Effect of Calcium Intake, Tennis Playing, and Body Composition on Bone-Mineral Density of Brazilian Male Adolescents

Claudia Ridel Juzwiak, Olga Maria Silverio Amancio, Maria Sylvia Souza Vitalle, Vera Lúcia Szejnfeld, Marcelo Medeiros Pinheiro
2008 International Journal of Sport Nutrition & Exercise Metabolism  
In this prospective, cross-sectional study male adolescent tennis players (44) and nonathletic controls (32) were evaluated to determine the effects of physical activity, dietary nutrient intakes, sexual maturation, and body composition on bone-mineral density (BMD). Dietary nutrient intakes and physical activity expenditure were estimated by 4-d diaries. Total body composition, bone-mineral content (BMC), and BMD (L1-L4, femur, and nondominant forearm) were assessed by dual-energy X-ray
more » ... iometry. Tennis players had significantly greater lean body mass ( mean [SEM] 50.6 [1.6] kg vs. 45.1 [1.7] kg, p = .022), trochanter BMD (1.0 [0.02] g/cm 2 vs. 0.9 [0.03] g/cm 2 , p = .032), and dominant forearm BMC (173.7 [7.4] g vs. 146.5 [9.3] g) but lower BMD in the nondominant forearm (0.7 [0.02] g/cm 2 vs. 0.8 [0.03] g/cm 2 , p = .028). Daily average calcium intake was below the recommendation in both groups. No correlation was found between BMD and calcium intake and exercise. Lean body mass was the best predictor of BMD and BMC for both tennis players and controls (R 2 = .825, .628, and .693 for L1-L4, total femur, and nondominant forearm, respectively). Based on these results the authors conclude that lean body mass is the best predictor of BMD and BMC for both tennis players and others. Tennis exerts a site-specific effect, and training should focus on ways minimize this effect. Although calcium intake showed no effect on BMD, nutrition education for young athletes should focus on promoting a balanced diet, providing energy and nutrients in adequate amounts.
doi:10.1123/ijsnem.18.5.524 pmid:19033613 fatcat:bitgz7sip5ca7k2675yyn34m4i