Self-reported physical activity during leisure time was favourably associated with body composition in Norwegian adolescents

Association between objectively measured physical activity and longitudinal changes in body composition in adolescents: the Tromsø study fit futures cohort

OBJECTIVES

Physical activity may be important in deterring the obesity epidemic. This study aimed to determine whether objectively measured physical activity in first year of upper secondary high school predicted changes in body composition over 2 years of follow-up in a cohort of Norwegian adolescents (n=431).

DESIGN

A longitudinal study of adolescents (mean age of 16 (SD 0.4) at baseline, 60.3% girls) participating in the Fit Futures studies 1 (2010-2011) and 2 (2012-2013).

SETTING

All eight upper secondary high schools in two municipalities in Northern Norway.

PARTICIPANTS

Students participating in both studies and under the age of 18 at baseline and with valid measurement of physical activity at baseline and body composition in both surveys.

PRIMARY AND SECONDARY OUTCOMES

Change in objectively measured body mass index and waist circumference and change in dual-energy X-ray absorptiometry measured fat mass index, lean mass index (LMI) and appendicular LMI (aLMI) between baseline and follow-up.

RESULTS

At baseline, boys had significantly higher physical activity volume (p=0.01) and spent on average of 6.4 (95% CI 2.1 to 10.6) more minutes in moderate-to-vigorous physical activity (MVPA) than girls (p<0.01). In girls, multivariate regression analyses showed that more sedentary time was negatively associated with changes in LMI (p<0.01) and aLMI (p<0.05), whereas more light activity had opposite effects on these measures (p<0.01 and p<0.05, respectively). No significant associations between measures of baseline physical activity and changes in body composition parameters were observed in boys.

CONCLUSIONS

In this cohort of Norwegian adolescents, sedentary and light physical activity was associated with changes in LMI and aLMI in girls, but not boys. Minutes spent in MVPA in first year of upper secondary high school was not associated with changes in measures of body composition in neither sex after 2 years.

Body Fat Mediates Association between Active Living and Health among Adolescents

The aim of this study was to explore the association of moderate-to-vigorous physical activity and organized leisure-time activities with self-rated health among adolescents and whether these associations are mediated by body fat percentage. We used data on 888 adolescents (mean age 12.97, SD 1.20, 56.0% boys) from the Health Behaviour in School-aged Children (HBSC) study conducted in 2018 in Slovakia. We used logistic regression models to examine associations within self-reported data (moderate-to-vigorous physical activity and organized leisure-time activities with self-rated health) and their mediation by anthropometric data (body fat percentage). The adolescents who were sufficiently physically active and with normal body fat were more likely to report good or excellent health (odds ratios-OR/95% confidence intervals-95% CI: 3.52/1.50-8.27 and 3.66/2.37-5.68). Similarly, the adolescents who were engaged in individual/team sport and with normal body fat were more likely to report good or excellent health (OR/95% CI: 2.04/1.31-3.17 and 3.66/2.37-5.68). Adjustment for body fat percentage reduced the association between moderate-to-vigorous physical activity and self-rated health by 27.6% and the association between leisure-time activities and self-rated health by 30.7%. Active living and normal body fat might contribute to better health in adolescence. Programs and efforts to increase physical activity and leisure-time activities in childhood and adolescence need to identify which aspects of these activities are important, effective, and crucial for the population of adolescents.