Rejc Enrico, di Prampero Pietro Enrico, Lazzer Stefano, Grassi Bruno, Simunic Bostjan, Pisot Rado, Antonutto Guglielmo, Narici Marco
Department of Medical and Biological Sciences, University of Udine, P.le Kolbe 4, 33100, Udine, Italy,
Eur J Appl Physiol. 2015 Jun;115(6):1323-30. doi: 10.1007/s00421-015-3111-2. Epub 2015 Jan 23.
Bilateral deficit (BLD) occurs when the force (or power) generated by both limbs together is smaller than the sum of the forces (or powers) developed separately by the two limbs. The amount of BLD can be altered by neural adaptations brought about by the repetitive execution of specific motor tasks (training). Prolonged disuse also leads to relevant neural adaptations; however, its effects on BLD are still unknown. Thus, the aim of this study was to investigate the effects of a 35-day bed rest on the BLD of the lower limbs.
Ten young healthy volunteers performed maximal explosive efforts on a sledge ergometer with both lower limbs or with the right and the left limb separately. Electromyography (EMG) of vastus lateralis, rectus femoris, biceps femoris and gastrocnemius medialis was also measured.
Before bed rest, maximal explosive power and peak force were significantly higher in monolateral than bilateral efforts (+18.7 and +31.0 %, respectively). Conversely, peak velocity was 11.9 % greater in bilateral than monolateral efforts. BLD attained a value of 18.1 % and was accompanied by lower EMG amplitude of knee extensors (-17.0 %) and gastrocnemius medialis (-11.7 %) during bilateral efforts. Bed rest led to a ~28.0 % loss in both bilateral and monolateral maximal explosive power. Neither BLD magnitude nor the difference in EMG amplitudes as well as in peak force and velocity between bilateral and monolateral efforts were affected by bed rest.
These results suggest that the neuromuscular factors underlying BLD are unaltered after prolonged disuse.
当双下肢共同产生的力量（或功率）小于两下肢分别产生的力量（或功率）之和时，就会出现双侧力量不足（BLD）。通过重复执行特定的运动任务（训练）所引起的神经适应性变化可以改变BLD的程度。长期不使用也会导致相关的神经适应性变化；然而，其对BLD的影响仍不清楚。因此，本研究的目的是调查35天卧床休息对下肢BLD的影响。
10名年轻健康志愿者分别用双下肢或右下肢和左下肢在雪橇测力计上进行最大爆发力测试。同时还测量了股外侧肌、股直肌、股二头肌和腓肠肌内侧头的肌电图（EMG）。
卧床休息前，单侧测试的最大爆发力和峰值力显著高于双侧测试（分别高出18.7%和31.0%）。相反，双侧测试的峰值速度比单侧测试高11.9%。双侧测试时，BLD达到18.1%，同时膝关节伸肌（-17.0%）和腓肠肌内侧头（-11.7%）的肌电图幅度较低。卧床休息导致双侧和单侧最大爆发力均下降约28.0%。卧床休息对BLD的大小、肌电图幅度差异以及双侧和单侧测试之间的峰值力和速度差异均无影响。
这些结果表明，长期不使用后，BLD潜在的神经肌肉因素未发生改变。
