1. 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 relived of 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?
2. When breathe is released after holding it for few minutes. What happens and give reason for its occurrence?
3. Why does an athlete breathe faster and deeper than usual after finishing the race?
Answers
Answer:
a) During heavy exercise like running a deficiency of oxygen is created in the muscle cells. This deficiency leads to anaerobic respiration in the muscle cells. During anaerobic respiration glucose which is present in the muscle cells breaks down into lactic acid which gets accumulated in the muscle cells of the legs thus causing pain and cramps.
b) While massaging, the flow of blood in the blood vessels (circulation) increases thus increasing the oxygen supply to the muscle cells. The proper supply of oxygen leads to complete breakdown of glucose.
Answer:
a) Pain in her legs might be because of the accumulation of lactic acid in her muscles. During heavy physical activity muscle, cells respire anaerobically producing lactic acid.
b) The massage gave her relief because it improves the circulation of blood leading to increased supply of oxygen to the muscle cells which helps in a complete breakdown of lactic acid into CO2 and water.