Effects of Protein yogurts vs. Whey protein on body composition, strength, and gut microbiome changes in untrained older adults during 8 weeks of supervised strength training: a randomized trial.

Effects of Protein yogurts vs. Whey protein on body composition, strength, and gut microbiome changes in untrained older adults during 8 weeks of supervised strength training: a randomized trial. | 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 Article Effects of Protein yogurts vs. Whey protein on body composition, strength, and gut microbiome changes in untrained older adults during 8 weeks of supervised strength training: a randomized trial. Matias Monsalves Alvarez, Paulina Calderon-Romero, Thomas Haynes-Ortiz, and 15 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8098210/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract Methods Seventeen untrained adults (60–70 years) were randomized to either consume WP (25 g) or PY (24.5 g) along with an 8-week supervised ST program (3 sessions/week). Initial and final assessments included body composition (BIA), strength (10RM, isokinetic torque, handgrip), gait speed, resting metabolic rate, and gut microbiome (16S rRNA sequencing). Data were analyzed using repeated-measures ANOVA and diversity metrics. Results Both groups increased skeletal muscle mass (WP: +0.47 kg; PY: +0.50 kg) and improved strength and gait speed (p < 0.01), with no between-group differences. Fat mass decreased only in WP (p = 0.02), while resting metabolic rate increased in PY (p = 0.03). Microbiome analysis revealed distinct shifts: WP increased the Firmicutes/Bacteroidota ratio and enriched Subdoligranulum , whereas PY enhanced alpha diversity and increased the abundance of Coprococcus . Functional pathway predictions indicated differential enrichment in metabolic and signaling processes. Conclusion High-protein yogurt and whey protein similarly improve muscle mass, strength, and functional capacity during ST, while exerting distinct effects on gut microbiome composition. Yogurt represents a cost-effective alternative to whey protein and may confer additional gut health benefits. Trial registration: Clinicaltrials.gov identifier NCT06412302 . Date of registration 2024-05-14. Health sciences/Health care Health sciences/Medical research Biological sciences/Microbiology Biological sciences/Physiology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Loss of muscle mass, strength, and functionality has been termed sarcopenia, a geriatric syndrome with a multifactorial etiology that increases with age ( 1 ). The determinants of sarcopenia are multifactorial, encompassing a range of biological, nutritional, and environmental factors, including decreased anabolic processes ( 2 ), increased chronic low-grade inflammation ( 3 ), gut microbiota dysbiosis ( 4 ), protein-deficient diets ( 5 ), and cessation of physical exercise ( 6 ). Exercise, particularly strength training (ST), is a potent stimulus for promoting skeletal muscle anabolism, resulting in metabolic and morphological improvements in this tissue, which can adapt to different frequencies, intensities, and exercise volumes at any age ( 7 , 8 ). Therefore, ST is considered a primary strategy for delaying and treating sarcopenia ( 9 ). In older adults, ST generates significant neuromuscular adaptations, including increases in power and strength-related abilities of daily living, such as rising from a chair, climbing and descending stairs, and active walking ( 10 ). A recent systematic review found increases of 4.7–58.1% in functionality and 3.4–7.5% in muscle mass in 16 studies using ST as a therapeutic measure ( 11 ). On the other hand, high-protein diet interventions may also potentiate ST-induced muscle mass gain. Vikberg et al. reported that a 10-week supervised ST resulted in a mean increase of ~ 1.4 kg lean mass and improved power and walking speed in functional tests in individuals under 70 years. Notably, these individuals consumed a milk-based high-protein supplement, although it was not mandatory as part of the intervention ( 12 ). This result suggests an additive effect of high-protein intake on the anabolic effects of ST ( 13 ). Protein is an essential nutrient primarily obtained from animal sources such as meat and dairy products (i.e., milk, yogurts, cheese) and, to a lesser extent, from plants (i.e., Soy, Peas, rice) ( 14 ). Differences in protein quality are based on biological value, net utilization, and the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) ( 15 ). These factors make the selection of protein sources crucial for absorption and tolerance when ingested ( 16 ). This is particularly relevant for dairy products, as these foods possess one of the highest biological values and PDCAAS ( 17 ). For example, milk-derived proteins are composed of casein and whey, which the sports supplement industry utilizes in various forms (i.e., isolated, hydrolyzed, concentrated casein). These forms differ in their absorption speed and digestibility, which can impact protein synthesis rates ( 18 ). Whey protein has rapid absorption; in contrast, casein, which constitutes about 80% of the protein content in milk, is absorbed more slowly, resulting in a different plasma amino acid appearance ( 19 , 20 ). Although protein supplements are a popular option for increasing protein intake, recent evidence from our group ( 21 ) and others ( 22 ) suggests that different protein supplement brands do not consistently provide the quality and quantity of proteins they declare on their nutritional labels. This information should encourage the promotion of other high-quality food protein sources, especially for older adults, to support muscle and overall health ( 23 ). In healthy, non-trained males, 12 weeks of Greek yogurt intake improved strength, muscle thickness, and fat-free mass (FFM) compared to a pudding (high in carbohydrates) placebo group ( 24 ). More recently, Bagheri et al. have shown that the intake of 18 grams of protein from Icelandic yogurt in older male adults (68 years) and ST improves lean body mass and strength compared to a placebo ( 25 ). These results suggest that yogurts, which are exceptionally high in protein, can be a low-cost alternative to support muscle mass at various ages. Yogurts not only possess almost the exact proportions of whey and casein that milk makes a good protein source ( 26 ) but are also recognized as functional foods by their impact on intestinal and metabolic health ( 27 ). In animal models, diets consisting of casein and whey refeed after a food restriction period differentially alter the bacterial population ( 28 ), providing evidence of the relevance of the protein source on the gut microbiome, which remains scarce in humans. Depending on the yogurt type (i.e., Stirred, extra protein, or Greek-style), fat, protein, physical, chemical, and probiotic characteristics can vary, as well as their functional effects on health ( 29 ). We recently showed that high-protein yogurts in Chile have a good relationship with the content declared on the label ( 30 ). Moreover, the amino acid profile found in most of the samples makes them similar to whey protein. However, no study has directly compared protein intake from high-protein yogurts and whey protein supplements during a strength training program in older adults. Thus, we aimed to determine the effects of high-protein yogurt and whey protein intake on muscle strength, body composition, and microbiome diversity in older adults undergoing a guided strength training regimen. Subjects and methods Study population Eligible participants were inactive men and women (60–70 years old) with < 1h of exercise per week and controlled blood pressure who had no impediments to being under an ST regime. Exclusion criteria were smoking, diabetes (type 1 or 2), alcohol consumption, lactose intolerance, regular intake of non-steroidal anti-inflammatory drugs, and use of sports supplements that alter muscle mass (i.e., Whey protein, Creatine, HMB) in the last 6 months. Participant recruitment Recruitment was advertised locally in the community, the Motion Health and Performance Centre website, and social media (i.e., Instagram). All potential participants were contacted, and the project's general aims, objectives, and procedures were thoroughly explained to them. Potential candidates were identified based on their medical history, healthy habits, resting electrocardiogram (ECG), baseline fasting plasma glucose levels, and blood pressure profiles. This study was conducted in accordance with the guidelines of the Declaration of Helsinki, and all procedures were approved by the Ethics Committee of the Universidad de O´Higgins (027-2023). Written informed consent was obtained from all participants. This study was registered at ClinicalTrials.gov (NCT06412302, 2025-05-14 , https://clinicaltrials.gov/study/NCT06412302 ). The sample size was calculated using G-Power®, accepting a significance level for α of 0.05, a power of 0.80 and an effect size of 0.5, 8 subjects per group were need it. Study design and intervention The present study is a randomized trial in which participants were randomly assigned to receive 25 g of Whey protein (WP) (Vanilla, ISO100, Dymatize, USA) or 24.5 g of protein from high-protein yogurt (PY) (Vanilla, Loncoleche, Chile) immediately after training sessions in an 8-week strength training regimen (Fig. 1 ) ( randomizer.org , MMA). As PY has a lower protein content per serving, two yogurts were prepared by the trainers (SB and FS) and mixed with filtered water to a total volume of 240 mL. At the same time, one scoop of WP was diluted with 240 mL of water to ensure a similar volume and intake among groups and given by trainers to participants ( Supplementary Fig. 1 ). Strength training (ST) sessions consisted of 3x8-12 reps with 1–2 repetitions in reserve (RIR). The training intensity ranged from 70% to 85% of 10 repetition maximum (RM), with 5% increases every 2 weeks. All sessions were supervised by a certified trainer at the Motion Health and Performance Center and were conducted in groups of 3 to ensure individualized prescriptions and participation. The training frequency was set at three days a week, with a (Monday, Wednesday, and Friday) lower, upper, and full body session schedule. The exercise selection for lower-body sessions was as follows: leg press, one-leg step-up, hip thrust, leg curl, leg extension, and calf raise. Upper sessions: Pull-down, One-arm dumbbell row, Smith bench press, Smith shoulder press, Biceps curl and triceps extension, and a full body session included: Hex-bar deadlifts, Goblet squats, Leg curl, Leg extension, Lat pull-down wide, and Smith incline bench press. All exercises were performed using Ilus equipment (Ilus Fitness Company®, Santiago, Chile). Measurements Biochemical analysis Before and after the 8-week intervention, approximately 5 mL of fasting blood samples were drawn from the antecubital vein and immediately centrifuged. The serum was separated and frozen at -80°C until analysis. Serum total cholesterol, Triglycerides, HDL, Albumin, BUN, Uric acid, Creatinine, GOT, GPT, and GGT concentrations were determined in an automated dry-chemistry multi-analyzer (Spotchem EZ SP-4430; Menarini Diagnostics, UK) using specific soft reagent strips (ARKRAY, Shiga, Japan). Body composition Body composition analysis was performed using a bioelectric impedance analyzer (InBody 970, InBody Co, South Korea). All participants were instructed to refrain from eating or drinking for 3–4 hours and from consuming alcohol and engaging in exercise for 24 hours before testing. Weight (kg), body fat mass (kg), total body water (L), skeletal muscle mass (kg), percent of body fat (%), visceral fat (kg), trunk lean mass (kg), leg lean mass (kg), and whole-body phase angle (PhA°, 50kHz) were determined before and after the 8-week intervention. Cardiorespiratory Fitness Aerobic capacity was determined by indirect calorimetry using a calibrated breath-by-breath gas analyzer (Metalyzer, Cortex, Germany). Participants were subjected to an incremental-maximal protocol on a cycloergometer until exhaustion, as previously described ( 31 ). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured and compared at baseline and the end of the intervention. Resting metabolic rate (RMR) The resting metabolic rate was determined using an indirect calorimeter (QNRG, Cosmed, Italy) with a flow-dilution canopy hood. After an overnight fast (8-12h), participants were instructed to remain in a resting condition for 15–20 minutes with a regular breathing pattern in a supine position, until a steady state (< 10% coefficient variation of one or more variables: VO 2 , VCO 2, or RQ) was reached, following standardized recommendations ( 32 ). 