Wakabayashi Hitoshi, Nishimura Takayuki, Wijayanto Titis, Watanuki Shigeki, Tochihara Yutaka
Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido, 060-8628, Japan.
Department of Public Health, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Int J Biometeorol. 2017 Jul;61(7):1261-1267. doi: 10.1007/s00484-016-1303-z. Epub 2017 Jan 12.
This study aimed to investigate the effect of repeated cooling of forearm muscle on adaptation in skeletal muscle metabolism. It is hypothesized that repeated decreases of muscle temperature would increase the oxygen consumption in hypothermic skeletal muscle. Sixteen healthy males participated in this study. Their right forearm muscles were locally cooled to 25 °C by cooling pads attached to the skin. This local cooling was repeated eight times on separate days for eight participants (experimental group), whereas eight controls received no cold exposure. To evaluate adaptation in skeletal muscle metabolism, a local cooling test was conducted before and after the repeated cooling period. Change in oxy-hemoglobin content in the flexor digitorum at rest and during a 25-s isometric handgrip (10% maximal voluntary construction) was measured using near-infrared spectroscopy at every 2 °C reduction in forearm muscle temperature. The arterial blood flow was occluded for 15 s by upper arm cuff inflation at rest and during the isometric handgrip. The oxygen consumption in the flexor digitorum muscle was evaluated by a slope of the oxy-hemoglobin change during the arterial occlusion. In the experimental group, resting oxygen consumption in skeletal muscle did not show any difference between pre- and post-intervention, whereas muscle oxygen consumption during the isometric handgrip was significantly higher in post-intervention than in pre-test from thermoneutral baseline to 31 °C muscle temperature (P < 0.05). This result indicated that repeated local muscle cooling might facilitate oxidative metabolism in the skeletal muscle. In summary, skeletal muscle metabolism during submaximal isometric handgrip was facilitated after repeated local muscle cooling.
本研究旨在探讨前臂肌肉反复冷却对骨骼肌代谢适应性的影响。研究假设，肌肉温度的反复降低会增加低温骨骼肌的耗氧量。16名健康男性参与了本研究。通过附着在皮肤上的冷却垫将他们的右前臂肌肉局部冷却至25°C。8名参与者（实验组）在不同日期将这种局部冷却重复8次，而8名对照组未接受冷暴露。为了评估骨骼肌代谢的适应性，在反复冷却期前后进行了局部冷却测试。在前臂肌肉温度每降低2°C时，使用近红外光谱法测量静息和25秒等长握力（最大自主收缩的10%）期间指浅屈肌中氧合血红蛋白含量的变化。在静息和等长握力期间，通过上臂袖带充气使动脉血流阻断15秒。通过动脉阻断期间氧合血红蛋白变化的斜率评估指浅屈肌的耗氧量。在实验组中，骨骼肌的静息耗氧量在干预前后没有显示出任何差异，而从热中性基线到31°C肌肉温度，等长握力期间的肌肉耗氧量在干预后显著高于测试前（P<0.05）。该结果表明，反复局部肌肉冷却可能会促进骨骼肌的氧化代谢。总之，反复局部肌肉冷却后，次最大等长握力期间的骨骼肌代谢得到促进。
