However, such avoidance-oriented strategies have been increasingly questioned for their sustainability, as they may limit individuals’ capacity to tolerate exercise-related discomfort over time (Bigliassi & Bertuzzi, 2020 ). In contrast to mindfulness, which emphasizes present-centered attention to bodily sensations, the distraction condition redirected attention outward and away from the body through engagement with historical narratives, providing a theoretically meaningful attentional comparison. In the control condition, participants were instructed not to use any attentional guidance strategies during exercise. To minimize auditory fatigue, audio content in both the mindfulness and distraction conditions was changed weekly. Although the specific content varied across weeks, recordings were matched across conditions in structure, duration, and presentation format. Detailed descriptions of the intervention materials, including weekly themes and cueing strategies, are provided in Table 2 . Participants wore personal headphones during each exercise session, and condition-specific audio files were distributed one week in advance. Audio playback during exercise was monitored by research staff to ensure adherence to the assigned condition. Table 2 Weekly intervention materials with themes and cues Week Condition Mindfulness Distraction 1 Theme: Attentional grounding on breathing and basic bodily sensations Cue: “Notice the sensations of breathing wherever they are felt in the body (e.g., nose, chest, abdomen). Observe each breath as air moves in and out, gently bringing attention back to breathing when it wanders.” Theme: Tang dynasty emperors Cue: Narratives about the life of Emperor Taizong of the Tang dynasty (Li Shimin), focusing on major historical events and key episodes of his reign. 2 Theme: Expanding awareness to bodily sensations Cue: “Allow awareness to extend beyond the breath to sensations throughout the body, particularly the legs during movement. Notice these sensations without judgment or attachment, simply observing how they change.” Theme: Yuan dynasty emperors Cue: Narratives about the life of Emperor Hongwu (Zhu Yuanzhang), focusing on major historical events and key episodes of his rise and reign. 3 Theme: Acceptance and nonjudgment of bodily experience Cue: “Notice sensations of effort, fatigue, or discomfort as they arise. Observe them without reacting or trying to change them, allowing sensations to come and go naturally.” Theme: Yuan dynasty emperors Cue: Narratives about Genghis Khan focusing on major life events and the early expansion of the Mongol Empire. 4 Theme: Decentered and nonreactive awareness Cue: “Observe bodily sensations, thoughts, and emotions as passing events. Note their presence and gently return attention to the body or breathing without becoming attached or reactive.” Theme: Qing dynasty emperors Cue: Narratives about the Yongzheng Emperor focusing on the succession process and early consolidation of imperial authority. ***Table 2 *** Measures Physical activity Physical activity was assessed using the short form of the International Physical Activity Questionnaire (IPAQ-SF; Craig et al., 2003). Participants reported the frequency (days per week) and duration (minutes per day) of physical activities performed during the past seven days at walking, moderate and vigorous intensity levels. The IPAQ-SF has been adapted for use in Chinese populations, with evidence supporting its reliability and validity (Macfarlane et al., 2007 ). Trait mindfulness Trait mindfulness was assessed using the Mindful Attention Awareness Scale (MAAS; Brown & Ryan, 2003 ). The Chinese version of the MAAS was revised and validated by Chen et al. ( 2012 ) in a sample of Chinese college students. The scale consists of 15 items, rated on a 6-point Likert scale ranging from 1 ( almost always ) to 6 ( almost never ). In the present study, the MAAS demonstrated good internal consistency (Cronbach’s α = .81). Intensity preference and intensity tolerance Preference for and tolerance of exercise intensity were measured using the Preference for and Tolerance of the Intensity of Exercise Questionnaire (PRETIE-Q; Ekkekakis et al., 2005 ). The Chinese version of the PRETIE-Q was adapted and validated by Wang et al. ( 2023 ) in a sample of Chinese college students. The questionnaire comprises two subscales—intensity preference and intensity tolerance—each containing 8 items, for a total of 16 items. Responses are rated on a 5-point Likert scale ranging from 1 ( strongly agree ) to 5 ( strongly disagree ). In the present study, internal consistency was good for both subscales, with Cronbach’s α = .80 for intensity preference and α = .81 for intensity tolerance. Exercise self-efficacy Exercise self-efficacy was assessed using the Exercise Self-Efficacy Scale (ESES; McAuley, 1993 ), which measures individuals’ confidence in their ability to engage in and maintain regular exercise behavior under challenging conditions. Exercise self-efficacy reflects a core social–cognitive determinant of exercise behavior and affective responses during physical activity. The scale consists of 18 items describing common barriers to exercise participation (e.g., “How confident are you that you could continue exercising when you feel tired?”). Participants rate their confidence on a 5-point Likert scale ranging from 1 ( not at all confident ) to 5 ( extremely confident ). The Chinese version of the ESES has demonstrated good reliability and validity in samples of Chinese college students (Wang & Xu, 2002 ). In the present study, the scale showed good internal consistency (Cronbach’s α = .84). Immediate post-exercise affective response Immediate post-exercise affective response was assessed using the Feeling Scale (FS; Hardy & Rejeski, 1989 ), a widely used single-item measure of affective valence in exercise contexts. The FS captures individuals’ immediate affective response following physical activity and has demonstrated strong validity and sensitivity to changes in exercise-related affect. Immediately after each exercise session, participants responded to the item “How do you feel right now?” Responses were recorded on an 11-point bipolar scale ranging from − 5 (very bad) to + 5 (very good), with 0 indicating a neutral affective state. Momentary mindfulness-related processes Momentary mindfulness-related psychological processes were assessed immediately following each exercise session. Each construct was measured using one item, adapted from established theoretical definitions and prior empirical work. To enhance temporal specificity and ecological validity, all items were framed with the same introductory phrase: “During the 20 minutes of exercise just completed …”. Attention–awareness was assessed with one item (“… I focused my attention on what I was doing in the present moment”). Acceptance was measured with one item adapted from Ullrich-French et al. ( 2021 ) (“… I acknowledged my bodily sensations without trying to change them”). Decentering was assessed with one item reflecting the ability to observe thoughts and feelings from a detached perspective (“… I was able to observe my thoughts and feelings objectively, like watching a movie”; Bernstein et al., 2015 ). Nonreactivity was measured with one item adapted from Baer et al. ( 2006 ) (“… to what extent were you able to pause and not react to your thoughts or feelings?”). Data analysis The data consisted of repeated exercise sessions (Level 1) nested within individuals (Level 2). Immediate post-exercise affective responses and mindfulness-related psychological processes were assessed following each session over a 4-week intervention period. Given this hierarchical and unbalanced longitudinal structure, analyses were conducted using multilevel linear mixed-effects models, which are well suited for intensive longitudinal data and explicitly account for within-person dependency and between-person variability (Raudenbush & Bryk, 2002 ; Snijders & Bosker, 2012 ). Unconditional random-intercept models were first estimated to quantify between-person variance in affective responses using intraclass correlation coefficients (ICCs). Time (session order) and its interaction with intervention condition were then examined to characterize overall temporal patterns and to provide a baseline for subsequent mechanism-focused analyses. To distinguish dynamic within-person processes from stable individual differences, all time-varying psychological variables were decomposed using person-mean centering. Session-specific deviations from an individual’s mean represented within-person components, whereas person-level means represented between-person components. This approach follows established recommendations for separating within-person and between-person effects in multilevel models and avoids conflating processes operating at different levels of analysis (Enders & Tofighi, 2007 ; Curran & Bauer, 2011 ). Primary analyses examined concurrent associations between mindfulness-related psychological processes and immediate post-exercise affective responses. Separate multilevel models were estimated for each process, including fixed effects for within-person and between-person components and random intercepts for participants. Random slopes for within-person predictors were included when supported by variance estimates and model convergence, consistent with recommendations for confirmatory multilevel modeling (Barr et al., 2013 ). Moderation by intervention condition was tested using cross-level interactions between within-person process components and condition, while controlling for corresponding between-person effects. Significant interaction terms were interpreted as evidence that intervention condition altered the strength of momentary process–affect coupling, consistent with multilevel approaches to modeling context-dependent psychological processes (Bolger & Laurenceau, 2013 ). Exploratory lagged analyses examined whether prior-session levels of selected mindfulness-related processes predicted subsequent affective responses beyond concurrent associations. Lagged predictors were constructed at the within-person level and entered simultaneously with current-session predictors and between-person means. Given unequal spacing between exercise sessions and recommendations for cautious interpretation of temporal effects in longitudinal data, lagged associations were treated as exploratory (Hamaker et al., 2015 ). All models were estimated using restricted maximum likelihood in R with the lme4 package (Bates et al., 2015 ). Statistical inference for fixed effects was based on Satterthwaite’s approximation implemented in lmerTest (Kuznetsova et al., 2017 ). Statistical significance was evaluated at α = 0.05 (two-tailed). Results A total of 91 participants contributed 863 immediate post-exercise affective observations, with exercise sessions nested within individuals. Baseline affective responses and preliminary temporal effects Unconditional multilevel models indicated substantial variability in immediate post-exercise affective responses at both the between- and within-person levels. The random intercept variance was significant (τ₀₀ = 0.22), and the intraclass correlation coefficient (ICC = 0.30) indicated that approximately 30% of the variance in affective responses was attributable to stable between-person differences (Table 3 ). Next, intervention condition was entered as a fixed effect. Relative to the control condition, participants in the mindfulness condition reported significantly higher overall post-exercise affect (β = 0.28, p = 0.036), whereas the distraction condition did not differ significantly from control (β = −0.23, p = 0.085). Inclusion of intervention condition modestly improved model fit, increasing the marginal R 2 from 0 to 0.06. Table 3 Baseline multilevel