24-hour food consumption recall The nutritional information was obtained before and after the intervention through a 24-hour recall at the first and last laboratory visits ( 33 ). The total calories and macronutrient intake were calculated using the Photographic Atlas of Typical Chilean Food and Preparations by the Institute of Nutrition and Food Technology (INTA). Universidad de Chile ( 34 ) and performed by a registered dietitian of our team (RD). Isokinetic strength An isokinetic test was performed at the beginning and after 8 weeks following ST intervention. The test was performed bilaterally on an isokinetic machine (Genu Plus; Easytech Italy, Prato, Italy), which was calibrated by a physical therapist from our team before the test session. In brief, participants spent a short period gaining confidence in the isokinetic method. Then they warmed up with 6 repetitions at 120°/sec, followed by 1 repetition at 60°/sec at 50% of the maximum. After the warm-up, all participants rest for 2 minutes to perform 4 repetitions at 60°/s to determine the maximal knee extension and flexion peak torque (Nm) ( 35 ). Maximal muscle strength Maximal strength was determined indirectly by the 10-repetition maximum (10RM) test as previously described ( 36 , 37 ). In brief, 10RM was performed on the same day in the following order: Bench press (BP), Lat pull-down (LPD), and leg press (LP). Before testing, standard instructions for the exercise technique, performance, and guidance from a certified personal trainer are provided. During the 10RM test, participants performed incremental loads until they could no longer complete 11 repetitions, with a maximum of 5 attempts and 3–5-minute intervals between trials. Hand Grip Strength Hand grip strength (HGS) was measured in the dominant and non-dominant hands using a Jamar Plus dynamometer (Jamar, Jackson, MI, USA), as described previously, and reported as the maximal value of the three attempts ( 38 ). Additionally, HGS was normalized by height and expressed as (Kg/M²) to account for body dimensions ( 39 ). Time Up and Go (TUG) Gait speed was determined using the Time Up and Go test (TUG) as previously described ( 40 ). Briefly, all participants refrained from standing from a chair, walked through a 3 m away cone, turned around, and sat back on the chair, walking at the fastest and safest comfortable speed. All subjects were familiarized with the test by performing it before the trials, during which the best time was recorded, and gait speed was calculated in meters per second (m/s). Microbiome Microbiome diversity, abundance, and specific bacterial groups were determined using stool samples collected before and after the intervention, as described previously ( 41 ). In brief, participants received a sample collection kit that included a fecal collection tube (DNA/RNA Shield™. Cat#R1101. Zymo Research), a disposable aluminum box to be used as a feces catcher, gloves, and an instruction manual. Each step of the procedure was thoroughly explained in detail to all subjects at the time they received the kit. After collection, the samples were kept at room temperature for approximately two weeks and then stored at -80 ºC until processing. DNA extraction from the fecal samples was performed using the Quick-DNA Fecal/Soil Microbe Miniprep Kit (Cat#D6010, Zymo Research), following the manufacturer's instructions. The quality of DNA extraction was verified using 1% agarose gel electrophoresis. The 16S rRNA gene sequencing was conducted using the primers 341F: CCTAYGGGRBGCASCAG and 806R: GGACTACHVGGGTWTCTAAT on the Illumina platform at Novogene (Beijing, China). Statistical Analysis Sample size was determined based on a previous study on strength and muscular measurements after yogurt intake and strength training ( 25 ), it was calculated using G-Power that eight subjects per group (n = 16) were required for a significance level of α = 0.05, power of 0.80, and an effect size of 0.5. An unpaired t-test was used to determine baseline differences between groups, and a two-way ANOVA with repeated measures was used to examine both between-group and within-group differences between WP and YP, using GraphPad software (Prism, Version 10.4.2). Only participants who achieved > 85% compliance to exercise training were considered for statistical analyses. For microbiome data analysis, the DADA2 and Phyloseq packages were used to process the 16S rRNA sequences and identify and quantify the microbial diversity of the samples. The sequence reads were processed to remove the first 28 bases and discard low-quality reads, using standard filtering and trimming parameters, except for maxEE and truncQ, which were set to 2. The SILVA V138 database was used as a reference to assign amplicon sequence variants (ASVs) for taxonomic determination, ranging from kingdom to genus. The data analysis included the Centered Log Ratio (CLR) transformation of the ASV matrix. The iNext package was used to calculate diversity using the Shannon index. Using Euclidean distances, Principal Component Analysis (PCA) was performed with the CLR-transformed data. Functional gene inference was performed using the PICRUSt2 pipeline, which predicts functional pathways from 16S rRNA gene sequences. LEfSe (Linear Discriminant Analysis Effect Size) analysis was employed to identify significant differences in metabolism between groups (log LDA score > 2 and p < 0.05). Additionally, LEfSe was used to identify differentially represented genera among the different groups. A Spearman correlation analysis was conducted to explore the relationships between seven differential genera and the 30 metabolic pathways with the highest correlation across groups. Wilcoxon tests were used for statistical analyses of phylum and genus comparisons, with significance defined as * p < 0.05, and non-significant results denoted as N.S. In the Spearman correlation analysis, the Benjamini-Hochberg correction was used to adjust p -values and control the false discovery rate (FDR), with results expressed as q -values ( q < 0.1). This approach enabled the identification of key interactions and associations relevant to the study objectives. All microbiome analyses were performed using R (version 4.2.0) and RStudio (version 2022.7.1.554). Results Baseline and nutritional modifications induced by yogurt and whey protein intake. Variable WP (n = 8, 5F/3M) PY (n = 9, 6F/3M) p-value Age (yr) 66.2 ± 4.4 65.6 ± 4.1 0.79 Weight (kg) 72.3 ± 20.2 65.1 ± 13.8 0.48 Body Mass Index (kg/m 2 ) 25.9 ± 4.4 24.7 ± 2.9 0.65 Systolic Blood pressure (mmHg) 140.3 ± 12.9 131.4 ± 12.0 0.24 Diastolic Blood pressure (mmHg) 80.2 ± 6.7 80.3 ± 8.5 0.94 Fasting glucose (mg/dL) 114.5 ± 12.8 113.8 ± 10.0 0.81 Resting Heart Rate (bpm) 63 ± 8.5 68.4 ± 8.7 0.20 Resting Metabolic Rate (kcal/d) 1698 ± 440 1611 ± 205 0.60 VO2 max (ml•kg•min − 1 ) 21.3 ± 2.9 22.2 ± 3.2 0.58 The WP and PY groups were well-balanced in terms of sex and showed no differences in baseline hemodynamic, metabolic, and aerobic capacities, as shown in Table 1 . After an 8-week intervention, calorie (kcal/d) and fat (g/d) intake were not significantly different within and between groups. In contrast, carbohydrate intake (g/d) decreased in the WP group after intervention (-36.9 ± 52.9g/d, p = 0.034), with no change in the PY group (-2.4g ± 37g/d, p = 0.87) ( Table 1 ) . As expected, WP and PY increase their total and weight-adjusted (g/kg) protein intake compared with baseline (WP; 22.2 ± 19g/d, 0.38 ± 0.0g/kg and YP; 31.7 ± 12.6 g/d, 0.5 ± 0.0g/kg), respectively, with no differences between groups ( Table 2 ). Regarding serum lipid, renal, and hepatic markers, no significant changes were observed following the 8-week intervention with either WP or PY. ( Supplementary Fig. 2). Table 1 Baseline body composition, metabolic, and cardiovascular fitness differences. VO2 max : Maximal oxygen consumption. Data are presented as the mean ± standard deviation (SD). Unpaired t-test, *p < 0.05. Variable WP (n = 8, 5F/3M) PY (n = 9, 6F/3M) ANOVA Pre Post p-value* Pre Post p-value* p-value # Calories (kcal/d) 1953 ± 615.1 1835 ± 460.9 0.283 1816.7 ± 465.3 1940.9 ± 443.5 0.232 0.66 Protein (g/d) 82.9 ± 30.6 105.1 ± 20.5 0.001* 79.9 ± 20.4 111.6 ± 17.3 0.000* 0.55 Protein (g/kg/) 1.2 ± 0.4 1.5 ± 0.4 0.002* 1.2 ± 0.3 1.7 ± 0.3 < 0.001* 0.21 Fat (g/d) 68.7 ± 32.7 63.1 ± 39.9 0.503 63.2 ± 24.6 60.8 ± 18.2 0.762 0.87 Carbohydrates (g/d) 242.0 ± 84.5 205.1 ± 50.4 0.034* 242.0 ± 62.1 239.6 ± 71.9 0.874 0.30 Carbohydrates (g/kg) 3.4 ± 1.3 3.0 ± 0.8 0.061 3.7 ± 0.7 3.7 ± 0.1 0.852 0.14 Table 2. Calorie and macronutrient intake assessed by 24-hour recall. Data are presented as the mean ± standard deviation (SD). * Denotes significant intragroup differences between pre-and post-intervention, # Denotes significant differences post-intervention between WP and YP groups. Two-way ANOVA (p < 0.05). Body composition metabolic changes after intervention 8-week intervention with ST consuming WP or PY did not affect body weight (p = 0.45) (Fig. 2 A). However, skeletal muscle mass was similarly increased in both groups after intervention (WP 0.47 ± 0.74 kg, p = 0.03, PY 0.50 ± 0.40kg, p = 0.02) (Fig. 2 B), and phase angle (PhA) (Fig. 2 C). In contrast, total fat mass (kg) significantly decreased only in WP group (p = 0.02) (Fig. 2 D). Importantly, neither skeletal muscle mass, PhA or fat mass was different between groups at the end of the intervention. Regarding metabolic parameters, the resting metabolic rate increased significantly after intervention in the PY group (150.1 ± 132, p = 0.03) compared to WP (131.8 ± 253.7, p = 0.08) (Fig. 2 E). In contrast, ST with neither nutritional intervention influenced VO2 max (Fig. 2 F). However, a significant increase in gait speed was found in both groups compared to baseline (WP 0.17 ± 0.16m/s, p = 0.007, PY 0.16 ± 0.15m/s, p = 0.009) with no group differences (Fig. 2 F). Strength improvements are similar between protein yogurt and whey protein. Bench (BP) (Fig. 3 A) and leg press (LP) (Fig. 3 B) one repetition maximum (1RM) increase significantly in both intervention groups compared to baseline (WP; BP: Δ10.9 ± 10.3kg, p = 0.002, LP: Δ38.5 ± 24,3kg,p = 0.003 and YP; BP: Δ12.4 ± 7.2kg, p = < 0.0001, LP: Δ57.1 ± 19,7kg, p = 0.007), while hand grip strength (HGS) normalized by height 2 improved only after PY intervention (p = 0.02) (Fig. 3 C). Regarding isokinetic strength, WP and PY improve right (WP Δ19.9 ± 8.20 Nm, p = 0.0004, PY Δ16.0 ± 15.2Nm, p = 0.001) and left quadriceps torque (WP Δ15.9 ± 11.46 Nm, p = 0.003, PY Δ12.4 ± 13.7Nm, p = 0.01) with no differences between groups at the end of the intervention (p = 0.18) (Fig. 3 D and F ). Although neither left nor right hamstrings showed significant differences between groups, PY had a positive trend (Δ7,78 ± 10,33Nm, p = 0.0504) after the intervention in the right hamstring compared to WP (Δ-1,1 ± 11,66Nm, p = 0.775). Protein intake from yogurt or whey protein alters the bacterial phyla, genus, and correlates with predicted functional pathways. Relative abundance of the six main phyla in the gut microbiome showed changes after ST in both WP and PY groups (Fig. 4 A). From these phyla specifically, Firmicute s and Bacteroidota significantly increased and decreased, respectively, only in the WP group after ST (p = 0.01 and p = 0.03). In contrast, the PY group showed no change after the intervention (Fig. 4 B, 4 C). As expected, the individual changes in the most abundant microbiome phyla alter their Firmicutes/Bacteroidota ratio (F/B), where the F/B in the WP group increased significantly (p = 0.01) compared to the PY group (p = 0.29) after the intervention. Regarding the genus, general changes were observed after intervention in both groups (Fig. 5 A). Additionally, the genera Coprococcus , Subdoligranulum , Prevotella , and DTU089 showed changes in their differential abundance. On the other hand, the genera Klebsiella , Eggerthellaceae (DNF00809) , Butyricicoccaceae, and UCG-008 were identified in the WP group through LEfSe (see Methods) ( data not shown ). Copprococcus and Subdoligranulum increased significantly (p = 0.03 and p = 0.02; Fig. 4 B, PRE, and POST). At the same time, Prevotella decreased (p = 0.038) after the exercise intervention, regardless of supplementation (Fig. 4 B, PRE, and POST). WP and PY interventions induced differential changes in the specific gut genus, where Coprococcus increased only on PY (Fig. 4 B, Protein Yogurt) (p = 0.012), whereas DTU089 increased (p = 0.014) and Prevotella decreased significantly in WP groups (p = 0.022) (Fig. 5 B, Whey Protein). Although Klebsiella , Subdoligranulum, DNF00809, and UCG-008 genus did not change significantly, there was a shift in gut populations confirmed with the changes in microbiome diversity in both groups