The health benefits of muscular fitness for children and adolescents: a systematic review and meta-analysis

Efficacy of time restricted eating and resistance training on body composition and mood profiles among young adults with overweight/obesity: a randomized controlled trial

BACKGROUND/OBJECTIVE

Dietary restriction or exercise regimens can promote weight loss or physical fitness among patients with obesity. However, intervention-associated adverse effects may impede patients' motivation to participate in dietary/exercise interventions. We examined the effects of time restricted eating (TRE) with or without resistance training (RT) on body composition, mood profile, and sleep quality in young college adults with overweight or obesity.

METHODS

Fifty-four young college students with overweight/obesity were randomized into control (CON), TRE, RT, and TRE plus RT (TRE+RT) trials. The TRE trials restricted to an eating window of 10-hour/day for 8-week. The RT trials performed supervised resistance exercise, while the control trial maintained a regular lifestyle. Changes in body composition variables, blood pressure, mood status, and sleep quality were measured before and after the intervention.

RESULTS

TRE intervention alone or in combination with RT significantly (p < 0.01) decreased body weight (>2 kg) and BMI (~1 kg/m2) in adults with overweight/obesity. Both RT alone and combined with TRE substantially decreased fat mass by 1.1 ± 0.5 and 3.2 ± 0.4 kg, respectively. The decreased fat mass was greater in the combination trial than in the RT trial, whereas TRE alone had no effect. In contrast, fat-free mass was significantly (p < 0.01) decreased with TRE (-2.3 ± 06 kg), increased with RT (1.6 ± 0.3 kg), and was stably maintained with combination interventions. The reduced waist and hip circumferences in the TRE (p < 0.01) were similar to those in the TRE+RT trials, however, RT alone had no effect. Time and group interaction showed a large effect size (partial eta squared) for all body composition variables. In addition, RT with or without TRE notably decreased diastolic blood pressure (RT: -5.5 ± 1.9 mmHg, TRE+RT: -4.1 ± 1.5 mmHg, p < 0.05). Mild anxiety levels at baseline in RT (4.8 ± 2.6) and TRE+RT (4.1 ± 3) trials were found to be normal at postintervention in TRE+RT (3.6 ± 1.7) but not in RT (5.6 ± 3.5). No depression or stress was recorded among the participants during the intervention. The reported poor sleep quality among participants at baseline was significantly improved with RT (4.8 ± 2.9; p < 0.05), and tended to improve with TRE+RT interventions (4.5 ± 1.9).

CONCLUSIONS

10-hour TRE is beneficial for weight/fat loss without affecting mood status. However, TRE combined with RT might be more effective for weight/fat loss, maintaining muscle mass, and good quality of sleep among young adults with overweight or obesity.

Effects of Implementing 15-Minute Physical Exercise Sessions During Physical Education Classes on Physical Fitness and Anthropometric Indicators in Rural Adolescents

BACKGROUND

The prevalence of overweight, obesity, and low physical fitness is associated with minimal engagement in physical exercise (PEx) and has increasingly affected children and adolescents in rural areas. This study examines the effects of a 15-minute PEx intervention on the levels of physical fitness and anthropometric indicators of overweight and obesity among rural school students.

METHODS

A total of 245 school students (135 boys and 110 girls), aged between 11 and 17 years, were randomly allocated into intervention and comparator groups. The intervention lasted for 12 weeks, comprising 24 PEx sessions. Physical fitness was measured through cardiorespiratory fitness, muscular strength/endurance, handgrip strength, lower limb power, flexibility, speed, and agility. The measured anthropometric indicators of overweight and obesity included body mass index, waist circumference, and the sum of subscapular and triceps skinfolds.

RESULTS

Generalized estimating equations analysis, performed with an intention-to-treat approach, indicated significant group × time interaction (P < .05) for flexibility, muscular strength/endurance, handgrip strength, cardiorespiratory fitness (only for boys), and waist circumference. For these 5 variables, there were no differences between groups at the baseline (P > .05), and the intervention group showed significantly greater improvements compared with the comparator group at the postintervention time (P < .05).

CONCLUSION

An intervention program consisting of 15 minutes of PEx during PE classes, conducted twice a week for 12 weeks, improves cardiorespiratory fitness, flexibility (only for boys), muscular strength/endurance, handgrip strength, body mass index (only for girls), and waist circumference of rural adolescent school students.

An Integrative Neuromuscular Training Program in Physical Education Classes Improves Strength and Speed Performance

Background/Objectives: This longitudinal randomized controlled study aimed to evaluate the effects of an integrative neuromuscular training (INT) intervention on strength and speed measures in Spanish students across different age groups. Methods: A total of 121 students, aged 11-12 (G1) and 15-16 (G2), were randomly assigned to four groups: two experimental groups, G1exp (n = 30) and G2exp (n = 31), and two control groups, G1con (n = 30) and G2 (n = 30). Experimental groups participated in two 20 min INT sessions per week for four weeks, focusing on physical literacy (agility, coordination, balance, and speed) and a resistance training program, integrated into the first part of physical education classes (PEC). Results: Experimental groups showed significant improvements (p < 0.001) in lower-body power (G1exp: t = -7.04; d = -1.30; G2exp: t = -5.19; d = -0.91), upper-body power (G1exp: t = -5.94; d = -1.10; G2exp: t = -3.52; d = -0.62), abdominal endurance strength (G1exp: t = -9.72; d = -1.80; G2exp: t = -4.75; d = -0.84) and sprinting (G1exp: t = 5.22; d = 0.96; G2exp: t = 5.90; d = 1.04). A comparison by age groups revealed significantly greater improvements in upper-body power in G1 vs. G2 (t:-2.83; p = 0.02). Conclusions: A four-week INT program implemented at the start of PE classes can improve strength and sprint performance in youth across all ages. We recommend incorporating INT into the first part of physical education sessions to contribute to meeting the physical activity, well-being and conditioning needs of young people.

Special Issue "Health and Performance Through Sports at All Ages 3.0"

In recent years, the growing attention of the scientific community on the benefits of sport and physical activity for health and performance has generated a significant body of research [...].

The Era of Resistance Training as a Primary Form of Physical Activity for Physical Fitness and Health in Youth Has Come

Resistance training (RT) is widely regarded as the gold standard approach for enhancing muscular fitness (i.e., muscle strength, power, and muscular endurance) in youth while also providing health and physical fitness benefits traditionally associated with aerobic training (e.g., enhanced cardiorespiratory fitness, reduced body fat, improved insulin sensitivity). Additionally, while bone health can be improved following RT (particularly after plyometric jump training), aerobic training may result in a lesser or even neutral impact on bone mineral density enhancement (e.g., swimming). Regarding mental health and cognition, while aerobic training has well-established positive effects, preliminary evidence in obese youth suggests that RT may offer greater benefits in certain aspects compared to aerobic training. Additionally, RT can reduce the risk and incidence of injuries in youth. Overall, we argue in this Current Opinion article that the current consideration of RT as an additional, rather than essential (possibly even the most essential), aspect of physical activity in current national and international guidelines needs to be reconsidered. Overall, there is an urgent need to inform relevant stakeholders that, while aerobic activities remain essential, the next generation of physical activity guidelines should place greater emphasis on the particular importance of RT, providing more comprehensive guidance on its implementation for youth.

The effect of exercise on cardiovascular disease risk factors in sedentary population: a systematic review and meta-analysis

Objective

The aim of this study (PROSPERO CRD42023443860) was to determine the dose-response associations of exercise on cardiovascular disease risk factors in sedentary populations using systematic evaluation and meta-analysis.

Methods

We conducted a systematic search of the literature up to July 2024 using PubMed, Web of Science, and SCOPUS. Of the 72,704 search records initially identified, 15 studies were considered eligible for systematic evaluation and meta-analysis. The methodological quality of the included literature was assessed using the Cochrane Risk Assessment Tool. Using a random-effects model, we pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) for key cardiovascular risk factors.

Results

Exercise improved systolic blood pressure [SMD = -0.33 (95% CI, -0.62 to -0.05), p = 0.02], diastolic blood pressure [SMD = -0.52 (95% CI, -0.92 to -0.12), p = 0.01], and resting heart rate [SMD = -0.30 (95% CI, -0.50 to -0.10), p = 0.004]. However, no significant effects were observed for total cholesterol [SMD = -0.03 (95% CI: -0.24 to 0.18), p = 0.78], HDL cholesterol [SMD = 0.06 (95% CI: -0.16 to 0.27), p = 0.6], LDL cholesterol [SMD = -0.21 (95% CI: -0.59 to 0.18), p = 0.29], triglycerides [SMD = -0.11 (95% CI: -0.42 to 0.21), p = 0.51], or body mass index [SMD = 0.01 (95% CI: -0.16 to 0.17), p = 0.94].

Conclusion

Regular exercise with a duration of 30-40 min per session and a frequency of 3-5 sessions per week significantly improves blood pressure and resting heart rate in sedentary populations, but does not appear to affect lipid profiles or body mass index.

Population-based trends and distributional characteristics in sit-ups performance among school-aged girls in urban China over three decades

This paper aims to assess population-based trends and distributional characteristics in the sit-ups performance, body height, body mass and body mass index (BMI) among school-aged girls in urban China from 1985 to 2019. Height, mass, BMI and sit-ups performance data for Han Chinese urban girls aged 7-18 years were obtained from the Chinese National Surveillance on Students' Constitution and Health surveys from 1985 to 2019. Population-based trends were estimated by a post-stratification population weighting procedure. There was a moderate improvement in sit-ups performance from 1985 to 2019, increasing by 25.7% or 0.69 effect size (ES). Girls aged 10-12 years experienced the smallest improvement (0.46 ES) and girls aged 16-18 years experienced the largest improvement (0.88 ES). Improvements in sit-ups performance were the major trend across periods, but there was a negligible improvement in the 1990s (0.04 ES) and a small decrease in the 2000s (-0.36 ES), while height, mass and BMI (from 2000 to 2019) continued to increase from 1985 to 2019. The distribution of the change in sit-ups performance was uneven, the improvements were somewhat greater at both ends of the distribution.The government should implement differentiated health promotion programs, especially for those with greater health risks.