linear mixed-effects models predicting post-exercise affect Model A Model B Model C Predictors Estimate [95% CI] Estimate [95% CI] Estimate [95% CI] Fixed effects (Intercept) 3.81 [3.69, 3.92] *** 3.79 [3.62, 3.97] *** 3.68 [3.42, 3.95] *** Group [Mindfulness] — 0.28 [0.02, 0.53] * 0.26 [–0.06, 0.58] Group [Distraction] — –0.23 [–0.48, 0.03] –0.17 [–0.50, 0.16] Time (session order) — — 0.02 [–0.01, 0.05] Mindfulness × Time — — 0.00 [–0.04, 0.11] Distraction × Time — — –0.01 [–0.04, 0.02] Random effects σ² (Residual) 0.51 0.50 0.50 τ₀₀ (Intercept, individual) 0.22 0.18 0.18 Model fit Marginal R² / Conditional R² 0.000 / 0.301 0.058 / 0.308 0.063 / 0.313 ICC 0.30 0.27 0.27 AIC 2009.46 2003.93 2025.45 BIC 2023.74 2027.73 2068.29 Note. Control group served as the reference category for intervention condition. * p < 0.05, ** p < 0.01, *** p < 0.001; significance codes are the same below. To examine changes in affective responses across the intervention period, time (session order) was added as a fixed effect along with its interaction with intervention condition. The main effect of time was small and not statistically significant (β = 0.02, p = 0.15), indicating no reliable linear change in post-exercise affect across sessions. Moreover, the time × condition interactions were non-significant for both the mindfulness (β = 0.00, p = 0.84) and distraction (β = −0.01, p = 0.55) conditions, suggesting that trajectories of post-exercise affect did not differ across intervention groups. ***Table 3 *** Mindfulness-related processes and post-exercise affective response Multilevel models examined concurrent within-person (WP) associations between mindfulness-related processes and immediate post-exercise affect, as well as moderation by intervention condition. All predictors were decomposed into WP and between-person (BP) components. Acceptance Session-specific increases in acceptance were associated with more positive post-exercise affect at the within-person level (β = 0.11, p = 0.035). A significant between-person effect was also observed, with higher average acceptance predicting higher overall affect (β = 0.59, p < 0.001). Moderation analyses indicated that the WP acceptance–affect association did not differ by intervention condition (mindfulness vs. control: β = 0.07, p = 0.61; distraction vs. control: β = 0.12, p = 0.36; Table 4 ). Table 4 Mindfulness-related processes and post-exercise affective response Predictor Acceptance Nonreaction Attention–Awareness Decentering Fixed effects Intercept 1.51 (0.36) *** 1.98 (0.29) *** 2.21 (0.22) *** 2.46 (0.25) *** Within-person (WP) 0.11 (0.05) * 0.13 (0.05) ** 0.31 (0.04) *** 0.20 (0.04) *** Between-person (BP) 0.59 (0.09) *** 0.55 (0.09) *** 0.47 (0.06) *** 0.39 (0.07) *** Moderation by condition WP × Distraction 0.12 (0.13) 0.25 (0.10) * 0.20 (0.10) * −0.07 (0.10) WP × Mindfulness 0.07 (0.14) 0.32 (0.11) ** 0.12 (0.10) −0.22 (0.10) * Random effects (variance) Intercept 0.13 0.13 0.12 0.15 WP slope 0.06 0.04 0.05 0.03 Residual 0.48 0.48 0.43 0.47 Note. Values are unstandardized coefficients with standard errors in parentheses. WP predictors represent person-mean centered session-level deviations; BP predictors represent person-level means. Intervention condition was dummy coded with the control group as the reference category. Nonreaction Within-person increases in nonreaction were positively associated with post-exercise affect (β = 0.13, p = 0.008), alongside a robust between-person effect (β = 0.55, p < 0.001). Importantly, the within-person nonreaction–affect association was moderated by intervention condition. Compared with the control group, both the distraction condition (β = 0.25, p = 0.018) and the mindfulness condition (β = 0.32, p = 0.003) showed significantly stronger coupling between nonreaction and post-exercise affect (Table 4 ). Attention–awareness Attention–awareness showed the strongest WP association with post-exercise affect (β = 0.31, p < 0.001), with a significant between-person effect (β = 0.47, p < 0.001). Moderation analyses revealed that the WP attention–awareness–affect association was stronger in the distraction condition than in control (β = 0.20, p = 0.050), whereas the corresponding interaction in the mindfulness condition was not significant (β = 0.12, p = 0.23; Table 4 ). Decentering Within-person increases in decentering were associated with more positive post-exercise affect (β = 0.20, p < 0.001), and higher average decentering predicted higher overall affect (β = 0.39, p < 0.001). Moderation analyses revealed that, relative to control, the mindfulness condition showed a weaker WP decentering–affect association (β = −0.22, p = 0.023), whereas the distraction condition did not differ significantly (β = −0.07, p = 0.50; Table 4 ). ***Table 4 *** Exploratory lagged effects of mindfulness-related processes Exploratory lagged multilevel models examined whether acceptance and nonreaction showed carry-over effects across exercise sessions. Lagged analyses were limited to acceptance and nonreaction, given their robust concurrent associations with post-exercise affect in the primary models. Each model included the concurrent WP effect, the lagged WP effect from the immediately preceding session (lag = 1), and the corresponding BP mean. For acceptance, the concurrent WP effect remained significant (β = 0.13, SE = 0.05, p = 0.007), whereas the lagged WP effect was small and non-significant (β = 0.04, SE = 0.05, p = 0.37; Table 5 ). This pattern indicates that session-specific increases in acceptance were associated with more positive immediate post-exercise affect, but acceptance experienced during the prior session did not predict affect at the subsequent session beyond the concurrent effect. Table 5 Exploratory lagged within-person effects of mindfulness-related processes on post-exercise affect Predictor Acceptance Nonreaction Fixed effects Intercept 1.51 (0.38) ** 1.95 (0.30) *** Within-person (WP) 0.13 (0.05) ** 0.11 (0.04) ** WP (lagged, session − 1) 0.04 (0.05) −0.03 (0.04) Between-person (BP) 0.59 (0.10) *** 0.56 (0.09) *** Random effects (variance) Intercept 0.14 0.14 Residual 0.50 0.50 A similar pattern emerged for nonreaction. The concurrent WP association with post-exercise affect was significant (β = 0.11, SE = 0.04, p = 0.007), while the lagged WP effect was not (β = −0.03, SE = 0.04, p = 0.54; Table 5 ). Thus, nonreaction was linked to affective responses primarily at the momentary level rather than through sustained effects across sessions. ***Table 5 *** Discussion The present study examined how mindfulness during exercise shapes affective experience by focusing on dynamic, momentary psychological mechanisms across a 4-week intervention. Using an EMA-informed multilevel modeling approach, we investigated concurrent within-person associations between mindfulness-related processes and immediate post-exercise affect, as well as whether these associations were moderated by intervention condition. Several key findings emerged from the present study. Momentary fluctuations in mindfulness-related processes—including acceptance, nonreaction, attention–awareness, and decentering—were consistently associated with immediate post-exercise affect at the within-person level, indicating that how individuals related to their internal experience during a given exercise session played a more critical role than stable individual differences alone. This pattern aligns with process-based accounts of mindfulness, which emphasize present-centered experiential engagement as a primary pathway through which mindfulness influences affective outcomes (Baer et al., 2006 ; Shapiro et al., 2006 ). Building on these findings, moderation analyses suggested that mindfulness-based exercise selectively shaped the momentary mechanisms linking experience to affect. Although acceptance, attention–awareness, nonreaction, and decentering were all positively associated with immediate post-exercise affect at the within-person level, only nonreaction showed a reliably stronger process–affect coupling in the mindfulness condition relative to control. This pattern highlights nonreactivity as a particularly salient mechanism through which mindfulness alters affective experience during exercise, consistent with theoretical accounts emphasizing reduced automatic reactivity to bodily sensations and internal events as a core function of mindfulness (Baer et al., 2006 ; Garland et al., 2019 ). In contrast, acceptance and attention–awareness appeared to confer affective benefits across conditions, suggesting that these processes may reflect general experiential qualities supportive of positive exercise-related affect rather than mechanisms uniquely enhanced by mindfulness training. Decentering exhibited a weaker association with affect in the mindfulness condition, potentially indicating a shift toward a more integrated, less explicitly metacognitive mode of engagement as mindfulness practice unfolds (Bernstein et al., 2015 ; Shapiro et al., 2006 ). Taken together, these findings partially supported our hypotheses by confirming that momentary mindfulness-related processes are linked to affective responses during exercise, while providing more selective support for the prediction that mindfulness-based exercise uniquely strengthens specific mechanisms, particularly nonreactivity. Exploratory lagged analyses indicated that mindfulness-related processes did not predict affective responses across exercise sessions beyond their concurrent, momentary effects. For both acceptance and nonreaction, prior-session levels were not associated with immediate post-exercise affect once session-specific states were taken into account. This pattern is consistent with conceptualizations of mindfulness as a present-centered mode of engagement, in which affective consequences arise from how individuals relate to their internal experience in the moment rather than from sustained carry-over across time (Baer et al., 2006 ; Shapiro et al., 2006 ). Given the variability of bodily sensations and contextual demands inherent in exercise, these findings underscore that mindfulness-related mechanisms primarily operate through immediate experiential processes during each exercise bout. Several limitations should be acknowledged. First, although the EMA-informed design allowed for the examination of momentary psychological processes across repeated exercise sessions, the proposed mechanisms were theoretically inferred rather than experimentally manipulated. As such, causal conclusions regarding specific mechanisms should be drawn cautiously. Second, mindfulness-related processes were assessed using brief items to minimize participant burden, which may have limited the precision with which these constructs were captured at each session. Third, the intervention period spanned four weeks and included a relatively homogeneous sample of physically inactive college students, which may constrain the generalizability of the findings to other populations or longer-term training contexts. Finally, although exploratory lagged analyses were informative, the unequal spacing between exercise sessions limits strong inferences about temporal ordering across sessions. Future research would benefit from designs that experimentally manipulate candidate mechanisms or employ higher-frequency assessments to further delineate the temporal dynamics of mindfulness during exercise. In summary, the present study provides evidence that mindfulness shapes affective experience during exercise through dynamic, momentary psychological processes rather than through sustained carry-over effects across sessions. Using an EMA-informed multilevel approach, we demonstrated that session-specific fluctuations in mindfulness-related mechanisms were closely linked to immediate post-exercise affect, with mindfulness-based exercise selectively strengthening nonreactive engagement with internal experience. These findings advance understanding of how mindfulness operates in exercise contexts by highlighting the central role of present-moment processes and underscore the importance of adopting dynamic, within-person perspectives when investigating affective mechanisms of behavioral interventions. Declarations Author Contribution J.L. conceptualized the study, developed the methodology, conducted the formal analyses, curated the data, and wrote the original draft of the manuscript. W.