A rapid systematic review of the effect of The Daily Mile™on children’s physical activity, physical health, mental health, wellbeing, academic performance and cognitive function

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22 A minority of children in the United Kingdom meet the recommended physical activity 23 guidelines. One initiative which has been introduced to try and increase the physical activity 24 levels of school children is The Daily Mile™ (TDM). The aim of this review was to 25 determine the effect of TDM on children’s physical activity levels, physical health, mental 26 health, wellbeing, academic performance and cognitive function. 27 28

29 Six databases were systematically searched from TDM’s inception (2012) to 30th June 2022. 30 Studies were included if they involved school-aged children (aged 4-12 years), taking part in 31 TDM and measured at least one pre-defined outcome. 32 33

34 Thirteen studies were included from the 123 studies retrieved. Longer-term participation in 35 TDM was found to increase moderate-to-vigorous physical activity and physical fitness. 36 None of the studies reported a significant change in Body Mass Index or academic 37 performance. An acute bout of TDM was not found to improve cognitive function, however 38 one good-quality study reported that longer-term participation in TDM increased visual 39 spatial working memory. There was evidence from one fair-quality design study that TDM 40 can improve mental health in the short term. There were no significant effects on wellbeing, 41 however scores on self-perceptions improved mainly for children with low baseline self-42 perceptions. 43 44 45 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 3

46 There is evidence to show that TDM can increase physical activity and physical fitness. 47 However, higher-quality research, with adequate participant randomisation and longer-term, 48 post-intervention follow-up is needed to ensure that any changes accurately reflect the 49 components of TDM and are sustained beyond an intervention time frame. Policy 50 recommendations of TDM increasing PA levels in the short term are supported by the 51 evidence in this review. However, long-term improvement on mental health, wellbeing, 52 academic performance and cognitive function requires further good-to excellent quality 53 research. Promisingly, several protocol articles that include randomised controlled trials with 54 long term follow-up have been published. These higher-quality design studies may provide a 55 stronger evidence-base on the effects of TDM on children’s health and should underpin 56 future recommendations in public health policy. 57 58 Systematic Review registration: PROSPERO CRD42022340303 59 Key Words 60 Daily Mile, physical activity, primary school, cognition, wellbeing, academic performance 61 62 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 4

63 There is convincing scientific evidence to support the benefits of promoting regular physical 64 activity (PA) to enhance children’s health. Health benefits from PA participation include 65 improving children’s fitness [1], maintaining healthy weight [2], strengthening muscles and 66 bones, improving sleep quality, and mental health and wellbeing enhancements [3]. There is 67 also some evidence that children who are active have improved cognitive outcomes, such as 68 academic performance and executive function [4]. In addition, children who are substantially 69 active during childhood and adolescence are more likely to maintain their physical activity 70 behaviour through adulthood [5]. Therefore, evidence highlights the importance of providing 71 children and young people with suitable opportunities for PA. 72 73 Recommendations from the United Kingdom (UK) Chief Medical Officers (CMO) is that 74 children and young people (5-18 years) should engage in at least 60-minutes per-day of PA at 75 a moderate-to-vigorous intensity level [6]. However, despite the known benefits of PA, 76 between 20-44.6% of children aged 5-16 years are currently meeting the recommended level 77 of PA in the UK [7] with children from socially disadvantaged backgrounds being less likely 78 to meet the PA recommendations [8,9]. For example in Northern Ireland where only 20% of 79 children from a low socio-economic status meet the recommended 60 minutes of Moderate-80 to-Vigorous Physical Activity (MVPA) per-day [10]. The World Health Organisation’s 81 (WHO) Global Action Plan on Physical Activity 2018-2030 aims to reduce the global 82 prevalence of physical inactivity by 10% by 2025 and by a further 5% by 2030 [11]. 83 84 PA levels are found to increase in children between the ages of three and six [12], this is due 85 to developmental changes leading to improvements in motor skills and co-ordination along 86 with growing language skills providing greater opportunities for interactive play with 87 caregivers and peers [13]. However, levels then begin to decrease from age six. A recent 88 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 5 study found that on average, levels of MVPA decreases by 2.2 minutes/day/year between the 89 ages of six and eleven (95% CI 1.9 to 2.5) [14]. Furthermore, children aged 15 years are less 90 likely to meet the PA guidelines than children aged nine [15]. As most children attend school 91 regularly, the school setting provides a suitable environment to intervene to try and increase 92 the PA levels of children from a wide range of backgrounds [2]. 93 94 The lack of sufficient time is reported as one of the most prevalent barriers for teachers when 95 attempting to implement PA interventions [16]. One initiative which has been introduced in 96 an attempt to overcome these challenges and increase the PA levels of school-aged children is 97 The Daily Mile (TDM) [17]. TDM began in Scotland in 2012 and involves children walking, 98 running or wheeling outside for 15 minutes (approximately one mile) on a minimum of three 99 days of the week [17]. TDM core principles state that it should take place in addition to 100 Physical Education time and should happen during curriculum time, and therefore not during 101 lunch or break time [17]. The practical premise behind TDM is that it is easy to set up, 102 requires no additional equipment, and can be easily integrated into the school day [17]. 103 Demonstrating its popularity, schools from across 87 countries have signed up to TDM, with 104 over 10,000 schools across the UK signed up [17]. Currently in Northern Ireland 490 schools 105 (over 50%) have signed up on the Daily Mile Foundation website. 106 107 The UK Childhood Obesity Plan encourages every school to implement an active mile 108 initiative such as The Daily Mile [18]. However, despite the large number of participating 109 schools, and Government recommendations, the scientific evidence to support the 110 effectiveness of TDM is mixed and arguably limited due to the short term follow up in 111 available research studies, and in some cases limited research designs [19,20]. With TDM 112 being incorporated into policy frameworks, there is the need for a strong evidence-base to 113 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 6 fully justify its inclusion [21], currently the evidence is not convincing. Furthermore, with 114 numerous schools incorporating TDM into their COVID-19 recovery plans with the aim to 115 improve children’s mental health and wellbeing, it is important to understand what effects, if 116 any, the TDM can have beyond increasing PA. Failing to provide such evidence exacerbates 117 the potential risk of a futile policy attempt to increase children’s activity. As such, it is 118 surprising that no systematic review of TDM has been conducted to date to inform policy 119 decision making. 120 121 To respond to the lack of any review of TDM, this rapid systematic review will identify the 122 published literature on TDM, evaluate their methodological quality, and summarise the 123 findings of the available evidence for TDM. Specifically, the review will determine the effect 124 of TDM on 4-12 year old school children’s PA levels, physical health, mental health, 125 wellbeing, academic performance and cognitive function. The practical application of TDM 126 in schools, the implications for policy makers and directions for further research are 127 discussed. 128 129

