Mohr Magni, Nordsborg Nikolai, Nielsen Jens Jung, Pedersen Lasse Danneman, Fischer Christian, Krustrup Peter, Bangsbo Jens
Institute of Exercise and Sport Sciences, Department of Human Physiology, August Krogh Institute, University of Copenhagen, Universitetsparken 13, 2100, Copenhagen Ø, Denmark.
Pflugers Arch. 2004 Jul;448(4):452-6. doi: 10.1007/s00424-004-1257-6. Epub 2004 Mar 27.
Accumulation of K+ in skeletal muscle interstitium during intense exercise has been suggested to cause fatigue in humans. The present study examined interstitial K+ kinetics and fatigue during repeated, intense, exhaustive exercise in human skeletal muscle. Ten subjects performed three repeated, intense (61.6+/-4.1 W; mean+/-SEM), one-legged knee extension exercise bouts (EX1, EX2 and EX3) to exhaustion separated by 10-min recovery periods. Interstitial [K+] ([K+]interst) in the vastus lateralis muscle were determined using microdialysis. Time-to-fatigue decreased progressively (P<0.05) during the protocol (5.1+/-0.4, 4.2+/-0.3 and 3.2+/-0.2 min for EX1, EX2 and EX3 respectively). Prior to these bouts, [K+]interst was 4.1+/-0.2, 4.8+/-0.2 and 5.2+/-0.2 mM, respectively. During the initial 1.5 min of exercise the accumulation rate of interstitial K+ was 85% greater (P<0.05) in EX1 than in EX3. At exhaustion [K+]interst was 11.4+/-0.8 mM in EX1, which was not different from that in EX2 (10.4+/-0.8 mM), but higher (P<0.05) than in EX3 (9.1+/-0.3 mM). The study demonstrated that the rate of accumulation of K+ in the muscle interstitium declines during intense repetitive exercise. Furthermore, whilst [K+]interst at exhaustion reached levels high enough to impair performance, the concentration decreased with repeated exercise, suggesting that accumulation of interstitial K+ per se does not cause fatigue when intense exercise is repeated.
有研究表明，剧烈运动期间骨骼肌间质中钾离子（K+）的积累会导致人体疲劳。本研究检测了人体骨骼肌在重复、剧烈、力竭性运动期间的间质K+动力学及疲劳情况。10名受试者进行了3次重复的、剧烈的（61.6±4.1瓦；平均值±标准误）单腿伸膝运动试验（EX1、EX2和EX3），直至力竭，每次试验间隔10分钟恢复期。使用微透析法测定股外侧肌的间质[K+]（[K+]interst）。在试验过程中，疲劳时间逐渐缩短（P<0.05）（EX1、EX2和EX3的疲劳时间分别为5.1±0.4、4.2±0.3和3.2±0.2分钟）。在这些试验之前，[K+]interst分别为4.1±0.2、4.8±0.2和5.2±0.2毫摩尔/升。在运动的最初1.5分钟内，EX1中间质K+的积累速率比EX3高85%（P<0.05）。力竭时，EX1中的[K+]interst为11.4±0.8毫摩尔/升，与EX2（10.4±0.8毫摩尔/升）无差异，但高于EX3（9.1±0.3毫摩尔/升）（P<0.05）。该研究表明，在剧烈重复运动期间，肌肉间质中K+的积累速率下降。此外，虽然力竭时的[K+]interst达到了足以损害运动表现的高水平，但随着重复运动，该浓度会降低，这表明当重复进行剧烈运动时，间质K+的积累本身并不会导致疲劳。
