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Effects of school-based squat training in adolescent girls.

BACKGROUND
For adolescent girls, less information on the effects of school-based exercise training is available from earlier studies. This study aimed to determine the effects of school-based squat training on body composition and muscular strength in adolescent girls.


METHODS
Fifty-two girls (13.8±0.6 years) were randomly assigned to the training and control groups. The training group conducted an 8-week body mass-based squat exercise training (100 reps/day, 45 sessions) as a part of after-school activity. Body composition (bioelectrical impedance analyzer), muscle thickness at the thigh anterior (ultrasound), and maximal isometric knee extension strength (myometer) were determined before and after the intervention. The magnitude of maturation was assessed using Tanner stage criteria of pubic hair before the intervention.


RESULTS
After the intervention, percent body fat decreased in the training group, but increased in the control group. The relative changes in lean body mass, muscle thickness and muscular strength were similar between both groups. In the training group, the relative change in knee extension strength was correlated to the magnitude of maturation before the intervention.


CONCLUSIONS
For adolescent girls, an 8-week body mass-based squat training is feasible for lowering percent body fat. In addition, the strength improvement for the knee extensors partially depends on the magnitude of maturation at start of the intervention.