Question

Why is it important to have rest periods between sets of an exercise or workout? in order to free up time to work on other activities in order to measure one's heart rate in order to prevent the risk of muscle strain and injury in order to ensure breakdown of muscle protein?

Answer 1

The last suggestion is correct....when you have setes of rest in between workouts..you allow the lactic acid to seep into your muscles and ensure that the muscle protein is broken down properly.