Muscle strength and soccer practice as major determinants of bone mineral density in adolescents

OBJECTIVES: To analyse the relationship between isokinetic strength of the lower limb muscles and bone mineral density and content (BMD, BMC) of adolescent male soccer players and age-matched controls not involved in sport (12-15years). METHODS: A random sample of 151 young males was divided into soccer players (SG; n=117) and control subjects (CG; n=34). Peak torque of knee extensors (PTE) and flexors (PTF) was measured during isokinetic knee joint movement (90°/s) of the dominant and non-dominant lower limbs. BMD and BMC of the whole-body, lumbar spine, dominant/non-dominant lower limb were determined by dual-energy X-ray absorptiometry. Physical activity was monitored with accelerometers during 5 days. Estimated maturity offset was used as an indicator of biological maturity status. RESULTS: Whole-body BMD (1.03±0.01 vs. 0.98±0.01g/cm(2), P=0.003) and dominant (1.09±0.01 vs. 1.02±0.01g/cm(2), P