-J.L. contributed to conceptualization and methodology, developed the software, performed validation, curated the data, and reviewed and edited the manuscript. Y.Q. contributed to methodology, data curation, validation, and reviewed and edited the manuscript. H.-M.J. contributed to conceptualization, methodology, formal analysis, data curation, supervised the project, managed project administration and resources, and reviewed and edited the manuscript. All authors reviewed and approved the final manuscript. Data Availability The data that support the findings of this study are publicly available on the Open Science Framework (OSF) at: https://osf.io/sy92k/overview?view_only=c3bb6eab4ae94641add2c7d3b0eb1d50 References Baer, R. A., Smith, G. T., Hopkins, J., Krietemeyer, J., & Toney, L. (2006). Using self-report assessment methods to explore facets of mindfulness. Assessment, 13 (1), 27–45. https://doi.org/10.1177/1073191105283504 Baer, R. A., Smith, G. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8431406","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":600616737,"identity":"e1033588-8845-48d8-96e9-40decf767461","order_by":0,"name":"Jiao Liu","email":"","orcid":"","institution":"Beijing Institute of Education","correspondingAuthor":false,"prefix":"","firstName":"Jiao","middleName":"","lastName":"Liu","suffix":""},{"id":600616739,"identity":"c58f4c78-eee1-4b34-bb73-ada5867e7e62","order_by":1,"name":"Wen-Jing Liu","email":"","orcid":"","institution":"Beijing Sport University","correspondingAuthor":false,"prefix":"","firstName":"Wen-Jing","middleName":"","lastName":"Liu","suffix":""},{"id":600616740,"identity":"8f5bf2cc-d59e-4abd-8535-0be4b93a3ed1","order_by":2,"name":"Yue Qiu","email":"","orcid":"","institution":"Xihua University","correspondingAuthor":false,"prefix":"","firstName":"Yue","middleName":"","lastName":"Qiu","suffix":""},{"id":600616741,"identity":"0c887894-bbac-4734-ac03-a3361f4dae52","order_by":3,"name":"Hong-Mei Jiang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYBACxmYQ0QDhHPxgUCPHxt5+gHgthyUKjhnz8ZxJIMIqqBYGng/MifMkHAzwqmZuZ3728OsOmzz5sMMHD0gYsKW3STAkMPyo2IbHYWzmxrJn0ooNb6clHCgwkMltk248wNhz5jY+v5hJS7YdTtw4O8cAZEtum8yBBGbGNnxa2L9BteR/OMBjwJzOJpFgQEALj5nkR6CW+dI5DCAtCcRoKZNmbEtL3CCdZnBYwuCYYRswkA/i84th//Ftkj/bbBLnz05+/PHDnxp5+fb2gw9+VODR0gAMaB4gw+AAkugBrGqhQB7kuB8gRgM+ZaNgFIyCUTCiAQD6WFsUf++TpgAAAABJRU5ErkJggg==","orcid":"","institution":"Beijing Union University","correspondingAuthor":true,"prefix":"","firstName":"Hong-Mei","middleName":"","lastName":"Jiang","suffix":""}],"badges":[],"createdAt":"2025-12-23 07:38:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8431406/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8431406/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103979893,"identity":"51da687f-4674-4aaf-888d-1e939c31d096","added_by":"auto","created_at":"2026-03-05 09:22:04","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":68594,"visible":true,"origin":"","legend":"\u003cp\u003eFlow of participants through recruitment, randomization, and analysis.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8431406/v1/6f4dbbad96c6289a252fe95d.png"},{"id":104402554,"identity":"628617bd-595a-4901-b500-f913d54b9d28","added_by":"auto","created_at":"2026-03-11 12:15:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1139025,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8431406/v1/92745c14-bdfc-48fb-8001-b8ca6661da20.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMindfulness has emerged as a promising strategy for enhancing affective responses to exercise and supporting engagement in physical activity. Accumulating evidence indicates that integrating mindfulness into exercise produces small-to-moderate improvements in affective responses associated with exercise (Liu et al., \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2026\u003c/span\u003e). Despite these promising findings, our understanding of why mindfulness enhances exercise-related affect remains limited, with little direct evidence clarifying the underlying psychological pathways.\u003c/p\u003e \u003cp\u003eMindfulness is commonly defined as the capacity to attend to present-moment experience with an attitude of openness, curiosity, and nonjudgment (Kabat-Zinn, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Mindfulness during exercise has been conceptualized as a mode of experiential engagement in which individuals intentionally attend to bodily sensations, movements, and internal states as they unfold during physical activity, rather than evaluating, avoiding, or disengaging from these experiences (Bigliassi \u0026amp; Bertuzzi, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Cox \u0026amp; Ullrich-French, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). From this perspective, mindfulness may alter how exercise is perceived and emotionally appraised, thereby shaping affective responses associated with physical activity.\u003c/p\u003e \u003cp\u003eExercise represents a unique affective context in which individuals are repeatedly exposed to salient bodily sensations, fluctuations in physiological arousal, and effort-related discomfort. Affective responses to exercise are therefore shaped not only by physical workload but also by how internal experiences are attended to, interpreted, and regulated in the moment (Ekkekakis et al., 2003; Ekkekakis et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). From this perspective, mindfulness may influence exercise-related affect by altering individuals\u0026rsquo; momentary engagement with bodily and psychological experiences during physical activity. Drawing on contemporary models of mindfulness (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Shapiro et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Lindsay \u0026amp; Creswell, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) and affective models of exercise (Ekkekakis, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Williams et al., \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), the present study focused on four potential mindfulness-related processes that are particularly relevant in the exercise context: attention\u0026ndash;awareness, decentering, nonreaction, and acceptance. These processes capture distinct yet complementary ways in which mindfulness may shape affective experience during and immediately following exercise.\u003c/p\u003e \u003cp\u003eAttention\u0026ndash;awareness, a foundational component of mindfulness, refers to sustained monitoring of present-moment internal and external experiences (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). In exercise contexts, attentional focus plays a critical role in shaping affective responses, as attending to bodily sensations versus disengaging from them can influence perceived exertion and pleasure (Gillman \u0026amp; Bryan, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Prior research suggests that mindfulness training enhances awareness of bodily sensations, emotions, and thoughts, thereby strengthening top\u0026ndash;down regulatory processes and emotional regulation (Chiesa et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Ron-Grajales et al., 2021), and may reduce negative affect by improving internal attentional awareness (Wu et al., 2022). Accordingly, attention\u0026ndash;awareness was hypothesized as a potential early-stage mechanism through which mindfulness may influence exercise-related affect.\u003c/p\u003e \u003cp\u003eAcceptance reflects an open, nonjudgmental, and receptive stance toward ongoing experiences (Lindsay \u0026amp; Creswell, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). By reducing experiential avoidance and altering individuals\u0026rsquo; relationships with aversive internal states, acceptance enables continued engagement in goal-directed behavior despite discomfort, and is therefore conceptualized as a higher-order regulatory process supporting persistence in challenging activities and adaptive affective responses (Hayes et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Lindsay \u0026amp; Creswell, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This regulatory function may be particularly relevant in exercise contexts, where physical discomfort and effort-related sensations are inherent and unavoidable. Rather than attempting to suppress or evaluate these sensations, an accepting stance may allow individuals to remain engaged while experiencing exertion, thereby shaping affective responses as exercise unfolds (Hayes et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Lindsay \u0026amp; Creswell, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Bigliassi \u0026amp; Bertuzzi, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Consistent with this view, prior research has linked mindfulness- and acceptance-related processes to both exercise adherence and affective experiences during physical activity (Ulmer et al., \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). Importantly, acceptance is thought to develop gradually through repeated practice rather than emerging immediately, suggesting that it may operate as a later-emerging mechanism through which mindfulness during exercise influences affective responses over time.\u003c/p\u003e \u003cp\u003eDecentering, also referred to as reperceiving, reflects the ability to adopt a distanced, observational perspective toward internal experiences (Shapiro et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Bernstein et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). According to mindfulness-based coping models, mindfulness enhances cognitive flexibility and broadens awareness, allowing individuals to reinterpret bodily sensations and effort-related discomfort during exercise (Garland et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). In physically demanding contexts, decentering may reduce affective reactivity by weakening identification with discomfort-related thoughts and sensations. Thus, decentering was considered a hypothesized mechanism through which mindfulness may alter affective appraisals during exercise.\u003c/p\u003e \u003cp\u003eNonreaction refers to the tendency to refrain from automatic emotional or behavioral responses to internal experiences (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). In exercise settings, nonreaction may help interrupt habitual negative responses to exertion-related sensations, such as tension or breathlessness. Although prior work has not consistently demonstrated direct associations between nonjudgment and positive exercise-related affect (Liu et al., \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), nonreaction may represent a more proximal and dynamically relevant process during exercise. Accordingly, nonreaction was included as an additional hypothesized mechanism.