Strength Gains Can Be Achieved Through An Active Lifestyle Promotion Intervention In Obese Adolescents

Abstract

Introduction: In obesity, fat mass increase is associated with functional abil- ity impairment and maximal strength reduction. The purpose of the present study was to analyze lower limb peak torque (PT) changes after a 6-month intervention aiming active lifestyle promotion in obese adolescents. Methods: 21 adolescents (14.62 ± 1.24yr; 32.50 ± 3.64kg/m2), 16 girls, participated in this study. Baseline and 6-month data were collected as- sessing thigh PT (Biodex System 3 – Biodex Corp., Shirley, NY, USA), and body composition (dual-energy X-ray absorptiometry – Holog- ic-QDR Hologic, Inc., Bedford, MA, USA). Descriptive analysis was performed, along with normality test (Kolmogorov-Smirnov test), paired samples t-test, and Pearson correlation. Results: An increase in PT was observed during knee extension at 60o (Δ=32.53Nm; p=.001) and 180o (Δ=16.13Nm; p=.002). No significant changes were found in knee flexion (p > .05). Significant associations were found, at baseline and at 6-month, between strength performance at 60o and lower body lean body mass (r=.692;p=.001 and r=.791;p<.001, respectively) and lower body percent fat mass (r = –.807;p<.001 and r = –.652;p=.001, respectively). Conclusion: An intervention planed to promote an active lifestyle in obese adolescents was successful in the development of knee extension maximal strength, which can be elicited through walking and activities of daily living, thus increasing adolescent’s functionality. The absence of improvement regarding knee flexion maximal strength might be ex- plained by the need of specific exercise strategies to be achieved. Even among obese adolescents, strength performance presents a positive asso- ciation with lean mass, as well as a negative association with fat mass.