Think of it this way your muscles are woven together like cotton, every time you exercise you create these microscopic tears, the less you warm up the bigger the tear, creating pulls, strains and tears.
Those cotton fibres will only go back together with rest and light compression, stretching them or putting movement and strain on them will make the tears bigger.
If a athlete is having reoccurring strains or pulls he hasnāt fully recovered and has done something wrong in his rehab.