Duncan Craig S, Blimkie Cameron J R, Cowell Christopher T, Burke Stephen T, Briody Julie N, Howman-Giles Robert
University of Sydney, Sydney, Australia.
Med Sci Sports Exerc. 2002 Feb;34(2):286-94. doi: 10.1097/00005768-200202000-00017.
This study investigated the influence of different exercise types and differences in anatomical distribution of mechanical loading patterns on bone mineral density (BMD) in elite female cyclists, runners, swimmers, triathletes, and controls (N = 15 per group). Associations between leg strength and BMD were also examined.
Areal BMD (g x cm(-2)) was assessed by duel-energy x-ray absorptiometry (DXA) (total body (TB), lumbar spine (LS), femoral neck (FN), legs, and arms). Right knee flexion and extension strength was measured using a Cybex Norm isokinetic dynamometer at 60 degrees x s(-1).
Runners had significantly higher unadjusted TB, LS, FN, and leg BMD than controls (P < 0.05); higher TB, FN, and leg BMD than swimmers (P < 0.05); and greater leg BMD than cyclists (P < 0.05). Absolute knee extension strength was significantly (P < 0.01) correlated (0.33 < or = r < or = 0.44) with TB, FN, LS, and leg BMD for all groups combined. Weaker but still significant correlations (0.28 < or = r < or = 0.33) existed for normalized (per leg lean tissue mass) knee extension strength and all BMD sites, except FN BMD. There were no significant correlations between absolute or normalized knee flexion strength and any of the BMD variables. Absolute knee extension strength was entered as the second independent predictor for LS and leg BMD in stepwise multiple linear regression analysis (MLRA), accounting for increments of 4% and 12%, respectively, in total explained variation.
We conclude that running, a weight bearing exercise, is associated with larger site-specific BMD than swimming or cycling, that the generalized anatomical distribution of loads in triathlon appears not to significantly enhance total body BMD status, and that knee extension strength is only a weak correlate and independent predictor of BMD in adolescent females.
本研究调查了不同运动类型以及机械负荷模式的解剖学分布差异对精英女性自行车运动员、跑步运动员、游泳运动员、铁人三项运动员及对照组（每组N = 15）骨密度（BMD）的影响。同时还研究了腿部力量与骨密度之间的关联。
采用双能X线吸收法（DXA）评估面积骨密度（g×cm⁻²）（全身（TB）、腰椎（LS）、股骨颈（FN）、腿部和手臂）。使用Cybex Norm等速测力计在60度/秒的速度下测量右膝屈伸力量。
跑步运动员未经调整的全身、腰椎、股骨颈和腿部骨密度显著高于对照组（P < 0.05）；全身、股骨颈和腿部骨密度高于游泳运动员（P < 0.05）；腿部骨密度高于自行车运动员（P < 0.05）。所有组合并后，绝对膝关节伸展力量与全身、股骨颈、腰椎和腿部骨密度显著相关（P < 0.01）（0.33 ≤ r ≤ 0.44）。除股骨颈骨密度外，标准化（每腿部瘦组织质量）膝关节伸展力量与所有骨密度部位的相关性较弱但仍显著（0.28 ≤ r ≤ 0.33）。绝对或标准化膝关节屈曲力量与任何骨密度变量之间均无显著相关性。在逐步多元线性回归分析（MLRA）中，绝对膝关节伸展力量作为腰椎和腿部骨密度的第二个独立预测因子，分别占总解释变异量的4%和12%。
我们得出结论，跑步作为一种负重运动，与游泳或骑自行车相比，与特定部位更大的骨密度相关；铁人三项中负荷的一般解剖学分布似乎并未显著提高全身骨密度状态；膝关节伸展力量只是青少年女性骨密度的弱相关因素和独立预测因子。