Comparison of physical activity, sedentary time, and physical fitness among Chinese children and adolescents in Qinghai between 2019 and 2023

This study aimed to assess the differences in physical activity and physical fitness in 2019 and 2023 among children and adolescents in Qinghai Province. Data were collected from the Chinese National Survey on Student Constitution and Health (CNSSCH) in 2019 and 2023. The study ultimately included 13,296 participants (5,039 in 2019 and 8,257 in 2023) aged 6-22, including primary, middle, and high school students in Qinghai Province, China. Physical fitness assessments included height, weight, vital capacity, sit-and-reach distance, pull-ups, timed sit-ups, standing long jump, 50-meter dash, 800-meter run, 1000-meter run, 50 m × 8 shuttles run, and timed rope-skipping. Independent samples T-tests and multiple linear regression analyses were employed to explore differences and associations in moderate-to-vigorous physical activity (MVPA), sedentary time (SED), and physical fitness in this population in 2019 and 2023. Compared to 2019, children and adolescents measured in 2023 showed a significant increase in MVPA and a significant decrease in SED. Vital capacity improved significantly across all academic stages, with primary school girls showing improved performance in the 50 × 8 shuttles run. Secondary school students significantly declined in their performance in 800 m and 1000 m runs. Standing long jump performance improved for middle and high school students, while pull-ups declined for high school boys. Timed sit-ups declined for middle school girls, with no significant changes at primary and high school. Flexibility improved for high school boys and both middle and high school girls but decreased for primary school boys and girls, as well as for middle school boys. Timed rope-skipping was measured only in primary school students, and it improved significantly. Speed performance, measured by the 50 m dash, improved in primary school students but declined in middle and high school students. Regression analysis revealed that MVPA was positively associated with vital capacity, 800 m running, standing long jump, pull-ups, and timed sit-ups, while negatively associated with 1000 m running, timed rope-skipping, and 50 m dash. SED was positively associated with 800 m and 1000 m running performance and timed sit-ups. Our study highlights distinct trends in physical fitness across school stages, and sex associations of MVPA and SED with fitness outcomes underscore the need for tailored, region-specific health strategies in high-altitude, underdeveloped areas.

Associations of Physical Fitness During Childhood with Arterial Structure and Stiffness in Adolescence: An 8-Year Follow-up Study

BACKGROUND

Cardiovascular diseases (CVDs) are the leading cause of morbidity and premature mortality globally. While the relationship between indicators of physical fitness and arterial structure and stiffness are reasonably well-studied in adults, these associations in children and adolescents remain less understood. The aim of this study was to investigate longitudinal associations of cardiorespiratory fitness, muscular fitness and motor fitness with arterial structure and stiffness from childhood to adolescence.

RESULTS

Higher mean value of VO2peak/LM from childhood to adolescence was associated with higher carotid intima-media thickness (cIMT) at 8-year follow-up (β = 0.184, 95% confidence interval [CI] = 0.019 to 0.350). Better performance in sit-up test at baseline was associated with lower cardio-ankle vascular index (CAVI) (β = - 0.219, 95% CI = - 0.387 to - 0.051) at 8-year follow-up, and higher mean sit-up performance from baseline to 8-year follow-up was associated with lower carotid-femoral pulse-wave velocity (cfPWV) (β = - 0.178, 95% CI = - 0.353 to - 0.003) and CAVI (β = - 0.190, 95% CI = - 0.365 to - 0.016) at 8-year follow-up. Also cross-sectionally, better sit-up performance at 8-year follow-up was associated with lower cfPWV (β = - 0.232, 95% CI = - 0.411 to - 0.054) and CAVI (β = - 0.185, 95% CI = - 0.365 to - 0.005) and higher carotid artery distensibility (β = 0.165, 95% CI = 0.004 to 0.327) at 8-year follow-up. Most of the associations were explained by body fat percentage (BF%).

CONCLUSIONS

Physical fitness had a weak if any association with indicators of arterial structure and arterial stiffness in adolescence. BF% largely explained the associations of higher VO2peak/LM with higher cIMT and better sit-up performance with lower arterial stiffness in adolescents. Therefore, preventing adiposity rather than improving CRF should be addressed in public health strategies to prevent CVDs in general paediatric populations.

KEY POINTS

Better sit-up performance was associated with lower arterial stiffness, but the association was largely explained by body fat percentage. Lower body muscular strength, handgrip strength, or motor fitness was not associated with arterial stiffness or carotid artery intima-media thickness. Measures other than cardiorespiratory fitness, muscular fitness, or motor fitness, such as adiposity, should be used to screen children and adolescents at increased risk of cardiovascular diseases.

Integrating Physical Activity into a Nutrition and Exercise Science Middle School Curriculum: The THINK Program

BACKGROUND/OBJECTIVES

Recent interest has emerged in novel initiatives that focus on the "whole child" to improve the health and well-being in youth. The purpose of this study was to determine whether a translational health in nutrition and kinesiology (THINK) program addressing physical, psychological, and educational well-being could improve personal health and lifestyle behaviors in youth.

METHODS

A total of 81 adolescents (44 males, 37 females, 12.50 + 0.62 years) were evaluated at the beginning and end of the spring semester across three different years: 2019, 2021, and 2023. The physical literacy measures included the Physical Activity Enjoyment Scale (PAES) and the Physical Activity Perception Scale (PAPS), along with knowledge-based tests in nutrition and exercise science. Social emotional learning (SEL), STEM education, and nutrition habits were evaluated using standard surveys and questionnaires. The physical evaluations included measures of body composition and physical fitness.

RESULTS

At the completion of the spring semester of each year, evaluations were compiled for all three years, with decreases found for % body fat (p < 0.001) and increases found for lean body mass (p < 0.001). The physical fitness components, including muscular strength (p < 0.001), cardiorespiratory fitness (p < 0.001), power (p < 0.001), and flexibility (p < 0.01), all improved. The physical literacy components, including the PACES (p < 0.001), PAPS (p < 0.001), exercise (p < 0.05), and nutrition science knowledge (p < 0.05) results, also improved. There were no significant changes in any other variables.

CONCLUSIONS

A novel in-school academic curriculum integrating the physical, psychological, and educational well-being of the whole child could lead to improved body composition, physical fitness, and physical literacy.

Handgrip Strength in Children and Adolescents Aged 3 to 16 Years and Residing in Spain: New Reference Values

Introduction: Handgrip strength, measured by dynamometry (HGD), is a key measure in assessing physical condition and nutritional status. Its correlation with anthropometric measures and body composition makes it an accessible method for the evaluation of cardiovascular health. This study aimed to develop a new reference for right-hand dynamometry in the Spanish population and compare it with previous references. Material and Methods: A total of 3281 subjects aged 3 to 16 years (1608 females) from the PESCA, PASOS, and ASOMAD projects were included. Handgrip strength was measured using the same methodology in all cases. Data on age, weight, height, and BMI were collected, and the handgrip strength per kilogram of body weight was calculated. Sexual dimorphism in the temporal development of strength was analyzed, and multiple correlations were established between dynamometry and anthropometric variables. Results: Percentile curves and tables for dynamometry are presented for each sex, including data from as early as 3 years old, for the first time. Conclusions: Sexual dimorphism in strength development is confirmed, becoming more pronounced with puberty. In absolute terms, our study shows a decrease in handgrip strength among adolescents, occurring earlier and more markedly in females. When compared to the previous literature, the 16-year-old male adolescents in our study exhibited lower strength than those from 40 and 16 years ago.

Mediation of obesity-related variables in the association between physical fitness and cardiometabolic risk in children and adolescents: a systematic review and meta-analysis

Objective

To examine the mediation of obesity-related variables in the association between physical fitness and cardiometabolic risk in children and adolescents.

Design

Systematic review and meta-analysis.

Data sources

Studies from electronic databases from inception to 31 December 2023.

Eligibility criteria for selecting studies

Included were 123 observational studies (cross-sectional and longitudinal) that assessed risk by constructing a continuous score incorporating cardiometabolic parameters. Studies were considered if they evaluated at least one fitness component as an exposure in children and adolescents (5-19 years). Thirty-one were included in the main meta-analyses.

Results

Cross-sectional findings indicate that cardiorespiratory fitness is modestly but beneficially associated with cardiometabolic risk, either indirectly via obesity-related variables (indirect standardized beta coefficient [βIndirect]=-0.17; 95% confidence interval [CI] -0.23; -0.11; inconsistency index [I2]=94.4%) or directly and independently from obesity-related variables (r=-0.11; 95% CI -0.15; -0.07; I2=87.4%), whereas muscular fitness seems to be associated with risk only via obesity-related variables (βIndirect=-0.34; 95% CI -0.47; -0.20; I2=85.1%). There was no cross-sectional difference between biological sexes (p≥0.199). Longitudinal findings indicate no total (r=-0.12; 95% CI -0.24; 0.01; I2=23.1%) and direct (r=-0.03; 95% CI -0.08; 0.03; I2=0%) associations.

Conclusion

The association between fitness and risk appears to take place either indirectly through the reduction of obesity-related levels or directly by influencing risk. The latter underscores that the inverse association extends beyond a mere reduction in obesity-related variables, encompassing specific enhancements linked to exercise training, including increased metabolic efficiency, and cardiovascular capacity.

PROSPERO registration number

CRD42022354628.

