Sex-specific associations of moderate and vigorous physical activity with physical fitness in adolescents

Sex Differences in Grip Strength From Birth to Age 16: A Meta-Analysis

In 1985, Thomas and French published results of a meta-analysis that examined sex differences in grip strength in children 5 years of age and older. Their analysis included results from only four studies, and no update has been published. The purpose of the current study was to use meta-analysis to examine sex differences in grip strength from birth to age 16. The analysis included 808 effects from 169 studies conducted in 45 countries between 1961 and 2023. The total sample was 353,676 (178,588 boys, 175,088 girls). From birth to 16 years of age, grip strength was consistently greater in boys than girls. Between 3 and 10 years old, the effect size was small-to-moderate, with female grip strength equaling 90% of male grip strength (Hedges g = 0.33-0.46). At age 11, the effect size decreased slightly, likely due to girls reaching puberty before boys (g = 0.29, 95% confidence intervals (CI) [0.22, 0.35]). At age 13, the effect size increased markedly likely due to male puberty (g = 0.63, 95% CIs [0.55, 0.70]). By age 16, the sex difference in grip strength was substantial, with female grip strength equaling 65% of male grip strength (g = 2.07, 95% CIs [1.86, 2.27]). Secondary analyses revealed that the sex difference in grip strength is broadly similar between countries and has been mostly stable since the 1960s, except for a narrowing of the difference among 5-10-year-olds after 2010. Various biological factors explain why, on average, boys are stronger than girls from birth onward.

Developmental Progression and Sex Differences in Agility During Continuous Two-Footed Jumping Among Children Aged 4–16 Years

We investigated performance levels on conducting continuous two-footed jumping of preschool children (4 years old) to high school students (16 years old) to clarify the developmental progression and sex differences in motor coordination and agility. In total, 450 children (boys: 227; girls: 223) participated in this study. We set 10 obstacles to jump over for continuous two-footed jumping and analyzed the movement time (MT), aerial time (AT), and contact time (CT), and variabilities in AT and CT in 7 year-based categories, using a high-speed camera. We also used multiple regression analysis to identify the predictors of MT. MT and CT shortened until 8 years, whereas AT continued to shorten after 8 years, suggesting that the jumping strategy differs between those younger/older than 8 years. MT, AT, and CT were significantly shorter among boys than girls from preschool children to high school students. In addition, when using multiple regression analysis, the main predictor of MT changed gradually from SD of CT to AT with increasing age. Our findings suggest that the motor control mechanisms related to continuous two-footed jumping differ depending on the age and sex and provide findings to advance understanding of the age-related motor coordination and agility in children.

Association between physical activity, sedentary time, and physical fitness of female college students in China

BACKGROUND

Prior research has highlighted the importance of Physical Activity (PA), Sedentary Time (ST), and Physical Fitness (PF) for health. However, there is limited research on the association between PA, ST, and PF in the context of female college students, particularly in Eastern cultures. Therefore, the purpose of this study was to investigate the association between PA, ST, and PF among Eastern female college students to inform policy and practice.

METHODS

The study was conducted from February to May 2022 at East China Normal University, Shanghai, China. A total of 512 Chinese female college students participated in this study through snowball sampling. Participants' PA and ST were investigated using the International PA Questionnaire, and PF was measured using the Chinese National Student Physical Fitness Test. Independent samples t-test and binary logistic regression were used to compare the differences in PF between Active Participants (AP) and Inactive Participants (IP), as well as between Low Sedentary Participants (LSP) and High Sedentary Participants (HSP). Multinomial logistic regression was used to compare the differences in PF between Active and Low Sedentary Participants (ALSP), Active and High Sedentary Participants (AHSP), Inactive and Low Sedentary Participants (ILSP), and Inactive and High Sedentary Participants (IHSP). Data analysis was performed using Statistical Package for the Social Sciences version 28. The level of significance was set at 0.05.

RESULTS

AP showed significantly higher cardiorespiratory fitness (p < 0.05) and overall fitness (p < 0.01) than IP. Compared to IP, AP was less likely to be classified as unfit in terms of cardiorespiratory fitness [Odds Ratio (OR), 0.57; 95% Confidence Interval (CI), 0.38-0.85; p < 0.05]. Compared to IHSP, ALSP (OR, 0.44; 95% CI 0.25-0.76; p < 0.01) and AHSP (OR, 0.54; 95% CI 0.32-0.93; p < 0.05) were less likely to be classified as unfit in terms of cardiorespiratory fitness. Furthermore, compared to IHSP, AHSP (OR, 1.66; 95% CI 1.02-2.70; p < 0.05) and ILSP (OR, 2.09; 95% CI 1.16-3.77; p < 0.05) were more likely to be classified as unfit in terms of their flexibility.