expressed in Shannon entropy (p = 0.010), and where this modification where mainly on PY group (p = 0.04) compared to WP (p = 0.14) ( Supplementary Fig. 3 ). Also, using PICRUSt2 and comparing it with the database (Permission N°254225), we conducted a Spearman analysis on the seven major abundant genera against the 50 most differential functional pathways. Here, we observed similarities between intra- and intergroup bacteria enriched after WP and PY interventions (Fig. 6 ). These changes were associated with a marked correlation in different signaling and cellular processes, including metabolism, transporters, and genetic information processing. Discussion This is the first study to compare the effects of consuming the same amount of protein from a high-protein yogurt or whey protein on body composition, physical function, and microbiome alterations during a strength training program in older adults. The key findings of the present study are that a) 8-week strength training (ST) induces important changes in muscle mass (SMM, PhA°), strength (1RM, Quadriceps peak torque (Nm)) and functional (gait speed) that are independent of the source of protein intake; b) ST with PY or WP differentially affect fat%, RMR, HG/ht(m) 2 and gut microbiome phyla and genera and; c) Microbiome changes induced by ST + PY or ST + WP are associated with the enrichment of different relevant metabolic pathways and cellular processes relevant for general health. Strength training (ST) is the most effective strategy for preventing and managing the majority of primary and secondary sarcopenia consequences in older adults ( 43 , 44 ). Importantly, training-induced changes in muscle mass and body composition are relevant and can be produced at any age ( 8 , 45 ). Here, the 8-week ST program decreased fat mass in the WP group, increasing skeletal muscle mass and PhA° in both groups. PhA° is commonly used as a marker of cell membrane integrity and function and has been proposed as a marker of muscle function and quality ( 46 ). Importantly, muscle quality is defined as the ability to generate force per unit of muscle mass or size, and it has also been correlated with muscle composition (i.e., myoestatosis) as a measure of muscle echogenicity ( 47 , 48 ). Although in the present study, muscle quality was not determined, gait speed (m/s), 1RM on leg and chest press (kg), and quadriceps peak torque (Nm) increased significantly upon intervention, independent of the supplementation regime, supporting that ST, accompanied with adequate protein intake and quality, induced important improvements on muscle strength and function in older adults. In order to promote an adequate protein intake during ST in the PY group, we provided individuals with two portions (240g) of a commercially available Chilean high-protein yogurt (Extra-Proteina, Loncoleche, Chile) and the WP group with a whey protein isolated (Iso100, Dymatize) ( 49 , 50 ) to ensure a protein intake of 24.5g and 25g on training days respectively. Our research team has previously analyzed this particular yogurt and protein brand using proximate analysis for macronutrient composition and high-performance liquid chromatography (HPLC) for amino acid profile determination ( 51 ), demonstrating its nutritional value. Recently, Bagheri et al. reported the efficacy of ST, along with the consumption of Icelandic yogurt (IR, formula verified) on training days (18g protein) in untrained older men (68 years) compared to a placebo group ( 25 ). Like our results, lean mass, bench press, and leg press increased significantly in both groups after the intervention (p < 0.001). Nevertheless, delta changes were more significant in the group consuming the Icelandic yogurt: lean mass (IR: Δ1.3kg, PL: Δ0.6kg), bench (IR: Δ4.3kg, PL: Δ2.3kg), and leg press (IR: Δ4.2kg, PL: Δ2.5kg) compared to the placebo. Also, the IR group had a ~ 20g/d increase in their daily protein (pre1.3 ± 0.9g/kg per d; post 1.6 ± 0.1g/kg per d) compared to placebo (pre 1.2 ± 0.1 g/kg per d, post 1.3 ± 0.1 g/kg per d) during the intervention ( 25 ) showing that yogurt is a cost-effective strategy to support ST in the older population. However, like Bagheri, the older males and females in the present study had adequate protein intake (~ 1.2g/kg per d) at the beginning of the intervention and, as expected, a significant increase in the final intake (~ 1.5-1.7g/kg per d), which is in line with the skeletal muscle mass and strength improvements shown by different protein sources when ST is performed on this particular population ( 19 , 52 , 53 ). Yogurt has also been shown to be a good source of protein for muscle adaptations in younger participants. Bridge et al. report that untrained university males increase lean mass after 12 weeks of strength training by consuming Greek yogurt (GY) compared to a placebo pudding (0g protein) ( 24 ). Particularly in this study, the GY group received an additional 60g of protein during training and 40g on non-training days compared to a placebo group, which supports that the difference in body composition obtained in the GY group was possible by the higher protein intake per se and not for the nutrient characteristics of the yogurt used. As mentioned, yogurts provide a high-quality protein source, particularly in terms of whey and casein content ( 54 , 55 ). They also contain bioactive compounds, such as bacteriocins, amino acids, peptides, and short-chain fatty acids (SCFA), that can improve overall ( 56 ) and gut health ( 57 ). It has been stated that aging induces alterations in gut microbiome dysbiosis, which could impact skeletal muscle mass and function ( 4 , 58 ). Compared to young adults, older adults have been shown to possess higher levels of Bacteroidetes and a lower proportion of Firmicutes, reflected in a reduced Firmicutes/Bacteroidetes ratio (F/B) using 16S rRNA sequencing ( 59 ). We show that ST and WP significantly increase the F/B, while PY also tends to increase. Firmicutes species, in particular, are responsible for butyrate production and other SCFAs, which play a prominent role in muscle metabolism, as shown in pre-clinical aging models ( 60 ). Although the increase in the F/B ratio is observed in some studies in adults with obesity ( 61 , 62 ), this ratio has also been positively correlated with cardiorespiratory fitness in young adults ( 63 ), suggesting a lack of consensus on this ratio when exercise is present. Regarding the bacterial genera, we reported an increase in Coprococcus (a butyrate-producing genus) in PY, a Subdoligranulum enrichment in WP, and a decrease in Prevotella after training, with significant changes observed only in the WP group. Similarly, a recent study led by Duan et al. ( 64 ) reports that ultra-marathon runners had an increase in the F/B ratio and enrichment of Coprococcus compared to sedentary controls ( 64 ). However, the mechanisms of this modulation are unknown. The results suggest that exercise intensity plays a vital role in microbiome alteration, especially in butyrate-producing genera ( 65 ). This particular area requires further study, especially among older populations with varying fitness conditions, and where yogurt could potentially enhance these benefits. Protein sources have also been considered relevant modulators of microbiome diversity ( 66 ). As mentioned, whey and casein contents in yogurt make it a good option for sustaining aminoacidemia ( 67 ) and supporting muscle health. Several authors have described an inverse correlation between frailty and microbiome biodiversity ( 68 , 69 ). In our study, the overall microbiome diversity of older adults increased in both groups. At the same time, PY intake resulted in the most significant increase in alpha diversity, as determined by Shannon entropy, compared to the WP group (Supplementary data). Recently, microbiome diversity was associated with physical activity levels in 101 older adults from 65–85 years ( 70 ), with a primary abundance of Lactobacillus, F. prausnitzii , and Roseburia intestinalis , and a lower abundance of disease-associated bacteria such as D. piger or Enterobacterales. This result suggests that physical activity improves healthy microbiota in older adults. Although we did not determine spontaneous physical activity levels, the training frequency could also be a relevant factor that warrants further study in this population. Future research should focus on assessing the specific effects of exercise types, frequency, and food sources on the gut health of older adults. Conclusion In conclusion, we demonstrate that older adults consuming either a classic whey protein supplement or a commercially available high-protein yogurt exhibit similar adaptations and improvements in muscle strength and functional capacity. At the same time, due to its digestibility, the protein matrix may have differential effects on the gut microbiome of older adults, especially on phyla and genera associated with metabolic pathways related to overall health. These findings highlight two key aspects: the effect of strength training on improving functional capacity and muscle mass, which are lost due to aging-induced sarcopenia, and the relevance of different food matrices´ compositions in supporting muscle adaptations. Although this work focused on protein intake, future research should focus on varying the content of other macronutrients, minerals, and small peptides in whey and casein, and examine their potential effects on gut health. Limitations Although the present results are relevant and highlight the role of strength training exercises and different protein sources, such as whey supplements and yogurts, on gut microbiome and overall health in older adults, it contains several limitations. First, our sample is limited to relatively healthy older adults, with no diabetes, smoking, or other medical complications that have been shown to alter the gut microbiome (i.e., dysbiosis), and where specific changes in phyla or genera could be pronounced. Second, as the present study focused mainly on the effects of the source of protein, the strength training-only group is absent. Therefore, the isolated effects of this exercise modality, especially on the gut health of older adults, still require further investigation. However, the effect of ST on muscle mass and function is widely recognized. Lastly, although the BIA equipment used in the present study for body composition analysis (Inbody 970) is reliable and comparable with Dual energy X-ray absorptiometry (DXA), especially with upper body muscle mass ( 71 ), some of the differences observed in body composition between groups could not be detected by the small number of subjects. Declarations Disclosure of interest The authors declare that they have no conflict of interest. Funding The manuscript was supported by research grants from Sociedad Chilena de Nutrición and Consorcio Lechero [M.MA], the National Fund for Science and Technological Development (ANID) (FONDECYT 11230186 [M.MA] and FONDECYT 1241959 [DV.I], the Fund for Research Centers in Priority Areas (ACT210006 [P.C.B], the Geroscience Center for Brain Health and Metabolism FONDAP-15150012, Financiamiento Basal para Centros Científicos y Tecnológicos de Excelencia Centro Ciencia and Vida, FB210008 [FA.C], and ANID/FONDAPP/15150012 [CG.B]. Author Contribution Conceptualization, M.MA, MFO, JG, CS, RT and DVI; Methodology, M.MA.PC.R, MFO, TH, SB, FS, CP, PU, CC, AR, JG, BZ, CS, RT, MPC, CG.B, FA.C and DVI; Validation M.MA.PC.R, MFO, RT, PCB, JG, CS, ST, MPC, FA.C and DVI; Investigation, M.MA.PC.R, MFO, RT, MPC, JG, CS, PCB, FA.C and DVI; Visualization: M.MA, MFO, JG, CS, RT and DVI; Supervision, M.MA, MFO, JG, CS, RT, PCB, FA.C and DVI; Project administration, M.M.A, MFO, RT, FA.C and DVI; Formal Analysis, M.MA, PC.R, MFO, JG, CS, RT and DVI; Writing – Original Draft Preparation; M.MA, PC.R, MFO, JG, CS, RT, PCB, CG.B FA.C and DVI; Writing – Review & Editing: M.MA, PC.R, MFO, JG, CS, RT, PCB, CG.B, FA.C and DVI Data Availability The datasets generated and/or analyzed during the current study are available in EMBL-EBI, specifically in the European Nucleotide Archive (ENA) repository under the code: PRJEB104255. References Roubenoff, R. & Hughes, V. A. Sarcopenia: Current Concepts. J. Gerontol. 