MICROANATOMY

Detailed explanation-1: -Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2. During intense exercise sustained to fatigue muscle pH decreases to about 6.4-6.6.

Detailed explanation-2: -Lactic acid is a byproduct of anaerobic metabolism, in which the body produces energy without using oxygen. Since the discovery of lactic acid, the popular notion has been that it is responsible for muscle fatigue and also tissue damage induced by the lactic acid following an intense workout.

Detailed explanation-3: -Improper exercise, long time combat, military training and some related diseases (for example, cancer and stroke) can cause muscle fatigue, which negatively affects athletic achievement, military combat ability and patient recovery.

Detailed explanation-4: -During heavy exercises or prolonged physical activity, there is a deficit of oxygen required to enable all the muscle cells to generate energy aerobically. Muscle cells then respire anaerobically and produces lactic acid. Accumulation of lactic acid in the muscles causes cramps.

Detailed explanation-5: -So, the correct answer is ‘muscle fatigue’.