Muscle fatigue: lactic acid or inorganic phosphate the major cause?
Level 5 - mechanism / opinion, no new human data
Narrative review discussing mechanism-based physiological studies without systematic synthesis.
PubMed 11821531 · doi:10.1152/physiologyonline.2002.17.1.17
What was done
This narrative review evaluates physiological literature on the causes of skeletal muscle fatigue, contrasting the traditional model of intracellular lactic acidosis with evidence regarding inorganic phosphate accumulation from creatine phosphate breakdown in mammalian muscle.
What was found
The abstract reports no numerical values or effect sizes. It states that recent studies in mammalian muscle at physiological temperatures demonstrate minimal direct impairment of muscle function from acidosis, whereas inorganic phosphate accumulation during fatigue emerges as a major causative factor.
Why it matters
It challenges the classical view that lactic acid is the primary driver of muscle fatigue, highlighting inorganic phosphate as a central mechanism in muscle performance limitation.
Limits
The abstract contains no quantitative data, search methodology, or study counts. The conclusions rely on mechanistic and preclinical mammalian muscle models rather than direct human clinical trials.
Cited by
- contradicts Lactic acid rapidly dissociates into lactate and hydrogen ions at physiological pH, and the resulting proton accumulation alters pH, interfering with muscle contractile processes and enzymatic function.