Vitamin C-Dependent Intergenerational Inheritance of Enhanced Endurance Performance Following Maternal Exercise

Declining levels of physical activity and fitness in children and youth are linked to negative health outcomes. This study investigates whether maternal exercise can enhance offspring's physical fitness. Our results demonstrate that maternal exercise improves offspring's endurance by changing muscle fiber composition and promoting mitochondrial biogenesis, with benefits lasting across generations. This improvement is associated with changes in DNA methylation, specifically the demethylation of the Slc23a2 gene, which codes for SVCT2, crucial for vitamin C (VC) transport, in F1 and F2 generations. Importantly, VC administration during pregnancy mimics the transgenerational benefits of exercise on offspring fitness, but these benefits are absent in genetic VC deficiency mice. VC supplementation increases TET2 expression in murine and human myogenic cells, regulating DNA methylation, promoting the development of oxidative fibers, and enhancing mitochondrial biogenesis. This study highlights the VC-TET2-SVCT2 pathway as a key mechanism for the transgenerational endurance benefits of maternal exercise, suggesting potential strategies to enhance maternal and child health.

The effect of diverse sports skills interventions on physical fitness and brain development among Chinese high school students: a cluster randomized controlled trial study protocol

BACKGROUND

During adolescence, research concerning physical fitness and brain development has become a focal point in health and neuroscience. Academic debates on the precise impact of different sports skills on adolescent physical fitness lack consensus. While exercise's positive effects on brain development in children and older adults are well-documented, its specific impact on adolescents remains unexplored. A year-long trial explores how diverse sports skills affect adolescents' physical fitness and brain development. The study has a dual focus: first, to examine the potential correlation between sports skills acquisition and indicators of adolescent physical fitness; and second, to investigate the mechanisms of brain plasticity in adolescents. This comprehensive study is poised to fill knowledge gaps, providing a scientific basis for targeted health interventions in adolescent populations.

METHODS

This study will employ a randomized controlled cluster design involving senior high school students in Shanghai. The expected sample size is approximately 450 students, divided into four experimental groups and a control group. The experimental groups will undergo 1 year of sports skills training in basketball, football, tennis, and martial arts, while the control group will receive regular physical education classes. Prior to intervention, data will be collected on students' physical fitness, sports skills, levels of physical activity, and functional magnetic resonance imaging (fMRI) measurements. Rigorous control of variables will ensure comparability and experimental validity. For data analysis, specialized software tools, including SPSS 18.0, AMOS 18.0, Matlab R2013b, and EXCEL, will be employed for comprehensive analysis and interpretation, validating potential differences between experimental and control groups in various aspects of physical fitness and sports skills.

DISCUSSION

This experiment aims to provide substantial scientific evidence on the impact of sports skills learning on diverse indicators of adolescent physical fitness. In addition, it aims to elucidate the effects of exercise on adolescent brain plasticity and its specific underlying mechanisms. This comprehensive evidence base is poised to serve as a basis for more effective interventions in the future, providing enhanced scientific guidance for promoting holistic adolescent development. It also provides scholars and practitioners with fresh perspectives on adolescent health development.

TRIAL REGISTRATION

The study was registered at the China Clinical Trial Registry (ChiCTR2300070942).  https://www.chictr.org.cn . Registered on April 10, 2023.

Trends in physical fitness among Lithuanian adolescents aged 11-17 years between 1992 and 2022

BACKGROUND

Physical fitness is an excellent marker of general health and performance. We aimed to calculate trends in physical fitness among Lithuanian adolescents between 1992 and 2022.

METHODS

Using a repeated cross-sectional design, body size and physical fitness data for 17 918 Lithuanian adolescents (50.3% female) aged 11-17 years were collected in 1992, 2002, 2012 and 2022. Body mass index (BMI) was calculated from measured height and body mass, with BMI z-scores (zBMI) calculated using WHO growth curves. Physical fitness was measured using the Eurofit test battery, with results converted to z-scores using European norms. With adjustment for zBMI, trends in mean fitness levels were calculated using general linear models. Trends in distributional characteristics were visually described and calculated as the ratio of SDs.

RESULTS

We found significant large declines (standardised effect size (ES) ≥ 0.80) in 20-m shuttle run and bent arm hang performance, and significant small declines (ES=0.20-0.49) in standing broad jump, plate tapping, sit-and-reach and sit-ups performance. In contrast, we found a significant moderate improvement (ES=0.50-0.79) in flamingo balance performance and a significant negligible improvement (ES<0.20) in 10×5-m shuttle run performance. Poorer trends were observed in low performers (below the 20th percentile) compared with high performers (above the 80th percentile).

CONCLUSION

Health-related fitness (ie, cardiorespiratory and musculoskeletal fitness) levels have declined among Lithuanian adolescents since 1992, particularly among those with low fitness. National health promotion policies are required to improve current trends.

Development and Testing of Physical Literacy Scales for Chinese Elementary School Students - China, 2022

Background

This study aimed to develop and validate test-based physical literacy scales (PLSs) for primary school students across different grades.

Methods

Data were collected through a field survey conducted from June 1 to July 31, 2022, involving 3,275 primary school students from four provinces in China. The questionnaires assessed four domains: physical knowledge, physical competence, physical motivation, and physical behavior. The Rasch model was employed for psychometric analysis.

Results

The variance explained by measures for the PLSs was 53.1%, 50.3%, and 54.7%, all exceeding the 50% threshold, confirming unidimensionality and robust internal consistency. This enabled effective differentiation among students with varying proficiency levels. The item-person map demonstrated optimal alignment between item difficulty and participant ability levels. Most items showed favorable fit statistics, with Infit mean square (MNSQ) and Outfit MNSQ values ranging between 0.5 and 1.5.

Conclusions

The PLSs demonstrate validity and reliability in measuring physical literacy among Chinese primary school students across four components: physical knowledge, physical competence, physical motivation, and physical behavior. The scales measure a unidimensional construct, supporting the use of summed total scores for assessment.

Weight-Specific Grip Strength as a Novel Indicator Associated With Cardiometabolic Risk in Children: The EMSNGS Study

CONTEXT

Handgrip strength (HGS) is an important indicator of sarcopenia and adverse health outcomes. However, evaluating HGS in children presents challenges, and its association with metabolism remains incompletely understood.

OBJECTIVE

To establish grip strength reference values for Chinese children and adolescents, as well as to evaluate the relationship between HGS and cardiometabolic risk.

METHODS

Data were collected from 4 072 participants aged 6-18 as part of the Evaluation and Monitoring on School-based Nutrition and Growth in Shenzhen (EMSNGS) study. HGS was measured, and relative HGS (RHGS) was normalized by body mass index. Age- or weight-specific HGS and RHGS were derived using the generalized additive model of location, scale, and shape model, and participants' values were categorized into quartiles, defining low strength as the lowest quartile. The cardiometabolic risk index (CMRI) z-score was calculated, with high risk defined as a z-score of ≥1.

RESULTS

Both boys and girls exhibited similar increases in age- and weight-specific grip strength. Low grip strength, classified by weight-specific HGS and RHGS, was linked to higher CMRI z-scores than classifications based on age-specific references in both sexes. A dose-dependent relationship was observed between weight-specific grip strength and cardiometabolic risk, particularly in boys. Compared with the middle category (P25th-P75th), the odds ratios for high cardiometabolic risks associated with low grip strength increased in both sexes.

CONCLUSION

This study established grip strength reference values for Chinese youth, introduced the concept of weight-specific HGS and RHGS, and demonstrated a dose-dependent relationship between weight-specific grip strength and cardiometabolic risk. These findings highlighted the association between low muscle strength and increased cardiometabolic risk.

Lower Musculoskeletal Fitness Among Youth with Disabilities, Ages 6 to 15 Years

BACKGROUND

Youth with disabilities (YWD) often exhibit deficits in physical fitness, but much of the literature is limited by small, non-representative samples. The purpose of this study was to examine differences in musculoskeletal fitness between youth with and without disabilities from the 2012 National Youth Fitness Survey (NYFS).

METHODS

A secondary analysis was conducted with cross-sectional data from the 2012 NYFS of youth, 6 to 15 years of age. Fitness measures included plank, modified pull-ups, and grip strength. Disability was identified by multiple parent report items. Logistic regression with sampling weights was employed to examine group differences and associated factors.

RESULTS

A total of 1177 youth were analyzed, including 173 YWD. A significantly greater proportion of YWD demonstrated low fitness in all three measures compared to youth without disabilities. Factors associated with low fitness included sex, engagement in physical activity, and the body mass index category. Age was not a significant factor for any fitness measure.

CONCLUSIONS

This secondary analysis provides additional evidence for lower musculoskeletal fitness among YWD, in particular for females and youth with obesity. Physical fitness continues to be an area in need of intervention to improve overall health among YWD.

Childhood Physical Fitness as a Predictor of Cognition and Mental Health in Adolescence: The PANIC Study

BACKGROUND

Cognitive and mental health problems are highly prevalent in adolescence. While higher levels of physical fitness may mitigate these problems, there is a lack of long-term follow-up studies on the associations of physical fitness from childhood with cognition and mental health in adolescence.

OBJECTIVE

We investigated the associations of physical fitness from childhood to adolescence over an 8-year follow-up with cognition and mental health in adolescence.

METHODS

The participants were 241 adolescents (112 girls), who were 6-9 years at baseline and 15-17 years at 8-year follow-up. Average and change scores for cardiorespiratory fitness (maximal power output [Wmax]; peak oxygen uptake [VO2peak]), motor fitness (10 × 5-m shuttle run), and muscular fitness (standing long jump; hand grip strength) were calculated. Global cognition score was computed from six individual cognitive tasks, and perceived stress and depressive symptoms were assessed at the 8-year follow-up. The data were analysed using linear regression models adjusted for age, sex, and parental education.

