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Background: Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle. However, vitamin D deficiency is a global problem, including athletes. Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results. Therefore, we aimed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta-analysis. Methods: PubMed, EMBASE, Cochrane Library, and Web of Science were searched for studies to identify randomized controlled trials or controlled trials meeting the inclusion criteria. By a meta-analysis, effect sizes (standardized mean differences, SMD) with 95% confidence intervals (CI) was calculated to compare reported outcomes across studies, I2 index was used to assessing heterogeneity, and heterogeneity factors were identified by regression analysis. The potential publication and sensitivity analyses were also assessed. Results: Eight RCTs involving 284 athletes were included. The protocols used to evaluate the muscle strength of athletes were inconsistent across the included studies, and muscle explosive power was assessed via vertical jump tests. The results indicated that vitamin D supplementation had no impact on overall muscle strength outcomes (SMD 0.05, 95% CI: -0.39 to 0.48, p = 0.84). In subgroup analysis, vitamin D supplementation had an effect on lower-limb muscle strength (SMD 0.55, 95% CI:0.12 to 0.98, p = 0.01) but not upper-limb muscle strength (SMD -0.19, 95% CI:-0.73 to 0.36, p = 0.50) or muscle explosive power (SMD 0.05, 95% CI:-0.24 to 0.34, p = 0.73). Vitamin D supplementation was more effective for athletes trained indoors (SMD 0.48, 95% CI:0.06 to 0.90, p = 0.02). Conclusions: Vitamin D supplementation positively affected lower limb muscle strength in athletes, but not upper limb muscle strength or muscle power. Different muscle groups and functions may respond differently to vitamin D supplementation. Additional studies should focus on determining the appropriate vitamin D supplementation methods and optimal serum 25(OH)D levels for athletes. Registration: The protocol for our study is registered in the international prospective register of systematic reviews (PROSPERO registration number ). [ABSTRACT FROM AUTHOR]

Purpose. To evaluate the relationships between objectively measured physical activity and physical fitness among preschool children. Methods. A total of 346 participants (201 boys and 145 girls) aged 3.5–5.5 years (M=4.5 yr, SD = 0.47) from Shanghai, China, completed physical fitness assessments, including triceps skinfold thickness (TSFT), grip strength, tennis throwing, sit and reach test, standing long jump, balance beam, 10mSRT, and 20mSRT. Physical activity was objectively measured by ActiGraphGT3X+ accelerometer. Multiple linear regression models were used to explore the cross-sectional associations between PA and physical fitness after adjusting for age, gender, BMI, and valid wearing time. Results. Positive associations were observed between stand long jump (p<.01), tennis throwing (p<.01), laps in 20mSRT (p<.01), and MVPA. However, TSFT (p<.05), time in 10mSRT (p<.01), and balance beam (p<.05) were negatively associated with MVPA. Furthermore, positive associations were found between stand long jump (p<.01), tennis throwing (p<.01), and MVPA only in boys. Negative associations were found between time on balance beam (p<.01) and MVPA only in girls. Conclusions. MVPA appears to be an effective and reliable predictor of preschoolers’ physical fitness. Boys’ body composition, muscular strength, explosive strength, agility, aerobic fitness, girls’ agility, aerobic fitness, and balance could improve as MVPA increases. [ABSTRACT FROM AUTHOR]

The aim of the study is to investigate the relationship between physical activity as assessed by accelerometers and cognitive development across the human age ranges (from children and adolescents to adults). Additionally, this study seeks to explore whether physical activity contributes to cognitive development via modification of plasma insulin-like growth factor 1 (IGF-1) and brain-derived neurotrophic factor (BDNF). In the study, 500 preschool children (3.5–5.5 years old) are taking part in 6 triennial assessment waves over the span of 15 years. At each wave, participant measures included (a) 7-day physical activity monitoring using ActiGraph’s GT3X accelerometers, (b) the evaluation of cognitive development, (c) anthropometric and physical fitness assessments, (d) plasma IGF-1 and BDNF concentrations, and (e) retrospective questionnaires. Linear regression models are used to examine the effect of physical activity on cognitive development; plasma IGF-1 and BDNF concentrations are considered as mediators into data analyses. The results of the study may help to inform future health interventions that utilize physical activity as a means to improve cognitive development in children, adolescents, and adults. Additionally, the study may assist in determining whether the putative effects occur via modification of plasma IGF-1 or BDNF concentrations. [ABSTRACT FROM AUTHOR]