130 Review Question 131 This review aimed to answer the following question: 132 1. What are the effects of participating in The Daily Mile on children's physical activity 133 levels, physical health, mental health, wellbeing, academic performance and cognitive 134 function? 135 136 137 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 7 Protocol 138 The review was registered on the International prospective register of systematic reviews 139 (PROSPERO Registration Number: CRD42022340303). The Preferred Reporting Items for 140 Systematic Reviews and Meta-Analyses (PRISMA) guidelines [22] were followed. A 141 PRISMA checklist is included as supplementary file one. 142 143 Eligibility criteria 144 For inclusion in the review, studies were published in a peer-reviewed academic journal and 145 written in English language. Conference abstracts and grey literature were not eligible for 146 inclusion. The eligibility criteria were structured around the Population, Intervention, 147 Control, Outcome (PICO) framework. 148 149 Population 150 The population was school-aged children, between the ages of 4 and 12. If children attended 151 a special education needs school, they were also eligible for inclusion. 152 153 Intervention 154 The intervention had to consist of TDM initiative. If a study included TDM initiative 155 alongside or in conjunction with another intervention, the study was excluded as it was not 156 possible to determine the independent effects of TDM on the specified outcomes. Studies 157 with PA interventions described as similar to TDM, but not specifically TDM were not 158 included. This was to ensure included interventions were based upon the principles of TDM 159 outlined earlier. 160 161 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 8 Control 162 Studies were included if they contained control or comparison groups, but this was not a 163 requirement. 164 165 Outcomes 166 For studies to be included, they had to measure at least one outcome pertaining to the 167 following six categories: Physical activity (PA) levels (self-report or objective measures 168 [accelerometers, pedometer worn devices]), physical fitness (e.g. shuttle run test, bleep test), 169 physical health (e.g. weight, body mass index [BMI], body composition), mental health, 170 psychological wellbeing, academic performance, and cognitive function. 171 172 Information sources and search strategy 173 A systematic search of six electronic databases (MEDLINE, Embase, Web of Science, 174 PsycINFO, SPORTDiscus and Scopus) was conducted. The search timeframe was 2012 (the 175 year of TDM ‘s inception) to the date of the search (30th June 2022). 176 177

were used in the searches, with truncation and MeSH terms used depending on the 178 database. The search strategy was developed by the authors, alongside the institute 179 librarian. The reference lists of eligible studies were also hand searched and Google Scholar 180 was searched using key words for any available studies. 181 182 Study selection 183 All references retrieved from the electronic databases were imported into Covidence, a web-184 based systematic review software programme (Covidence systematic review software, 185 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 9 available at: https://www.covidence.org). Covidence automatically removes duplicate 186 articles, these were then checked by a reviewer (MH) to ensure they were exact duplicates. 187 After de-duplication at least two independent reviewers screened all titles and abstracts to 188 assess for eligibility. Articles which met the eligibility criteria were sourced and full-text 189 articles were uploaded into Covidence. The full-text articles were screened independently 190 against the inclusion and exclusion criteria by all authors. The screening tool used is included 191 in supplementary file two. At least two independent reviewers screened each article, with any 192 disagreements being resolved through consensus with a third reviewer. 193 194 Data extraction 195 The review team developed a data extraction form, and a single reviewer (MH) extracted the 196 data. A second reviewer (GB, NB or SS) checked the data extraction. Any disagreements 197 were discussed with the other members of the research team where necessary. Only data 198 relevant to the study was extracted, these included: study aim, study design, timings (how 199 long TDM was implemented), participant demographics, baseline characteristics, outcomes, 200

and information for quality assessment. 201 202 Methodological quality assessment 203 The quality of the included studies was assessed using a modified version of the Downs and 204 Black checklist [23]. The checklist includes 27 items which covers reporting, external 205 validity, internal validity (bias), internal validity (confounding) and power [23]. The Downs 206 and Black checklist can be used to assess the methodological quality of both random and 207 non-randomised studies [23]. Randomised studies can score a maximum of 28 and non-208 randomised studies can score a maximum of 25. Based on the overall score given to a study, 209 they were classified as excellent (26-28); good (20-25); fair (15-19); and poor (≤ 14). These 210 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 10 categories for classification have been previously used and reported elsewhere [24-26]. One 211 included study was a process evaluation and therefore it was not appropriate to use the 212 Downs and Black checklist and consequently the relevant sections of the Mixed Methods 213 Appraisal Tool (MMAT) were used [27]. The quality assessment was carried out by two 214 reviewers independently (MH, NB, BMcC or BMcKR). Scores were compared and any 215 disagreements were resolved through discussions and a third reviewer was consulted if 216 required. 217 218