CONCLUSION

There was a positive association between PA, cardiorespiratory fitness, and overall fitness. There was also an association between cardiorespiratory fitness, flexibility, and the combination of PA and ST. These findings suggest that both PA and ST can influence different PF items. Therefore, we recommend that public health policy and practice for college female students should consider PF items when selecting different PA and ST intervention strategies.

Different Types of Screen Behavior and Depression in Children and Adolescents

The purpose of this study was to examine the associations between different types of screen behavior and depression, taking into account exercise and sleep among children and adolescents. A total of 23,573 Japanese children and adolescents (aged 8-15 years) participated in this cross-sectional study. Different types of screen behavior, weekly exercise time, sleep duration, and prevalence of depression were assessed using a questionnaire. Independent associations between various types of screen behavior and prevalence of depression were examined using logistic regression analyses after adjusting for age, school, sleep duration, exercise time, and other screen behavior types. A two-way analysis of covariance was conducted to examine whether exercise and sleep can attenuate the negative effects of screen behavior. The associations between screen behavior and depression varied by screen behavior types and participant characteristics. More time spent engaging in newer types of screen behavior, including social media, online games, and online videos, was associated with a higher prevalence of depression. In contrast, more time spent on TV was associated with a lower prevalence of depression. Sufficient exercise can lower the prevalence of depression, regardless of the length of time and content of the screen, and its associations were particularly significant for junior high school girls. Sleep was not associated with the prevalence of depression among any participant group except elementary school boys. Our findings suggest that age- and sex-specific intervention strategies that also consider screen-based behavior can effectively lower the risk of depression in children and adolescents.

Association of the Use of the Mobile Phone with Physical Fitness and Academic Performance: A Cross-Sectional Study

The aim of this study was to analyse the association of the use of the mobile phone with physical fitness (PF) and academic performance in secondary school students and its gender-related differences. A total of 501 high school students participated in the study (236 girls and 265 boys; 12–18 years). Use of the mobile phone and sample distributions were done with the Mobile-Related Experience Questionnaire (CERM): low use of mobile phone (LMP = 10–15 points), medium use of mobile phone (MMP = 16–23 points) and high use of mobile phone (HMP = 24–40 points). PF via Eurofit test battery and academic performance were recorded, and gender was used as a differentiating factor. The HMP group registered lower values than the LMP group for academic performance (Spanish: 4.78 ± 2.26 vs. 3.90 ± 1.96 points; p = 0.007, Mathematics: 4.91 ± 2.23 vs. 4.00 ± 1.84 points; p = 0.007) and PF (Abdominals: 6.83 ± 2.40 vs. 5.41 ± 2.46 points; p < 0.001, Broad jump: 6.24 ± 3.02 vs. 4.94 ± 2.28 points; p = 0.013). The boy students showed greater values than girl students for PF in the LMP (medicine-ball-throw: 6.34 ± 2.24 vs. 5.28 ± 1.86 points, p = 0.007) and MMP (medicine-ball-throw: 6.49 ± 2.52 vs. 5.02 ± 1.68 points; p < 0.001) groups, but no gender-related differences were found in the HMP group. In conclusion, high use of the mobile phone was related to worse results in the PF tests and academic performance. Gender-related differences were found for academic performance regardless of the use of the mobile, but for physical fitness no gender differences were found in HMP group.

Physical activity patterns in a representative sample of adolescents from the largest city in Latin America: a cross-sectional study in Sao Paulo

OBJECTIVES

We examined the patterns of total and domain-specific physical activity (PA) by sex, socioeconomic status and maternal education level in adolescents from Sao Paulo city, Brazil.

DESIGN

Cross-sectional study.

PARTICIPANTS

We included a representative sample of 2682 (52.2% boys) adolescents aged 14-15 years from public and private schools in Sao Paulo, 2017. Socioeconomic status was assessed using a wealth index derived from principal component analysis. Descriptive analyses evaluated differences in total and domain-specific PA by sex, socioeconomic status and maternal education level.

OUTCOME MEASURES

We collected data on the frequency and duration that adolescents spent in each PA domain (active transportation, leisure PA and physical education classes) through a self-report questionnaire.