RESULTS

Average motor fitness was positively associated with global cognition score (standardised regression coefficient [β] - 0.164, 95% confidence interval [CI] - 0.318 to - 0.010) and inversely with perceived stress (β = 0.182, 95% CI 0.032-0.333) and depressive symptoms (β = 0.181, 95% CI 0.028-0.333). Average cardiorespiratory fitness was inversely associated with perceived stress (Wmax: β =  - 0.166, 95% CI - 0.296 to - 0.036; VO2peak: β =  - 0.149, 95% CI - 0.295 to - 0.002) and depressive symptoms (Wmax: β =  - 0.276, 95% CI - 0.405 to - 0.147; VO2peak: β =  - 0.247, 95% CI - 0.393 to - 0.102). A larger increase in cardiorespiratory fitness was associated with lower perceived stress (Wmax: β =  - 0.158, 95% CI - 0.312 to - 0.003; VO2peak: β =  - 0.220, 95% CI - 0.395 to - 0.044) and depressive symptoms (Wmax: β =  - 0.216, 95% CI - 0.371 to - 0.061; VO2peak: β =  - 0.257, 95% CI - 0.433 to - 0.080).

CONCLUSIONS

Higher levels of motor fitness in childhood and adolescence were associated with better cognition in adolescence. Higher levels of and larger increases in cardiorespiratory fitness from childhood to adolescence were associated with better mental health in adolescence.

RETRAGAM: Resistance training based on gamification during physical education. Rationale and study protocol

Children's physical inactivity and increasing sedentary behaviour have become major public health concerns, with a concurrent decline in muscular fitness (MF) contributing to poor physical outcomes during childhood and adolescence, highlighting the importance of developing resistance training (RT) programs. Furthermore, several educational strategies such as gamification seem to increase students' motivation which can produce an increase in performance outcomes. This study describes the rationale and protocol of a school-based randomized controlled trial called "RETRAGAM" (REsistance TRAining based on GAMification). For this investigation, a total of ≃180 children (grades 5 and 6; 10-12 years of age) from 6 randomly selected schools in Valencia (Spain) will be enrolled for 8 weeks in one of the experimental groups: EG (15 min of RT Functional HIIT circuit program), EG + G (the same EG program but with a gamification approach) or CG (Control Group). Outcomes will include physical activity profile, MF, anthropometry and body composition, as well as the enjoyment and motivation during Physical Education (PE). An interactive app for digital devices will be used for gamified storytelling, earning points for personalized children's avatars, and implementing a flipped classroom learning model. We conclude that the RETRAGAM will provide information about the effectiveness and implementation of a school-based RT intervention during PE with and without gamification in students' MF, body composition, motivation and enjoyment.

The Effects of Using a Cycling Desk at School on Executive Function, Physical Fitness, and Body Composition in Primary School Children: Impact of Socioeconomic Status

CONTEXT

Physical inactivity and sedentary behaviors are associated with adverse health outcomes in both adults and children. The purpose of this study was to investigate the effects of a 9-week program using a Cycle Desk during school time in French primary school children from high or low socioeconomic status (SES) on body composition, physical fitness (PF), and executive function.

METHODS

Seventy-five (n = 75) children completed a test battery before and after 9 weeks of use of Cycle Desk to evaluate anthropometric characteristics, body composition, PF, and executive function.

RESULTS

Body mass index increased significantly (P = .0095), while body fat decreased after the use of Cycle Desks (P < .0001). Specifically, lean mass increased in the high-SES group while it decreased in the low-SES group (P < .0001). After 9 weeks, there was an improvement in motor skills (P < .0001), upper and lower limbs' strength (P < .0001), and executive function performance (P < .0001). More specifically, the low-SES group had a greater improvement in motor skills and maximal aerobic speed between T0 and T1, compared to the high-SES group (P = .001, P = .023, respectively). In contrast, the high-SES group had a greater improvement in executive function at 9 weeks of use of Cycle Desk compared with the low-SES group (P = .0084).

CONCLUSIONS

The promotion of low-intensity physical activity with the use of a Cycle Desk at school may help offset some adverse effects of excess sedentary behavior among children. Moreover, this strategy appears to be particularly effective in children from low-SES backgrounds. What's New: The use of a Cycle Desk during school time has no deleterious effects on PF as well as cognitive executive functions in primary children. Modifications are more beneficial in children from low SES.

Associations Between Fundamental Movement Skills, Muscular Fitness, Self-Perception and Physical Activity in Primary School Students

Background/Objectives: Positive self-perception, physical activity and fundamental movement skill (FMS) proficiency are important aspects of a child's healthy development. The objective of this research was twofold: first, to explore associations between FMS, muscular fitness, self-perception and physical activity in school children; and second, to identify key predictors of FMS proficiency, athletic self-perception, physical activity levels in these participants and the differences between biological sexes. Methods: Primary school-aged children (n = 104; 53.85% female) from 8 to 10 years old (M = 9.04, SD = 0.69) engaged in two days of testing. All students were measured on FMS, standing long jump (SLJ), countermovement jump (CMJ), seated medicine ball chest throw and self-perception, followed by correlation and stepwise multiple linear regression analyses. Results: The findings revealed significant positive correlations between FMS proficiency, lower body muscular fitness (CMJ, SLJ), and athletic self-perception for the entire cohort, with varying results between male and female subgroups. Additionally, athletic self-perception showed strong relationships with other self-perception domains. Notably, forward stepwise regression analysis identified FMS proficiency as a significant predictor of physical activity levels, explaining 12.8% of the variance. SLJ, scholastic perception, and physical activity explained 45.5% of FMS variance for females. In males, FMS proficiency significantly predicted physical activity, accounting for 13.3% of the variance. SLJ and athletic competence self-perception explained 42.1% of FMS variance in males. Conclusions: The study indicates that FMS, self-perception, muscular fitness, and physical activity levels may mutually enhance each other, and that there is a need for biological sex-specific strategies to be considered in physical education programs.

Secular trends in motor abilities of Xinjiang children and adolescents aged 7-18 years from 1985 to 2019

Objective

To assessment the secular trend in physical fitness of children and adolescents aged 7-18 years in Xinjiang from 1985 to 2019.

Method

The data are derived from test scores of Xinjiang Chinese children and adolescents aged 7-18 years by the China National Student Health Monitoring Centre National Student Physical Fitness Monitoring in 1985, 1991, 1995, 2000, 2005, 2010, 2014, and 2019. The physical fitness indicators included speed, cardiorespiratory fitness, muscular strength, power, and flexibility.

Results

The overall physical fitness of Xinjiang children and adolescents aged 7-18 in Xinjiang demonstrated downward trend from 1985 to 2019. During the period from 1985 to 1995, the speed, power, and cardiorespiratory fitness improved significantly but worsened from 1995 to 2005. The pace of decline in physical fitness slowed down from 2005 to 2014. Some components of physical fitness improved, but most components of physical fitness continued to worsen from 2014 to 2019.

Conclusion

In conclusion, the overall physical fitness of Xinjiang children and adolescents aged 7-18 years worsened from 1985 to 2019, and some relatively positive trends have been found in recent years. Trends in physical fitness vary among children and adolescents by gender and age, and these differences should be emphasized in the development of relevant physical fitness policies as well as interventions.

Effects of different supervised and structured physical exercise on the physical fitness trainability of children and adolescents: a meta-analysis and meta-regression : Physical fitness trainability in children and adolescents' health

BACKGROUND

Physical fitness has been considered an important health indicator. Several factors can impact the increase in physical fitness in children and adolescents, including chronological age, sex and BMI, in addition to training variables such as weekly frequency, session and intervention duration, and types of exercises performed. To know the importance of variables that can impact physical fitness, it is important for health professionals to identify the most efficient way of prescribing physical exercises for children and adolescents. The aim is review and meta-analyses of the effects of supervised and structured physical exercise on the physical fitness trainability of children and adolescents.

METHODS

Relevant articles were searched in the PubMed, Cochrane Library, Embase and Scopus platform databases and selected based on the following criteria: children and adolescents aged between 7 and 17 years who performed any type of structured physical exercise compared to a control group without exercise and evaluating physical fitness (strength or muscular power, cardiorespiratory fitness (CRF) or speed. The results are reported in accordance with PRISMA 2020.

RESULTS

Eighty studies were included with a total of 5769 participants. Strength exercises (ES: 1.073; 95% CI, 0.612-1.533; P < 0.001; I2: 74%), concurrent (ES: 1.054; 95% CI, 0.255-1.853; P < 0.010; I2: 72%) and sports (ES: 0.573; 95% CI, 0.015 to 1.132; P < 0.044; I2: 34%) seem to be the most effective in increasing muscular strength. Aerobic activities (ES: 0.400; 95% CI, 0.258-0.542; P < 0.001; I2: 74%), sports (ES: 0.271; 95% IC, 0.148-0.394; P < 0.001; I2: 15), or HIIT (ES: 0.668; 95% IC, 0.333-1.003; P < 0.001; I2: 29%) resulted in increased CRF (ES: 0.514; 95% IC, 0.220-1.808; P < 0.001; I2: 66%). The practice of physical exercise increased muscular power (ES: 0.241; 95% CI, 0.053-0.429; P = 0.012; I2: 0%). The practice of HIIT impacts MAS gains (ES: 0.048; 95% CI, 0.050 - 0.026; P = 0.029; I2: 44%).

CONCLUSION

Supervised and structured physical exercise can improve muscular strength (15-35%), CRF (5.4-8.5%), muscular power (5.6-11.8%), and MAS (5.4%) trainability in children and adolescents. Sex, BMI of the subjects and type of exercise performed (aerobic activities, exclusive to strength, HIIT or sports) should be considered when prescribing the exercise.

Handgrip strength, cardiometabolic risk and body composition in youth with type 1 diabetes: the Diactive-1 Cohort Study

Objective

This study aimed to explore the association between handgrip strength, cardiometabolic risk (CMR) and body composition in youth with type 1 diabetes.

Methods

For this prospective cohort study, muscular fitness was assessed via handgrip test and relativised by weight, and body composition, evaluated through dual-energy X-ray absorptiometry in type 1 diabetes patients aged 6-18 years. CMR score included z-scores for total body fat, blood pressure, glycated haemoglobin (HbA1c), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglyceride-glucose index.

