Paheli participated in a 400 m race competition held at her school and won the race

cbse
cbse-class-7-science
respiration-organism

#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 relieved of the pain. Answer the following questions related to the situation.

  • What can be the possible reasons for the pain in her legs?
  • Why did she feel comfortable after a massage?

Answer:

  • The pain in her legs could be because of the accumulation of lactic acid in
  • the muscles. During heavy exercise or running, etc., the muscle cells respire anaerobically and produce lactic acid.
  • The massage gave her reliefbecause it improves the circulation of blood leading to increased supply of oxygen to the muscle cells which helps in complete breakdown of lactic acid into CO, and water.