\u003c/p\u003e \u003cp\u003eTo better capture the present-centered nature of mindfulness and the immediate impact of momentary mindfulness-related processes on affective responses to exercise, the present study employed ecological momentary assessment (EMA) as its primary methodological approach to explore these hypothesized psychological mechanisms. EMA refers to the repeated, near real-time assessment of individuals\u0026rsquo; experiences in their natural or semi-natural contexts, thereby reducing retrospective bias and enhancing ecological validity (Stone \u0026amp; Shiffman, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Shiffman et al., \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). In the present study, EMA was implemented in an event-contingent manner, with affective responses and mindfulness-related psychological processes assessed immediately following each exercise session across a 4-week intervention period. This design yielded repeated, session-specific observations nested within individuals, allowing for the examination of momentary fluctuations in psychological processes over the course of the intervention.\u003c/p\u003e \u003cp\u003eThe present study examined how mindfulness during exercise shapes affective responses by testing dynamic, momentary psychological mechanisms using an event-contingent EMA design embedded within a 4-week exercise intervention. We hypothesized that, at the within-person level, session-specific increases in attention\u0026ndash;awareness, decentering, nonreaction, and acceptance would be associated with more positive immediate post-exercise affective responses, and that corresponding between-person differences in these processes would be associated with overall affective responses to exercise. We further hypothesized that these momentary process\u0026ndash;affect associations would be stronger in the mindfulness condition than control conditions, reflecting a specific advantage of mindfulness-based exercise in shaping affective experience. Finally, exploratory lagged analyses were conducted to examine whether mindfulness-related processes exhibited carry-over effects across exercise sessions beyond concurrent associations.\u003c/p\u003e"},{"header":"Method","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cdiv id=\"Sec4\" class=\"Section3\"\u003e \u003ch2\u003eSample size determination\u003c/h2\u003e \u003cp\u003ePower estimation for linear mixed-effects models (LMMs), the primary analytic method employed in the present study, is complex and highly dependent on assumptions regarding fixed and random effects. Accordingly, a repeated-measures mixed factorial ANOVA was used to approximate the primary within\u0026ndash;between interaction effects tested in the LMM, an approach commonly adopted in longitudinal research (Bolger \u0026amp; Laurenceau, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Snijders \u0026amp; Bosker, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). In fully crossed designs, power estimates from repeated-measures ANOVA closely approximate those obtained from LMMs (Twisk, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Power calculations were conducted using G*Power 3.1 (Faul et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), targeting the within\u0026ndash;between interaction effect with α\u0026thinsp;=\u0026thinsp;.05 and 95% power. A medium effect size was assumed (Cohen\u0026rsquo;s \u003cem\u003ef\u003c/em\u003e\u0026thinsp;=\u0026thinsp;.25), with three intervention conditions and eight repeated measurements, defined as post-exercise assessments collected across the planned exercise sessions during the 4-week intervention period. Under these assumptions, the required total sample size was estimated at approximately \u003cem\u003eN\u003c/em\u003e\u0026thinsp;=\u0026thinsp;30. To account for expected attrition and incomplete repeated measurements inherent in intensive longitudinal designs, a substantially larger sample than the minimum required was recruited, ensuring adequate power for the planned multilevel analyses.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e\n\u003ch3\u003eRecruitment and eligibility\u003c/h3\u003e\n\u003cp\u003eParticipants were recruited via online advertisements posted on university-affiliated platforms and social media. Interested individuals completed an online screening survey that included the International Physical Activity Questionnaire (Craig et al., 2003). Consistent with guidelines from the World Health Organization and the American College of Sports Medicine, individuals were classified as having low physical activity levels if they reported engaging in less than 150 minutes of moderate-intensity physical activity per week or less than 75 minutes of vigorous-intensity physical activity per week. Only individuals meeting these criteria were eligible to participate.\u003c/p\u003e \u003cp\u003eParticipants were Asian college students recruited from a university population. Additional eligibility criteria included (a) current enrollment as a college student, (b) no self-reported history of psychiatric disorders, and (c) medical clearance for exercise as indicated by completion of the Physical Activity Readiness Questionnaire (PAR-Q; Shephard, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e1988\u003c/span\u003e). Only individuals who met all eligibility criteria were enrolled in the study. Participants who completed the entire study protocol received monetary compensation of 80 RMB.\u003c/p\u003e\n\u003ch3\u003eParticipants characteristics\u003c/h3\u003e\n\u003cp\u003eA total of 101 participants met the physical activity inclusion criteria and were enrolled in the study. Participants were randomly assigned to one of three intervention conditions. The intervention protocol required participants to attend two to three supervised exercise sessions per week over a four-week period, yielding a planned total of 8\u0026ndash;12 sessions per participant. To ensure adequate exposure to the intervention, participants who completed fewer than eight exercise sessions were excluded from the final analyses. Based on this criterion, 10 participants were excluded due to insufficient session attendance, resulting in a final analytic sample of 91 participants. A flow diagram summarizing participant recruitment, eligibility screening, and inclusion in the final analyses is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e***Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e***\u003c/p\u003e \u003cp\u003eBaseline demographic, physical, and psychological characteristics\u0026mdash;including age, sex, education level, baseline physical activity, and baseline affective and psychological measures\u0026mdash;did not differ significantly across intervention conditions (all \u003cem\u003ep\u003c/em\u003es\u0026thinsp;\u0026gt;\u0026thinsp;.12), indicating successful randomization and baseline equivalence among groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). All participants provided written informed consent prior to participation, and the study protocol was approved by the institutional ethics committee.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and baseline psychological characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMindfulness\u003c/p\u003e \u003cp\u003e(\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDistraction\u003c/p\u003e \u003cp\u003e(\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;31)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003cp\u003e(\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;30)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTest statistic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.07\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.61\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.50\u0026thinsp;\u0026plusmn;\u0026thinsp;2.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.485\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25 (83.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 (80.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27 (90.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eχ\u0026sup2;\u003csub\u003e(2)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.626\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEducation level, \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eχ\u0026sup2;\u003csub\u003e(2)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.657\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUndergraduate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26 (86.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27 (87.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 (83.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGraduate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (13.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (12.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (12.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHRR (bpm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e150.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e149.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e151.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.665\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e161.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e162.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e163.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.539\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54.7\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.166\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u0026sup2;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.61\u0026thinsp;\u0026plusmn;\u0026thinsp;2.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.84\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.43\u0026thinsp;\u0026plusmn;\u0026thinsp;6.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.303\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExercise preference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.838\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExercise tolerance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.797\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrait mindfulness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.127\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eExercise self-efficacy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.657\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRigorous PA (min/week)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.67\u0026thinsp;\u0026plusmn;\u0026thinsp;10.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.45\u0026thinsp;\u0026plusmn;\u0026thinsp;16.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.00\u0026thinsp;\u0026plusmn;\u0026thinsp;14.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2, 88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.739\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerate PA (min/week)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.3\u0026thinsp;\u0026plusmn;\u0026thinsp;61.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48.7\u0026thinsp;\u0026plusmn;\u0026thinsp;55.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51.0\u0026thinsp;\u0026plusmn;\u0026thinsp;59.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.913\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ewalking (min/week)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e138.5\u0026thinsp;\u0026plusmn;\u0026thinsp;166.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e142.1\u0026thinsp;\u0026plusmn;\u0026thinsp;171.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e149.3\u0026thinsp;\u0026plusmn;\u0026thinsp;180.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e\u003csub\u003e(2,88)\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.973\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003cb\u003eNote.\u003c/b\u003e Values are mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD unless otherwise indicated. Group differences were tested using one-way ANOVA for continuous variables and chi-square tests for categorical variables. HHR\u0026thinsp;=\u0026thinsp;heart rate reserve; 50%-65% HRR = ([HRmax\u0026thinsp;\u0026minus;\u0026thinsp;HRrest] \u0026times; [55%\u0026ndash;65%]\u0026thinsp;+\u0026thinsp;HRrest); BMI\u0026thinsp;=\u0026thinsp;body mass index; PA\u0026thinsp;=\u0026thinsp;physical activity.