Is the intracellular pH threshold an anaerobic threshold from the view point of intracellular events?: a brief review

Intracellular biochemical changes could be monitored noninvasivery and continuously by using nuclear magnetic resonance (NMR). In about the last decade, intracellular behavior of phosphorus compounds and pH during muscle contraction in man have been studied by 31P nuclear magnetic resonance spectroscopy (31P-MRS). During incremental load, lactic acidosis was followed by a decline in intracellular pH. 31P-MRS studies has been definitely proved that this change in intracellular pH shows the threshold behavior. Some reports discussed the intracellular pH threshold (pHT) as an anaerobic threshold (AT) from the view point of intracellular events. However, our studies revealed that pHT did not reflect the onset of lactate production. In this article, studies of intracellular pH of working muscle were reviewed in relation to an anaerobic threshold.