RESULTS

On average, adolescents spent 197.7 min/week (95% CI 190.6-204.8) in total PA. The proportion of adolescents achieving at least 60 min/day (≥420 min/week) was 12.7% (95% CI 11.4-14.1), with a higher prevalence in boys (18.3%) and in those with higher socioeconomic status (17.4%). Similar patterns were observed for leisure PA and physical education classes. Active transportation was higher in girls (46.0 min/week; 95% CI 42.6-49.6) than in boys (43.4 min/week, 95% CI 39.9-46.6). Boys and adolescents with higher socioeconomic status and higher maternal education level had higher levels of total PA.

CONCLUSIONS

We found a variation in patterns of total and domain-specific PA by sex, socioeconomic status and maternal education level in adolescents from Sao Paulo. Initiatives for promoting PA in adolescents should take these findings into account.

Anthropometry, dietary intake, physical activity and sitting time patterns in adolescents aged 15-17 years: an international comparison in eight Latin American countries

BACKGROUND

Although there is high prevalence of obesity and other cardiovascular risk factors among Latin American adolescents, there is limited evidence on dietary intake and physical activity (PA) patterns in this population. Therefore, we characterized anthropometry, dietary intake, PA and sitting time (ST) in adolescents aged 15-17 years from eight Latin American countries.

METHODS

Six hundred seventy-one adolescents (41.4% girls) from the Latin American Study of Nutrition and Health (ELANS) were included. Nutritional status was classified by four BMI (kg/m²) categories. Waist circumference (WC) was categorized as above or below thresholds. Dietary intake was assessed through two non-consecutive 24-h dietary recalls. PA and ST were measured using the International Physical Activity Questionnaire (IPAQ). We calculated overall and country-specific estimates by sex and tested for differences between boys and girls.

RESULTS

Differences in the prevalence of overweightness (15.1 and 21.6%) and obesity (8.5 and 6.5%) between boys and girls, respectively, were statistically insignificant (p = 0.059). Average energy intake was 2289.7 kcal/day (95% CI: 2231-2350) for boys and 1904.2 kcal/day (95% CI: 1840-1963) for girls (p < 0.001). In relation to macronutrient intake for boys and girls, respectively, the average intake (expressed as percentage of total energy) was 15.0 and 14.9% for protein; 55.4 and 54.9% for carbohydrates; 14.1 and 14.5% for added sugar; 29.5 and 30.1% for total fat; and 9.6 and 9.9% for saturated fat (p > 0.05 for all outcomes). There was no statistically significant difference in the prevalence of total energy (TE) saturated fat and added sugar (>10% of TE) between girls and boys (49.6% versus 44.8 and 81.7% versus 76.1%, respectively). Prevalence of physical inactivity was 19% in boys and 43.7% in girls (p < 0.001). Median levels of vigorous-intensity PA and total PA were significantly higher for boys than for girls (p < 0.05 for both outcomes); whereas levels of ST were similar (273.7 versus 220.0 min/day for boys and girls, respectively; p > 0.05).

CONCLUSIONS

These findings highlight the high prevalence of poor dietary intake and physical inactivity in adolescents from Latin American countries. Therefore, effective and sustainable strategies and programmes are needed that promote healthier diets, regular PA and reduce ST among Latin American adolescents.

TRIAL REGISTRATION

Clinical Trials NCT02226627. Retrospectively registered on August 27, 2014.

Estimated Physical Activity in Adolescents by Wrist-Worn GENEActiv Accelerometers

BACKGROUND

Reports of physical activity (PA) measured via wrist-worn accelerometers in adolescents are limited. This study describes PA levels in adolescents at baseline of an obesity prevention and weight management trial.

METHODS

Adolescents (n = 930) at 8 high schools wore an accelerometer for 7 days, with average acceleration values of <50 mg, >150 mg, and >500 mg categorized as sedentary, moderate, and vigorous PA, respectively. In a 3-level mixed-effects generalized linear model, PA was regressed on sex, weight status, and day of week. Daily PA was nested within students, and students within schools, with random effects included for both.

RESULTS

Adolescents accumulated a median of 40 minutes daily of moderate to vigorous PA (MVPA). MVPA was significantly different for teens with obesity versus teens with normal weight (-5.4 min/d, P = .03); boys versus girls (16.3 min/d, P < .001); and Sundays versus midweek (-16.6 min/d, P < .001). Average sedentary time increased on weekends (Saturday: 19.1 min/d, P < .001; Sunday: 44.8 min, P < .001) relative to midweek but did not differ by sex or weight status.