219 Search Results 220 The literature search generated 123 articles. Duplicate articles were then removed (n=85), 221 leaving 38 titles and abstracts for review (Fig 1). Of these, 19 articles did not meet the 222 inclusion criteria and were excluded. At full text screening another seven articles were 223 excluded. As a result, 12 articles were deemed to meet the inclusion criteria and were 224 included in the review. Studies were excluded because they were the wrong intervention (not 225 TDM) or a combination of interventions, no outcomes of interest were included or were 226 conference abstracts. At the initial search stage, one preprint of a study was identified as 227 meeting all the inclusion criteria, with the exception that it was not peer reviewed, and as a 228

it was initially excluded. However, it was peer reviewed and published at a later stage 229 (August 2022), therefore was included in the review. A final total of 13 articles were included 230 in the systematic review. 231 232 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 11 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 Fig 1. PRISMA 2020 flow diagram 272 273 Description of studies 274 The study characteristics are provided in Table 1. Fields included: author’s names, year, 275 study design, duration and sample characteristics. 276 277 Records identified from: Databases (n =123) Records removed before screening: Duplicate records removed (n =85) Records screened (n = 38) Records excluded (n =19) Reports sought for retrieval (n = 19) Reports not retrieved (n =0) Reports assessed for eligibility (n = 19) Reports excluded: Wrong outcomes (n =3) Conference abstract (n = 2) Wrong intervention (n = 2) Studies included in the review (n =13) Identification of studies via databases and registers Identification Screening Included Article under review during the search but subsequently published (n=1) . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 12 Table 1: Author, year, study design, duration and sample characteristics of included studies 278 Author, Year Study design; duration Sample characteristics Arkesteyn et al. 2022 [28] Single-arm pilot; 20 weeks Schools (n=7), Children (n=550), 289 males (203 males completed SPPC) age=9.64 (1.87) Booth et al. 2022 [29] Quasi experimental between groups; Part of BBC Terrific Scientific project- data collected from schools on participation in TDM and categorised them as no participation, shorter term participation (2 months or less) and longer-term participation (3 months or more). School classes (n=503) Children (n=6908) 50% female, Age=10.2 (0.7) Breheny et al. 2020 [20] Cluster RCT; 12 months Schools (n=40) Children (n=2280) (baseline) (47.5% female) Age=8.9 (1) Brustio et al. 2019 [30] Quasi experimental Pre/post-test; 3months 5 schools, Children (n=795) C=49.8% female, I=45.7% female. Age=8(1) Brustio et al. 2020 [31] Quasi-experimental; 6 months N=548 (49.1% female) Age=9.14 Chesham et al. 2018 [32] Repeated measures pilot study; Intervention group- 8months, Control 4 months Schools (n=2) Children (n=379) C=50% female I=49% female Age=8.2 (2.0) De Jonge et al. 2020 [33] Multi-arm, partly RCT with 3 groups; 12 weeks Schools (n=9), Children (n=659) C=52.1% female, Intervention combined=50.2% female. Age C=10.1 (0.1) I=10.0 (0.1) Dring et al. 2022 [34] Quasi-experimental: 5 weeks Schools (n=2) Children (n=79) Gender not reported Age=10.3 (0.8) Harris et al. 2020 [35] Two-phase multi-method; 3 months Schools (n=1) Children (n=75) Age=7 years 8months Hatch et al. 2021a [36] Within subject randomised crossover counterbalanced; single bout of TDM and resting separated by 7 days Schools (n=8) Children (n=104) (46% female) Age=10.4 (0.7) Hatch et al. 2021b [37] Cross-sectional descriptive; Single bout of TDM Schools (n=8) Children (n=80) (50% female) Age=10.4 (0.7) Marchant et al. 2020 [38] Natural experiment; 3-6 months depending on school Schools (n=6), Children (n=258 imputed) (46% female) Age=10.2 (0.9) baseline imputed Morris et al. 2019 [19] RCT; one session of TDM School classes (n=14) Children (n=303) C=57% female, I=56% female. Age=8.99 (0.5) 279 280 SPPC Self-Perception Profile for Children C-control I-Intervention RCT- Randomised Controlled Trial 281 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 13 All articles were published between 2018 and 2022. Nine studies were conducted in the UK 282 [19, 20, 29, 32, 34-38,], two conducted in Italy [30,31], one in Belgium [28] and one in The 283 Netherlands [33]. The study sample sizes ranged from 75 participants [35] to 6908 [29]. Nine 284 of the studies included control or comparison groups [19, 20, 29-34, 36]. Four of these nine 285 studies employed some type of randomisation; two of the nine were randomised controlled 286 trials [19, 20], one partial randomisation (schools which had volunteered to implement and 287 perform TDM were randomised into intervention and intervention-plus groups) [33] and one 288 adopted a within subject randomised crossover counterbalanced design [36]. 289 290 The children in the included studies participated in TDM for different lengths of time, 291 ranging from one session of TDM [19, 36, 37] to 12 months participation [20]. The modal 292 duration of participation was three months [30, 33, 35]. 293 294 Methodological quality assessment 295 The quality of the included studies varied, with scores ranging from 15 [37] to 26 [19]. One 296 study was classified as excellent [19], six as good [20, 29-31, 34, 36], five as fair [28, 32, 33, 297 37, 38] and none were rated poor. Due to the type of study design, one study was assessed 298 using the Mixed Methods Appraisal Tool [27]. This study met 100% of the quality criteria 299 [35]. Modified Downs and Black quality checklist scoring for the included studies are 300 provided in Table 2. 301 302 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 14 Table 2: Modified Downs and Black quality checklist scoring for included studies 303 Study Domain Items Arkesteyn et al. 2022 [28] Booth et al. 2022 [29] Breheny et al. 2020 [20] Brustio et al. 2019 [30] Brustio et al. 2020 [31] Chesham et al. 2018 [32] de Jonge et al. 2020 [33] Dring et al. 2022 [34] Hatch et al. 2021a [36] Hatch et al. 2021b [37] Marchant et al. 2020 [38] Morris et al. 2019 [19] Reporting 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 3 1 1 1 1 1 1 1 0 1 1 1 1 4 1 1 1 1 1 1 1 1 1 1 1 1 5 0 2 2 2 2 2 1 0 2 0 2 2 6 1 1 1 1 1 1 1 1 1 1 1 1 7 1 1 1 1 1 1 1 1 1 1 1 1 8 0 0 1 1 0 0 0 0 0 0 0 1 9 1 0 1 0 1 0 0 1 0 0 0 1 10 1 1 1 1 1 1 0 1 1 1 1 1 External validity 11 1 1 1 1 1 0 1 1 1 1 1 1 12 1 1 1 1 1 1 1 1 1 1 1 1 13 1 1 1 1 1 1 1 1 1 1 1 1 Internal validity- bias 14 0 0 0 0 0 0 0 0 0 0 0 0 15 0 0 1 0 0 0 0 0 0 0 0 0 16 1 1 1 1 1 1 1 1 1 1 0 1 17 1 1 1 1 1 0 1 1 1 1 0 1 18 1 1 1 1 1 1 1 1 1 1 1 1 19 1 1 0 1 1 0 1 1 1 1 0 1 20 1 1 1 1 1 1 1 1 1 1 1 1 Internal validity- confoundin g 21 0 1 1 1 1 1 1 1 1 0 1 1 22 1 1 1 1 1 0 1 1 1 0 0 1 23 0 0 1 0 0 0 0 0 1 0 0 1 24 0 0 0 0 0 0 0 0 0 0 0 1 25 0 1 1 0 1 1 0 1 1 0 1 1 26 1 0 1 1 1 0 1 1 1 0 1 1 Power 27 0 0 1 0 0 0 1 1 1 0 0 1 Total (28) 18 20 25 21 22 16 19 20 23 15 17 26 Quality Fair Good Good Good Good Fair Fair Good Good Fair Fair Excellent 304 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 15 Delivery mode 305 There were variations in the implementation and execution of TDM across studies, and not 306 all studies followed the core principles set out by TDM Foundation (i.e., 15-minutes in 307 length, performed in all weather, at least 3x/week, teacher to decide when to perform TDM, 308 no change in clothes, aim to jog or run for full 15 minutes). For those studies in line with the 309 core principles, eight studies reported the duration of TDM should be 15-minutes [19, 20, 28, 310 30-32, 34, 35] and two studies reported 20 minutes duration [36, 37]. Several studies reported 311 allowing teachers to choose the time of day to carry out TDM [20, 28, 30-32]. Additionally, 312 several studies reported the desired frequency of TDM, with three studies encouraging daily 313 participation [28, 20, 34]. One study suggested TDM should be performed on all days 314 without Physical Education lessons [33] and one study stated it should be performed on at 315 least three days of the week [29]. There was also some variation in the specified exercise 316 intensity with some studies reporting children should run or walk [20, 28, 31, 32, 36, 37] and 317 one reported that children were asked to run or jog, only stopping for occasional rests if 318 required [30]. 