School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UK.
Exp Gerontol. 2012 Jun;47(6):437-43. doi: 10.1016/j.exger.2012.03.013. Epub 2012 Mar 28.
The inter-relationship between muscle strength and serum testosterone is not fully understood, and may be confounded or influenced by age. The polymorphism of androgen receptor gene CAG number (AR CAGn) could also influence these variables. The study examined the relationship between total testosterone (TT), free testosterone (FT) and AR CAGn with the muscle strength of young (YM, 18-30 yrs, n=82) and older (OM, 60-70 yrs, n=101) Caucasian men. Knee extensor strength was measured isometrically and isokinetically, and thigh and whole-body lean mass of the OM was determined by DXA. TT and serum hormone binding globulin (SHBG) were assayed by ELISA and used to calculate FT. AR CAGn was determined using polymerase chain reaction and microchip electrophoresis. OM were weaker than YM (-20 to -29%, all P<0.001), and serum androgens were lower (TT, -13%; FT, -13%; both P<0.001). TT was unrelated to any strength measurement in YM or OM. In the OM only, FT had a weak positive association with all three strength measures (r(2)=4.1-9.3%, P<0.036) and both whole body and thigh lean mass (r(2)=6.1-8.6%; P<0.013). Muscle strength was unrelated to AR CAGn for either the YM or OM, or when data were collapsed across both age groups (age normalised strength). Lean mass in the older cohort was also independent of AR CAGn. In conclusion, FT, but not TT or AR CAGn, was positively associated with muscle strength, but only as values declined with age.
肌肉力量与血清睾丸酮之间的相互关系尚未完全明了，其可能会受到年龄的影响或与之相关。雄激素受体基因 CAG 数（AR CAGn）的多态性也可能影响这些变量。本研究调查了总睾丸酮（TT）、游离睾丸酮（FT）和 AR CAGn 与年轻（YM，18-30 岁，n=82）和年老（OM，60-70 岁，n=101）白种男性的肌肉力量之间的关系。通过等长和等速测力法测量膝关节伸肌力量，并用 DXA 测定 OM 的大腿和全身瘦体重。采用 ELISA 法测定 TT 和血清性激素结合球蛋白（SHBG），并用于计算 FT。采用聚合酶链反应和微芯片电泳法测定 AR CAGn。OM 比 YM 弱（-20 至-29%，均 P<0.001），血清雄激素也较低（TT，-13%；FT，-13%；均 P<0.001）。在 YM 或 OM 中，TT 与任何力量测量均无关。在 OM 中，FT 与所有三种力量测量（r(2)=4.1-9.3%，P<0.036）以及全身和大腿瘦体重（r(2)=6.1-8.6%；P<0.013）均呈弱正相关。对于 YM 或 OM，或当将数据按年龄组汇总时（年龄归一化的力量），肌肉力量与 AR CAGn 无关。在较年长的队列中，瘦体重也与 AR CAGn 无关。总之，FT 与肌肉力量呈正相关，但仅在 TT 和 AR CAGn 随年龄下降时才相关。
