Felici Francesco, Bazzucchi Ilenia, Sgrò Paolo, Quinzi Federico, Conti Alessandra, Aversa Antonio, Gizzi Leonardo, Mezzullo Marco, Romanelli Francesco, Pasquali Renato, Lenzi Andrea, Di Luigi Luigi
Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Roma, Italy.
Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Roma, Italy.
J Electromyogr Kinesiol. 2016 Jun;28:184-92. doi: 10.1016/j.jelekin.2015.12.004. Epub 2015 Dec 19.
To indirectly evaluate the effect of androgens on neuromuscular system in humans we analyzed if an induced short-term hypogonadal state (serum total testosterone-TT<2.3ng/ml) may affect central drive to skeletal muscle and/or muscle neuro-mechanical performance.
We compared voluntary and electrically evoked muscle sEMG signals from biceps brachii in nine hypogonadal male volunteers (Hypo) and in ten healthy controls (Cont). Serum TT and dihydrotestosterone (DHT) were assayed.
With respect to Hypo, Cont exhibited significantly higher median frequency content (MDF) at any angular velocity; normalized MDF [95.9% (SD=23.3) vs 73.8% (SD=9.3)]; muscle fiber conduction velocity (CV) from lowest to highest angular velocities; initial MDF at fatigue test [91.78Hz (SD=22.03) vs 70.94Hz (SD=11.06)] as well as was the normalized slope [-0.64 (SD=0.14 vs -0.5 (SD=0.11)]. In the non-fatigued state, Hypo showed a slower single twitches time to peak (TTP). In Cont, half relaxation time (HRT) decreased after fatigue while increased in Hypo (p<0.05 between groups). A significant correlation between both TT and dihydrotestosterone with MDF and CV was found during voluntary contractions only.
A brief exposure to very low serum TT concentration in males seem to determine a reduced excitability of the NM system which, in turn, would favor a predominant recruitment of slow twitch MUs.
为了间接评估雄激素对人类神经肌肉系统的影响，我们分析了诱导产生的短期性腺功能减退状态（血清总睾酮-TT<2.3ng/ml）是否会影响骨骼肌的中枢驱动和/或肌肉神经机械性能。
我们比较了9名性腺功能减退男性志愿者（Hypo）和10名健康对照者（Cont）肱二头肌的自主和电诱发肌肉表面肌电图信号。检测血清TT和双氢睾酮（DHT）。
与Hypo组相比，Cont组在任何角速度下均表现出显著更高的中位频率含量（MDF）；标准化MDF[95.9%（标准差=23.3）对73.8%（标准差=9.3）]；从最低到最高角速度的肌纤维传导速度（CV）；疲劳试验时的初始MDF[91.78Hz（标准差=22.03）对70.94Hz（标准差=11.06）]以及标准化斜率[-0.64（标准差=0.14）对-0.5（标准差=0.11）]。在非疲劳状态下，Hypo组单收缩达到峰值的时间（TTP）较慢。在Cont组中，疲劳后半松弛时间（HRT）缩短，而在Hypo组中则增加（组间p<0.05）。仅在自主收缩期间发现TT和双氢睾酮与MDF和CV之间存在显著相关性。
男性短期暴露于极低血清TT浓度似乎会导致神经肌肉系统兴奋性降低，进而有利于慢肌运动单位的优先募集。