319 320 An additional core principle of TDM is that it should be inclusive for every child, and 321 children with mobility difficulties should take part [17]. Two studies reported that children 322 with a physical or intellectual disability were excluded from the study [20, 30], two studies 323 included children with physical or intellectual disabilities in the intervention, but they were 324 excluded from the analysis [19, 31]. One study recruited two special education schools 325 (n=36), the children took part in the study, but did not complete the Self-Perception Profile 326 For Children (SPPC) [28]. 327 328 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 16 There was a large variation in intervention fidelity, with some studies not measuring 329 compliance and implementation. Those that did, reported compliance in the intervention and 330 intervention plus groups as 88% and 90% respectively [33]. One study reported school level 331 compliance, with two schools performing TDM 3x/week, two schools performing TDM 332 4x/week and three schools performing it 5x/week [28]. One study reported that all but seven 333 participants out of 79 participated in TDM daily [34]. 334 335 Outcomes 336 There was large variation in the outcome measures reported across the 13 studies. The 337 outcome measures and measurement tools, main findings and any comments of note 338 regarding any methodological issues (i.e., missing data etc) are provided in Table 3. 339 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 17 Table 3: Study outcome measures, measurement tools, main findings and comments 340 Authors (year of study) Outcome measure (s) and measurement tool Main findings Comments Arkesteyn et al. 2022 [28] Self-perceived competence &self-esteem- (SPPC self-reported). Mental health (SDQ parents complete) Small but significant increase in perceived global self-worth (p=.041) Children with low baseline SPPC scores showed significant increases with large effect sizes for global self-worth (p=<.001), scholastic competence (p=.001), social competence (p=.003), athletic competence (p=.002), physical appearance (p=<.001) and behavioural conduct (p=.003) Total difficulties score- no interaction effect for time x gender. Significant reductions over time reported by parents for total difficulties (p<.001), hyperactivity (p=.004), peer problems (p=.008) and emotional symptoms (p=<.001) Most increases occurred between week 10 and week 20. Compliance was monitored- 2 schools participated 3x/week 2 schools 4x/week 3 schools 5x/week Booth et al. 2022 [29] Cognition: Inhibition- (stop-signal task), visual spatial working memory- (static boxes search task), verbal working memory (reading span task) (self- completed on computer). Subjective wellbeing- (Adapted Children’s Feeling scale and Felt Arousal Scale children self-report). Fitness (20m shuttle run test child complete) Significant difference in visual spatial working memory scores in unadjusted models. Longer term group significantly higher scores in visual working memory (adjusted for age, sex, SES) p<0.001, compared to those who did not participate in TDM No statistically significant differences in wellbeing between those participating in TDM and those who did not take part Longer Term participation group greater shuttle distance than the group who did not do the TDM p<0.05. And those who had shorter term participation, p<0.01. Remained statistically significant when adjusted for age, sex and SES Longer term participation (more than 3 months) but was not possible to quantify further . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 18 Breheny et al. 2020 [20] BMIz score at 12 months (British 1990 growth ref data) Fitness (British Athletics Linear Track Test) Child reported QOL &Wellbeing (CHU9D & MDI Self-reported electronically under teacher supervision) Academic Performance (teacher rated) No significant impact on BMIz scores. Subgroup analysis showed significant interaction by sex- modest and statistically significant intervention effect on BMIz for girls at 12 months Fitness: Small difference in favour of control group at both 4 and 12 months but not statistically significant for imputed or complete case analysis QOL and Wellbeing: Small non-significant differences between groups in favour of intervention Academic performance: Small difference in academic attainment in favour of intervention at 12 months (p=< 0.001). Only significant in complete case analysis and not after imputation High levels of missing data in secondary outcomes Brustio et al. 2019 [30] Fitness (6-minute run test) BMI After correcting for age and gender significant group x time interactions were observed. TDM group showed an increased result between baseline and post-test (estimated difference=25.15m, SE=6.39m, p<0.001; percent change=3.1%, compared with control group (estimated difference =4.44m, SE=6.69m, p=0.911; percent change =0.5%) No significant group x time interactions were observed in BMI On average, TDM was implemented 3x/week Brustio et al. 2020 [31] Fitness- (6-minute run test child complete) Waist-to-height ratio BMI Fitness: Significant group*time interactions reported after correcting for age and BMI. I2 different T1-T2 and T1-T3. I3 different T2-T3 and T1-T3, but not T1-T2. Control different T2-T3 and T1-T3 Effect size greater for 3xweek (effect size 0.51) rather than 2xweek (effect size 0.29) Waist-to-height ratio: Significant difference in group x time interaction effect, with I3 lower between pre and mid test. No difference in BMI between groups Data in results differs from abstract . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 19 Chesham et al. 2018 [32] MVPA (Accelerometer), Fitness (20m SRT, Body composition skin folds (Standard ISAK procedures) MVPA relative increase of 9.1 minutes per day (95% CI 5.1min- 13.2min) p=0.027 Fitness: Total shuttle distance relative increase of 39.1m (95% CI 21.9 to 56.3m p=0.037) Skin folds- relative decrease of 1.4mm (-2.0 to -0.8) p=0.034 Some methodological issues- Different duration and data collection points of control and intervention groups Dring et al. 2022 [34] Cognitive function (Stroop test, Sternberg paradigm, flanker task Children self-complete on laptop) Body composition (4 skinfold sites) Body mass and BMI (Age and sex- specific British 1990 growth reference). Physical fitness (MSFT- 20m shuttle runs (child complete) Stroop test- No difference in response times on the simple level. Response times on complex level intervention group significantly faster at follow up compared to control group p=0.048. For accuracy no difference between intervention and control group at follow-up for either simple (p=0.434) or complex (p=0.580) levels Sternberg Paradigm and Flanker test- No difference for response times or accuracy at any level No difference between the intervention and control group in body composition, body mass or BMI Significant difference between the intervention and control group at follow-up for distance covered on MSFT. Intervention group 880m, compared to control group 740m p=0.002 De Jonge et al. 2020 [33] Fitness (SRT child complete) Significant increase in SRT between control and intervention groups. The change in SRT score in the intervention group was significantly greater than the change intervention-plus group Two intervention groups, Intervention plus group- additional support for teachers didn’t make any difference Harris et al. 2020 [35] MVPA (SOFIT administered by one observer) KS1 students- 100% of TDM in MVPA. Max time spent performing MVPA occurred when students interacted with peers & teachers promoted activity. KS2 students spend 13mins (88.1%) of TDM at MVPA KS1 did TDM on 54/59 (91.5%) days. KS2 did TDM on 51/59 (86.4%) days . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 20 Hatch et al. 2021a [36] Inhibitory control (Stroop test) Visual working memory (Sternberg paradigm) cognitive flexibility (Flanker test) All self-completed on laptop No difference in response times between TDM and resting Hatch et al. 2021b [37] Fitness- (Multi-stage fitness test child complete) Highest fit children ran further than less fit children (main effect of fitness, p<0.001) Marchant et al. 2020 [38] Fitness (20m SRT child complete) Both groups equal increases in shuttle runs. No significant difference in shuttle run increase for deprived compared to non- deprived children when age and gender were adjusted for Seasonal differences in data collection between schools Morris et al. 2019 [19] PA (Accelerometers) Maths fluency (MASSAT children complete) Executive function (Trail Making Task, Digit Recall, Flanker and Animal Stroop children self-complete 4 paper tests) Children in TDM engaged in statistically significantly more MVPA p≤0.001. Achieving 10.67±2.74min of MVPA during TDM compared to the control (0.44±0.95min) Maths fluency: No significant improvements Executive function: No significant difference 341 I2- Intervention group 2x week Daily Mile participation. I3- Intervention group 3x week Daily Mile participation SPPC -Self-perception Profile 342 for Children SDQ-The Strengths and Difficulties Questionnaire BMI- Body Mass Index SRT-Shuttle run test QOL- Quality of Life CHU9D-343 Child Health Utility 9 Dimension MYDI-Middle Years Development Instrument MVPA-Moderate to vigorous physical activity SOFIT-System 344 for observing fitness instruction time ISAK- The International Society for the Advancement of Kinanthropometry. MSFT-Multistage fitness test 345 PA- Physical activity MASSAT-Maths Addition and Subtraction, Speed and Accuracy Test346 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 21 Effects on physical activity 347 Three studies measured and reported PA levels or PA intensity [19, 32, 35]. One session of 348 TDM resulted in a greater amount of MVPA (10.67±2.74 min) compared to the control 349 group, (0.44±0.95 min), the difference was statistically significant [19]. One study reported 350 PA levels after longer term (8 months) participation in TDM, for MVPA there was a relative 351 increase of 9.1 minutes per day [32]. Harris and colleagues reported that Key Stage 1 children 352 spent 100% of time during TDM at MVPA and at Key Stage 2 the children spent 88.1% of 353 TDM at MVPA [35]. 354 355 Effects on physical fitness 356 Nine studies [20, 29-34, 37, 38] measured and reported physical fitness. A variety of different 357 tests were use; 6-minute run test [30,31], 20m shuttle run test [32-34, 38], Multi-stage fitness 358 test [37] and British Athletics Linear Track Test [20]. Six studies [29-34] reported a 359 significant improvement in fitness in the intervention group compared to the control group. 360 One study categorised children by fitness quartile and reported ‘highest fit children ran 361 further than less fit children’ (p<0.001) [37]. One study compared the shuttle run distances 362 completed by children categorised as deprived and those who were non-deprived and found 363 both groups had equal increases in shuttle run distance [38]. One study found small increases 364 in fitness at both four and 12 months in favour of the control group (p=0.048), however there 365 were high levels of missing data, and this result was not statistically significant when only 366 complete cases were analysed or when imputed values were used [20]. 367 368 Effects on physical health 369 Three studies reported BMI pre and post intervention [30, 31, 34], however none of the 370 studies found a significant difference in BMI between groups. In one study where BMIz 371 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 22 scores (Body mass index z-scores, are a measure of relative weight adjusted for child age and 372 sex) were reported [20] although TDM did not have a significant impact on BMIz scores at 373 12 months, subgroup analysis indicated significant interaction by sex, with the intervention 374 effect for girls being modest and statistically significant at 12 months [20]. 375 376 Three studies reported on body composition [31, 32, 34]. One study reported no difference in 377 waist circumference, hip circumference, or sum of skin folds, between intervention and 378 control groups [34]. One study reported a relative decrease of 1.4mm in skin folds [32]. In 379 one study, lower waist-to-height ratios were found between pre and mid test in the group who 380 completed TDM more than 2.5 times a week on average [31]. 381 382 Effects on psychological wellbeing 383 Psychological wellbeing was reported in two studies [20, 29], one study found small 384 differences in favour of the intervention group after 12 months of TDM, but the results were 385 not statistically significant [20] and the other study found no statistically significant 386 differences in wellbeing between those participating in TDM and those who did not take part 387 [29]. 388 389 Small but significant increases in perceived global self-worth were found using The Self-390 Perception Profile for Children (SPPC) [28]. Children with low baseline SPPC scores showed 391 significant increases with large effect sizes for global self-worth, scholastic competence, 392 social competence, athletic competence, physical appearance and behavioural conduct [28]. 393 394 395 396 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 23 Effects on Mental Health 397 One study [28] reported the impact of participation in TDM on mental health, as measured by 398 The Strengths and Difficulties Questionnaire [39] completed by their parents. There were 399 significant reductions over time reported by parents for total difficulties, hyperactivity, peer 400 problems and emotional symptoms [28]. 401 402 Effects on academic performance 403 Two studies reported the effect of TDM on academic performance [19, 20]. One study found 404 a small difference in teacher rated academic attainment in favour of the intervention group at 405 12 months, however there was high levels of missing data (over 50%), and this was only 406 significant when complete cases were analysed and not when imputed values were used [20]. 407 One study found no significant improvements in maths fluency scores after a single bout of 408 TDM [19]. 409 410 Effects on cognition 411 Two studies included explored the effects of an acute bout of TDM on various aspects of 412 cognitive function [19, 36]. No significant improvements were found in executive function 413 [19], inhibitory control [36], cognitive flexibility [36] or working memory [36] after a single 414 bout of TDM. 415 416 However, one study where children had longer term participation in TDM (3 months or 417 more) found that those who had participated in TDM for longer had higher scores in visual 418 spatial working memory than those who did not participate in TDM [29]. In addition, 419 although one study did not find five weeks participation in TDM to increase response times 420 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 24 in the simple level in the Stroop test, response times were significantly faster on more 421 complex versions of the Stroop test in the intervention group [34]. 422 423