Results

Eighty-three patients were analysed at baseline and 1-year follow-up (44.6% females, mean age 12.77 years). Individuals with high handgrip strength tended to have lower CMR and body fat compared with those with low handgrip strength. Over a year, individuals with high handgrip strength showed reduced HbA1c, CMR and subcutaneous fat. Consistently meeting high handgrip strength criteria resulted in reductions in HbA1c levels, CMR score and subcutaneous adipose tissue compared with those who never complied or lost compliance during follow-up. Additionally, subjects classified with high handgrip strength both at baseline and follow-up had a lower likelihood of being classified with high CMR (OR=0.241, 95% CI 0.121 to 0.947, p=0.044).

Conclusions

High handgrip strength was associated with significant cardiometabolic and body composition benefits in youth with type 1 diabetes. This tool could be considered of potential clinical value for incorporating assessments like handgrip tests to monitor and address cardiometabolic health.

Unveiling Gaps in High School Strength and Conditioning: CSCS Certification, Coaching Leadership, and Facilities

ABSTRACT

Judge, LW, Marsh, JP, Petersen, JC, Pearson, D, and Bellar, D. Unveiling gaps in high school strength and conditioning: CSCS certification, coaching leadership and facilities. J Strength Cond Res 38(12): 2088-2098, 2024-The aim of this study was to examine the prevalence of Certified Strength and Conditioning Specialist (CSCS) and/or dedicated strength coaches overseeing strength and conditioning facilities (SCFs) at the high school level in a Southwestern state. An online survey, comprising 72 items based on a validated instrument, collected data on SCFs from high school athletic directors statewide. A total of 245 surveys were completed representing a 17.5% response rate. Descriptive, Pearson correlation, chi-square, and ANOVA analyses were conducted with an a priori alpha level of p < 0.05 established. The results revealed that only 9.4% of SCF supervisors held CSCS certification, 27.8% lacked certification, and 62.9% did not have a dedicated strength coach overseeing the SCF. Facilities led by CSCS coaches had several areas of greater equipment resources, including bench press stations ( F [2, 244] = 5.143, p = 0.006), squat stations ( F [2, 244] = 3.570, p = 0.030), and power clean stations ( F [2, 244] = 4.573, p = 0.011). This study highlights the importance of prioritizing safety considerations and meeting the developmental needs of high school athletes by addressing the absence of CSCS certifications and dedicated strength coaches overseeing SCFs. The scarcity of CSCS-credentialed coaches in high schools is troubling, considering adolescent athletes' developmental needs and recently enacted National Collegiate Athletic Association Division I safety standards for strength and conditioning coaches.

Sport participation, weight status, and physical fitness in French adolescents

The primary objective of this study was to investigate the associations between sport participation and weight status with physical fitness among French adolescents. The secondary aim was to establish sex- and age-specific physical fitness percentiles for French adolescents. The sample comprised 8084 adolescents (4126 boys, 3958 girls), aged 10-14 years. Participants were tested on cardiorespiratory fitness and muscular strength using the following tests: 20-m shuttle run test and handgrip strength test. A questionnaire on organized sport participation was completed. Physical fitness levels were better in boys (P < 0.005). Handgrip strength increased with age whereas 20-m shuttle run performance decreased with age. Overweight and obese adolescents had significantly lower cardiorespiratory fitness levels than their normal-weight peers (P < 0.005), whereas normal-weight adolescents had lower cardiorespiratory fitness than thin adolescents (P < 0.005). Sport participation was higher for boys (57.2% boys vs. 52.8% girls) (P < 0.001). Adolescents who participated in at least one organized sport (either through a club or at school) were fitter than those who did not participate in organized sports (P < 0.005). Adolescents who engaged in organized sports were more active and physically fit than those who did not participate. The fitness benefits of club sports are greater than those provided by school-based sports, highlighting the potential of sports clubs as a key setting for promoting health. What is Known: • Physical fitness is a strong marker of health in children and adolescents. • The last French Report Card highlighted the lack of fitness data and the need for nationwide programs, while showing a significant decline in cardiorespiratory fitness among youth in recent decades.. What is New: • This study reveals that adolescents participating in organized sports have better physical fitness compared to their peers who do not, emphasizing the potential advantages of club sports over school-based activities. • We highlight the need for targeted strategies, particularly for overweight or obese adolescents and girls, to increase participation in organized sports and enhance health outcomes. • The study emphasizes the need to develop policies that improve access to organized sports clubs and expand physical education in schools, aiming to improve CRF in adolescents.

Temporal trends in muscular fitness among French children and adolescents between 1999 and 2023

The aim was to estimate national temporal trends in muscular fitness for French youth between 1999 and 2023. Data were obtained from five cross-sectional studies on 53,314 children and adolescents (age range: 6-16 years). Lower- and upper-body strength were assessed by standing broad jump (SBJ) and handgrip strength (HGS). BMI z-scores (BMIz) were calculated using WHO growth curves. We found a statistically significant negligible decline in SBJ performance (standardised effect size (ES) trend per decade [95%CI]: -0.08 [-0.10, -0.07] or -2.1 cm [95%CI: -2.4, -1.8]) and a statistically significant negligible improvement in HGS (ES trend per decade [95%CI]: 0.11 [0.08, 0.13]) or 0.6 kg [(95%CI: 0.4, 0.8]). We found evidence of significant increases in distributional variability and asymmetry, with poorer trends in the low performers (<25th percentile) and better trends in the high performers (>75th percentile) compared to the average performers. Our data suggest negligible trends in mean SBJ and HGS, coupled with increased distributional variability and asymmetry. Trends were not uniform across the population distribution with data suggesting an increase over time in the gap between low and high performers. These results reinforce the importance of interventions and programmes aiming at improving muscular fitness specifically in children and adolescents with low muscular strength.

Evaluating the Efficacy of Irisin Injection in Mimicking the Molecular Responses Induced by Endurance Exercise in Mouse Liver Tissue

Background

Physical activity has been found to improve liver health by reducing oxidative stress (OS), possibly through the protein irisin. Heat shock proteins (HSPs) and microRNAs (miRNAs) help regulate the body's response to stress and maintain cellular health. This study aimed to investigate the expression of the HSP70 gene and protein, miR-223a, and serum irisin levels in the liver after 8 weeks of endurance exercise or irisin injection.

Methods

Twenty-one mice were randomly assigned to a control group, an endurance training group, and an irisin injection group. The expression of the HSP70 gene and miR-223a was analyzed using real-time polymerase chain reaction (PCR), while HSP70 protein levels were measured using immunohistochemistry (IHC) and Western blot analysis. The concentration of irisin in the mouse serum was evaluated using the enzyme-linked immunosorbent assay (ELISA) method.

Results

The endurance training and irisin injection groups exhibited a significant increase in the HSP70 gene (405.30% and 816.03%, respectively) and protein expression (173.89% in IHC, 36.76% in Western blot for endurance training; 206.73% in IHC, 59.80% in Western blot for irisin injection) as well as elevated serum irisin levels (49.75% for endurance training and 60.65% for irisin injection) compared with the control group. In contrast, miR-223a expression decreased in both the endurance training (21.37%) and irisin injection (52.80%) groups (P < 0.05 in all cases). Mice in the irisin injection group demonstrated higher levels of the HSP70 gene (81.28%) and protein expression (11.99% in IHC and 16.84% in Western blot) and lower miR-223a levels (39.97%) than those in the endurance training group (P < 0.05).

Conclusions

The study concludes that irisin administration can replicate the effects of long-term endurance exercise on HSP70 and miR-223a and may have a more significant impact on their production than exercise training alone.

Effects of modern dance programs on improving health-related physical fitness in girls

Introduction

As creative physical activity influences many aspects of child development-including physical, social, and emotional wellbeing-the effects of two experimental modern dance programs on the development of health-related physical fitness in young school-aged girls were assessed in this longitudinal study.

Materials and methods

The study sample comprised 203 girls aged 7-11 years, 102 of whom (the control group) were recruited from the elementary school "Vuk Karadžić" from Bačka Palanka, while Experimental Group 1 (n = 51) and Experimental Group 2 (n = 50) respectively consisted of girls who have been involved in a modern dance program for no longer than 1 year and at least 2 years. The participants were also divided into AGE 1 (7-9 years, n = 103) and AGE 2 (9-11 years, n = 100) groups to assess the influence of age on the treatment effect. During the six-month experimental period, Experimental Group 1 met three times a week while Experimental Group 2 had five weekly training sessions. All participants were subjected to the extended ALPHA battery of tests both at baseline and at the end of the study.

Results

The Experimental Group 1 and Experimental Group 2 results showed a statistically significant difference (p = 0.005) between the initial and final measurements, suggesting that participation in a modern dance program had a positive impact on the transformation of morphological characteristics by increasing muscle mass and reducing subcutaneous fat. In addition, both experimental groups had a greater muscle strength, muscle endurance, and aerobic fitness at the end of the treatment.

Conclusion

The study findings support the view that health-related physical fitness in young school-aged children can be improved through modern dance.

Physical fitness and body build parameters of children and adolescents participating in the physical activity promotion programme "Athletics for all!"

BACKGROUND

This study attempts to analyse physical fitness and basic anthropometric parameters of children and adolescents participating in the nationwide physical activity promotion programme "Athletics for All!" (AFA). The programme aims to establish a national system for diagnosing, selecting, recruiting, and identifying talents in youth training. It also aims to build a career development path for athletics, forming the basis of a new structure for youth training in Poland. The primary goal of this study was to assess physical fitness of AFA participants over the years of its implementation (2015-2022) and to identify the leading motor ability with consideration for age, gender, and body build parameters determined with Body Mass Index and Ponderal Index.

