Holewijn M, Heus R
NLRGC, Netherlands Aerospace Medical Centre, Department of Research and Development, Soesterberg.
Eur J Appl Physiol Occup Physiol. 1992;65(6):541-5. doi: 10.1007/BF00602362.
The effects of 30 min of cooling (15 degrees C water) and warming (40 degrees C water) on arm muscle function were measured. A reference condition (24 degrees C air) was included. Of nine young male subjects the maximal grip force (Fmax), the time to reach 66% of Fmax (rate of force buildup) and the maximal rhythmic grip frequency were determined, together with surface electromyographic activity (EMG) of a forearm muscle (flexor digitorum superficialis). The results showed that in contrast to warming, cooling resulted in a significant decrease of 20% in the Fmax and a significant 50% decrease in force build-up time and the maximal rhythmic grip frequency. The relationship between the root mean square value (rms) of the EMG and the static grip force did not change due to temperature changes. The median power frequency (MPF) in the power spectrum of the EMG signal decreased by 50% due to cooling but remained unchanged with heating. During a sustained contraction at 15% of Fmax (Fmax depending on the temperature) the increase in the rms value with contraction time was 90% larger in the warm condition and 80% smaller in the cold condition compared to the increase in the reference condition. The MPF value remained constant during the warm and reference conditions but in the cold it started at a 50% lower value and increased with contraction time.(ABSTRACT TRUNCATED AT 250 WORDS)
测量了30分钟冷却（15摄氏度水）和加热（40摄氏度水）对手臂肌肉功能的影响。纳入了一个参考条件（24摄氏度空气）。在9名年轻男性受试者中，测定了最大握力（Fmax）、达到Fmax的66%所需时间（力量增长速率）和最大节律性握力频率，以及前臂肌肉（指浅屈肌）的表面肌电图活动（EMG）。结果表明，与加热相反，冷却导致Fmax显著下降20%，力量增长时间和最大节律性握力频率显著下降50%。EMG的均方根值（rms）与静态握力之间的关系并未因温度变化而改变。EMG信号功率谱中的中位功率频率（MPF）因冷却而下降50%，但加热时保持不变。在以Fmax的15%（Fmax取决于温度）进行持续收缩时，与参考条件下的增加相比，温暖条件下rms值随收缩时间的增加幅度大90%，寒冷条件下小80%。MPF值在温暖和参考条件下保持恒定，但在寒冷条件下开始时低50%，并随收缩时间增加。（摘要截断于250字）
