Effect of impact load and active load on bone metabolism and body composition of adolescent athletes

Purpose: It is unclear whether adolescents involved in nonweight-bearing ac tivities experience a delay in bone growth acquisition and sexual maturatio n. The purpose of this study was to compare bone mineral density (BMD), bod y composition. hormonal profile, and bone biochemical markers of adolescent athletes active in sports involved in impact load sports with those partic ipating in active load sports. Methods: Forty-five male Caucasian athletes aged 12-18 yr were divided into two groups according to type of skeleton lo ading, impact (N = 18). or active (N = 27). Twenty-four male Caucasian adol escents (12-18 yr) served as controls and only performed the activities inc luded in their physical education classes. All subjects were assessed for b one mass, body composition. and bone age by dual x-ray absorptiometry (DXA) . Serum calcium (Ca), phosphorus (P), bone-specific alkaline phosphatase (B AP), total testosterone, FSH, LH, urinary calcium to creatinine ratio (Ca/C r), and urinary deoxypyridinoline crosslinks to creatinine ratio (DPD/Cr) w ere measured. Results: The impact load group presented the highest BMD amon g the three groups for all studied sites. Lean mass and absolute weight wer e correlated with all of the bone mass measurements. BAP levels were signif icantly higher and testosterone levels significantly lower in the active lo ad group compared with the impact group. Conclusion: High-impact load exerc ises have a beneficial effect on bone mass in male adolescents. There is al so a positive correlation of weight and body composition with BMD. However. further longitudinal studies are necessary to determine whether there is a delay in bone growth acquisition among adolescents involved in a nonweight -bearing exercise regimen and its association with sex hormones.