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Supplementary Files 11SupplementaryFigure3ShannonEntropyandPrincipalComponentAnalysisofthegutmicrobiota.docx 10SupplementaryFigure2Serumlipidrenalandhepaticmarkersdifferences.docx SupplementaryTable1.NutritionalLabelingsuppplements.docx Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 12 Feb, 2026 Reviews received at journal 10 Feb, 2026 Reviews received at journal 30 Jan, 2026 Reviews received at journal 26 Jan, 2026 Reviewers agreed at journal 22 Jan, 2026 Reviewers agreed at journal 22 Jan, 2026 Reviewers agreed at journal 30 Dec, 2025 Reviewers agreed at journal 24 Dec, 2025 Reviewers invited by journal 24 Dec, 2025 Editor assigned by journal 17 Dec, 2025 Editor invited by journal 17 Dec, 2025 Submission checks completed at journal 16 Dec, 2025 First submitted to journal 15 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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07:57:49","extension":"xml","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":162848,"visible":true,"origin":"","legend":"","description":"","filename":"ecb667beb2af44aab36295885626cfc21structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/44182a5ad802515d1d276419.xml"},{"id":100174601,"identity":"df50c810-4acc-45d8-b00e-ba4150252089","added_by":"auto","created_at":"2026-01-13 17:35:38","extension":"html","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":186189,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/92ce5634fd6556ccd28ecac7.html"},{"id":100174576,"identity":"86a83b04-3276-4a5e-98c9-d53f10dce814","added_by":"auto","created_at":"2026-01-13 17:35:38","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":317223,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCONSORT 2010 Flow Diagram\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/62df16dc02cc25fc67666926.jpeg"},{"id":100368912,"identity":"f2fe4070-1d3a-412d-bd75-38ade2208bec","added_by":"auto","created_at":"2026-01-16 07:58:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":17059,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBody composition and functional physical tests. A) \u003c/strong\u003eBody weight (kg),\u003cstrong\u003e B) \u003c/strong\u003eSkeletal muscle Mass (SMM, kg)\u003cstrong\u003e, C) \u003c/strong\u003ePhase Angle (PhA, 50kHz),\u003cstrong\u003e D) \u003c/strong\u003eTotal fat mass (kg),\u003cstrong\u003e E) \u003c/strong\u003eREE (Kcal/day),\u003cstrong\u003e F) \u003c/strong\u003eMaximal Oxygen Consumption (VO\u003csub\u003e2max\u003c/sub\u003e, ml*kg*min\u003csup\u003e-1\u003c/sup\u003e), \u003cstrong\u003eG) \u003c/strong\u003eGait speed in TUG test (m/s).\u003cstrong\u003e \u003c/strong\u003eData are presented as the mean ± standard deviation (SD). Two-way ANOVA, * denotes significant intragroup differences between pre-and post-intervention (*\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05, **\u003cem\u003ep\u003c/em\u003e \u0026lt; 0,001, ns = no significant).\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/5c52a6dbf71c80768a2d8c10.png"},{"id":100174584,"identity":"a853a609-354f-44db-87e0-ef61713f2f74","added_by":"auto","created_at":"2026-01-13 17:35:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":16716,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMaximal and Isokinetic strength. A) \u003c/strong\u003e1 repetition maximum\u003cstrong\u003e \u003c/strong\u003eBench press (kg),\u003cstrong\u003e B) \u003c/strong\u003e1 repetition maximum\u003cstrong\u003e \u003c/strong\u003eLeg press (kg),\u003cstrong\u003e C) \u003c/strong\u003eDominant handgrip strength (Kg/Height\u003csup\u003e2\u003c/sup\u003e),\u003cstrong\u003e D) \u003c/strong\u003eRight quadriceps peak torque (Newton/m),\u003cstrong\u003e E) \u003c/strong\u003eRight hamstring peak torque (Newton/m),\u003cstrong\u003e F) \u003c/strong\u003eLeft quadriceps peak torque (Newton/m), \u003cstrong\u003eG) \u003c/strong\u003eLeft hamstring peak torque (Newton/m).\u003cstrong\u003e \u003c/strong\u003eData are presented as the mean ± standard deviation (SD). Two-way ANOVA, * and ** denote significant intragroup differences between pre-and post-intervention (*\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05, **\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001, and ns = no significant).\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/d99224edbcb57d031ab56c0e.png"},{"id":100368968,"identity":"72efb5ea-3d3e-43b4-9dbf-bdc84cc8f1e2","added_by":"auto","created_at":"2026-01-16 07:58:34","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":327592,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRelative abundance of bacterial phyla in the gut microbiome\u003c/strong\u003e. \u003cstrong\u003eA\u003c/strong\u003e) Relative abundance of all samples before (PRE) and after (POST) the intervention of physical activity and protein supplementation. The six main phyla shown are \u003cem\u003eActinobacteriota,\u003c/em\u003e \u003cem\u003eBacteroidota, Firmicutes, Fusobacteriota, Proteobacteria, and Verrucomicrobiota\u003c/em\u003e; the rest were grouped as \"Others.\" \u003cstrong\u003eB\u003c/strong\u003e and \u003cstrong\u003eC\u003c/strong\u003e) Specific comparisons of the relative abundance of the two most abundant phyla. Firmicutes (green) and Bacteroidota (blue). \u003cstrong\u003eD\u003c/strong\u003e) \u003cem\u003eFirmicutes/Bacteroidota\u003c/em\u003e Ratio Comparison. The ratio between the phyla \u003cem\u003eFirmicutes and Bacteroidota\u003c/em\u003e was evaluated before (PRE) and after (POST) the intervention involving physical activity and protein supplementation. Each point represents the ratio calculated for an individual sample. The black line in the bar represents the average, and the vertical line indicates the standard deviation of the group, as calculated using the applied supplement. Each circle represents the relative abundance of each sample. A Wilcoxon test was performed on the PRE and POST pairs of each protein supplement for statistical analysis. * p \u0026lt; 0.05. NS indicates not significant.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/a17799d3d97dba69a5829d09.png"},{"id":100174581,"identity":"24d0d9ad-43a9-4836-906c-3c734796ddb9","added_by":"auto","created_at":"2026-01-13 17:35:38","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":483980,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRelative abundance of bacterial genera in the gut microbiota\u003c/strong\u003e. \u003cstrong\u003eA\u003c/strong\u003e) Distribution of the 16 most abundant genera before (PRE) and after (POST) the physical activity intervention. The remaining genera were grouped under the category \"Others,\" denoted in gray. \u003cstrong\u003eB\u003c/strong\u003e) Relative abundance of seven genera: \u003cem\u003eCoprococcus\u003c/em\u003e, \u003cem\u003eEggerthellanceae DNF00809\u003c/em\u003e, \u003cem\u003eRuminococcaceae\u003c/em\u003e \u003cem\u003eDTU089\u003c/em\u003e, \u003cem\u003eKlebsiella\u003c/em\u003e, \u003cem\u003ePrevotella\u003c/em\u003e, \u003cem\u003eSubdoligranulum, \u003c/em\u003eand \u003cem\u003eButyricicoccaceae\u003c/em\u003e \u003cem\u003eUCG-008\u003c/em\u003e. A Wilcoxon test was performed between PRE and POST pairs for statistical analysis of each protein supplement. * p \u0026lt; 0.05.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/845a039505e5d8bc51f66c13.jpeg"},{"id":100368465,"identity":"139f8af5-cb88-40dd-af57-c9846cdcb0c8","added_by":"auto","created_at":"2026-01-16 07:57:59","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":78828,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSpearman correlation analysis between seven differential genera and the top 50 differential KEGG\u003c/strong\u003e. The heat map displays the correlation coefficients, represented by color gradients ranging from red (positive correlation) to blue (negative correlation). The analysis includes post-intervention groups, one supplemented with WP and the other with PY. The Benjamini-Hochberg (p-value adjusted) correction was used to control for false discoveries and adjusted as q-values, with *q-value (q \u0026lt; 0.1). Pathway annotations were derived from the KEGG database (42).\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/9852f2fc74a33f4a538c793e.jpg"},{"id":100546039,"identity":"67303340-6de5-43c0-8224-e239ae64162d","added_by":"auto","created_at":"2026-01-19 07:35:40","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2537151,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/66914864-a59f-42c2-8707-558a1b61429b.pdf"},{"id":100369882,"identity":"3b98ecdf-5685-42b4-97c4-6d23dca6014a","added_by":"auto","created_at":"2026-01-16 07:59:36","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":122874,"visible":true,"origin":"","legend":"","description":"","filename":"11SupplementaryFigure3ShannonEntropyandPrincipalComponentAnalysisofthegutmicrobiota.docx","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/3fa48f0983523363768ccb32.docx"},{"id":100368955,"identity":"33b1a14f-a571-400c-aa62-70cacb211939","added_by":"auto","created_at":"2026-01-16 07:58:32","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":98580,"visible":true,"origin":"","legend":"","description":"","filename":"10SupplementaryFigure2Serumlipidrenalandhepaticmarkersdifferences.docx","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/5f09afe57ff3c5ca0dabf802.docx"},{"id":100368394,"identity":"6c4c3e71-51fa-4f07-978b-b54eb093b083","added_by":"auto","created_at":"2026-01-16 07:57:54","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":15983,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryTable1.NutritionalLabelingsuppplements.docx","url":"https://assets-eu.researchsquare.com/files/rs-8098210/v1/05c155bfb049e0dde72f2d58.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effects of Protein yogurts vs. Whey protein on body composition, strength, and gut microbiome changes in untrained older adults during 8 weeks of supervised strength training: a randomized trial.","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLoss of muscle mass, strength, and functionality has been termed sarcopenia, a geriatric syndrome with a multifactorial etiology that increases with age (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). The determinants of sarcopenia are multifactorial, encompassing a range of biological, nutritional, and environmental factors, including decreased anabolic processes (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e), increased chronic low-grade inflammation (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e), gut microbiota dysbiosis (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e), protein-deficient diets (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), and cessation of physical exercise (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Exercise, particularly strength training (ST), is a potent stimulus for promoting skeletal muscle anabolism, resulting in metabolic and morphological improvements in this tissue, which can adapt to different frequencies, intensities, and exercise volumes at any age (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Therefore, ST is considered a primary strategy for delaying and treating sarcopenia (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn older adults, ST generates significant neuromuscular adaptations, including increases in power and strength-related abilities of daily living, such as rising from a chair, climbing and descending stairs, and active walking (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). A recent systematic review found increases of 4.7\u0026ndash;58.1% in functionality and 3.4\u0026ndash;7.5% in muscle mass in 16 studies using ST as a therapeutic measure (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). On the other hand, high-protein diet interventions may also potentiate ST-induced muscle mass gain. Vikberg et al. reported that a 10-week supervised ST resulted in a mean increase of ~\u0026thinsp;1.4 kg lean mass and improved power and walking speed in functional tests in individuals under 70 years. Notably, these individuals consumed a milk-based high-protein supplement, although it was not mandatory as part of the intervention (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). This result suggests an additive effect of high-protein intake on the anabolic effects of ST (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eProtein is an essential nutrient primarily obtained from animal sources such as meat and dairy products (i.e., milk, yogurts, cheese) and, to a lesser extent, from plants (i.e., Soy, Peas, rice) (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Differences in protein quality are based on biological value, net utilization, and the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). These factors make the selection of protein sources crucial for absorption and tolerance when ingested (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). This is particularly relevant for dairy products, as these foods possess one of the highest biological values and PDCAAS (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). For example, milk-derived proteins are composed of casein and whey, which the sports supplement industry utilizes in various forms (i.e., isolated, hydrolyzed, concentrated casein). These forms differ in their absorption speed and digestibility, which can impact protein synthesis rates (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). Whey protein has rapid absorption; in contrast, casein, which constitutes about 80% of the protein content in milk, is absorbed more slowly, resulting in a different plasma amino acid appearance (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Although protein supplements are a popular option for increasing protein intake, recent evidence from our group (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) and others (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e) suggests that different protein supplement brands do not consistently provide the quality and quantity of proteins they declare on their nutritional labels. This information should encourage the promotion of other high-quality food protein sources, especially for older adults, to support muscle and overall health (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). In healthy, non-trained males, 12 weeks of Greek yogurt intake improved strength, muscle thickness, and fat-free mass (FFM) compared to a pudding (high in carbohydrates) placebo group (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). More recently, Bagheri et al. have shown that the intake of 18 grams of protein from Icelandic yogurt in older male adults (68 years) and ST improves lean body mass and strength compared to a placebo (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). These results suggest that yogurts, which are exceptionally high in protein, can be a low-cost alternative to support muscle mass at various ages.