There is some, albeit inconsistent, evidence supporting sex differences in preschoolers' motor competence (MC), with these observations not uniform when analyzed by age, and cultural groups. Thus, this study examined sex differences across ages in 3‐ to 5‐year‐old children's MC. A cross‐country pooled sample of 6241 children aged 3–5 years (49.6% girls) was assessed for MC using the Test of Gross Motor Development—2nd/3rd edition, and children were categorized into groups of age in months. Multiple linear regression models and predictive margins were calculated to explore how sex and age in months affect scores of MC (i.e., locomotor and ball skills), with adjustments for country and BMI. The Chow's Test was used to test for the presence of a structural break in the data. Significant differences in favor of girls were seen at 57–59 and 66–68 months of age for locomotor skills; boys performed better in ball skills in all age periods, except for 42–44 and 45–47 months of age. The higher marginal effects were observed for the period between 45–47 and 48–50 months for locomotor skills (F = 30.21; and F = 25.90 for girls and boys, respectively), and ball skills (F = 19.01; and F = 42.11 for girls and boys, respectively). A significantly positive break point was seen at 45–47 months, highlighting the age interval where children's MC drastically improved. The identification of this breakpoint provides an evidence‐based metric for when we might expect MC to rapidly increase, and an indicator of early delay when change does not occur at that age. [ABSTRACT FROM AUTHOR]

Early childhood is a critical period for development of cognitive function, but research on the association between physical activity and cognitive function in preschool children is limited and inconclusive. This study aimed to examine the association between technology-assessed physical activity and cognitive function in preschool children. A cross-sectional analysis of baseline data from the Physical Activity and Cognitive Development Study was conducted in Shanghai, China. Physical activity was measured with accelerometers for 7 consecutive days, and cognitive functions were assessed using the Chinese version of Wechsler Young Children Scale of Intelligence (C-WYCSI). Linear regression analyses were used to assess the association between physical activity and cognitive function. A total of 260 preschool children (boys, 144; girls, 116; mean age: 57.2 ± 5.4 months) were included in analyses for this study. After adjusting for confounding factors, we found that Verbal Intelligence Quotient, Performance Intelligence Quotient, and Full Intelligence Quotient were significantly correlated with light physical activity, not moderate to vigorous physical activity, in boys. Standardized coefficients were 0.211, 0.218, and 0.242 (all p < 0.05) in three different models, respectively. However, the correlation between physical activity and cognitive functions were not significant in girls (p > 0.05). These findings suggest that cognitive function is apparently associated with light physical activity in boys. Further studies are required to clarify the sex-specific effect on physical activity and cognitive functions. [ABSTRACT FROM AUTHOR]

Background and Objective: One in five preschool children are overweight/obese, and increased weight status over time increases the risks of poorer future health. Motor skill competence may be a protective factor, giving children the ability to participate in health-enhancing physical activity. Yet, we do not know when the relationship between motor competence and weight status first emerges or whether it is evident across the body mass index (BMI) spectrum. This study examined the association between motor skill competence and BMI in a multi-country sample of 5545 preschoolers (54.36 ± 9.15 months of age; 50.5% boys) from eight countries. Methods: Quantile regression analyses were used to explore the associations between motor skill competence (assessed using the Test of Gross Motor Development, Second/Third Edition) and quantiles of BMI (15th; 50th; 85th; and 97th percentiles), adjusted for sex, age in months, and country. Results: Negative associations of locomotor skills, ball skills, and overall motor skill competence with BMI percentiles (p < 0.005) were seen, which became stronger at the higher end of the BMI distribution (97th percentile). Regardless of sex, for each raw score point increase in locomotor skills, ball skills, and overall motor skill competence scores, BMI is reduced by 8.9%, 6.8%, and 5.1%, respectively, for those preschoolers at the 97th BMI percentile onwards. Conclusions: Public health policies should position motor skill competence as critical for children's obesity prevention from early childhood onwards. Robust longitudinal and experimental designs are encouraged to explore a possible causal pathway between motor skill competence and BMI from early childhood. [ABSTRACT FROM AUTHOR]