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e***Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e***\u003c/p\u003e\n\u003ch3\u003eProcedure\u003c/h3\u003e\n\u003cp\u003eAfter completion of baseline screening and eligibility assessment, participants were randomly assigned to one of three experimental conditions (mindfulness, distraction, control). Randomization was conducted at the individual level using a computer-generated random allocation sequence to ensure equal probability of assignment to each condition. Allocation was performed prior to the start of the intervention and was independent of participant characteristics.\u003c/p\u003e \u003cp\u003eAt the first exercise visit, prior to engaging in any exercise activities, participants provided written informed consent and completed baseline assessments, including a demographic questionnaire, measures of trait mindfulness, exercise intensity preference and tolerance, and exercise self-efficacy. Resting heart rate was also assessed at this time. Participants then completed their first supervised exercise session in accordance with their assigned experimental condition. Prior to each subsequent intervention week (with the exception of the first week), participants prepared an exercise schedule for the upcoming week. They attended the designated exercise location at their scheduled times and completed two to three supervised exercise sessions per week over the four-week intervention period, following the procedures specified for their assigned condition. Immediately following each exercise session, participants accessed an online survey via a QR code and completed momentary assessments of immediate post-exercise affective responses and mindfulness-related psychological processes.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eExercise protocol\u003c/h2\u003e \u003cp\u003eThe intervention phase lasted 4 weeks, during which participants completed 2\u0026ndash;3 exercise sessions per week, with each session lasting 30 minutes (5 minutes of warm-up, 20 minutes of structured exercise, and 5 minutes of cool-down), consistent with prior exercise-based intervention protocols (Siqueira et al., \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). All exercise sessions were conducted at the university fitness facility.\u003c/p\u003e \u003cp\u003eBecause all participants were classified as having low baseline physical activity levels, a progressive exercise intensity protocol was implemented across the intervention period to ensure safety and adherence. During Week 1, participants engaged in low-intensity walking; during Week 2, they performed moderate-intensity brisk walking; and during Weeks 3 and 4, they completed moderate-intensity running. Exercise intensity was prescribed using heart rate reserve (HRR), with low- and moderate-intensity exercise defined as 45%\u0026ndash;55% and 55%\u0026ndash;65% of HRR, respectively, in accordance with established exercise prescription guidelines (Garber et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eIntervention\u003c/h3\u003e\n\u003cp\u003e In the mindfulness condition, participants listened to guided mindfulness audio instructions throughout each exercise session. The audio, which matched the duration of the main exercise period (20 minutes), was designed to cultivate nonjudgmental attention to present-moment bodily sensations and experiential awareness during exercise and was delivered over neutral ambient instrumental background music.\u003c/p\u003e \u003cp\u003e In the distraction condition, participants listened to a series of historical narratives delivered over the same type of neutral ambient instrumental background music, intended to direct attention away from bodily sensations and the exercise experience. Distraction was included as an active control condition because attentional diversion is a commonly used strategy in exercise contexts to enhance affective responses by shifting attention away from aversive bodily sensations (Brick et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Hutchinson et al., \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). However, such avoidance-oriented strategies have been increasingly questioned for their sustainability, as they may limit individuals\u0026rsquo; capacity to tolerate exercise-related discomfort over time (Bigliassi \u0026amp; Bertuzzi, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). In contrast to mindfulness, which emphasizes present-centered attention to bodily sensations, the distraction condition redirected attention outward and away from the body through engagement with historical narratives, providing a theoretically meaningful attentional comparison.\u003c/p\u003e \u003cp\u003eIn the control condition, participants were instructed not to use any attentional guidance strategies during exercise. To minimize auditory fatigue, audio content in both the mindfulness and distraction conditions was changed weekly. Although the specific content varied across weeks, recordings were matched across conditions in structure, duration, and presentation format. Detailed descriptions of the intervention materials, including weekly themes and cueing strategies, are provided in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Participants wore personal headphones during each exercise session, and condition-specific audio files were distributed one week in advance. Audio playback during exercise was monitored by research staff to ensure adherence to the assigned condition.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eWeekly intervention materials with themes and cues\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eWeek\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eCondition\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMindfulness\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDistraction\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTheme: Attentional grounding on breathing and basic bodily sensations\u003c/p\u003e \u003cp\u003eCue: \u0026ldquo;Notice the sensations of breathing wherever they are felt in the body (e.g., nose, chest, abdomen). Observe each breath as air moves in and out, gently bringing attention back to breathing when it wanders.\u0026rdquo;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTheme: Tang dynasty emperors\u003c/p\u003e \u003cp\u003eCue: Narratives about the life of Emperor Taizong of the Tang dynasty (Li Shimin), focusing on major historical events and key episodes of his reign.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTheme: Expanding awareness to bodily sensations\u003c/p\u003e \u003cp\u003eCue: \u0026ldquo;Allow awareness to extend beyond the breath to sensations throughout the body, particularly the legs during movement. Notice these sensations without judgment or attachment, simply observing how they change.\u0026rdquo;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTheme: Yuan dynasty emperors\u003c/p\u003e \u003cp\u003eCue: Narratives about the life of Emperor Hongwu (Zhu Yuanzhang), focusing on major historical events and key episodes of his rise and reign.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTheme: Acceptance and nonjudgment of bodily experience\u003c/p\u003e \u003cp\u003eCue: \u0026ldquo;Notice sensations of effort, fatigue, or discomfort as they arise. Observe them without reacting or trying to change them, allowing sensations to come and go naturally.\u0026rdquo;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTheme: Yuan dynasty emperors\u003c/p\u003e \u003cp\u003eCue: Narratives about Genghis Khan focusing on major life events and the early expansion of the Mongol Empire.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTheme: Decentered and nonreactive awareness\u003c/p\u003e \u003cp\u003eCue: \u0026ldquo;Observe bodily sensations, thoughts, and emotions as passing events. Note their presence and gently return attention to the body or breathing without becoming attached or reactive.\u0026rdquo;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTheme: Qing dynasty emperors\u003c/p\u003e \u003cp\u003eCue: Narratives about the Yongzheng Emperor focusing on the succession process and early consolidation of imperial authority.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e***Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e***\u003c/p\u003e\n\u003ch3\u003eMeasures\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePhysical activity\u003c/h2\u003e \u003cp\u003ePhysical activity was assessed using the short form of the \u003cem\u003eInternational Physical Activity Questionnaire\u003c/em\u003e (IPAQ-SF; Craig et al., 2003). Participants reported the frequency (days per week) and duration (minutes per day) of physical activities performed during the past seven days at walking, moderate and vigorous intensity levels. The IPAQ-SF has been adapted for use in Chinese populations, with evidence supporting its reliability and validity (Macfarlane et al., \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eTrait mindfulness\u003c/h2\u003e \u003cp\u003eTrait mindfulness was assessed using the \u003cem\u003eMindful Attention Awareness Scale\u003c/em\u003e (MAAS; Brown \u0026amp; Ryan, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). The Chinese version of the MAAS was revised and validated by Chen et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) in a sample of Chinese college students. The scale consists of 15 items, rated on a 6-point Likert scale ranging from 1 (\u003cem\u003ealmost always\u003c/em\u003e) to 6 (\u003cem\u003ealmost never\u003c/em\u003e). In the present study, the MAAS demonstrated good internal consistency (Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.81).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eIntensity preference and intensity tolerance\u003c/h2\u003e \u003cp\u003ePreference for and tolerance of exercise intensity were measured using the \u003cem\u003ePreference for and Tolerance of the Intensity of Exercise Questionnaire\u003c/em\u003e (PRETIE-Q; Ekkekakis et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). The Chinese version of the PRETIE-Q was adapted and validated by Wang et al. (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) in a sample of Chinese college students. The questionnaire comprises two subscales\u0026mdash;intensity preference and intensity tolerance\u0026mdash;each containing 8 items, for a total of 16 items. Responses are rated on a 5-point Likert scale ranging from 1 (\u003cem\u003estrongly agree\u003c/em\u003e) to 5 (\u003cem\u003estrongly disagree\u003c/em\u003e). In the present study, internal consistency was good for both subscales, with Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.80 for intensity preference and α\u0026thinsp;=\u0026thinsp;.81 for intensity tolerance.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eExercise self-efficacy\u003c/h2\u003e \u003cp\u003eExercise self-efficacy was assessed using the \u003cem\u003eExercise Self-Efficacy Scale\u003c/em\u003e (ESES; McAuley, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e1993\u003c/span\u003e), which measures individuals\u0026rsquo; confidence in their ability to engage in and maintain regular exercise behavior under challenging conditions. Exercise self-efficacy reflects a core social\u0026ndash;cognitive determinant of exercise behavior and affective responses during physical activity. The scale consists of 18 items describing common barriers to exercise participation (e.g., \u0026ldquo;How confident are you that you could continue exercising when you feel tired?