Maturity negates the gender-related difference in physical activity among youth. Is this equally justified whatever the accelerometer cut-off point used?

Exploring the relationship between adolescent biological maturation, physical activity, and sedentary behaviour: a systematic review and narrative synthesis

CONTEXT

Across adolescence, there is a notable decline in physical activity in boys and girls. Maturational timing may be a risk factor for disengagement from physical activity and increased sedentary behaviours during adolescence.

OBJECTIVE

This systematic review aimed to summarise literature that examined the relationship between maturational timing, physical activity and sedentary behaviour in adolescents.

METHODS

Six electronic databases were searched for articles that assessed biological maturation and physical activity (including sports participation and active transportation) or sedentary behaviours in adolescents. Two reviewers conducted title, abstract, and full-text screening, reference and forward citation searches. Included articles were evaluated for quality using a standardised tool. A narrative synthesis was used to analyse the findings due to the heterogeneity of the studies.

RESULTS

Searches yielded 78 articles (64 unique studies) that met the inclusion criteria, representing 242,316 participants (153,179 unique). Studies ranged from 30.0% (low) to 91.7% (high) in quality. An inverse relationship between maturational timing and physical activity (in 50 and 60% of studies in boys and girls, respectively) and a positive relationship between maturational timing and sedentary behaviour (in 100% and 53% of studies in boys and girls, respectively) was most commonly reported. Evidence supporting an association between maturational timing, sports participation, and active transportation was inconsistent.

CONCLUSIONS

While this review demonstrates some evidence for early maturational timing as a risk factor for disengagement from physical activity and increase in sedentary behaviours, the reviewed literature also demonstrates that this relationship is complex. Future research that tracks maturity-related variations in physical activity and sedentary behaviours over adolescence is warranted.

Impact of Interactions Between Self-Reported Psychological Stress and Habitual Exercise on the Dietary Intake of Japanese Men and Women: a Large-Scale Cross-Sectional Study

BACKGROUND

Modifying lifestyle factors such as diet and exercise can reduce the risk of cancer. Psychological stress (PS) might be indirectly associated with cancer because it alters lifestyle factors. However, the relationship among these variables has not been fully investigated. Thus, we examined interactions between self-reported PS (SRPS) and habitual exercise on diet.

MATERIALS AND METHODS

In all, 5,587 men and 2,718 women were divided into "exerciser" and "non-exerciser" groups, based on whether they exercised regularly, and classified into three SRPS levels: low, moderate and high. Diet was estimated using a validated food frequency questionnaire. Using a general linear model, food and nutrient consumption was estimated for each SRPS level in the 2 exercise groups, and the interactions between SRPS levels and exercise were calculated.

RESULTS

In women, the intake of pork and beef, low fat milk and yogurt, natto (fermented soybean), carrots and squash, other root vegetables, mushrooms, seaweeds, and wine, along with the nutrients vegetable protein, soluble, insoluble and total dietary fiber, daidzein, genistein, carotene, retinol equivalents, vitamin B2, pantothenic acid, potassium, calcium, magnesium, phosphorus and iron demonstrated significant interaction with SRPS and habitual exercise (p for interaction <0.05). In men, raw and green leafy vegetables and fruit and vegetable juice significantly interacted with SRPS and habitual exercise (p for interaction <0.05).

CONCLUSIONS

We suggest that certain foods and nutrients, which are thought to have a protective effect against cancer, interact with SRPS and habitual exercise, especially in women. This information is valuable for understanding and improving interventions for cancer prevention.

Different Methods Yielded Two-Fold Difference in Compliance with Physical Activity Guidelines on School Days

Introduction

The aim was to compare the average and the days method in exploring the compliance of children with physical activity guidelines and describe their physical activity patterns in different school day segments.

Methods

Physical activity was objectively measured in 472 children aged 6–13 for one school week. Children were compliant when fulfilling PA recommendations 1) on average over all measured days (average method) or 2) on at least four measured days (days method). To explore the difference in moderate to vigorous physical activity (MVPA) minutes between compliant and non-complaint children (using both the average and days method) in various day segments, linear mixed models was used.

Results

Compliance with physical activity guidelines was significantly higher with the average compared to the days method (51.7% and 23.7%, respectively). In segmented-day analysis, compliant children accrued more MVPA minutes in all day segments, especially during after-school. Gender differences appeared only during the in-school segments, where girls spent less time in MVPA (average method: -4.39 min, 95% CI = -5.36,-3.42, days method: -4.45 min, 95%CI = -5.46,-3.44). Older children accrued more MVPA minutes during physical education classes, but less during breaks, compared to younger children.

Conclusions

The used methods yielded remarkably different prevalence estimates for compliance to physical activity recommendations. To ensure comparability between studies, interventions and reports, there is a need for internationally agreed operationalization and assessment methods of physical activity guidelines. As non-compliant children had lower MVPA during all day segments, greater efforts should be made to provide physical activity opportunities both during and after school.

Maturity-Related Differences in Moderate, Vigorous, and Moderate-to-Vigorous Physical Activity in 10–14-Year-Old Boys

The goal of this study was to investigate differences in physical activity (PA) levels between early, average, and late maturing boys and the effect of chronological age, body mass index, and fat mass. PA was measured by accelerometry in 10–14-yr.-old boys ( N = 265) during seven consecutive days. Biological maturation groups (early, average, and late) were created. Average and late maturing boys had significantly higher moderate PA and moderate-to-vigorous PA compared to early maturing boys. Late maturers also had higher vigorous PA compared to early maturers. Differences in moderate PA and moderate-to-vigorous PA remained significant after controlling for chronological age; however, after controlling for Body Mass Index or fat mass the differences were no longer significant. Mean differences in PA between early, average, and late maturing boys are not independent of Body Mass Index or fat mass. Vigorous PA differences between maturity groups were not independent of chronological age.