\u003c/p\u003e \u003cp\u003eYogurts not only possess almost the exact proportions of whey and casein that milk makes a good protein source (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e) but are also recognized as functional foods by their impact on intestinal and metabolic health (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). In animal models, diets consisting of casein and whey refeed after a food restriction period differentially alter the bacterial population (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e), providing evidence of the relevance of the protein source on the gut microbiome, which remains scarce in humans. Depending on the yogurt type (i.e., Stirred, extra protein, or Greek-style), fat, protein, physical, chemical, and probiotic characteristics can vary, as well as their functional effects on health (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). We recently showed that high-protein yogurts in Chile have a good relationship with the content declared on the label (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). Moreover, the amino acid profile found in most of the samples makes them similar to whey protein. However, no study has directly compared protein intake from high-protein yogurts and whey protein supplements during a strength training program in older adults. Thus, we aimed to determine the effects of high-protein yogurt and whey protein intake on muscle strength, body composition, and microbiome diversity in older adults undergoing a guided strength training regimen.\u003c/p\u003e"},{"header":"Subjects and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eEligible participants were inactive men and women (60\u0026ndash;70 years old) with \u0026lt;\u0026thinsp;1h of exercise per week and controlled blood pressure who had no impediments to being under an ST regime. Exclusion criteria were smoking, diabetes (type 1 or 2), alcohol consumption, lactose intolerance, regular intake of non-steroidal anti-inflammatory drugs, and use of sports supplements that alter muscle mass (i.e., Whey protein, Creatine, HMB) in the last 6 months.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eParticipant recruitment\u003c/h3\u003e\n\u003cp\u003eRecruitment was advertised locally in the community, the Motion Health and Performance Centre website, and social media (i.e., Instagram). All potential participants were contacted, and the project's general aims, objectives, and procedures were thoroughly explained to them. Potential candidates were identified based on their medical history, healthy habits, resting electrocardiogram (ECG), baseline fasting plasma glucose levels, and blood pressure profiles. This study was conducted in accordance with the guidelines of the Declaration of Helsinki, and all procedures were approved by the Ethics Committee of the Universidad de O\u0026acute;Higgins (027-2023). Written informed consent was obtained from all participants. This study was registered at \u003cem\u003eClinicalTrials.gov (NCT06412302, 2025-05-14\u003c/em\u003e, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://clinicaltrials.gov/study/NCT06412302\u003c/span\u003e\u003cspan address=\"https://clinicaltrials.gov/study/NCT06412302\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e \u003cp\u003eThe sample size was calculated using G-Power\u0026reg;, accepting a significance level for α of 0.05, a power of 0.80 and an effect size of 0.5, 8 subjects per group were need it.\u003c/p\u003e\n\u003ch3\u003eStudy design and intervention\u003c/h3\u003e\n\u003cp\u003eThe present study is a randomized trial in which participants were randomly assigned to receive 25 g of Whey protein (WP) (Vanilla, ISO100, Dymatize, USA) or 24.5 g of protein from high-protein yogurt (PY) (Vanilla, Loncoleche, Chile) immediately after training sessions in an 8-week strength training regimen (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) (\u003cem\u003erandomizer.org\u003c/em\u003e, MMA). As PY has a lower protein content per serving, two yogurts were prepared by the trainers (SB and FS) and mixed with filtered water to a total volume of 240 mL. At the same time, one scoop of WP was diluted with 240 mL of water to ensure a similar volume and intake among groups and given by trainers to participants (\u003cb\u003eSupplementary Fig.\u0026nbsp;1\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eStrength training (ST) sessions consisted of 3x8-12 reps with 1\u0026ndash;2 repetitions in reserve (RIR). The training intensity ranged from 70% to 85% of 10 repetition maximum (RM), with 5% increases every 2 weeks. All sessions were supervised by a certified trainer at the Motion Health and Performance Center and were conducted in groups of 3 to ensure individualized prescriptions and participation. The training frequency was set at three days a week, with a (Monday, Wednesday, and Friday) lower, upper, and full body session schedule. The exercise selection for lower-body sessions was as follows: leg press, one-leg step-up, hip thrust, leg curl, leg extension, and calf raise. Upper sessions: Pull-down, One-arm dumbbell row, Smith bench press, Smith shoulder press, Biceps curl and triceps extension, and a full body session included: Hex-bar deadlifts, Goblet squats, Leg curl, Leg extension, Lat pull-down wide, and Smith incline bench press. All exercises were performed using Ilus equipment (Ilus Fitness Company\u0026reg;, Santiago, Chile).\u003c/p\u003e\n\u003ch3\u003eMeasurements\u003c/h3\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eBiochemical analysis\u003c/h2\u003e \u003cp\u003eBefore and after the 8-week intervention, approximately 5 mL of fasting blood samples were drawn from the antecubital vein and immediately centrifuged. The serum was separated and frozen at -80\u0026deg;C until analysis. Serum total cholesterol, Triglycerides, HDL, Albumin, BUN, Uric acid, Creatinine, GOT, GPT, and GGT concentrations were determined in an automated dry-chemistry multi-analyzer (Spotchem EZ SP-4430; Menarini Diagnostics, UK) using specific soft reagent strips (ARKRAY, Shiga, Japan).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eBody composition\u003c/h2\u003e \u003cp\u003eBody composition analysis was performed using a bioelectric impedance analyzer (InBody 970, InBody Co, South Korea). All participants were instructed to refrain from eating or drinking for 3\u0026ndash;4 hours and from consuming alcohol and engaging in exercise for 24 hours before testing. Weight (kg), body fat mass (kg), total body water (L), skeletal muscle mass (kg), percent of body fat (%), visceral fat (kg), trunk lean mass (kg), leg lean mass (kg), and whole-body phase angle (PhA\u0026deg;, 50kHz) were determined before and after the 8-week intervention.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCardiorespiratory Fitness\u003c/h3\u003e\n\u003cp\u003eAerobic capacity was determined by indirect calorimetry using a calibrated breath-by-breath gas analyzer (Metalyzer, Cortex, Germany). Participants were subjected to an incremental-maximal protocol on a cycloergometer until exhaustion, as previously described (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured and compared at baseline and the end of the intervention.\u003c/p\u003e\n\u003ch3\u003eResting metabolic rate (RMR)\u003c/h3\u003e\n\u003cp\u003eThe resting metabolic rate was determined using an indirect calorimeter (QNRG, Cosmed, Italy) with a flow-dilution canopy hood. After an overnight fast (8-12h), participants were instructed to remain in a resting condition for 15\u0026ndash;20 minutes with a regular breathing pattern in a supine position, until a steady state (\u0026lt;\u0026thinsp;10% coefficient variation of one or more variables: VO\u003csub\u003e2\u003c/sub\u003e, VCO\u003csub\u003e2,\u003c/sub\u003e or RQ) was reached, following standardized recommendations (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cb\u003e24-hour food consumption recall\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe nutritional information was obtained before and after the intervention through a 24-hour recall at the first and last laboratory visits (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). The total calories and macronutrient intake were calculated using the Photographic Atlas of Typical Chilean Food and Preparations by the Institute of Nutrition and Food Technology (INTA). Universidad de Chile (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) and performed by a registered dietitian of our team (RD).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eIsokinetic strength\u003c/h2\u003e \u003cp\u003eAn isokinetic test was performed at the beginning and after 8 weeks following ST intervention. The test was performed bilaterally on an isokinetic machine (Genu Plus; Easytech Italy, Prato, Italy), which was calibrated by a physical therapist from our team before the test session. In brief, participants spent a short period gaining confidence in the isokinetic method. Then they warmed up with 6 repetitions at 120\u0026deg;/sec, followed by 1 repetition at 60\u0026deg;/sec at 50% of the maximum. After the warm-up, all participants rest for 2 minutes to perform 4 repetitions at 60\u0026deg;/s to determine the maximal knee extension and flexion peak torque (Nm) (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eMaximal muscle strength\u003c/h2\u003e \u003cp\u003eMaximal strength was determined indirectly by the 10-repetition maximum (10RM) test as previously described (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e). In brief, 10RM was performed on the same day in the following order: Bench press (BP), Lat pull-down (LPD), and leg press (LP). Before testing, standard instructions for the exercise technique, performance, and guidance from a certified personal trainer are provided. During the 10RM test, participants performed incremental loads until they could no longer complete 11 repetitions, with a maximum of 5 attempts and 3\u0026ndash;5-minute intervals between trials.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eHand Grip Strength\u003c/h2\u003e \u003cp\u003eHand grip strength (HGS) was measured in the dominant and non-dominant hands using a Jamar Plus dynamometer (Jamar, Jackson, MI, USA), as described previously, and reported as the maximal value of the three attempts (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). Additionally, HGS was normalized by height and expressed as (Kg/M\u0026sup2;) to account for body dimensions (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eTime Up and Go (TUG)\u003c/h2\u003e \u003cp\u003eGait speed was determined using the Time Up and Go test (TUG) as previously described (\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e). Briefly, all participants refrained from standing from a chair, walked through a 3 m away cone, turned around, and sat back on the chair, walking at the fastest and safest comfortable speed. All subjects were familiarized with the test by performing it before the trials, during which the best time was recorded, and gait speed was calculated in meters per second (m/s).