Longitudinal differences of physical activity and adiposity in adolescents: a 2-year follow-up

Abstract

It is commonly believed that boys are more physically active than girls, which could affect body composition changes during adolescence. One major point not always considered or controlled is the maturational differences between boys and girls of similar chronological age. So, it remains to be determined the importance of physical activity (PA) behaviors adjusted by sex and maturation on body composition modifications. This study complement the published results by evaluating the effects of gender, sexual maturation level on PA and body composition changes. PURPOSE: To explore PA and adiposity alterations in Spanish students during adolescence. METHODS: Sixty-eight healthy adolescents were followed-up during 2-year (32 girls and 36 boys). A PA score was estimated by Physical Activity Questionnaire (PAQ-A). Adiposity was assessed by anthropometric measurements, BMI and fat mass percent (FMP) were calculated using classical equation, and waist circumference (WC) as abdominal adiposity marker. Tanner’s maturation stages were evaluated. Three assessments were performed: September 2011, 2012 and 2013 (S1, S2, and S3, respectively). Repeated measures were carried out between three moments for all variables and adjusted by maturation level and sex. RESULTS: Significant differences for FMP were found between S1 and S2 (22.30±8.22 vs. 21.15±7.73, P<0.05); a significant interaction with sex was observed (P<0.05), but not for maturation. Regarding PA, S2 was significantly higher than S3 (2.68±0.68 vs. 2.23±0.72, P<0.001). An interaction between PA and maturation was statically significant (P<0.05). CONCLUSION: The main finding of this follow-up was a reduction in PA after S2 period without changes in adiposity. In opposite, a reduction of FMP was only significant between S1 and S2, while PA was not modified. Our results suggest that body composition and PA changes observed during adolescence are not parallel. Moreover, the interaction analysis highlighted that maturation affect PA behavior, but not sex.