Despite the well-documented role of swimming competence in preventing childhood drowning, little is known about how preschoolers' swimming competence differs across cultural contexts. This study aimed to examine cross-regional variations in swimming competence and related behavioral and environmental factors among preschoolers. Parent-child dyads (N = 2059) from the United States (n = 500), Australia (n = 500), Singapore (n = 507), and Hong Kong (n = 552), with children aged 2-6years (Mage = 4.23 [1.10]y), completed the Swimming Competence Questionnaire. Preschoolers had an average maximum swimming distance (max-dis) of 17.80 (61.12)m, and a swimming competence index (SCI) of 15.50 (19.56) out of 100. Preschoolers from Australia (Mmax-dis = 13.46 [12.24]m; MSCI = 19.59 [20.46]) and the United States (Mmax-dis = 13.91 [11.98]m; MSCI = 16.35 [18.77]) had significantly better swimming competence than those from Singapore (Mmax-dis = 26.46 [50.19]m; MSCI = 14.77 [18.44]) and Hong Kong (Mmax-dis = 18.96 [21.05]m; MSCI = 12.80 [20.35]). Compared with those from other regions, preschoolers from Australia had the highest swimming frequency and greatest accessibility to swimming facilities, and they were more likely to receive professional swimming instruction. Findings underscore the importance of providing children with opportunities to engage in swimming to improve swimming competence.

The purpose of this study was to explore whether incorporating gyroscopic and accelerometer data will improve the prediction of energy expenditure (EE) of preschool children. Three model configurations were developed and compared using (1)accelerometer, (2)gyroscope, and (3)accelerometer + gyroscope data (dual sensor). Participants (n = 39; aged 3 to <6 years) were equipped with OPAL, GT9X, and GENEActiv devices, worn on the right hip, right wrist, and left wrist, while EE was simultaneously measured using a portable metabolic unit. The protocol consisted of semistructured activities spanning a range of intensities from low to high. A total of 54 machine learning models were developed to predict EE (2 EE measures [metabolic equivalents, kilojoules per minute] × 3 wear locations × 3 model types [random forest, linear regression, and fully connected neural network] × 3 sensor configurations). Model performance was evaluated using root mean squared error. Our findings reveal that, across the various configurations, the random forest model utilizing dual-sensor data achieved marginally lower mean root mean squared error in the majority of cases. Given the minimal improvements observed and the challenges associated with data acquisition, we recommend that researchers utilize accelerometer-based models moving forward.

Fundamental motor skills (FMS) support children's participation in health-enhancing physical activity (PA), yet it remains unclear whether postintervention motor skill gains translate into increased PA. This study used cross-sectional and prospective analyses to examine associations between changes in preschoolers' FMS and PA immediately following the Children's Health Activity Motor Program and again 6months later. Preschoolers (N = 153; 86 girls, mean age = 53.14mo [4.43y]) from 3 preschool centers participated. Process-oriented FMS were assessed using the Test of Gross Motor Development-Third Edition, and product measures were collected for running, jumping, hopping, kicking, and throwing. Moderate to vigorous PA was measured using wrist-worn ActiGraph accelerometers. Linear mixed models tested associations between FMS and PA changes, controlling for age, sex, and body mass index and accounting for preschool center differences. Improvements in locomotor skills were positively associated with increased moderate to vigorous PA postintervention, whereas improvements in object control skills were negatively associated with moderate to vigorous PA at the same time point. No significant prospective associations were observed. These findings suggest that locomotor skill gains may support short-term PA among preschoolers, but further research is needed to clarify additional aspects of the FMS-PA relationship after motor skill interventions.

To examine longitudinal changes in exercise-induced hormonal responses in adolescent male basketball players. Fifteen adolescent males were assigned to prepeak height velocity (pre-PHV) and post-PHV groups according to the predicted age at PHV. Salivary testosterone, cortisol levels, and the testosterone-to-cortisol ratio were evaluated before (PRE), immediately after (POST), and 15minutes after a bodyweight resistance training session, which was repeated after 1year to analyze longitudinal changes in testosterone and cortisol levels. Resting testosterone levels and acute testosterone responses after bodyweight resistance training increased in both groups after 1year at all measurement points. The POST testosterone levels at initial measurement and PRE and 15-minute postexercise levels at 1year in the post-PHV group were significantly higher than those in the pre-PHV group. Cortisol levels significantly decreased in the post-PHV group at baseline and 1year later. In the post-PHV, the testosterone-to-cortisol ratio after bodyweight resistance training was significantly increased at baseline and 1year later. Although testosterone levels increase with age, no acute response to bodyweight resistance training was observed after 1year. The change in anabolic status indicated by the testosterone-to-cortisol ratio was due to a decrease in cortisol levels.