424 This systematic review summarised the results from 13 studies, examining the impact of 425 TDM on children’s physical activity levels, physical fitness, physical health, psychological 426 wellbeing, academic performance, and cognitive function. To the best of our knowledge, this 427 is the first systematic review of TDM initiative for primary school-aged children. Over the 428 past ten years there has been a rapid adoption of TDM and other ‘active miles’ in schools, 429 community settings, and such approaches have been cited in, and formed the basis of 430 Government policy. This review was conducted in response to the limited evidence base to 431 support such widescale adoption, and to guide the future integration of TDM into health 432 interventions and potential policy. All studies included in this review were also assessed for 433 methodological quality to examine what degree of confidence could be placed alongside 434 study outcomes. 435 436 Overall, both acute and longer-term participation in TDM was found to increase MVPA by 437 approximately ten minutes per-day [19, 32]. This is a relatively greater increase in MVPA 438 than found by other PA interventions in primary school children [40, 41]. Although findings 439 show that children do not spend the whole 15-minutes of TDM at a moderate-to-vigorous 440 intensity [19, 32, 35], the reported increases are welcomed given higher levels of MVPA 441 have been associated with improved cardiometabolic health in children [42]. Additionally, it 442 goes some way to help children achieve the public health recommended 60 minutes of 443 MVPA per day. 444 445 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 25 In addition to an increase in MVPA, in general, the included studies reported a positive effect 446 of TDM on physical fitness, however, the variety different fitness tests used across studies 447 makes direct comparisons difficult. One of the studies which lasted for 5 weeks, reported the 448 intervention group completed 140 metres more than the control group in the multi-stage 449 fitness test at follow-up [34]. This shows that improvements in fitness can be achieved in a 450 relatively short space of time when TDM is conducted five days per-week [34]. Frequency of 451 participation is an important factor to consider, with those who participated at least twice a 452 week showing an increase of 5.6% in a 6-minute run test, whereas those who performed 453 TDM three or more times a week had an increase of 8.8% [31]. These results suggest there 454 may be a dose-response associated with TDM, requiring implementation according to the 455 core principles (performed at least 3x/week) to maximise improvements in physical fitness. 456 457 None of the included studies reported a significant reduction in BMI. This is in contrast with 458 a Cochrane Review which found that PA interventions can reduce BMI in children aged six 459 to 12 [43]. This likely suggests the effect of 15 minutes of daily (3-4 times week) exercise is 460 not enough to substantially impact weight. However, as children’s body composition is 461 naturally changing at this developmental stage, a reduction in BMI should not be a primary 462 aim of TDM implementation. 463 464 Longer-term (20 weeks) participation in TDM was reported to improve children’s mental 465 health as measured by The Strengths and Difficulties Questionnaire, along with small but 466 significant increases in perceived global self-worth [28]. The greatest increase occurred 467 between weeks 10 and 20, suggesting that the changes in self-esteem may only take place 468 when the PA in school is sustained for a longer period of time [28]. In addition, the finding 469 that children with lower baseline SPPC scores had large positive increases in perceptions of 470 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 26 competence, physical appearance and behavioural conduct (see Table 2) indicates that the 471 effect of TDM may be greater for children with lower initial perceptions of self-worth and 472 self-competence. Although these results are promising, especially with schools adopting 473 TDM into their COVID-19 recovery plans for children’s mental health and wellbeing, the 474