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eMicrobiome\u003c/h2\u003e \u003cp\u003eMicrobiome diversity, abundance, and specific bacterial groups were determined using stool samples collected before and after the intervention, as described previously (\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e). In brief, participants received a sample collection kit that included a fecal collection tube (DNA/RNA Shield\u0026trade;. Cat#R1101. Zymo Research), a disposable aluminum box to be used as a feces catcher, gloves, and an instruction manual. Each step of the procedure was thoroughly explained in detail to all subjects at the time they received the kit. After collection, the samples were kept at room temperature for approximately two weeks and then stored at -80 \u0026ordm;C until processing. DNA extraction from the fecal samples was performed using the Quick-DNA Fecal/Soil Microbe Miniprep Kit (Cat#D6010, Zymo Research), following the manufacturer's instructions. The quality of DNA extraction was verified using 1% agarose gel electrophoresis. The 16S rRNA gene sequencing was conducted using the primers 341F: CCTAYGGGRBGCASCAG and 806R: GGACTACHVGGGTWTCTAAT on the Illumina platform at Novogene (Beijing, China).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eSample size was determined based on a previous study on strength and muscular measurements after yogurt intake and strength training (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), it was calculated using G-Power that eight subjects per group (n\u0026thinsp;=\u0026thinsp;16) were required for a significance level of α\u0026thinsp;=\u0026thinsp;0.05, power of 0.80, and an effect size of 0.5. An unpaired t-test was used to determine baseline differences between groups, and a two-way ANOVA with repeated measures was used to examine both between-group and within-group differences between WP and YP, using GraphPad software (Prism, Version 10.4.2). Only participants who achieved\u0026thinsp;\u0026gt;\u0026thinsp;85% compliance to exercise training were considered for statistical analyses.\u003c/p\u003e \u003cp\u003eFor microbiome data analysis, the DADA2 and Phyloseq packages were used to process the 16S rRNA sequences and identify and quantify the microbial diversity of the samples. The sequence reads were processed to remove the first 28 bases and discard low-quality reads, using standard filtering and trimming parameters, except for maxEE and truncQ, which were set to 2. The SILVA V138 database was used as a reference to assign amplicon sequence variants (ASVs) for taxonomic determination, ranging from kingdom to genus. The data analysis included the Centered Log Ratio (CLR) transformation of the ASV matrix. The iNext package was used to calculate diversity using the Shannon index. Using Euclidean distances, Principal Component Analysis (PCA) was performed with the CLR-transformed data.\u003c/p\u003e \u003cp\u003eFunctional gene inference was performed using the PICRUSt2 pipeline, which predicts functional pathways from 16S rRNA gene sequences. LEfSe (Linear Discriminant Analysis Effect Size) analysis was employed to identify significant differences in metabolism between groups (log LDA score\u0026thinsp;\u0026gt;\u0026thinsp;2 and p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Additionally, LEfSe was used to identify differentially represented genera among the different groups. A Spearman correlation analysis was conducted to explore the relationships between seven differential genera and the 30 metabolic pathways with the highest correlation across groups. Wilcoxon tests were used for statistical analyses of phylum and genus comparisons, with significance defined as *\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, and non-significant results denoted as N.S. In the Spearman correlation analysis, the Benjamini-Hochberg correction was used to adjust \u003cem\u003ep\u003c/em\u003e-values and control the false discovery rate (FDR), with results expressed as \u003cem\u003eq\u003c/em\u003e-values (\u003cem\u003eq\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.1). This approach enabled the identification of key interactions and associations relevant to the study objectives. All microbiome analyses were performed using R (version 4.2.0) and RStudio (version 2022.7.1.554).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e \u003cb\u003eBaseline and nutritional modifications induced by yogurt and whey protein intake.\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\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\u003eWP\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;8, 5F/3M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePY\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;9, 6F/3M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (yr)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e66.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e65.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.79\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=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e72.3\u0026thinsp;\u0026plusmn;\u0026thinsp;20.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e65.1\u0026thinsp;\u0026plusmn;\u0026thinsp;13.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBody Mass Index (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e25.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e24.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSystolic Blood pressure (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e140.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e131.4\u0026thinsp;\u0026plusmn;\u0026thinsp;12.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiastolic Blood pressure (mmHg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e80.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e80.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFasting glucose (mg/dL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e114.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e113.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResting Heart Rate (bpm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e63\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e68.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eResting Metabolic Rate (kcal/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e1698\u0026thinsp;\u0026plusmn;\u0026thinsp;440\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1611\u0026thinsp;\u0026plusmn;\u0026thinsp;205\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVO2\u003csub\u003emax\u003c/sub\u003e (ml\u0026bull;kg\u0026bull;min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e21.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e22.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.58\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\u003eThe WP and PY groups were well-balanced in terms of sex and showed no differences in baseline hemodynamic, metabolic, and aerobic capacities, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. After an 8-week intervention, calorie (kcal/d) and fat (g/d) intake were not significantly\u003c/p\u003e \u003cp\u003edifferent within and between groups. In contrast, carbohydrate intake (g/d) decreased in the WP group after intervention (-36.9\u0026thinsp;\u0026plusmn;\u0026thinsp;52.9g/d, p\u0026thinsp;=\u0026thinsp;0.034), with no change in the PY group (-2.4g\u0026thinsp;\u0026plusmn;\u0026thinsp;37g/d, p\u0026thinsp;=\u0026thinsp;0.87) \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. As expected, WP and PY increase their total and weight-adjusted (g/kg) protein intake compared with baseline (WP; 22.2\u0026thinsp;\u0026plusmn;\u0026thinsp;19g/d, 0.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0g/kg and YP; 31.7\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6 g/d, 0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.0g/kg), respectively, with no differences between groups (\u003cb\u003eTable\u0026nbsp;2\u003c/b\u003e). Regarding serum lipid, renal, and hepatic markers, no significant changes were observed following the 8-week intervention with either WP or PY. (\u003cb\u003eSupplementary Fig.\u0026nbsp;2).\u003c/b\u003e\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\u003e\u003cb\u003eBaseline body composition, metabolic, and cardiovascular fitness differences.\u003c/b\u003e VO2\u003csub\u003emax\u003c/sub\u003e: Maximal oxygen consumption. Data are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). Unpaired t-test, *p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\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=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\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\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eWP\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;8, 5F/3M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003ePY\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;9, 6F/3M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eANOVA\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePre\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePost\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePre\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePost\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003ep-value*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep-value #\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalories (kcal/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1953\u0026thinsp;\u0026plusmn;\u0026thinsp;615.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1835\u0026thinsp;\u0026plusmn;\u0026thinsp;460.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.283\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1816.7\u0026thinsp;\u0026plusmn;\u0026thinsp;465.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1940.9\u0026thinsp;\u0026plusmn;\u0026thinsp;443.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.232\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProtein (g/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e82.9\u0026thinsp;\u0026plusmn;\u0026thinsp;30.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e105.1\u0026thinsp;\u0026plusmn;\u0026thinsp;20.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e79.9\u0026thinsp;\u0026plusmn;\u0026thinsp;20.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e111.6\u0026thinsp;\u0026plusmn;\u0026thinsp;17.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.000*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProtein (g/kg/)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.002*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFat (g/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.7\u0026thinsp;\u0026plusmn;\u0026thinsp;32.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e63.1\u0026thinsp;\u0026plusmn;\u0026thinsp;39.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.503\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e63.2\u0026thinsp;\u0026plusmn;\u0026thinsp;24.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e60.8\u0026thinsp;\u0026plusmn;\u0026thinsp;18.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.762\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbohydrates (g/d)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e242.0\u0026thinsp;\u0026plusmn;\u0026thinsp;84.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e205.1\u0026thinsp;\u0026plusmn;\u0026thinsp;50.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.034*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e242.0\u0026thinsp;\u0026plusmn;\u0026thinsp;62.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e239.6\u0026thinsp;\u0026plusmn;\u0026thinsp;71.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.874\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCarbohydrates (g/kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.852\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.14\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 \u003cb\u003eTable\u0026nbsp;2. Calorie and macronutrient intake assessed by 24-hour recall.\u003c/b\u003e Data are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). * Denotes significant intragroup differences between pre-and post-intervention, # Denotes significant differences post-intervention between WP and YP groups. Two-way ANOVA (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eBody composition metabolic changes after intervention\u003c/h2\u003e \u003cp\u003e8-week intervention with ST consuming WP or PY did not affect body weight (p\u0026thinsp;=\u0026thinsp;0.45) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). However, skeletal muscle mass was similarly increased in both groups after intervention (WP 0.