Rigorous evidence concerning the reliability of physical tests among young athletes is lacking. Therefore, this study aimed to comprehensively determine the retest reliability of the most commonly used tests to assess physical qualities in adolescent rugby league players, and to provide the standard error of measurement and minimal detectable change for each test to support objective athlete monitoring. A repeated-measures design was employed with 50 adolescent, schoolboy rugby league players (16.2 [1.3]y) completing the same testing battery across 2 consecutive weeks. Within each week, stature, body mass, and ∑4 skinfold thickness assessments,as well as countermovement jump, medicine ball throw, and 1-repetition maximum bench press, back squat, and prone row tests were conducted on the first testing day. Forty-eight hours later, a second testing day contained the 10- and 20-m linear sprints, 505-Agility Test, L-run Test, and Multistage Fitness Test. Nonsignificant (P > .05), trivial differences (dav = 0.00-0.16) were evident between trials in all tests. The coefficient of variation ranged from 0.05% to 4.02% across tests. The intraclass correlation ranged from .704 to .999. All tests presented relatively low standard error of measurement, with accompanying minimal detectable change provided. These data can help inform decision making among end-users when implementing tests in a repeated manner and interpreting testing data.

The aim of this study is to investigate the postural balance in children with intellectual disabilities who participate in soccer training compared with their sedentary peers. Two groups of boys with intellectual disabilities aged 8-10years participated in this study: a soccer group (n = 12) and a sedentary group (n = 12). Postural balance was assessed using a force platform under 4 different conditions: open eyes, and closed eyes, on firm and foam surfaces. The Timed Up and Go Test, 10-m Walking Test, and Four-Square Step Test were also conducted. The soccer group had significantly lower (P < .05) center of pressure values compared with the sedentary group, on both firm and foam surfaces, but only under the open eyes condition. They were significantly faster (P < .05) in the Timed Up and Go Test, 10-m Walking Test, and Four-Square Step Test compared with their sedentary peers. However, there were no significant differences between the 2 groups on the sit-to-stand and turn-to-sit phases of the Timed Up and Go Test. Soccer participation may have a positive effect on postural balance in boys with intellectual disabilities. These findings may have implications for the development of exercise programs to improve postural balance and reduce the risk of falls in this population.

Rating of perceived exertion (RPE) is a convenient and cost-effective tool that can be used to monitor high-intensity interval exercise (HIIE). However, no methodological study has demonstrated the validity of RPE in this context. Therefore, the aim of this study was to validate and calibrate RPE for monitoring HIIE in adolescents. RPE, heart rate (HR), and oxygen uptake (V˙O2) data were retrospectively extracted from 3 lab-based crossover studies, with a pooled sample size of 45 adolescents, performing either cycling-based or running-based HIIE sessions. Within-participant correlations were calculated for RPE-HR and RPE-V˙O2, and receiver operator characteristic curve analysis was used to establish RPE cut points. The results showed that RPE-HR demonstrated acceptable criterion validity (r = .53-.74, P < .01), while RPE-V˙O2 had poor validity (r = .40-.48, P < .01), except for HIIE at 100% peak power (r = .59, P < .01). RPE cut points of 4 and 5 were established in corresponding to HR/V˙O2 based thresholds. RPE has some utility in evaluating intensity during lab-based running or cycling HIIE in adolescents. Future studies should expand the validation and calibration of RPE for prescribing and monitoring HIIE in children and adolescents in field-based contexts.

The purpose of this study was to compare the gross motor skills of children with a chronic physical illness with those of their healthy peers. Data for children with a chronic physical illness come from the Multimorbidity in Children and Youth Across the Life Course study, and data from children without a physical illness come from the Health Outcomes and Physical Activity in Preschoolers study. Multimorbidity in Children and Youth Across the Life Course and Health Outcomes and Physical Activity in Preschoolers included children ages 3-5years and administered the Peabody Development Motor Scales-second edition. Participants were sex and age matched (20 male and 15 female pairs; Mage = 54.03 [9.5]mo). Gross motor skills scores were "below average" for 47% of children with a physical illness compared with 9% of children without a physical illness (P = .003). Matched-paired t tests detected significant differences in total gross motor scores (dz = -0.35), locomotor (dz = -0.31), and object control (dz = -0.39) scores, with healthy children exhibiting better motor skills, and no significant difference in stationary scores (dz = -0.19). This skill gap may increase burden on children with physical illnessand future research should assess gross motor skills longitudinally to establish whether the gap widens with age.

To explore the multivariate pattern associations between physical fitness and adiposity with cardiometabolic risk among children and adolescents. Cross-sectional study including 6405 participants (6-18y; 3567 females). Waist circumference, sum of 3 skinfolds, and physical fitness measures (abdominal endurance, agility, cardiorespiratory fitness, flexibility, speed, and lower/upper limb power) were assessed. A continuous risk score (cMetS) was calculated as the mean of the z-scores for glucose, systolic blood pressure, total cholesterol and high-density lipoprotein cholesterol ratio, and triglycerides. Three models were tested using multivariate patterns analysis, of which the following explanatory variables were included: (1)both physical fitness and adiposity measures, (2)only physical fitness, and (3)physical fitness adjusted for adiposity measures. In the latter model, cMetS was also adjusted for adiposity. Inverse associations with cMetS were found for abdominal endurance, agility, cardiorespiratory fitness, lower limb power, and speed among males; and agility and cardiorespiratory fitness among females; without adjustment for adiposity. When cMetS and physical fitness were adjusted for adiposity, agility (only among males) and cardiorespiratory fitness remained associated with cMetS. The findings highlight the consistent adiposity-independent role of cardiorespiratory fitness as the primary fitness marker associated with cardiometabolic health during childhood and adolescence, alongside evidence linking agility to risk.