were found in a single arm pilot study so there was not a control group for 475 comparison. 476 477 More research is needed with regards to the effect of TDM on academic performance, with 478 only two studies reporting outcomes of academic performance [19, 20]. In one study [20] 479 academic performance was measured through teacher reported scores, which has potential for 480 bias. In addition, there was a large degree of missing data (over 56%) and therefore these 481

should be interpreted with caution. 482 483 This review found that a single bout of TDM did not have a significant effect on cognition. 484 This is in contrast with two systematic reviews which found the majority of acute PA 485 interventions in children improved cognitive function [44, 45]. These results suggests that 15 486 minutes of exercise may not be enough to impact cognition and a longer bout of exercise may 487 be required to see benefits, or there may have been methodological issues that did not capture 488 the potential effects. However, longer term participation in TDM improved visual spatial 489 working memory [29] and increased response times on complex levels in the Stroop test [34]. 490 However, the latter finding was based on a small study (n=79) with a quasi-experimental 491 design. Consequently, larger, randomised controlled trials are needed to strengthen the 492 evidence base of what, if any, effects are present for TDM on cognition. 493 494 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 27 Many of the findings suggest that timing of data sampling and the length of intervention are 495 important factors to consider. In one study, improvements in waist-to-height ratios in the 496 intervention group were reported at three months but at six months they had reverted to 497 similar scores to baseline [31]. No formal process evaluation was carried out so it is not 498 possible to assess how often TDM was performed and how this may have changed over the 499 duration of the study. These results may suggest that compliance and motivation dropped off 500 after the initial excitement of participation or that TDM only has benefits initially [20]. Given 501 the implications for both research recommendations and TDM implementation in practice, 502 future studies should record compliance and report on intervention fidelity throughout the 503 intervention period. 504 505 One study reported that although children enjoyed participating in TDM they expressed an 506 appeal for more variety in activity types and described TDM as ‘a bit boring’ [36]. This was 507 also reported by Marchant and colleagues [38] where pupils discussed one of the barriers to 508 TDM being lack of enjoyment and boredom associated with it, suggesting that after initial 509 excitement wore off motivation decreased [38]. 510 511 One of the key attractive features of TDM is the simplicity of adoption and delivery by 512 teachers, with no equipment or special training required. However, research into the barriers 513 and facilitators of TDM have found that approximately half the teachers use some form of 514 reward system to increase motivation [46]. Different methods include awarding tokens, 515 tracking distance, or teachers running with pupils [46]. According to theories of motivation 516 (i.e., Self-Determination Theory [47]), if this is done in an outcome-orientated, controlling 517 style, it may undermine longer term autonomous motivation for PA. Additional planning and 518 preparation by teachers can add to their already heavy workload and may result in waning 519 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 28 participation in TDM. Qualitative research supports this feeling, suggesting TDM may not be 520 as simple to implement in practice with additional costs associated with extra staff time to 521 prepare for an engaging and exciting Daily Mile experience [48]. Teachers reported the need 522 to keep TDM ‘fresh’ by adding new motivational strategies to keep pupils engaged [48]. 523 524 The intensity TDM is performed at is another important consideration. The majority of 525 longer-term studies failed to measure or report the intensity that TDM was performed. As a 526 result, it is not possible to report the effect of intensity on the outcomes in most studies. It is 527 probable that the studies in which the children performed TDM at a higher intensity saw 528 greater improvements in physical fitness. One study reported a large variation in intensity 529 with the most active children spending the duration of TDM in MVPA, compared to the least 530 active children who only spent 33% at MVPA [19]. More attention in future research could 531 assess intensity, and if intensity levels are implicated in affective experiences of TDM [49]. 532 533 There is also a concern that the long-term sustainability of TDM is limited due to the lack of 534 behaviour change theory principles underpinning it in the school environment. It has been 535 suggested that it may be beneficial to develop a programme theory in order to help 536 understand and explain the behaviour of staff and pupils involved in TDM [50]. Physical 537 activity interventions which were theoretically underpinned have been found to have the 538 greatest effect on long-term behaviour change [51]. More so, the potential theoretical 539 underpinnings of TDM should consider principles from a broad range of approaches, 540 including social-cognitive, humanistic, dual-process, and socioecological frameworks [52]. 541 542 Another factor which needs to be considered in further research is the need to include 543 children with physical or intellectual disabilities. These children were not included in many 544 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 29 of the studies in this review, or were excluded from analysis, despite one of TDM core 545 principles being inclusivity. Children with intellectual or physical disabilities are an 546 important group to target as are often reported as being less fit and have poorer health than 547 their non-disabled peers [53]. The ‘Walk-Buds’ trial which is currently underway, operates a 548 peer buddy system, where younger children are partnered with an older peer with similar 549 interests to complete their physical activity [54]. A similar approach may be worth 550 considering with TDM. Furthermore, evaluation into the impact of TDM for children with 551 intellectual or physical disabilities is needed to provide evidence of the benefits for these 552 groups. 553 554 Strengths and limitations 555 This systematic review followed the PRISMA guidelines, and all papers were screened 556 independently by two authors. Data extraction was done by one author and checked by a 557 second, and quality assessment was completed independently by two reviewers. This review 558 implemented a comprehensive search strategy which was developed by the team and 559 institution librarian. A further strength of the study was that it looked at both the acute and 560 long-term effect of TDM. However, there were limitations. There was a high level of 561 heterogeneity between the studies included in the review and therefore it was difficult to 562 compare studies directly. One such difference was how TDM was implemented; for example, 563 the duration of TDM, how many times a week it was performed and the intensity at which it 564 was performed. Moreover, there were large variations in both the reporting of intervention 565 fidelity and the compliance to the intervention. Future studies need to record and report 566 fidelity and compliance data at an individual level as it may be a potential confounder. 567 568 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 30 Most studies included in this review involved schools who had self-selected themselves to 569 take part, it is likely that schools with staff who have an interest in PA and are aware of the 570 benefits and importance of it were more likely to take part and were more motivated to 571 facilitate TDM and as a result there could be some sampling bias. 572 573

