Question

Cramps in the leg muscle after running a long distance are because of
A.Build up of acetic acid
B.Build up of oxalic acid
C.Build up of lactic acid
D.Build up of Pyruvic acid

Answer 1

Hint: Cramping means the painful involuntary contraction of muscle which is either caused by fatigue or strain. The real cause of cramp is an imbalance between nerve signals which excite a particular muscle and those that inhibit its contractions. That imbalance generally occurs when the muscle is fatigued.

Complete answer:
-Due to anaerobic respiration, the lactic acid starts building up in the muscle cells when the required amount of oxygen is not available for aerobic respiration which generally happens due to excessive exercise. It ultimately leads to restlessness and causes cramps in the muscles. The unavailability of oxygen means that the muscles cannot breakdown glucose and glycogen. There are two kinds of lactic acid, namely, L-lactate and D-lactate. Excess of L-lactate causes lactic acidosis. Cramps can also occur if a person does not take enough rest for the body to recover after too much exercise. One of the side effects of high lactate levels is that it increases the acidity in muscle cells, along with disturbance in metabolites.
Hence, option C: Build up of lactic acid is the correct answer.

Note: As our bodies take part in strenuous exercise, the body pumps more blood and tries to provide most of the energy by aerobic means such as oxygen. In some cases like sprinting, or running a marathon, the body cannot provide the desired oxygen. In that case, the body uses anaerobic respiration by breaking down glucose.