What is one of the major causes of short-term fatigue during exhaustive exercise?

One of the major causes of short-term fatigue during exhaustive exercise is the depletion of ATP (adenosine triphosphate) and CP (creatine phosphate) reserves. During high-intensity activities, the body relies heavily on these energy sources to produce the necessary ATP for muscle contraction. As these energy stores become depleted, the ability of the muscles to sustain maximal effort diminishes, leading to fatigue.

The ATP/CP system is the primary energy pathway for very short bursts of activity (typically lasting up to about 10 seconds). Once this system is exhausted, the muscles cannot contract with the same intensity, and performance declines. This physiological response is particularly evident during activities such as sprinting, heavy lifting, or any exercise that requires rapid bursts of energy.

Other factors, like muscle pH changes, insufficient salt intake, and oxygen availability do play roles in fatigue, but they are typically more relevant in different contexts or during prolonged, rather than short-term, exercise. For example, increased muscle acidity from lactic acid accumulation can contribute to fatigue in sustained exercise, but it is not the primary cause in the initial phase of exhaustive exercise. Thus, the depletion of ATP/CP reserves is a critical and direct contributor to short-term fatigue.