and future directions 574 The Daily Mile is performed in over 15,600 schools and nurseries across the world [17], in 575 addition to underpinning some public health policy. However, the evidence supporting its 576 benefits is limited to a relatively small number of mostly fair-to-good quality studies (n=13). 577 As such, this systematic review has gone some way to clarify the quality and robustness of 578 this existing evidence base. Findings from this review suggest TDM can increase children’s 579 physical fitness and MVPA levels. There is also some fair-to-good quality evidence that it 580 may improve body composition, mental health, and self-perceptions. TDM did not affect 581 BMI or academic performance, however. An acute bout of TDM did not affect cognitive 582 function, although longer term participation was found to improve some areas of cognitive 583 function. Whilst initial results are promising, the long-term benefits are unclear due to an 584 insufficient number of studies, and a dearth of good and excellent quality study designs 585 across each of the outcomes reported. As such, higher quality research is needed with longer 586 term follow up to explore the sustainability of intervention effects. There is also a need for 587 process evaluations and proper reporting to ascertain implementation. 588 589 A longitudinal quasi-experimental cohort study is currently underway, following children 590 from year 1 to year 6 [55]. It is hoped this, and future studies will provide greater evidence to 591 support the long-term benefits of TDM not only on PA, but on the other outcomes covered in 592 this review. In addition, as only four of the included studies employed any randomisation, 593 . CC-BY 4.0 International licenseIt is made available under a perpetuity. is the author/funder, who has granted medRxiv a license to display the preprint in(which was not certified by peer review)preprint The copyright holder for thisthis version posted November 4, 2022. ; https://doi.org/10.1101/2022.11.03.22281578doi: medRxiv preprint 31 future randomised controlled trials are required to ensure that any public policy 594 recommendations for TDM on improving mental health, wellbeing, cognitive function and 595 academic achievement are centred on a stronger scientific evidence base. 596 597 Acknowledgments 598 We would like to acknowledge the support of the Daily Mile Network Northern Ireland, 599 Nicola Topping from the Education Authority Northern Ireland and Colette Brolly from the 600 Public Health Agency in Northern Ireland. 601 602

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