Lännergren J, Westerblad H
Institutionen för fysiologi och farmakologi, Karolinska institutet, Stockholm.
Nord Med. 1994;109(1):23-7.
Strenuous physical activity results in depressed muscle function characterised by diminished force production, reduced speed and slowed relaxation. Studies of isolated muscle fibres have shown reduced force to be due to a combination of impaired cross-bridge function, reduced Ca(2+)-sensitivity and decreased Ca(2+)-release. The first two changes are caused by an accumulation of inorganic phosphate and a lowering of pH as a result of increased energy metabolism; the cause of the reduced Ca(2+)-release is unclear. Reduced speed is due to lowered pH and possibly to an increase in ADP (adenosine diphosphate). Slowed relaxation appears to be due to metabolically induced changes both in Ca(2+)-reuptake and cross-bridge function.
剧烈的体力活动会导致肌肉功能下降，其特征是力量产生减少、速度降低和放松减慢。对分离的肌纤维的研究表明，力量降低是由于横桥功能受损、钙敏感性降低和钙释放减少共同作用的结果。前两个变化是由于能量代谢增加导致无机磷酸盐积累和pH值降低引起的；钙释放减少的原因尚不清楚。速度降低是由于pH值降低，也可能是由于二磷酸腺苷（ADP）增加所致。放松减慢似乎是由于代谢诱导的钙再摄取和横桥功能的变化所致。
