Question

Paheli participated in a 400 m race competition held at her school and won the race. When she came home she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage, she was relieved of the pain. Answer the following questions related to the situation.

(a.) What can be the possible reasons for the pain in her legs?

(b.) Why did she feel comfortable after a massage?

Answer 1

Anaerobic respiration: It is a type of respiration which occurs in absence of oxygen.

1. During heavy exercise, the demand for energy increases.
2. The supply of oxygen to produce energy is limited.
3. Breakdown of glucose produces lactic acid in muscles.

(a) During heavy exercise, enough oxygen is not delivered to the muscle cells.

1. The condition is referred to as an oxygen-deficient.
2. This deficiency leads to anaerobic respiration.
3. Glucose breaks down into lactic acid (accumulated in muscle cells).
4. It causes cramps and pain in the legs.

(b) She feels comfortable after a massage because it increases the oxygen supply to muscle cells.

1. The flow of blood in blood vessels increases.
2. A proper supply of oxygen leads to a complete breakdown of glucose.