Piedrahita Hugo, Oksa Juha, Rintamäki Hannu, Malm Christer
Human Work Sciences Department, Luleå University of Technology, Luleå, Sweden.
Eur J Appl Physiol. 2009 Feb;105(3):429-38. doi: 10.1007/s00421-008-0920-6. Epub 2008 Nov 12.
This study was designed to find out if local leg cooling affects muscle function and trajectories of the upper limb during repetitive light work as well as capability to maintain dynamic balance. Nine healthy female subjects performed repetitive lifting task with right hand for 60 min while standing in front of a table with six target angles (30 degrees -220 degrees ) and with the legs inside a container with 15 degrees C cold water (Cold condition, C) or without water (Normal condition, N). Muscle temperature of the medial aspect of the gastrocnemius, rectal, and skin temperatures were measured continuously. The trajectories of the right upper limb were recorded with a 3D motion analysis system. Muscular strain (averaged EMG, a-EMG) and EMG gaps in eight muscles of the right upper limb were measured. End point excursion depicting the ability to maintain dynamic balance was measured before and after each experiment. Leg cooling decreased significantly (P < 0.05) the muscle and the mean skin temperature in C compared with N (6.7 and 2.2 degrees C, respectively). No marked changes in the trajectories or EMG activity were observed between the different environmental conditions. The end point excursion was significantly (P < 0.05) reduced in C compared with N and a positive correlation between excursion and muscle temperature was found at the end of the working period in C. In conclusion, local leg cooling did not affect upper limb muscle function or trajectories, but ability to maintain dynamic balance was reduced.
本研究旨在探究在重复性轻度工作期间，局部腿部降温是否会影响上肢的肌肉功能和运动轨迹以及维持动态平衡的能力。九名健康女性受试者站在一张有六个目标角度（30度至220度）的桌子前，用右手进行60分钟的重复性举重任务，腿部置于装有15摄氏度冷水的容器中（寒冷条件，C）或无水（正常条件，N）。持续测量腓肠肌内侧的肌肉温度、直肠温度和皮肤温度。用三维运动分析系统记录右上肢的运动轨迹。测量右上肢八块肌肉的肌肉应变（平均肌电图，a-EMG）和肌电图间隙。在每次实验前后测量描绘维持动态平衡能力的终点偏移。与N相比，腿部降温使C组的肌肉和平均皮肤温度显著降低（P<0.05）（分别为6.7摄氏度和2.2摄氏度）。在不同环境条件下，未观察到运动轨迹或肌电图活动有明显变化。与N相比，C组的终点偏移显著降低（P<0.05），并且在C组工作期结束时发现偏移与肌肉温度呈正相关。总之，局部腿部降温不影响上肢肌肉功能或运动轨迹，但维持动态平衡的能力降低。
