title: Effect of calcium intake, tennis playing, and body composition on bone-mineral density of Brazilian male adolescents.
abstract: 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 absorptiometry. 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/cm2 vs. 0.9 [0.03] g/cm2, 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/cm2 vs. 0.8 [0.03] g/cm2, 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 (R2 = .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.
authors.affiliation: Pediatric Department, Federal University of Sao Paulo, Brazil.
authors.forename: Claudia Ridel
authors.initials: CR
authors.lastname: Juzwiak
authors.forename: Olga Maria Silverio
authors.initials: OM
authors.lastname: Amancio
authors.forename: Maria Sylvia Souza
authors.initials: MS
authors.lastname: Vitalle
authors.forename: Vera Lucia
authors.initials: VL
authors.lastname: Szejnfeld
authors.forename: Marcelo Medeiros
authors.initials: MM
authors.lastname: Pinheiro
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena / Q000502:physiology; D001823:Body Composition / Q000187:drug effects* / Q000502:physiology; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D001846:Bone Development; D001842:Bone and Bones / Q000378:metabolism; D001938:Brazil; D002136:Calcium, Dietary / Q000008:administration & dosage*; D016022:Case-Control Studies; D002648:Child; D003430:Cross-Sectional Studies; D005269:Femur; D006801:Humans; D008159:Lumbar Vertebrae; D008297:Male; D011446:Prospective Studies; D012741:Sexual Maturation / Q000502:physiology; D013715:Tennis / Q000502:physiology*
chemical_list: D050071:Bone Density Conservation Agents; D002136:Calcium, Dietary