First, the muscles in the strained area have not recovered excessively because there is not enough rest. Therefore, the more the pulled muscle is torn, the weaker it is, while the more the moving muscle is torn, the stronger it is, because it has enough recovery, resulting in "excessive recovery."

Second, the essential reason of muscle strain is that the body is in a structural state that does not conform to human mechanics, while most movements in fitness training conform to human mechanics (some do not, such as guillotine bench press). However, the imbalance of muscle movement during fitness may lead to posture problems, which may lead to local muscle strain.