METHODS

Nationwide measurements of basic anthropometric parameters as well as physical fitness tests were conducted among 31,790 girls (F) and 22,260 boys (M) participating in the AFA programme. Physical fitness assessments were performed using the OSF test (3 × 10 m shuttle run, standing broad jump, 1 kg medicine ball throw, 4-minute run). Comparative analysis of OSF test results, considering gender, was conducted using the independent samples T-test. The strength and direction of correlations between variables were calculated using the rho-Spearman coefficient.

RESULTS

OSF test results were converted into points, considering age and gender. Gender was found to be a significantly differentiating factor in physical fitness of AFA participants. Among twelve- and fifteen-year-olds, statistically significant differences were observed in all analysed variables, i.e. in each of the four tests and the overall score. It was noted that the examined girls aged 11 to 17 exhibited higher levels of strength compared to their male counterparts. Statistical analysis revealed significant correlations between OSF test results and the age and body build indicators, with the strength of the correlations being negligible in most cases.

CONCLUSIONS

Participants of the nationwide programme "Athletics for All!" demonstrate a high level of physical fitness, with endurance being a fundamental motor ability. Physical fitness levels show significant correlations with the anthropometric parameters of children and adolescents. The study results confirm the need and justification for implementing physical activity promotion programmes for the younger generation.

Mediators of the association between physical activity and executive functions in primary school children

There is growing interest in identifying the mechanisms underpinning the effects of physical activity on executive functions (e.g. inhibitory control, cognitive flexibility) in children. Our study examined cardiorespiratory fitness, muscular fitness, and motor competence as potential mediators of this relationship. The study used baseline data from the Learning to Lead (L2L) cluster randomised controlled trial. In total, 675 children (7-11 years, 49.5% girls) completed measures of moderate-to-vigorous physical activity (MVPA), cardiorespiratory fitness, muscular fitness, motor competence, and executive functions. Structural equation modelling was used to examine the potential mediating roles of cardiorespiratory fitness, muscular fitness, and motor competence in the cross-sectional association between MVPA and executive functions. Cardiorespiratory fitness (β = 0.06, SE = 0.021, p = 0.004) partially mediated the association between MVPA and cognitive flexibility. Muscular fitness was a significant mediator of the association between MVPA and both inhibitory control (β = 0.03, SE = 0.014, p = 0.027) and cognitive flexibility (β = 0.06, SE = 0.021, p = 0.005). No significant mediated effects were found for motor competence. Our findings suggest cardiorespiratory and muscular fitness (but not motor competence) mediate the association between physical activity and executive functions in children.

Field-based physical fitness assessment in preschool children in China

BACKGROUND

Physical fitness in the preschool years is considered a marker of current and future health. Therefore, understanding physical fitness levels of preschool children is necessary. Furthermore, the use of field-based methods to measure physical fitness is essential for assessing children in authentic venues such as schools. Hence, the main purpose of this study was to describe the physical fitness of Chinese preschool children across field-based methods considering a statement of confidence intervals for reference in physical fitness in each age and genders.

METHODS

A total of 619 children (296 boys and 323 girls) aged 3-6 years old from China participated in the present study. Physical fitness was measured using the Chinese National Physical Fitness Measurement (CNPFM-Pre) battery, which included the tennis ball throw (upper-limb muscular strength), standing long jump (lower-limb muscular strength), shuttle run test (speed-agility), double-leg timed hop (coordination), sit-and-reach (flexibility), and balance beam test (dynamic balance).

RESULTS

The results revealed significant differences in gender for standing long jump (SLJ; η2 = 0.012, p = 0.007), tennis ball throw (TT; η2 = 0.081, p < 0.001), sit-and-reach (SR; η2 = 0.114, p < 0.001), and one-legged stance test (OST; η2 = 0.037, p < 0.001). Age had positive effects on all physical fitness performance tests, as the shuttle run test (η2 = 0.672, p < 0.001), SLJ (η2 = 0.513, p < 0.001), TT (η2 = 0.394, p < 0.001), double-legged timed hop test (DTH; η2 = 0.445, p < 0.001), SR (η2 = 0.069, p < 0.001), balance beam test (BBT; η2 = 0.367, p < 0.001), and OST (η2 = 0.336, p < 0.001). Older preschool children performed better than their younger counterparts in all the tests. No significant interactions between age groups and gender were found.

CONCLUSIONS

This study provided age- and gender-specific physical fitness performance data in Chinese preschool children. Gender differences in physical fitness tests performance already exists at the preschool age. All physical fitness component results increased with age in this cohort. These findings can help healthcare, physical education, and pediatric professionals understand the physical fitness development of preschool children at different ages and help design sports tasks for preschool boys and girls.

Developing the optimal gross movement interventions to improve the physical fitness of 3-10 year-old children: a systematic review and meta-analysis

Objective

To identify the optimal parameters of gross movement interventions to yield the strongest effects on physical fitness among children aged 3-10 years and to provide a reference for the development of gross movement interventions to improve the physical fitness of children.

Background

There has been a global decline in children's physical fitness. Previous studies have shown that gross movement interventions can improve children's physical fitness, but the optimal intervention parameters for achieving the strongest effects have yet to be determined. Therefore, we conducted this meta-analysis to determine the optimal intervention parameters for yielding the strongest effects on children's physical fitness.

Methods

We searched the Web of Science, PubMed, China Biology Medicine, China National Knowledge Infrastructure, Wanfang Data, and China Science and Technology Journal databases to identify randomized controlled trials on the effects of gross movement interventions (walking, running, jumping, throwing, batting, rolling, spinning, catching, and leg lifting) on children's physical fitness (upper-body strength, lower-body strength, explosive power, speed, flexibility, and balance). We included studies published up to September 2023. The inclusion and exclusion criteria were developed based on the PICOS framework, and the quality of the included studies was evaluated. Subgroup analysis was performed using Review Manager 5.3, and the data were pooled using a random effects model to obtain the SMD (or WMD) and 95% confidence intervals (CIs).

Results

A total of 23 studies involving 2007 healthy children aged 3-10 years met the inclusion criteria. Gross movement interventions significantly improved the explosive power of children aged 3-10 years [WMD, 6.2]. The most effective intervention duration was 16-18 weeks [WMD, 0.45]. The most effective intervention frequency was one session per week [WMD, 1.06]. The optimal duration of single sessions was 60 min [WMD, 0.47]. Children aged 7-10 years [WMD, 1.41] showed the most significant improvements in physical fitness after gross movement interventions.

Conclusion

Gross movement interventions had a positive effect on the physical fitness of children aged 3-10 years. The optimal intervention parameters include 60-min sessions once a week across a total duration of 16-18 weeks.

Influence of vitamin D supplementation on muscle strength and exercise capacity in South African schoolchildren: secondary outcomes from a randomised controlled trial (ViDiKids)

Objective

To determine whether vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness and risk of exercise-induced bronchoconstriction (EIB) in South African schoolchildren.

Methods

Substudy (n=450) in Cape Town schoolchildren aged 8-11 years nested within a phase 3 randomised placebo-controlled trial (ViDiKids). The intervention was weekly oral doses of 10 000 IU vitamin D3 (n=228) or placebo (n=222) for 3 years. Outcome measures were serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations, grip strength, standing long jump distance, peak oxygen uptake (VO2peak, determined using 20 m multistage shuttle run tests) and the proportion of children with EIB, measured at end-study.

Results

64.7% of participants had serum 25(OH)D3concentrations <75 nmol/L at baseline. At 3-year follow-up, children randomised to vitamin D versus placebo had higher mean serum 25(OH)D3 concentrations (97.6 vs 58.8 nmol/L, respectively; adjusted mean difference 39.9 nmol/L, 95% CI 36.1 to 43.6). However, this was not associated with end-study differences in grip strength, standing long jump distance, VO2peak or risk of EIB.

Conclusion

A 3-year course of weekly oral supplementation with 10 000 IU vitamin D3 elevated serum 25(OH)D3 concentrations in South African schoolchildren but did not influence muscle strength, exercise capacity or risk of EIB.

Influence of vitamin D supplementation on muscle strength and exercise capacity in Mongolian schoolchildren: secondary outcomes from a randomised controlled trial

Objective

To determine whether weekly oral vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness or spirometric lung volumes in Mongolian schoolchildren.

Methods

Multicentre, randomised, placebo-controlled clinical trial conducted in children aged 6-13 years at baseline attending 18 schools in Ulaanbaatar. The intervention was weekly oral doses of 14 000 IU vitamin D3 (n=4418) or placebo (n=4433) for 3 years. Outcome measures were grip strength, standing long jump distance and serum 25-hydroxyvitamin D (25(OH)D) concentrations (determined in all participants), peak oxygen uptake (VO2peak, determined in a subset of 632 participants using 20 m multistage shuttle run tests) and spirometric outcomes (determined in a subset of 1343 participants).

Results

99.8% of participants had serum 25(OH)D concentrations <75 nmol/L at baseline, and mean end-study 25(OH)D concentrations in children randomised to vitamin D versus placebo were 77.4 vs 26.7 nmol/L (mean difference 50.7 nmol/L, 95% CI 49.7 to 51.4). However, vitamin D supplementation did not influence mean grip strength, standing long jump distance, VO2peak, spirometric lung volumes or peak expiratory flow rate, either overall or within subgroups defined by sex, baseline 25(OH)D concentration <25 vs ≥25 nmol/L or calcium intake <500 vs ≥500 mg/day.

Conclusion

A 3-year course of weekly oral supplementation with 14 000 IU vitamin D3 elevated serum 25(OH)D concentrations in Mongolian schoolchildren with a high baseline prevalence of vitamin D deficiency. However, this intervention did not influence grip strength, explosive leg power, peak oxygen uptake or spirometric lung volumes, either overall or in subgroup analyses.

Trial registration number

NCT02276755.