AbstractObjectiveMethodResultsConclusionTo explore the effects of a 12-week aerobic exercise program with different frequencies on executive functions (EFs) in preschool children.Four kindergartens, comprising 126 preschool children in Shanghai, were enrolled in this 12-week cluster randomized controlled trial with a 12-week follow-up period. Kindergartens were allocated to high-frequency (three times a week) or low-frequency (once a week) exercise groups using stratified block randomization. Three core sub-EFs, including inhibition, working memory, and cognitive flexibility, were assessed at baseline, post-intervention, and the 12-week follow-up.Compared to baseline, both groups showed significant improvements in inhibition and working memory after the intervention and at the 12-week follow-up. However, only the high-frequency exercise group demonstrated a significant improvement in cognitive flexibility after the follow-up period. Nonetheless, there were no significant differences in the core sub-functions of EFs between the two groups at the end of the intervention or the follow-up periods.A 12-week aerobic exercise of three times a week was insufficient to significantly improve EFs in preschool children compared to once a week. Future studies are needed to examine the dose-response relationship of aerobic exercise on EFs and to verify the effects of different exercise modalities on EFs in preschool children. [ABSTRACT FROM AUTHOR]

Introduction: The aim here is to examine the association between objectively measured usual walking speed (UWS) and bone status in community-dwelling older Chinese. Materials and methods: This is a cross-sectional study of a population of 1528 adults (817 females, mean age 68.5 ± 5.3; 711 males, mean age 69.1 ± 5.2) aged 60–79, living in communities in Shanghai. Walking speed was assessed using a 4-m walk test at a usual-pace walking speed a walking speed at which the subject felt relaxed—and bone status measured by quantitative ultrasound (QUS). The health-related characteristics of participants include family background, physical activity level, chronic disease, smoking and alcohol consumption, frequency of falls, vitamin intake, and hormone therapy. Results: Multiple linear regression is used to analyses any association between UWS and bone status, adjusting for confounding factors showing a significant association between faster UWS and a higher calcaneal stiffness index (SI) (p < 0.01). Comparing the lowest quartile of the data set with the highest at UWS, a high SI is achieved with 5.34 (95% CI = 3.22, 7.46) (p < 0.01), after adjusting for confounders. An increase of 1 dm/s was associated with a 0.91 (95% CI = 0.53, 1.29) increase in SI. This relationship for most subgroups is consistent. Conclusion: Our findings suggest that UWS can be a sensitive indicator of calcaneal bone loss among an older population. [ABSTRACT FROM AUTHOR]

