运动所致血浆K^+和血pH值的变化对肌肉疲劳和表面肌电图的影响

Effect of Change of Plasma K^+ and pH Value Induced by Exercise on Muscle Fatigue and Surface EMG

目的 探讨血 K+、H+与肌肉疲劳和肌电变化的关系。方法 对同一批受试者在 2 0 0 W和 12 0 W蹬功率车之前和运动至疲劳后即刻、5 min、10 min、2 0 m in时 ,测定血浆 K+、血 p H值以及活动肌和非活动肌定量负荷等长收缩 10 s的肌电图 (EMG)。结果 两次运动后血浆 K+和活动肌平均功率频率 (AM- MPF)均明显改变 (P<0 .0 1) ,二者高度负相关 ,并在 2 0 min时基本恢复。 2 0 0 W运动后 2 0 min内血 p H值一直明显低于安静值 (P<0 .0 1) ,但在 12 0 W运动后无变化 ,并与肌电无相关关系。 12 0 W运动后 2 0 min内的非活动肌积分肌电图值 (IM-IEMG)明显低于安静值 (P<0 .0 5 )。结论 细胞外高 K+是肌肉疲劳和 AM- MPF下降的主要因素之一 ,并可能也是 IM- IEMG下降的原因之一。 H+不是疲劳形成的主因 。

Objective This study was undertaken to explore the relationship between plasma K +,H + and muscle fatigue as well as electromyogram changes. Methods Fourteen male students enrolled as the subjects of this study performed two exercise tests of different intensity (200 W; 120 W) on a cycle ergometer till being fatigued. The plasma K +,pH value and electromyography (EMG) of active and inactive muscles during 10 s isometric contraction fixed load were measured before exercise and at 0, 5, 10, 20 minutes after exercise. Results Both plasma K + and mean power frequency (MPF) of the active muscles changed significantly (P<0.01) after exercise, but recovered in 20 minutes and were highly negatively correlated. Plasma pH at 20 minutes after 200 W exercise was significantly lower than that at rest (P<0.01), but did not change after 120 W exercise, and no correlation was found between pH and EMG. Integral electromyography (IEMG) of inactive muscles at 20 minutes after 120 W exercise was significantly lower than that at rest (P<0.05). Conclusion The results showed that high extra cellular K + concentration for exercise is one of the main factors inducing fatigue and MPF decrease of the active muscles as well as IEMG decrease of the inactive muscle, but H + is not a main factor for fatigue and it has no direct effect on EMG.