\u0026rdquo;). Participants rate their confidence on a 5-point Likert scale ranging from 1 (\u003cem\u003enot at all confident\u003c/em\u003e) to 5 (\u003cem\u003eextremely confident\u003c/em\u003e). The Chinese version of the ESES has demonstrated good reliability and validity in samples of Chinese college students (Wang \u0026amp; Xu, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). In the present study, the scale showed good internal consistency (Cronbach\u0026rsquo;s α\u0026thinsp;=\u0026thinsp;.84).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eImmediate post-exercise affective response\u003c/h2\u003e \u003cp\u003eImmediate post-exercise affective response was assessed using the \u003cem\u003eFeeling Scale\u003c/em\u003e (FS; Hardy \u0026amp; Rejeski, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1989\u003c/span\u003e), a widely used single-item measure of affective valence in exercise contexts. The FS captures individuals\u0026rsquo; immediate affective response following physical activity and has demonstrated strong validity and sensitivity to changes in exercise-related affect. Immediately after each exercise session, participants responded to the item \u0026ldquo;How do you feel right now?\u0026rdquo; Responses were recorded on an 11-point bipolar scale ranging from \u0026minus;\u0026thinsp;5 (very bad) to +\u0026thinsp;5 (very good), with 0 indicating a neutral affective state.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eMomentary mindfulness-related processes\u003c/h2\u003e \u003cp\u003eMomentary mindfulness-related psychological processes were assessed immediately following each exercise session. Each construct was measured using one item, adapted from established theoretical definitions and prior empirical work. To enhance temporal specificity and ecological validity, all items were framed with the same introductory phrase: \u003cem\u003e\u0026ldquo;During the 20 minutes of exercise just completed \u0026hellip;\u0026rdquo;.\u003c/em\u003e Attention\u0026ndash;awareness was assessed with one item (\u0026ldquo;\u0026hellip; I focused my attention on what I was doing in the present moment\u0026rdquo;). Acceptance was measured with one item adapted from Ullrich-French et al. (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) (\u0026ldquo;\u0026hellip; I acknowledged my bodily sensations without trying to change them\u0026rdquo;). Decentering was assessed with one item reflecting the ability to observe thoughts and feelings from a detached perspective (\u0026ldquo;\u0026hellip; I was able to observe my thoughts and feelings objectively, like watching a movie\u0026rdquo;; Bernstein et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Nonreactivity was measured with one item adapted from Baer et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e) (\u0026ldquo;\u0026hellip; to what extent were you able to pause and not react to your thoughts or feelings?\u0026rdquo;).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eThe data consisted of repeated exercise sessions (Level 1) nested within individuals (Level 2). Immediate post-exercise affective responses and mindfulness-related psychological processes were assessed following each session over a 4-week intervention period. Given this hierarchical and unbalanced longitudinal structure, analyses were conducted using multilevel linear mixed-effects models, which are well suited for intensive longitudinal data and explicitly account for within-person dependency and between-person variability (Raudenbush \u0026amp; Bryk, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Snijders \u0026amp; Bosker, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Unconditional random-intercept models were first estimated to quantify between-person variance in affective responses using intraclass correlation coefficients (ICCs). Time (session order) and its interaction with intervention condition were then examined to characterize overall temporal patterns and to provide a baseline for subsequent mechanism-focused analyses.\u003c/p\u003e \u003cp\u003eTo distinguish dynamic within-person processes from stable individual differences, all time-varying psychological variables were decomposed using person-mean centering. Session-specific deviations from an individual\u0026rsquo;s mean represented within-person components, whereas person-level means represented between-person components. This approach follows established recommendations for separating within-person and between-person effects in multilevel models and avoids conflating processes operating at different levels of analysis (Enders \u0026amp; Tofighi, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Curran \u0026amp; Bauer, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePrimary analyses examined concurrent associations between mindfulness-related psychological processes and immediate post-exercise affective responses. Separate multilevel models were estimated for each process, including fixed effects for within-person and between-person components and random intercepts for participants. Random slopes for within-person predictors were included when supported by variance estimates and model convergence, consistent with recommendations for confirmatory multilevel modeling (Barr et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Moderation by intervention condition was tested using cross-level interactions between within-person process components and condition, while controlling for corresponding between-person effects. Significant interaction terms were interpreted as evidence that intervention condition altered the strength of momentary process\u0026ndash;affect coupling, consistent with multilevel approaches to modeling context-dependent psychological processes (Bolger \u0026amp; Laurenceau, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eExploratory lagged analyses examined whether prior-session levels of selected mindfulness-related processes predicted subsequent affective responses beyond concurrent associations. Lagged predictors were constructed at the within-person level and entered simultaneously with current-session predictors and between-person means. Given unequal spacing between exercise sessions and recommendations for cautious interpretation of temporal effects in longitudinal data, lagged associations were treated as exploratory (Hamaker et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAll models were estimated using restricted maximum likelihood in \u003cem\u003eR\u003c/em\u003e with the \u003cem\u003elme4\u003c/em\u003e package (Bates et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Statistical inference for fixed effects was based on Satterthwaite\u0026rsquo;s approximation implemented in \u003cem\u003elmerTest\u003c/em\u003e (Kuznetsova et al., \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Statistical significance was evaluated at α\u0026thinsp;=\u0026thinsp;0.05 (two-tailed).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 91 participants contributed 863 immediate post-exercise affective observations, with exercise sessions nested within individuals.\u003c/p\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eBaseline affective responses and preliminary temporal effects\u003c/h2\u003e \u003cp\u003eUnconditional multilevel models indicated substantial variability in immediate post-exercise affective responses at both the between- and within-person levels. The random intercept variance was significant (τ₀₀ = 0.22), and the intraclass correlation coefficient (ICC\u0026thinsp;=\u0026thinsp;0.30) indicated that approximately 30% of the variance in affective responses was attributable to stable between-person differences (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Next, intervention condition was entered as a fixed effect. Relative to the control condition, participants in the mindfulness condition reported significantly higher overall post-exercise affect (β\u0026thinsp;=\u0026thinsp;0.28, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.036), whereas the distraction condition did not differ significantly from control (β = \u0026minus;0.23, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.085). Inclusion of intervention condition modestly improved model fit, increasing the marginal \u003cem\u003eR\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e from 0 to 0.06.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline multilevel linear mixed-effects models predicting post-exercise affect\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModel A\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModel B\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eModel C\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictors\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEstimate [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEstimate [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEstimate [95% CI]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFixed effects\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e(Intercept)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.81 [3.69, 3.92]\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.79 [3.62, 3.97]\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.68 [3.42, 3.95]\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup [Mindfulness]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.28 [0.02, 0.53]\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.26 [\u0026ndash;0.06, 0.58]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup [Distraction]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ndash;0.23 [\u0026ndash;0.48, 0.03]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;0.17 [\u0026ndash;0.50, 0.16]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime (session order)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.02 [\u0026ndash;0.01, 0.05]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMindfulness \u0026times; Time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.00 [\u0026ndash;0.04, 0.11]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDistraction \u0026times; Time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;0.01 [\u0026ndash;0.04, 0.02]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRandom effects\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eσ\u0026sup2; (Residual)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eτ₀₀ (Intercept, individual)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModel fit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarginal R\u0026sup2; / Conditional R\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.000 / 0.301\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.058 / 0.308\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.063 / 0.313\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eICC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAIC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2009.46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2003.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2025.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBIC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2023.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2027.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2068.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003e\u003cb\u003eNote.\u003c/b\u003e Control group served as the reference category for intervention condition. \u003csup\u003e*\u003c/sup\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, \u003csup\u003e**\u003c/sup\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01, \u003csup\u003e***\u003c/sup\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; significance codes are the same below.