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.74 kg, p\u0026thinsp;=\u0026thinsp;0.03, PY 0.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40kg, p\u0026thinsp;=\u0026thinsp;0.02) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB), and phase angle (PhA) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). In contrast, total fat mass (kg) significantly decreased only in WP group (p\u0026thinsp;=\u0026thinsp;0.02) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD). Importantly, neither skeletal muscle mass, PhA or fat mass was different between groups at the end of the intervention. Regarding metabolic parameters, the resting metabolic rate increased significantly after intervention in the PY group (150.1\u0026thinsp;\u0026plusmn;\u0026thinsp;132, p\u0026thinsp;=\u0026thinsp;0.03) compared to WP (131.8\u0026thinsp;\u0026plusmn;\u0026thinsp;253.7, p\u0026thinsp;=\u0026thinsp;0.08) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eE). In contrast, ST with neither nutritional intervention influenced VO2\u003csub\u003emax\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eF). However, a significant increase in gait speed was found in both groups compared to baseline (WP 0.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16m/s, p\u0026thinsp;=\u0026thinsp;0.007, PY 0.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15m/s, p\u0026thinsp;=\u0026thinsp;0.009) with no group differences (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eF).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eStrength improvements are similar between protein yogurt and whey protein.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eBench (BP) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA) and leg press (LP) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB) one repetition maximum (1RM) increase significantly in both intervention groups compared to baseline (WP; BP: Δ10.9\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3kg, p\u0026thinsp;=\u0026thinsp;0.002, LP: Δ38.5\u0026thinsp;\u0026plusmn;\u0026thinsp;24,3kg,p\u0026thinsp;=\u0026thinsp;0.003 and YP; BP: Δ12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.2kg, p\u0026thinsp;=\u0026thinsp;\u0026lt;\u0026thinsp;0.0001, LP: Δ57.1\u0026thinsp;\u0026plusmn;\u0026thinsp;19,7kg, p\u0026thinsp;=\u0026thinsp;0.007), while hand grip strength (HGS) normalized by height\u003csup\u003e2\u003c/sup\u003e improved only after PY intervention (p\u0026thinsp;=\u0026thinsp;0.02) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC). Regarding isokinetic strength, WP and PY improve right (WP Δ19.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.20 Nm, p\u0026thinsp;=\u0026thinsp;0.0004, PY Δ16.0\u0026thinsp;\u0026plusmn;\u0026thinsp;15.2Nm, p\u0026thinsp;=\u0026thinsp;0.001) and left quadriceps torque (WP Δ15.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.46 Nm, p\u0026thinsp;=\u0026thinsp;0.003, PY Δ12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7Nm, p\u0026thinsp;=\u0026thinsp;0.01) with no differences between groups at the end of the intervention (p\u0026thinsp;=\u0026thinsp;0.18) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD \u003cb\u003eand F\u003c/b\u003e). Although neither left nor right hamstrings showed significant differences between groups, PY had a positive trend (Δ7,78\u0026thinsp;\u0026plusmn;\u0026thinsp;10,33Nm, p\u0026thinsp;=\u0026thinsp;0.0504) after the intervention in the right hamstring compared to WP (Δ-1,1\u0026thinsp;\u0026plusmn;\u0026thinsp;11,66Nm, p\u0026thinsp;=\u0026thinsp;0.775).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eProtein intake from yogurt or whey protein alters the bacterial phyla, genus, and correlates with predicted functional pathways.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eRelative abundance of the six main phyla in the gut microbiome showed changes after ST in both WP and PY groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). From these phyla specifically, Firmicute\u003cem\u003es\u003c/em\u003e and Bacteroidota significantly increased and decreased, respectively, only in the WP group after ST (p\u0026thinsp;=\u0026thinsp;0.01 and p\u0026thinsp;=\u0026thinsp;0.03). In contrast, the PY group showed no change after the intervention (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC). As expected, the individual changes in the most abundant microbiome phyla alter their Firmicutes/Bacteroidota ratio (F/B), where the F/B in the WP group increased significantly (p\u0026thinsp;=\u0026thinsp;0.01) compared to the PY group (p\u0026thinsp;=\u0026thinsp;0.29) after the intervention.\u003c/p\u003e \u003cp\u003eRegarding the genus, general changes were observed after intervention in both groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). Additionally, the genera \u003cem\u003eCoprococcus\u003c/em\u003e, \u003cem\u003eSubdoligranulum\u003c/em\u003e, \u003cem\u003ePrevotella\u003c/em\u003e, and \u003cem\u003eDTU089\u003c/em\u003e showed changes in their differential abundance. On the other hand, the genera \u003cem\u003eKlebsiella\u003c/em\u003e, \u003cem\u003eEggerthellaceae (DNF00809)\u003c/em\u003e, \u003cem\u003eButyricicoccaceae, and UCG-008\u003c/em\u003e were identified in the WP group through LEfSe (see Methods) (\u003cem\u003edata not shown\u003c/em\u003e). \u003cem\u003eCopprococcus\u003c/em\u003e and \u003cem\u003eSubdoligranulum\u003c/em\u003e increased significantly (p\u0026thinsp;=\u0026thinsp;0.03 and p\u0026thinsp;=\u0026thinsp;0.02; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, PRE, and POST). At the same time, \u003cem\u003ePrevotella\u003c/em\u003e decreased (p\u0026thinsp;=\u0026thinsp;0.038) after the exercise intervention, regardless of supplementation (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, PRE, and POST). WP and PY interventions induced differential changes in the specific gut genus, where \u003cem\u003eCoprococcus\u003c/em\u003e increased only on PY (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, Protein Yogurt) (p\u0026thinsp;=\u0026thinsp;0.012), whereas \u003cem\u003eDTU089\u003c/em\u003e increased (p\u0026thinsp;=\u0026thinsp;0.014) and \u003cem\u003ePrevotella\u003c/em\u003e decreased significantly in WP groups (p\u0026thinsp;=\u0026thinsp;0.022) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB, Whey Protein). Although \u003cem\u003eKlebsiella\u003c/em\u003e, \u003cem\u003eSubdoligranulum, DNF00809, and UCG-008\u003c/em\u003e genus did not change significantly, there was a shift in gut populations confirmed with the changes in microbiome diversity in both groups expressed in Shannon entropy (p\u0026thinsp;=\u0026thinsp;0.010), and where this modification where mainly on PY group (p\u0026thinsp;=\u0026thinsp;0.04) compared to WP (p\u0026thinsp;=\u0026thinsp;0.14) (\u003cb\u003eSupplementary Fig.\u0026nbsp;3\u003c/b\u003e). Also, using PICRUSt2 and comparing it with the database (Permission N\u0026deg;254225), we conducted a Spearman analysis on the seven major abundant \u003cem\u003egenera\u003c/em\u003e against the 50 most differential functional pathways. Here, we observed similarities between intra- and intergroup bacteria enriched after WP and PY interventions (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). These changes were associated with a marked correlation in different signaling and cellular processes, including metabolism, transporters, and genetic information processing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis is the first study to compare the effects of consuming the same amount of protein from a high-protein yogurt or whey protein on body composition, physical function, and microbiome alterations during a strength training program in older adults. The key findings of the present study are that a) 8-week strength training (ST) induces important changes in muscle mass (SMM, PhA\u0026deg;), strength (1RM, Quadriceps peak torque (Nm)) and functional (gait speed) that are independent of the source of protein intake; b) ST with PY or WP differentially affect fat%, RMR, HG/ht(m)\u003csup\u003e2\u003c/sup\u003e and gut microbiome phyla and genera and; c) Microbiome changes induced by ST\u0026thinsp;+\u0026thinsp;PY or ST\u0026thinsp;+\u0026thinsp;WP are associated with the enrichment of different relevant metabolic pathways and cellular processes relevant for general health.\u003c/p\u003e \u003cp\u003eStrength training (ST) is the most effective strategy for preventing and managing the majority of primary and secondary sarcopenia consequences in older adults (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e). Importantly, training-induced changes in muscle mass and body composition are relevant and can be produced at any age (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e). Here, the 8-week ST program decreased fat mass in the WP group, increasing skeletal muscle mass and PhA\u0026deg; in both groups. PhA\u0026deg; is commonly used as a marker of cell membrane integrity and function and has been proposed as a marker of muscle function and quality (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e). Importantly, muscle quality is defined as the ability to generate force per unit of muscle mass or size, and it has also been correlated with muscle composition (i.e., myoestatosis) as a measure of muscle echogenicity (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e). Although in the present study, muscle quality was not determined, gait speed (m/s), 1RM on leg and chest press (kg), and quadriceps peak torque (Nm) increased significantly upon intervention, independent of the supplementation regime, supporting that ST, accompanied with adequate protein intake and quality, induced important improvements on muscle strength and function in older adults.\u003c/p\u003e \u003cp\u003eIn order to promote an adequate protein intake during ST in the PY group, we provided individuals with two portions (240g) of a commercially available Chilean high-protein yogurt (Extra-Proteina, Loncoleche, Chile) and the WP group with a whey protein isolated (Iso100, Dymatize) (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e) to ensure a protein intake of 24.5g and 25g on training days respectively. Our research team has previously analyzed this particular yogurt and protein brand using proximate analysis for macronutrient composition and high-performance liquid chromatography (HPLC) for amino acid profile determination (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e), demonstrating its nutritional value. Recently, Bagheri et al. reported the efficacy of ST, along with the consumption of Icelandic yogurt (IR, formula verified) on training days (18g protein) in untrained older men (68 years) compared to a placebo group (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). Like our results, lean mass, bench press, and leg press increased significantly in both groups after the intervention (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Nevertheless, delta changes were more significant in the group consuming the Icelandic yogurt: lean mass (IR: Δ1.3kg, PL: Δ0.6kg), bench (IR: Δ4.3kg, PL: Δ2.3kg), and leg press (IR: Δ4.2kg, PL: Δ2.5kg) compared to the placebo. Also, the IR group had a\u0026thinsp;~\u0026thinsp;20g/d increase in their daily protein (pre1.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9g/kg per d; post 1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1g/kg per d) compared to placebo (pre 1.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1 g/kg per d, post 1.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1 g/kg per d) during the intervention (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e) showing that yogurt is a cost-effective strategy to support ST in the older population. However, like Bagheri, the older males and females in the present study had adequate protein intake (~\u0026thinsp;1.2g/kg per d) at the beginning of the intervention and, as expected, a significant increase in the final intake (~\u0026thinsp;1.5-1.7g/kg per d), which is in line with the skeletal muscle mass and strength improvements shown by different protein sources when ST is performed on this particular population (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). Yogurt has also been shown to be a good source of protein for muscle adaptations in younger participants. Bridge et al. report that untrained university males increase lean mass after 12 weeks of strength training by consuming Greek yogurt (GY) compared to a placebo pudding (0g protein) (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). Particularly in this study, the GY group received an additional 60g of protein during training and 40g on non-training days compared to a placebo group, which supports that the difference in body composition obtained in the GY group was possible by the higher protein intake per se and not for the nutrient characteristics of the yogurt used.