Purpose:Although walking has been demonstrated as one of the best forms for promoting physical activity (PA), little is known about Chinese city children and youth's walking behavior. The purpose of this study was therefore to assess ambulatory PA behavior of Chinese city children and youth.Method:The daily steps of 2,751 children and youth (1,415 boys, 1,336 girls; aged 9 to 17 years old,Mage = 154.78 ± 44.63 months) from 11 cities in China were recorded using ActiGraph GT3X accelerometers for 7 consecutive days.Results:The most active walking day was on Friday (M ± SD = 11,183 ± 5,130 steps), followed by Monday (M ± SD = 10,780 ± 4,921), Thursday (M ± SD = 10,705 ± 4,607), Tuesday (M ± SD = 10,687 ± 5,038), Wednesday (M ± SD = 10,428 ± 4,697), Saturday (M ± SD = 9,734 ± 5,582), and Sunday (M ± SD = 9,303 ± 5,569). Participants walked more steps during weekdays (M ± SD = 10,615 ± 4,411) than they did during weekend days (M ± SD = 9,444 ± 5,224;t = 15.71,p < .01,d = 0.34); boys walked more steps (M ± SD = 10,847 ± 4,322) than did girls (M ± SD = 9,938 ± 4,282;t = 4.92,p < .01,d = 0.22). The most active age was 11 years old in boys (M ± SD = 12,984 ± 4,897) and 10 years old in girls (M ± SD = 11,745 ± 4,721), and older children walked fewer steps. The data suggest that depending on age (9 to 17 years old), a range of 5.71% to 35.73%, 29.70% to 56.65%, and 15.96% to 47.62% boys and 22.86% to 40.14%, 29.41% to 46.26%, and 12.94% to 40.14% girls met 3 different health-related criteria for daily steps, respectively.Conclusion:Boys walked more than girls walked, but a majority of the Chinese city children and youth did not meet the recommended health-related steps/day. [ABSTRACT FROM PUBLISHER]

Objective: The purpose of this study was to evaluate the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiovascular disease (CVD) risk factors in adults with overweight and obesity. Methods: Twenty-two articles were included by searching six databases, the total number of subjects was 620 in these articles. Outcomes were synthesised using a random-effects meta-analysis of the Standardized mean difference (SMD) in CVD risk factors. Results: HIIT and MICT resulted in statistically significant reductions in Weight, BMI, fat%, total cholesterol(TC), and improvement in VO2max. Compared with MICT, subgroup of durations of HIIT training interval ≥2 min can significantly increase VO2max (SMD = 0.444, 95% CI:0.037~0.851,P = 0.032), subgroup of energy expenditure of HIIT equal to MICT can significantly increase VO2max (SMD = 0.399, 95% CI:0.106~0.692,P = 0.008). Conclusions: HIIT appears to provide similar benefits to MICT for improving body composition, VO2maxand TC, but HIIT spent less time than MICT by 9.7 min on one session. HIIT is superior to MICT in improving cardiopulmonary fitness when durations of HIIT training interval ≥2 min or energy expenditure of HIIT same as MICT. PROSPERO ID: CRD42016045835. [ABSTRACT FROM AUTHOR]

Background: Data on the longitudinal association of walking pace with the risk of cognitive decline and dementia are inconsistent and inconclusive. Therefore, researchers conducted a meta-analysis of prospective cohort studies to quantitatively assess the association of walking pace with the risk of cognitive decline and dementia among elderly populations.Methods: Eligible studies were searched in PubMed and EMBASE through April 22, 2016. Additional information was retrieved through Google Scholar or hand review of the reference lists from the relevant studies. Prospective cohort studies were included if they reported relative risk (RR) and the corresponding 95% confidence interval (CI) of cognitive decline or dementia in relation to walking pace.Results: Seventeen studies were identified, including 10 studies reporting the RR of cognitive decline (9,949 participants and 2,547 events) and 10 presenting the RR of dementia (14,140 participants and 1,903 events). Comparing the lowest to the highest category of walking pace, the pooled RR was 1.89 (95% CI = 1.54-2.31) for cognitive decline and 1.66 (95% CI = 1.43-1.92) for dementia. With every 1 dm/s (360 m/h) decrement in walking pace, the risk of dementia was increased by 13% (RR = 1.13; 95% CI = 1.08-1.18).Conclusions: This meta-analysis provides accumulated evidence supporting that slow or decreased walking pace is significantly associated with elevated risk of cognitive decline and dementia in elderly populations. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationships between daily step counts and physical fitness in preschool children. Methods: Preschoolers' step counts were assessed by ActiGraph accelerometers consecutively for seven days. Physical fitness was assessed by a 20 m shuttle run test (cardiorespiratory fitness), the handgrip and standing long jump tests (musculoskeletal fitness), and the 2 × 10 m shuttle run test (speed/agility). A composite score was created from the mean of the standardized values of all physical fitness tests. Results: A total of 301 preschoolers (134 girls, mean age 57.40 ± 5.47 months; 167 boys, mean age 58.10 ± 5.34 months) were included in the final analysis. Compared with the lowest tertile, boys and girls in the highest tertile of step counts achieved high physical fitness with odds ratio (OR) being 5.39 (95% CI = 1.65–17.59) and 4.42 (95% CI = 1.30–14.99), respectively, after adjusting for confounders. Meanwhile, a relationship was observed for each 1000 steps/day increment being associated with 43% (OR = 1.43, 95% CI = 1.10–1.85) and 62% (OR = 1.62, 95% CI = 1.20–2.19) increment for high physical fitness in boys and girls, respectively. In addition, significant non-linear relationship was observed between daily steps and physical fitness in boys, which indicated that accumulated 8000 steps/day was associated with the highest ratio to achieve high physical fitness. Conclusions: Positive relationships between step counts and physical fitness were observed in preschool children, and the relationships were strongest for those who accumulated 8000 steps/day in boys. To confirm the findings in this study, well-designed and large-scale longitudinal studies are needed in the future. [ABSTRACT FROM AUTHOR]

