Decreased Myofilament Calcium Sensitivity Plays a Significant Role in Muscle Fatigue

Muscle fatigue can result from either the accumulation of metabolic by-products (e.g., P-i and H+) or a decrease in myoplasmic Ca++; however, individually, neither change can explain quantitatively the decrease in force capacity. Therefore, the emerging view is that, by decreasing the sensitivity of myofilaments to calcium, P-i and H+ act synergistically with decreased Ca++ levels to contribute to fatigue.