Final answer:
Fatigue from long-term submaximal activities is primarily due to the exhaustion of energy reserves, while short duration, high-intensity exercises cause fatigue due to the buildup of lactic acid.
Step-by-step explanation:
Fatigue in Response to Exercise:
Fatigue that occurs in response to extended submaximal exertion is usually due to exhaustion of energy reserves whereas fatigue to a short duration of maximal exertion involves buildup of lactic acid levels.Muscle Fatigue and Exercise Type: Different types of exercise cause muscle fatigue through various ways. During extended exercises such as running a marathon, the body's energy reserves are gradually depleted, which includes glycogen stores in the muscles. This type of fatigue is often associated with aerobic activities where there is sufficient oxygen for metabolic processes. However, during high-intensity, short-duration activities like sprinting, muscles rely on anaerobic glycolysis which leads to the accumulation of lactic acid. When lactate production exceeds its clearance rate, it contributes to muscle fatigue.Additionally, factors such as ATP availability, intracellular pH, Na+ and K+ balance, and Ca++ regulation play significant roles. Intense exercise can also cause muscle soreness and fatigue through microscopic damage, known as delayed onset muscle soreness (DOMS).
Training and Muscular Endurance:
Fatigue resistance varies among individuals due to genetic factors influencing muscle fiber types. Individuals with a higher proportion of slow-twitch fibers may experience longer endurance, while those with more fast-twitch fibers may fatigue faster during intense exercises. Regular training can improve anaerobic activity effectiveness, reducing the fatigue impact.