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTo examine changes in affective responses across the intervention period, time (session order) was added as a fixed effect along with its interaction with intervention condition. The main effect of time was small and not statistically significant (β\u0026thinsp;=\u0026thinsp;0.02, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.15), indicating no reliable linear change in post-exercise affect across sessions. Moreover, the time \u0026times; condition interactions were non-significant for both the mindfulness (β\u0026thinsp;=\u0026thinsp;0.00, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.84) and distraction (β = \u0026minus;0.01, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.55) conditions, suggesting that trajectories of post-exercise affect did not differ across intervention groups.\u003c/p\u003e \u003cp\u003e***Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e***\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eMindfulness-related processes and post-exercise affective response\u003c/h2\u003e \u003cp\u003eMultilevel models examined concurrent within-person (WP) associations between mindfulness-related processes and immediate post-exercise affect, as well as moderation by intervention condition. All predictors were decomposed into WP and between-person (BP) components.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eAcceptance\u003c/h2\u003e \u003cp\u003eSession-specific increases in acceptance were associated with more positive post-exercise affect at the within-person level (β\u0026thinsp;=\u0026thinsp;0.11, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.035). A significant between-person effect was also observed, with higher average acceptance predicting higher overall affect (β\u0026thinsp;=\u0026thinsp;0.59, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Moderation analyses indicated that the WP acceptance\u0026ndash;affect association did not differ by intervention condition (mindfulness vs. control: β\u0026thinsp;=\u0026thinsp;0.07, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.61; distraction vs. control: β\u0026thinsp;=\u0026thinsp;0.12, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.36; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMindfulness-related processes and post-exercise affective response\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAcceptance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNonreaction\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAttention\u0026ndash;Awareness\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eDecentering\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFixed effects\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.51 (0.36)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.98 (0.29)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.21 (0.22)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.46 (0.25)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWithin-person (WP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.11 (0.05)\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.13 (0.05)\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.31 (0.04)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.20 (0.04)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBetween-person (BP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.59 (0.09)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.55 (0.09)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.47 (0.06)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.39 (0.07)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModeration by condition\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWP \u0026times; Distraction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.12 (0.13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.25 (0.10)\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.20 (0.10)\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.07 (0.10)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWP \u0026times; Mindfulness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.07 (0.14)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.32 (0.11)\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.12 (0.10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.22 (0.10)\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRandom effects (variance)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWP slope\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResidual\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cb\u003eNote.\u003c/b\u003e Values are unstandardized coefficients with standard errors in parentheses. WP predictors represent person-mean centered session-level deviations; BP predictors represent person-level means. Intervention condition was dummy coded with the control group as the reference category.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003eNonreaction\u003c/h2\u003e \u003cp\u003eWithin-person increases in nonreaction were positively associated with post-exercise affect (β\u0026thinsp;=\u0026thinsp;0.13, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008), alongside a robust between-person effect (β\u0026thinsp;=\u0026thinsp;0.55, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Importantly, the within-person nonreaction\u0026ndash;affect association was moderated by intervention condition. Compared with the control group, both the distraction condition (β\u0026thinsp;=\u0026thinsp;0.25, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.018) and the mindfulness condition (β\u0026thinsp;=\u0026thinsp;0.32, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003) showed significantly stronger coupling between nonreaction and post-exercise affect (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eAttention\u0026ndash;awareness\u003c/h2\u003e \u003cp\u003eAttention\u0026ndash;awareness showed the strongest WP association with post-exercise affect (β\u0026thinsp;=\u0026thinsp;0.31, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with a significant between-person effect (β\u0026thinsp;=\u0026thinsp;0.47, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Moderation analyses revealed that the WP attention\u0026ndash;awareness\u0026ndash;affect association was stronger in the distraction condition than in control (β\u0026thinsp;=\u0026thinsp;0.20, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.050), whereas the corresponding interaction in the mindfulness condition was not significant (β\u0026thinsp;=\u0026thinsp;0.12, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.23; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003eDecentering\u003c/h2\u003e \u003cp\u003eWithin-person increases in decentering were associated with more positive post-exercise affect (β\u0026thinsp;=\u0026thinsp;0.20, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and higher average decentering predicted higher overall affect (β\u0026thinsp;=\u0026thinsp;0.39, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Moderation analyses revealed that, relative to control, the mindfulness condition showed a weaker WP decentering\u0026ndash;affect association (β = \u0026minus;0.22, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.023), whereas the distraction condition did not differ significantly (β = \u0026minus;0.07, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.50; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e***Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e***\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003eExploratory lagged effects of mindfulness-related processes\u003c/h2\u003e \u003cp\u003eExploratory lagged multilevel models examined whether acceptance and nonreaction showed carry-over effects across exercise sessions. Lagged analyses were limited to acceptance and nonreaction, given their robust concurrent associations with post-exercise affect in the primary models. Each model included the concurrent WP effect, the lagged WP effect from the immediately preceding session (lag\u0026thinsp;=\u0026thinsp;1), and the corresponding BP mean.\u003c/p\u003e \u003cp\u003eFor acceptance, the concurrent WP effect remained significant (β\u0026thinsp;=\u0026thinsp;0.13, \u003cem\u003eSE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), whereas the lagged WP effect was small and non-significant (β\u0026thinsp;=\u0026thinsp;0.04, \u003cem\u003eSE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.05, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.37; Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). This pattern indicates that session-specific increases in acceptance were associated with more positive immediate post-exercise affect, but acceptance experienced during the prior session did not predict affect at the subsequent session beyond the concurrent effect.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eExploratory lagged within-person effects of mindfulness-related processes on post-exercise affect\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePredictor\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAcceptance\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNonreaction\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFixed effects\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.51 (0.38)\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.95 (0.30)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWithin-person (WP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.13 (0.05)\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.11 (0.04)\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWP (lagged, session \u0026minus;\u0026thinsp;1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.04 (0.05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.03 (0.04)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBetween-person (BP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.59 (0.10)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.56 (0.09)\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRandom effects (variance)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntercept\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResidual\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eA similar pattern emerged for nonreaction. The concurrent WP association with post-exercise affect was significant (β\u0026thinsp;=\u0026thinsp;0.11, \u003cem\u003eSE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007), while the lagged WP effect was not (β = \u0026minus;0.03, \u003cem\u003eSE\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.04, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.54; Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Thus, nonreaction was linked to affective responses primarily at the momentary level rather than through sustained effects across sessions.