Assessment of Motor Performance and Self-Perceived Psychophysical Well-Being in Relation to Body Mass Index in Italian Adolescents

BACKGROUND/OBJECTIVES

The relationship between psychophysical self-perception (PSP), body mass index (BMI) and motor performance (MP) levels, in quantitative and qualitative terms, can be a very interesting connection to investigate. This study aimed to assess MP and PSP according to gender and weight differences (normal weight-Nw/overweight-obese-Ov-Ob) and their relationship to BMI in Italian adolescents.

METHODS

In total, 144 students (F = 72; M = 72) aged between 11 and 13 y.o. participated in this study. They were divided into two groups by gender and into two subgroups based on weight (Nw/Ov-Ob). Standing long jump, sit-and-reach, 10 × 5 m shuttle and sit-up tests to assess MP were carried out, and an ad hoc questionnaire to evaluate PSP was administrated.

RESULTS

In comparing the Nw and Ov-Ob subgroups on the basis of BMI for each gender, statistically significant differences emerged in all motor skill tests administered. Regarding PSP, the Nw subgroup showed high and positive levels, while Ov-Ob showed low and negative levels, highlighting a relationship between high BMI and poor motor performance as well as negative psychophysical perception in the Ov-Ob subgroup.

CONCLUSIONS

this study supports the importance of physical sport activity to regulate excess weight but also contribute to better psychophysical well-being.

Test-Retest Reliability of a Physical Activity Behavior, Health and Wellbeing Questionnaire in Adolescents

Background

The aim of this study was to examine the test-retest reliability of the physical activity behavior, health and wellbeing questionnaire, in adolescent populations, administered by teachers in school settings, in the Republic of Ireland.

Methods

A cross-sectional, mixed sample of 55 participants (45.5% males: Age, 13.94 (±.40) years) were included. The participants completed the questionnaire on two occasions (T1 and T2), on the same day and time, one week apart following identical procedures. Variables for testing included physical activity behavior (n=13), health (n=11) and wellbeing (n=2). Test-retest reliability of the questionnaire's covariates, including family affluence and physical impairments were also examined.

Results

Systematic error (Bland-Altman plots) was found to be near to zero for each of the physical activity behavior, health and wellbeing variables. The combined mean coefficient of variation was lower for females (10.19%) in comparison to males (13.01%). The combined mean intraclass correlation coefficients were higher for females (0.901) than males (0.822). Similarly, the combined mean Cronbach alpha coefficient were higher for girls (0.908) than boys (0.821).

Conclusions

This study found the physical activity behavior, health and wellbeing questionnaire to be reliable for use in adolescent populations.

Process- and Product-Oriented Fundamental Movement Skills in Early Childhood as Predictors of Later Health-Related Fitness

INTRODUCTION

The skill domains of fundamental movement skills (FMS), emphasizing gross motor movements, including locomotor skills (LMS) and object control skills (OCS), along with process- and product-oriented measures of FMS, may predict cardiorespiratory fitness (CRF) and muscular fitness (MF) differently. This study investigates the longitudinal relationship from early childhood FMS, focusing on process-oriented LMS and OCS and product-oriented FMS, to CRF and MF in late childhood.

METHODS

The study involved 441 Finnish children (49.9% female; mean age at baseline, 5.5 yr) over a 6-yr period. FMS was evaluated using the Test of Gross Motor Development, third version, for process-oriented LMS and OCS, and the Körperkoordinationstest Für Kinder (KTK) was used to evaluate the product-oriented FMS. CRF was assessed through the total number of laps completed in the 20-m shuttle run test, whereas MF was measured via repetitions of curl-ups and push-ups. Employing a two-level cross-classified regression analysis and Cholesky decomposition, this study aimed to determine the contributions of product-oriented KTK and process-oriented LMS and OCS. Adjustments for variations in age, measurement intervals, and maturation were achieved through residualization. In addition, gender and body mass index were incorporated as covariates in the analysis.

RESULTS

The analysis revealed that process-oriented LMS (CRF: Δ R2 = 0.016; MF: Δ R2 = 0.014) significantly predicted later health-related fitness, whereas OCS did not. However, KTK exhibited a better ability to predict both CRF (Δ R2 = 0.092) and MF (Δ R2 = 0.032), overshadowing process-oriented measures.

CONCLUSIONS

In conclusion, the findings suggest that KTK, which potentially encompasses a broader spectrum of fitness elements along with FMS, more effectively predicts health-related fitness components than process-oriented FMS.

A multivariate multilevel approach to unravel the associations between individual and school factors on children's motor performance in the REACT project

OBJECTIVE

The aim was to (1) estimate the relationship between physical fitness (PF) and object control fundamental movement skills (FMS), (2) identify child characteristics that relate with PF and FMS, and (3) examine associations between the school environment, PF, and FMS.

METHODS

The sample included 1014 Portuguese children aged 6-10 years from the REACT project. PF was assessed via running speed, shuttle run, standing long jump, handgrip, and the PACER test. Object control FMS were assessed with stationary dribble, kick, catch, overhand throw, and underhand roll. Test performances were transformed into z-scores, and their sum was expressed as overall PF and FMS. Child-level variables included body mass index (BMI) z-scores, accelerometer-measured sedentary time and moderate-to-vigorous physical activity, and socioeconomic status (SES). School size, physical education classes, practice areas, and equipment were also assessed.

RESULTS

Approximately, 90% of the variance in object control PF and FMS was at the child level, and 10% at the school level. The correlation between PF and object control FMS was .62, which declined to .43 with the inclusion of covariates. Older, more active, and higher SES children had higher object control PF and FMS, and boys outperformed girls. BMI was negatively associated with PF but not with object control FMS. Sedentary time and number of physical education classes were not significant predictors. Most school predictors did not jointly associate with PF and object control FMS.

CONCLUSION

PF and object control FMS z-scores were moderately related. Not all child characteristics were associated with both PF and object control FMS, and their effect sizes were different. School characteristics only explained 10% of the total variation in PF and object control FMS.

Cardiorespiratory fitness and muscular fitness correlates in youth: A hierarchy of behavioral, contextual, and health-related outcomes

OBJECTIVES

Despite the health importance of identifying correlates of physical fitness in youth, no investigation to date has explored the influence of behavioral, health-related, and contextual correlates simultaneously. We investigated the hierarchical relationship of multiple modifiable correlates favoring or diminishing cardiorespiratory and muscular fitness in youth.

DESIGN

Cross-sectional investigation.

METHODS

In a sample of 5174 children and adolescents, 31 correlates were hierarchized according to their impact on cardiorespiratory and muscular fitness assessed using the FITESCOLA® fitness battery. A Chi-squared Automatic Interaction Detection approach was employed and measures of correlation and association were used to investigate the relationship between physical fitness and correlates.

RESULTS

In children, body mass index was the most relevant factor to discriminate between high and low cardiorespiratory and muscular fitness of the upper, middle, and lower body. While body mass index was more important than any other correlate to differentiate levels of upper and lower body muscular fitness during adolescence, specific characteristics of sports participation emerged as key factors to discriminate between high and low cardiorespiratory fitness and middle body muscular fitness. Other correlates, including the self-report of active recess time, active commuting to school, favorable neighborhood conditions, and limited time on screens and cellphones, were demonstrative of favorable physical fitness levels.

CONCLUSIONS

Both body composition and sports-related characteristics emerged as the two most relevant factors of physical fitness in youth. Additional health benefits may be obtained from building supportive environments for sports and healthy exercise habits within the household and at different school education levels.

Physical Fitness Surveillance and Monitoring Systems Inventory for Children and Adolescents: A Scoping Review with a Global Perspective

Surveillance of health-related physical fitness can improve decision-making and intervention strategies promoting health for children and adolescents. However, no study has comprehensively analyzed surveillance/monitoring systems for physical fitness globally. This review sought to address this gap by identifying: (1) national-level surveillance/monitoring systems for physical fitness among children and adolescents globally, (2) the main barriers and challenges to implementing surveillance/monitoring systems, and (3) governmental actions related to existing surveillance/monitoring systems. We used a scoping review to search, obtain, group, summarize, and analyze available evidence. Our review involved three stages: (1) identification of surveillance systems through a systematic literature review, with complementary search of the grey literature (e.g., reference lists, Google Scholar, webpages, recommendations), (2) systematic consultation with relevant experts using a Delphi method to confirm/add systems and to gather and analyze information on the barriers and challenges to implementing systems, and (3) Web searches for public documents on government sites and surveillance/monitoring system pages, and direct internet searches to identify relevant governmental actions related to surveillance systems. A total of 15 fitness surveillance/monitoring systems met our inclusion criteria. Experts identified a lack of government support and funding, and the low priority of fitness on the public health agenda as the main barriers/challenges to implementation. Several governmental actions related to surveillance systems were identified, including policies, strategies, programs, and guidelines. We propose a Global Observatory of Physical Fitness to help address these issues.

A Novel Summer Camp Integrating Physical, Psychological, and Educational Health in Youth: The THINK Program

Numerous youth summer programs focus upon physical fitness, nutritional health, psychological well-being, or education. Few, however, have integrated all of these elements into a single program. The Translational Health in Nutrition and Kinesiology (THINK) program provides an integrative nutrition and exercise science curriculum that is interfaced with social emotional learning (SEL) and STEM education to enhance healthy behaviors in youth. The purpose of this study was to determine whether the THINK program could improve physical fitness, nutrition habits, SEL, and STEM education in a 6-week summer program covering a 3-year period. Participants from South Miami were enrolled in THINK (n = 108, 58 males, 50 females, 12.03 + 0.56 years). Physical fitness assessments, the Positive Youth Development Inventory (PYDI), the Students' Attitude Towards STEM Survey, and the Adolescent Food Habits Checklist (ADFH) were recorded at baseline and post-testing. Means and standard error values were evaluated for all dependent variables. Paired samples t-tests (SPSS version 27) were used to determine changes. Improvements in cardiorespiratory fitness (p < 0.001), power (p < 0.006), flexibility (p < 0.001), agility (p < 0.001), muscular endurance (p < 0.001), lean body mass (p < 0.001), ADFH (p < 0.001), and PYDI (p = 0.038) were found. An integrative summer fitness program can result in improvements in physical fitness, nutrition habits, and SEL in as little as six weeks.

