No abstract

Background: Resistance training is a known method for weight reduction, but in apparently healthy adolescents the effects on health aspects are not clear. Aims: Was to analyze the relationship between resistance training (RT) and body composition in adolescents over a 12-month follow-up. Methods: Longitudinal study conducted at a public university in Presidente Prudente, SP, Brazil. Data from a study entitled the “ABCD- Growth Study” were used. The sample consisted of 190 adolescents of both sexes from schools (public and private) and sports clubs in Presidente Prudente, Brazil, divided into 3 groups according to RT practice: non-engagement (n=121), irregular engagement (n=44), and frequent engagement (n=25). Engagement in RT was assessed by face-to-face interviews. The bone mineral density (BMD), lean soft tissue (LST), and body fatness (BF) were analyzed using dual-energy x-ray absorptiometry (DXA). All data analyses were performed using BioEstat statistical software (version 5.0) and the statistical significance was set at 5% (p-value <0.05). Results: After 12-months of follow-up, adolescents frequently engaged in RT presented higher gains in LST (6.160 kg [3.727 to 8.593]) and BMD-upper limbs (0.096 g/cm2 [0.072 to 0.121]) when compared to adolescents who were not engaged in RT (2.452 kg [1.461 to 3.442] and 0.096 g/cm2 [0.072 to 0.121], respectively). Findings were more consistent for boys than girls. Conclusion: Regular engagement in RT seems to be related to higher gains in muscle mass and bone density, especially among boys.