\u003c/p\u003e \u003cp\u003e***Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e***\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present study examined how mindfulness during exercise shapes affective experience by focusing on dynamic, momentary psychological mechanisms across a 4-week intervention. Using an EMA-informed multilevel modeling approach, we investigated concurrent within-person associations between mindfulness-related processes and immediate post-exercise affect, as well as whether these associations were moderated by intervention condition. Several key findings emerged from the present study. Momentary fluctuations in mindfulness-related processes\u0026mdash;including acceptance, nonreaction, attention\u0026ndash;awareness, and decentering\u0026mdash;were consistently associated with immediate post-exercise affect at the within-person level, indicating that how individuals related to their internal experience during a given exercise session played a more critical role than stable individual differences alone. This pattern aligns with process-based accounts of mindfulness, which emphasize present-centered experiential engagement as a primary pathway through which mindfulness influences affective outcomes (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Shapiro et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eBuilding on these findings, moderation analyses suggested that mindfulness-based exercise selectively shaped the momentary mechanisms linking experience to affect. Although acceptance, attention\u0026ndash;awareness, nonreaction, and decentering were all positively associated with immediate post-exercise affect at the within-person level, only nonreaction showed a reliably stronger process\u0026ndash;affect coupling in the mindfulness condition relative to control. This pattern highlights nonreactivity as a particularly salient mechanism through which mindfulness alters affective experience during exercise, consistent with theoretical accounts emphasizing reduced automatic reactivity to bodily sensations and internal events as a core function of mindfulness (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Garland et al., \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). In contrast, acceptance and attention\u0026ndash;awareness appeared to confer affective benefits across conditions, suggesting that these processes may reflect general experiential qualities supportive of positive exercise-related affect rather than mechanisms uniquely enhanced by mindfulness training. Decentering exhibited a weaker association with affect in the mindfulness condition, potentially indicating a shift toward a more integrated, less explicitly metacognitive mode of engagement as mindfulness practice unfolds (Bernstein et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Shapiro et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Taken together, these findings partially supported our hypotheses by confirming that momentary mindfulness-related processes are linked to affective responses during exercise, while providing more selective support for the prediction that mindfulness-based exercise uniquely strengthens specific mechanisms, particularly nonreactivity.\u003c/p\u003e \u003cp\u003eExploratory lagged analyses indicated that mindfulness-related processes did not predict affective responses across exercise sessions beyond their concurrent, momentary effects. For both acceptance and nonreaction, prior-session levels were not associated with immediate post-exercise affect once session-specific states were taken into account. This pattern is consistent with conceptualizations of mindfulness as a present-centered mode of engagement, in which affective consequences arise from how individuals relate to their internal experience in the moment rather than from sustained carry-over across time (Baer et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Shapiro et al., \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Given the variability of bodily sensations and contextual demands inherent in exercise, these findings underscore that mindfulness-related mechanisms primarily operate through immediate experiential processes during each exercise bout.\u003c/p\u003e \u003cp\u003eSeveral limitations should be acknowledged. First, although the EMA-informed design allowed for the examination of momentary psychological processes across repeated exercise sessions, the proposed mechanisms were theoretically inferred rather than experimentally manipulated. As such, causal conclusions regarding specific mechanisms should be drawn cautiously. Second, mindfulness-related processes were assessed using brief items to minimize participant burden, which may have limited the precision with which these constructs were captured at each session. Third, the intervention period spanned four weeks and included a relatively homogeneous sample of physically inactive college students, which may constrain the generalizability of the findings to other populations or longer-term training contexts. Finally, although exploratory lagged analyses were informative, the unequal spacing between exercise sessions limits strong inferences about temporal ordering across sessions. Future research would benefit from designs that experimentally manipulate candidate mechanisms or employ higher-frequency assessments to further delineate the temporal dynamics of mindfulness during exercise.\u003c/p\u003e \u003cp\u003eIn summary, the present study provides evidence that mindfulness shapes affective experience during exercise through dynamic, momentary psychological processes rather than through sustained carry-over effects across sessions. Using an EMA-informed multilevel approach, we demonstrated that session-specific fluctuations in mindfulness-related mechanisms were closely linked to immediate post-exercise affect, with mindfulness-based exercise selectively strengthening nonreactive engagement with internal experience. These findings advance understanding of how mindfulness operates in exercise contexts by highlighting the central role of present-moment processes and underscore the importance of adopting dynamic, within-person perspectives when investigating affective mechanisms of behavioral interventions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.L. conceptualized the study, developed the methodology, conducted the formal analyses, curated the data, and wrote the original draft of the manuscript. W.-J.L. contributed to conceptualization and methodology, developed the software, performed validation, curated the data, and reviewed and edited the manuscript. Y.Q. contributed to methodology, data curation, validation, and reviewed and edited the manuscript. H.-M.J. contributed to conceptualization, methodology, formal analysis, data curation, supervised the project, managed project administration and resources, and reviewed and edited the manuscript. All authors reviewed and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data that support the findings of this study are publicly available on the Open Science Framework (OSF) at: https://osf.io/sy92k/overview?view_only=c3bb6eab4ae94641add2c7d3b0eb1d50\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eBaer, R. A., Smith, G. T., Hopkins, J., Krietemeyer, J., \u0026amp; Toney, L. (2006). Using self-report assessment methods to explore facets of mindfulness. \u003cem\u003eAssessment, 13\u003c/em\u003e(1), 27\u0026ndash;45. https://doi.org/10.1177/1073191105283504\u003c/li\u003e\n \u003cli\u003eBaer, R. A., Smith, G. T., Hopkins, J., Krietemeyer, J., \u0026amp; Toney, L. (2006). Using self-report assessment methods to explore facets of mindfulness. \u003cem\u003eAssessment, 13\u003c/em\u003e(1), 27\u0026ndash;45. https://doi. org/10.1177/1073191105283504\u003c/li\u003e\n \u003cli\u003eBarr, D. J., Levy, R., Scheepers, C., \u0026amp; Tily, H. J. (2013). Random effects structure for confirmatory hypothesis testing: Keep it maximal. \u003cem\u003eJournal of Memory and Language, 68\u003c/em\u003e(3), 255\u0026ndash;278. https://doi.org/10.1016/j.jml.2012.11.001\u003c/li\u003e\n \u003cli\u003eBarr, D. J., Levy, R., Scheepers, C., \u0026amp; Tily, H. J. (2013). Random effects structure for confirmatory hypothesis testing: Keep it maximal. \u003cem\u003eJournal of Memory and Language, 68\u003c/em\u003e(3), 255\u0026ndash;278. https://doi.org/10.1016/j.jml.2012.11.001\u003c/li\u003e\n \u003cli\u003eBates, D., M\u0026auml;chler, M., Bolker, B., \u0026amp; Walker, S. (2015). 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A., \u0026amp; Salmon, P. G. (2010). Mindfulness and acceptance are associated with exercise maintenance in YMCA exercisers. \u003cem\u003eBehaviour Research and Therapy, 48\u003c/em\u003e(8), 805\u0026ndash;809. https://doi.org/10.1016/j.brat.2010.04.009\u003c/li\u003e\n \u003cli\u003eWang, C.-M., \u0026amp; Xu, R.-X. (2002). Development and validation of the exercise self-efficacy scale. \u003cem\u003eChina Sport Science\u003cem\u003e, 22\u003c/em\u003e\u003c/em\u003e(4), 38\u0026ndash;42.\u003c/li\u003e\n \u003cli\u003eWang, T., Kuang, J., Herold, F., Taylor, A., Ludyga, S., Zhang, Z., \u0026amp; Zou, L. (2023). Validity and Reliability of the Preference for and Tolerance of the Intensity of Exercise Questionnaire among Chinese College Students. \u003cem\u003eInternational Journal of Mental Health Promotion\u003c/em\u003e, 25(1), 127\u0026ndash;138. https://doi.org/10.32604/ijmhp.2022.022504\u003c/li\u003e\n \u003cli\u003eWilliams, D. M., Dunsiger, S., Ciccolo, J. T., Lewis, B. A., Albrecht, A. E., \u0026amp; Marcus, B. H. (2008). Acute affective response to a moderate-intensity exercise stimulus predicts physical activity participation 6 and 12 months later. \u003cem\u003ePsychology of Sport and Exercise, 9\u003c/em\u003e(3), 231\u0026ndash;245. https://doi.org/10.1016/j.psychsport.2007.04.002\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Mindfulness, Exercise, Affective responses, Ecological momentary assessment, Dynamic psychological mechanisms, Nonreactivity","lastPublishedDoi":"10.21203/rs.3.rs-8431406/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8431406/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eMindfulness-based exercise has been shown to enhance affective responses to exercise, yet the momentary psychological mechanisms underlying these effects remain poorly understood. The present study examined how mindfulness during exercise shapes affective experience by focusing on dynamic, momentary psychological processes across a four-week intervention.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003ePhysically inactive college students were randomly assigned to a mindfulness-based exercise condition, a distraction condition, or a control condition and completed 2\u0026ndash;3 supervised exercise sessions per week for four weeks. Using an ecological momentary assessment (EMA)\u0026ndash;informed design, immediate post-exercise affect and mindfulness-related psychological processes were assessed following each exercise session. Multilevel models decomposed within-person and between-person effects to examine concurrent associations between psychological processes and affect, moderation by intervention condition, and exploratory lagged effects across sessions.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eSession-specific fluctuations in acceptance, nonreaction, attention\u0026ndash;awareness, and decentering were all positively associated with immediate post-exercise affect at the within-person level. Moderation analyses indicated that mindfulness-based exercise selectively strengthened the momentary association between nonreaction and affect, whereas other mechanisms showed comparable associations across conditions. Exploratory lagged analyses revealed no evidence that prior-session levels of acceptance or nonreaction predicted affective responses at subsequent sessions beyond concurrent effects.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThese findings suggest that mindfulness influences affective experience during exercise primarily through dynamic, momentary psychological processes rather than sustained carry-over effects. By highlighting nonreactive engagement with internal experience as a key mechanism, the present study advances a process-based understanding of how mindfulness operates in exercise contexts and underscores the value of EMA approaches for capturing dynamic affective mechanisms.\u003c/p\u003e","manuscriptTitle":"How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-05 09:21:59","doi":"10.21203/rs.3.rs-8431406/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3ac857a2-080c-47c4-a0a3-641490d31ff1","owner":[],"postedDate":"March 5th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-22T03:23:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-05 09:21:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8431406","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8431406","identity":"rs-8431406","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}