The Influence of Kindergarten Environment on the Development of Preschool Children's Physical Fitness

The aim of this research is to find out to what extent the special qualifications of physical education teachers and the physical environment of kindergartens influence the physical development of preschoolers. Forty-four kindergartens across Estonia participated in the study, half of which had a physical education teacher (PEt), whereas the remaining 22 kindergartens were taught by non-qualified kindergarten teachers (NoPEt). Six Eurofit fitness tests were used to assess the physical development of children (n = 704; aged 6-7 years old, with an average age of 6.55 ± 0.5 years). An analysis of variance was used to compare the mean values of the fitness test results of the two groups. Linear regression analysis was applied to clarify the influence of individual and environmental factors on children's fitness scores. In kindergartens where the position of a PEt had been created, the results of children's physical fitness were statistically significantly better, more specifically in handgrip strength (m = 12.0, 95% CI = 11.8-12.3 vs. m = 11.5, 95% CI = 11.2-11.7) and in speed tests (m = 23.0, 95% CI = 22.8-23.2 vs. m = 23.6, 95% CI = 23.3-23.8). According to the teacher interviews, these kindergartens also had more rooms and areas specially created for physical exercises. The study revealed that the physical development of children is, when controlling for other individual and environmental factors, influenced by the professional qualification of the PE teacher (95% CI = 0.06-0.56) as well as children's participation in sports training (95% CI = 0.29-0.83). These findings are important for preschool institutions and municipalities in designing the optimal physical environment for facilitating children's physical fitness.

High muscular fitness level may positively affect bone strength and body composition in children with overweight and obesity

Muscular fitness plays a major role in bone health and body composition in overweight and obese children. It is key that the development of this muscle fitness is affected by absolute isometric strength and dynamic strength.

PURPOSE

To compare bone health and body composition between overweight/obese children considering muscular fitness (MF) levels, and to investigate whether weight-bearing dynamic or absolute isometric strength, both involved in the development of this muscular fitness, are more related with bone health.

METHODS

MF of 59 overweight or obese children (10.1 ± 0.9 years, 27 females) was measured by a countermovement jump (CMJ), handgrip, and maximal isometric strength of knee extension. Participants were divided into four groups depending on their MF level performing a cluster analysis: 16 children with high MF (HMF) in all tests, 18 with high performance in isometric strength (HIS), 15 with high performance in CMJ (HCMJ) and 10 low isometric and low dynamic force values (LMF). Body composition values were measured by dual energy X-ray absorptiometry, and bone strength values were assessed by peripheral quantitative computed tomography. Motor skills were evaluated using TGMD-3. Multivariate analysis of covariance test was applied to analyse bone strength differences between children in the different MF groups, using maturity offset, height and weight as covariates, and correlations were investigated.

RESULTS

HMF excelled in bone health. HIS had higher cortical bone area, periosteal circumference, bone mass, polar strength strain index and fracture load than LMF, while HCMJ only showed better results in trabecular bone area than LMF. HMF had significantly better values of fracture load and periosteal and endosteal circumferences than HCMJ, but not than HIS.

CONCLUSIONS

High MF level shows positive effects on bone health in overweight/obese children. Those with highest isometric strength had better bone health compared to those with higher dynamic strength.

TRIAL REGISTRATION

The research project was registered in a public database Clinicaltrials.gov in June 2020 with the identification number NCT04418713.

Comparison of Estonian Schoolchildren's Physical Activity and Fitness Indicators before and after the COVID-19 Pandemic's Period of Restricted Mobility

It is recognized that the time adolescents spend on physical activity, and the corresponding physical fitness indicators, have diminished over time. However, the exact impact of the COVID-19 pandemic restriction period on physical activity and health-related physical fitness indicators remains unclear. This study sought to determine if and to what degree the primary indicators of physical activity (exercise frequency, exercise intensity, and outdoor physical activity) and health-related physical fitness (strength and endurance) among schoolchildren have shifted, by comparing data from before and after the coronavirus pandemic period. Students aged 12-17 years took part in the study. The physical activity questionnaire and fitness tests were conducted in the autumn of 2017 and spring of 2022. The main results show that moderate- and vigorous-intensity physical activity time and time spent actively outdoors have decreased among adolescents (p < 0.05). There were no significant changes in exercise frequency (p > 0.05). However, there was a statistically significant decline in strength (standing broad jump, bent arm hang) (p < 0.05) and endurance (20 m shuttle run, curl-up) (p < 0.01) when comparing results from before and after the COVID-19 pandemic restriction period. In conclusion, restricted mobility had the greatest impact on the time spent outdoors and, in turn, on physical fitness.

The impact of reduced muscular fitness on cardiometabolic risk factors in children aged 9-11 years

AIM

To analyse the relationships between muscular fitness (MF), fat mass (FM), fat-free mass (FFM) and its combined ratio with cardiometabolic risk (CMR) and whether the relationship between MF and CMR is mediated by body composition in schoolchildren.

METHODS

A cross-sectional study was conducted on schoolchildren from Cuenca, Spain, between September and November 2017. FM and FFM were estimated using bioimpedance analysis. The CMR index was calculated from triglycerides-HDL-c ratio, arterial pressure and fasting insulin. The MF index was assessed using handgrip and standing long jump tests. Analysis of covariance models assessed CMR index differences across the MF index and the FM/FFM ratio categories. Mediation analysis examined whether the MF index and the CMR index association were mediated by FM, FFM or FM/FFM ratio.

RESULTS

The analyses involved 485 schoolchildren aged 9-11 years (55.4% girls). Children with a higher MF index had a lower CMR index (p < 0.05). This association did not persist after controlling for FM/FFM. FM, FFM and FM/FFM ratio mediated the relationship between the MF index and the CMR index.

CONCLUSION

Better levels of MF are associated with better cardiometabolic profile, but a healthy body composition is determinant to improve future health.

Effects of School-Based High-Intensity Interval Training on Hemodynamic Parameters and Heart Rate Variability: A Randomized Controlled Trial

ABSTRACT

Ketelhut, S, Ketelhut, K, Ketelhut, SR, and Ketelhut, RG. Effects of school-based high-intensity interval training on hemodynamic parameters and heart rate variability: A randomized controlled trial. J Strength Cond Res 38(6): 1033-1040, 2024-The purpose of this study was to assess the effects of a child-specific school-based high-intensity interval training (HIIT) implemented into physical education (PE) classes on various hemodynamic parameters and heart rate variability indices. Forty-six students (age 11 ± 1 year) were randomized into an intervention (INT n = 22) and a control group (CON n = 24). During a 12-week period, the INT and CON groups participated in regular PE twice weekly (45-90 minutes). The INT group received HIIT during the first 20 minutes of the 2 PE classes. Systolic and diastolic blood pressure, total peripheral resistance, aortic pulse wave velocity (aPWV), heart rate, SD of normal to normal heartbeat intervals, the root mean square of successive differences between normal heartbeats (RMSSD), the proportion of differences between adjacent normal to normal heartbeat intervals of more than 50 ms, low-frequency power, high-frequency power, and the LF/HF ratio were assessed before and after the experimental period. A p value ≤0.05 was considered statistically significant. Forty students (20 INT; 20 CON) were included in the analysis. A significant time × group interaction was detected for aPWV ( p = 0.05, η2 = 0.099), RMSSD ( p = 0.010, η2 = 0.161), low-frequency power ( p = 0.009, η2 = 0.165), high-frequency power ( p < 0.001, η2 = 0.272), and the LF/HF ratio ( p < 0.001, η2 = 0.354). The INT group revealed significant improvements for the respective parameters. School-based HIIT can induce improvements in cardiovascular parameters. These results highlight the potential of embedding HIIT within the school setting, offering a time-efficient exercise intervention.

Could BIA-derived phase angle predict health-related musculoskeletal fitness? A cross-sectional study in young adults

OBJECTIVES

To our knowledge, little evidence exists on the relationships between body composition and health-related physical fitness; in particular, musculoskeletal fitness. Bioimpedance index phase angle (bioelectrical impedance analysis raw variables) is a candidate predictor of health-related fitness, a marker of fat-free and body cell mass, respectively. The aim of this study was to evaluate body composition, raw bioelectrical impedance analysis variables, and health-related fitness in young adults and investigate their mutual relationships to identify predictors of muscle strength.

METHODS

The study included 229 young adults (115 men and 114 women; 24.2 ± 3 y; body mass index 19-30 kg/m²). Anthropometry was measured with standardized procedures. Whole-body BIA (50 kHz) was performed for impedance and phase angle. Predictive equations estimated fat-free mass and percentage body fat. The bioimpedance index was calculated as stature²/impedance. Musculoskeletal fitness was assessed by handgrip strength, standing broad jump, squat jump, and countermovement jump.

RESULTS

In both sexes, health-related fitness had stronger associations with body composition than stature or weight. Handgrip strength was related to fat-free mass and bioimpedance index, while an inverse association with percent body fat emerged for standing broad jump, squat jump and countermovement jump. Phase angle is directly correlated with handgrip strength, standing broad jump, squat jump, and countermovement jump. In multiple regression analysis phase angle was an independent predictor of all health-related fitness tests, along with fat-free mass (or bioimpedance index) for handgrip strength, and with sex and percent body fat for the three jump tests.

CONCLUSIONS

The present study provided consistent information on the relationships between body composition and health-related fitness in young adults. Phase angle emerged as a significant predictor of all health-related fitness measures and might be useful for a more consistent assessment of musculoskeletal fitness.