\u003c/p\u003e \u003cp\u003eAs mentioned, yogurts provide a high-quality protein source, particularly in terms of whey and casein content (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e). They also contain bioactive compounds, such as bacteriocins, amino acids, peptides, and short-chain fatty acids (SCFA), that can improve overall (\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e) and gut health (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e). It has been stated that aging induces alterations in gut microbiome dysbiosis, which could impact skeletal muscle mass and function (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e). Compared to young adults, older adults have been shown to possess higher levels of Bacteroidetes and a lower proportion of Firmicutes, reflected in a reduced Firmicutes/Bacteroidetes ratio (F/B) using 16S rRNA sequencing (\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e). We show that ST and WP significantly increase the F/B, while PY also tends to increase. Firmicutes species, in particular, are responsible for butyrate production and other SCFAs, which play a prominent role in muscle metabolism, as shown in pre-clinical aging models (\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e). Although the increase in the F/B ratio is observed in some studies in adults with obesity (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e, \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e), this ratio has also been positively correlated with cardiorespiratory fitness in young adults (\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e), suggesting a lack of consensus on this ratio when exercise is present.\u003c/p\u003e \u003cp\u003eRegarding the bacterial genera, we reported an increase in \u003cem\u003eCoprococcus\u003c/em\u003e (a butyrate-producing genus) in PY, \u003cem\u003ea Subdoligranulum\u003c/em\u003e enrichment in WP, and a decrease in \u003cem\u003ePrevotella\u003c/em\u003e after training, with significant changes observed only in the WP group. Similarly, a recent study led by Duan et al. (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e) reports that ultra-marathon runners had an increase in the F/B ratio and enrichment of \u003cem\u003eCoprococcus\u003c/em\u003e compared to sedentary controls (\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e). However, the mechanisms of this modulation are unknown. The results suggest that exercise intensity plays a vital role in microbiome alteration, especially in butyrate-producing genera (\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e). This particular area requires further study, especially among older populations with varying fitness conditions, and where yogurt could potentially enhance these benefits.\u003c/p\u003e \u003cp\u003eProtein sources have also been considered relevant modulators of microbiome diversity (\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e). As mentioned, whey and casein contents in yogurt make it a good option for sustaining aminoacidemia (\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e) and supporting muscle health. Several authors have described an inverse correlation between frailty and microbiome biodiversity (\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e). In our study, the overall microbiome diversity of older adults increased in both groups. At the same time, PY intake resulted in the most significant increase in alpha diversity, as determined by Shannon entropy, compared to the WP group (Supplementary data). Recently, microbiome diversity was associated with physical activity levels in 101 older adults from 65\u0026ndash;85 years (\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e), with a primary abundance of \u003cem\u003eLactobacillus, F. prausnitzii\u003c/em\u003e, and \u003cem\u003eRoseburia intestinalis\u003c/em\u003e, and a lower abundance of disease-associated bacteria such as \u003cem\u003eD. piger\u003c/em\u003e or Enterobacterales. This result suggests that physical activity improves healthy microbiota in older adults. Although we did not determine spontaneous physical activity levels, the training frequency could also be a relevant factor that warrants further study in this population. Future research should focus on assessing the specific effects of exercise types, frequency, and food sources on the gut health of older adults.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, we demonstrate that older adults consuming either a classic whey protein supplement or a commercially available high-protein yogurt exhibit similar adaptations and improvements in muscle strength and functional capacity. At the same time, due to its digestibility, the protein matrix may have differential effects on the gut microbiome of older adults, especially on phyla and genera associated with metabolic pathways related to overall health. These findings highlight two key aspects: the effect of strength training on improving functional capacity and muscle mass, which are lost due to aging-induced sarcopenia, and the relevance of different food matrices\u0026acute; compositions in supporting muscle adaptations. Although this work focused on protein intake, future research should focus on varying the content of other macronutrients, minerals, and small peptides in whey and casein, and examine their potential effects on gut health.\u003c/p\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eAlthough the present results are relevant and highlight the role of strength training exercises and different protein sources, such as whey supplements and yogurts, on gut microbiome and overall health in older adults, it contains several limitations. First, our sample is limited to relatively healthy older adults, with no diabetes, smoking, or other medical complications that have been shown to alter the gut microbiome (i.e., dysbiosis), and where specific changes in \u003cem\u003ephyla\u003c/em\u003e or \u003cem\u003egenera\u003c/em\u003e could be pronounced. Second, as the present study focused mainly on the effects of the source of protein, the strength training-only group is absent. Therefore, the isolated effects of this exercise modality, especially on the gut health of older adults, still require further investigation. However, the effect of ST on muscle mass and function is widely recognized. Lastly, although the BIA equipment used in the present study for body composition analysis (Inbody 970) is reliable and comparable with Dual energy X-ray absorptiometry (DXA), especially with upper body muscle mass (\u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e), some of the differences observed in body composition between groups could not be detected by the small number of subjects.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDisclosure of interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe manuscript was supported by research grants from Sociedad Chilena de Nutrici\u0026oacute;n and Consorcio Lechero [M.MA], the National Fund for Science and Technological Development (ANID) (FONDECYT 11230186 [M.MA] and FONDECYT 1241959 [DV.I], the Fund for Research Centers in Priority Areas (ACT210006 [P.C.B], the Geroscience Center for Brain Health and Metabolism FONDAP-15150012, Financiamiento Basal para Centros Cient\u0026iacute;ficos y Tecnol\u0026oacute;gicos de Excelencia Centro Ciencia and Vida, FB210008 [FA.C], and ANID/FONDAPP/15150012 [CG.B].\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization, M.MA, MFO, JG, CS, RT and DVI; Methodology, M.MA.PC.R, MFO, TH, SB, FS, CP, PU, CC, AR, JG, BZ, CS, RT, MPC, CG.B, FA.C and DVI; Validation M.MA.PC.R, MFO, RT, PCB, JG, CS, ST, MPC, FA.C and DVI; Investigation, M.MA.PC.R, MFO, RT, MPC, JG, CS, PCB, FA.C and DVI; Visualization: M.MA, MFO, JG, CS, RT and DVI; Supervision, M.MA, MFO, JG, CS, RT, PCB, FA.C and DVI; Project administration, M.M.A, MFO, RT, FA.C and DVI; Formal Analysis, M.MA, PC.R, MFO, JG, CS, RT and DVI; Writing \u0026ndash; Original Draft Preparation; M.MA, PC.R, MFO, JG, CS, RT, PCB, CG.B FA.C and DVI; Writing \u0026ndash; Review \u0026amp; Editing: M.MA, PC.R, MFO, JG, CS, RT, PCB, CG.B, FA.C and DVI\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated and/or analyzed during the current study are available in EMBL-EBI, specifically in the European Nucleotide Archive (ENA) repository under the code: PRJEB104255.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRoubenoff, R. \u0026amp; Hughes, V. 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Bone Metab. agosto de\u003c/em\u003e. \u003cb\u003e31\u003c/b\u003e (3), 219\u0026ndash;227 (2024).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":true,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8098210/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8098210/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eSeventeen untrained adults (60\u0026ndash;70 years) were randomized to either consume WP (25 g) or PY (24.5 g) along with an 8-week supervised ST program (3 sessions/week). Initial and final assessments included body composition (BIA), strength (10RM, isokinetic torque, handgrip), gait speed, resting metabolic rate, and gut microbiome (16S rRNA sequencing). Data were analyzed using repeated-measures ANOVA and diversity metrics.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eBoth groups increased skeletal muscle mass (WP: +0.47 kg; PY: +0.50 kg) and improved strength and gait speed (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01), with no between-group differences. Fat mass decreased only in WP (p\u0026thinsp;=\u0026thinsp;0.02), while resting metabolic rate increased in PY (p\u0026thinsp;=\u0026thinsp;0.03). Microbiome analysis revealed distinct shifts: WP increased the Firmicutes/Bacteroidota ratio and enriched \u003cem\u003eSubdoligranulum\u003c/em\u003e, whereas PY enhanced alpha diversity and increased the abundance of \u003cem\u003eCoprococcus\u003c/em\u003e. Functional pathway predictions indicated differential enrichment in metabolic and signaling processes.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eHigh-protein yogurt and whey protein similarly improve muscle mass, strength, and functional capacity during ST, while exerting distinct effects on gut microbiome composition. Yogurt represents a cost-effective alternative to whey protein and may confer additional gut health benefits. Trial registration: Clinicaltrials.gov identifier \u003cem\u003eNCT06412302\u003c/em\u003e. Date of registration 2024-05-14.\u003c/p\u003e","manuscriptTitle":"Effects of Protein yogurts vs. Whey protein on body composition, strength, and gut microbiome changes in untrained older adults during 8 weeks of supervised strength training: a randomized trial.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-13 17:35:33","doi":"10.21203/rs.3.rs-8098210/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-12T07:12:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-10T20:08:20+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-30T21:58:58+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-26T23:45:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"70014399255629547203197237452044650812","date":"2026-01-22T12:58:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"304643027369213971611600686334101416198","date":"2026-01-22T11:11:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"281152220964943521134080844381124523499","date":"2025-12-30T15:15:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"33554141685435154246634912802032005278","date":"2025-12-24T23:51:20+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-24T17:17:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-17T18:50:31+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-17T14:31:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-16T15:32:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-12-15T15:01:53+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"0aaa461e-0b7d-4b77-b871-ecf6f17793f2","owner":[],"postedDate":"January 13th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":60527754,"name":"Health sciences/Health care"},{"id":60527755,"name":"Health sciences/Medical research"},{"id":60527756,"name":"Biological sciences/Microbiology"},{"id":60527757,"name":"Biological sciences/Physiology"}],"tags":[],"updatedAt":"2026-04-27T05:38:51+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-13 17:35:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8098210","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8098210","identity":"rs-8098210","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}