Final answer:
The statement suggesting that muscle fatigue is associated with the reduced ability of the sarcoplasmic reticulum to release Ca2+ is true. Compromised calcium regulation, along with ATP depletion and other factors, contribute to the onset of muscle fatigue.
Step-by-step explanation:
The statement that fatigue appears due to the reduced ability of the sarcoplasmic reticulum (SR) to release Ca2+ with neural stimulation is generally considered true. Muscle fatigue can indeed be associated with compromised calcium regulation within muscle fibers. During muscle contraction, ATP is necessary for both the movement of the myosin heads (creating cross-bridges) and for pumping Ca2+ back into the SR for muscle relaxation. A decrease in ATP, as well as potential damage to the SR and the sarcolemma from prolonged exercise, can impair this process, leading to difficulty in muscle contraction and an onset of fatigue. Additional factors contributing to fatigue can include a build-up of lactic acid, affecting intracellular pH, and imbalances in Na+ and K+ concentrations that further disrupt the Ca2+ flow.