CONCLUSIONS

Interventions to increase PA in adolescents may benefit from focusing on increasing weekend PA and increasing MVPA in girls.

Secular trends in the grip strength and body mass index of sport university students between 1973 and 2016: J-Fit＋study

Background/Objective

Sport university students are a unique population because they usually have a strong sport background since early childhood. In this study, we aimed to examine secular trends in grip strength of male, first-year sport university students in comparison with the general population between 1973 and 2016.

Methods

Existing data on the grip strength of 6,308 sport university students aged 18 years were examined. The data were obtained from the Juntendo Fitness Plus Study, a study of the Department of Physical Education/Health and Sports Science of Juntendo University. For reference, age- and sex-matched data (18 years old, male) on the grip strength were obtained from a national database.

Results

Compared with the general population, the sport university students had greater body mass index and stronger grip strength at all times.

Conclusions

The grip strength of sport university students significantly declined between the 1980s and 1990s, and it has plateaued since 2000, albeit at low levels. Compared with the peak performance of sport university students in 1984, the grip strength of students in 2016 was significantly lower by 8.1 kg. The downward trends were also confirmed in the general population during the same periods. In conclusion, the grip strength of sport university students has significantly declined over the last few decades.

Self-perception of physical activity and fitness is related to lower psychosomatic health symptoms in adolescents with unhealthy lifestyles

The general aim of the present study was to examine how physical activity, participation in sports, and beliefs about personal physical activity and physical fitness are associated with adolescents' psychosomatic health complaints (PHC) in relation to their lifestyles.

METHODS

A total of 3284 11-19-year-old adolescents (average age 14.9 ± 2.0; 48.6% male) participated in the population-based cross-sectional study. Self-administered questionnaires addressed lifestyle, sports participation, physical activity, physical fitness perception, and PHC.

RESULTS

Female gender (OR = 1.92; 95% CI = 1.57-2.35), smoking (OR = 1.31; 95%PI = 1.01-1.68), alcohol consumption (OR = 1.60; 95%PI = 1.30-1.97), unhealthy foods (OR = 1.14; 95%PI = 1.04-1.26), hours of internet use (OR = 1.14; 95%PI = 1.07-1.21), and poor personal fitness perception (OR = 1.60; 95% CI = 1.27-2.02) were associated with PHC in adolescents. Lower physical activity and self-perceived insufficient physical activity, perception of physical fitness as being poor, and not participating in sports were associated with greater somatic and psychological complaints controlling for age, gender, and BMI. Participation in sports and physical activity did not change PHC in adolescents involved in unhealthy behaviour. However, a positive perception of one's own physical activity and physical fitness decreased PHC in adolescents who reported an unhealthy lifestyle.

CONCLUSIONS

Adolescents demonstrating poorer health-related behavioural profiles showed higher PHC. Physical activity and sports participation were related to lower PHC. Positive physical activity and physical fitness perception changed the associations between PHC and unhealthy lifestyle: adolescents perceiving themselves as sufficiently physically active and those evaluating their physical fitness as good showed lower PHC, despite the presence of unhealthy habits (high screen time, drinking alcohol, smoking, and consuming unhealthy foods). It is important to study cognitive factors when exploring the associations between adolescent lifestyles and PHC. These results are important for health promotion and education programmes aimed at improving healthy lifestyle and psychosocial well-being in adolescents.

Relative Age Effect in Physical Fitness Among Elementary and Junior High School Students

The present study investigated characteristics of the relative age effect (RAE) among a general sample of Japanese elementary and junior high school students. Japan applies a unique annual age-grouping by birthdates between April 1 and March 31 of the following year for sport and education. Anthropometric and physical fitness data were obtained from 3,610 Japanese students, including height, weight, the 50-m sprint, standing long jump, grip strength, bent-leg sit-ups, sit and reach, side steps, 20-m shuttle run, and ball throw. We examined RAE-related differences in these data using a one-way analysis of variance by comparing students with birthdates in the first (April-September) versus second (October-March of the following year) semesters. We observed a significant RAE for boys aged 7 to 15 years on both anthropometric and fitness data, but a significant RAE for girls was only evident for physical fitness tests among elementary school and not junior high school students. Thus, a significant RAE in anthropometry and physical fitness was evident in a general sample of school children, and there were RAE gender differences among adolescents.