Purpose: Examine the effects of active video games (AVGs) on children's school-day energy expenditure (EE) and physical activity (PA)-related self-efficacy, social support, and outcome expectancy over 9 months. Method: Participants were 81 fourth grade students ( X ¯ age = 9.23 years, SD = 0.62; 39 girls) from two urban Minnesota elementary schools. A once-weekly 50 min AVG intervention was implemented in the intervention school for 9 months in 2014–2015 while the control school continued regular recess. Children's school-day EE (daily caloric expenditure) and mean daily metabolic equivalent (MET) values were estimated via accelerometry whereas self-efficacy, social support, and outcome expectancy were assessed with psychometrically-validated questionnaires. All measures were completed at baseline and at the 4th and 9th months. Results: We observed significant interaction effects for daily caloric expenditure, F(1, 58) = 15.8, p < 0.01, mean daily MET values, F(1, 58) = 11.3, p < 0.01, and outcome expectancy, F(1, 58) = 4.5, p < 0.05. Specifically, intervention children had greater increases in daily caloric expenditure (91 kilocalorie/day post-intervention group difference), with control children decreasing daily caloric expenditure over time. We observed identical trends for mean daily MET values (0.35 METs/day post-intervention group difference). Interestingly, we observed outcome expectancy to increase in the control children, but decrease among intervention children, at post-intervention (1.35 group difference). Finally, we observed a marginally significant interaction effect for social support, F(1, 58) = 3.104, p = 0.08, with an increase and decrease seen in the intervention and control children, respectively. We observed no interaction or main effects for self-efficacy. Discussion: Observations suggested an AVG intervention contributed to longitudinal increases in school-day EE and social support compared to the control condition. Future research should examine how self-efficacy and outcome expectancy might be promoted during school-based AVG interventions. [ABSTRACT FROM AUTHOR]

A meta-analysis was conducted to evaluate the association between non-occupational physical activity (PA) during pregnancy and the risk of preterm birth (PTB). By searching PubMed and EMBASE from inception to August 20, 2016, 25 observational studies (18 cohorts and 7 case-controls) and 12 interventional studies were identified. Comparing the highest to the lowest category of leisure-time PA during pregnancy, the pooled relative risk (RR) of PTB was 0.83 [95% confidence interval (CI) = 0.74-0.93] for cohort studies and 0.60 (95% CI = 0.43-0.84) for case-control studies. No overall significant association was found between domestic or commuting PA and the risk of PTB. In addition, PA intervention did not indicate significant beneficial effect on the risk of PTB. Evidence from the observational studies suggested that leisure-time, but not domestic or commuting, PA during pregnancy was inversely associated with the risk of PTB. The findings were not supported by small-scale and short-term interventional studies. Further research with objective measurement on leisure-time PA is warranted. [ABSTRACT FROM AUTHOR]