title: Changes in bone mineral content in male athletes. Mechanisms of action and intervention effects.
abstract: OBJECTIVE
  To determine changes in bone mineral content (BMC) in male athletes, to examine the mechanisms of changes, and to evaluate the effects of intervention.
  
  
  METHODS
  Dual-energy x-ray absorptiometry (DEXA) tests were administered over a 2-year period, and calcium loss during training was determined by analysis of sweat and urine. Calcium supplementation was administered during year 2. SETTING--A midsouth university.
  
  
  METHODS
  Eleven members of a college Division I-A basketball team.
  
  
  METHODS
  Based on observed calcium loss, athletes received differential levels of calcium supplementation. Intervention commenced the week prior to the fall training season and continued through postseason play. MAIN OUTCOME MEASURE--Changes in BMC.
  
  
  RESULTS
  Total body BMC decreased 3.8% from preseason to midseason of year 1 (mean decrease, 133.4 g, P = .02), increased nonsignificantly by 1.1% (mean increase, 35.3 g, P = .22) during the offseason, but decreased an additional 3.3% during summer months when practices resumed (mean decrease, 113.1 g, P = .01). Dermal calcium loss averaged 247 mg [corrected] per training session. From preseason to late summer, there was an overall decrease of 6.1% in total BMC and a 10.5% decrease in BMC of the legs. Calcium supplementation was associated with significant increases in BMC and lean body mass.
  
  
  CONCLUSIONS
  Bone loss is calcium related and exercise is positively related to BMC provided that calcium intake is sufficient to offset dermal loss.
authors.affiliation: Department of psychology, University of Memphis, TN 38152, USA. bklesges@msuvx1.memphis.edu
authors.forename: R C
authors.initials: RC
authors.lastname: Klesges
authors.forename: K D
authors.initials: KD
authors.lastname: Ward
authors.forename: M L
authors.initials: ML
authors.lastname: Shelton
authors.forename: W B
authors.initials: WB
authors.lastname: Applegate
authors.forename: E D
authors.initials: ED
authors.lastname: Cantler
authors.forename: G M
authors.initials: GM
authors.lastname: Palmieri
authors.forename: K
authors.initials: K
authors.lastname: Harmon
authors.forename: J
authors.initials: J
authors.lastname: Davis
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D001823:Body Composition; D015519:Bone Density / Q000502:physiology*; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism* / Q000652:urine; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013177:Sports / Q000502:physiology*; D013542:Sweat / Q000737:chemistry; D014807:Vitamin D / Q000008:administration & dosage / Q000378:metabolism
chemical_list: D002136:Calcium, Dietary; D014807:Vitamin D; D002119:Calcium Carbonate; D002118:Calcium