what is reason for mascular pains after strenuous exercises ?

What is the main reason for feeling pain in muscles after strenuous exercise ?

Panting after vigorous exercise is due to

Panting after vigorous exercise is due to

Panting after vigorous exercise is due to

Expiration rate after exercises.

Study the graph given below and analyse the reasons for accumulation of lactic acid in blood after strenuous exercise.

Parameter that remains unchanged during conditions of strenuous exercise in an individual is