The squat exercise is not detrimental to knee joint stability when performed correctly. Weight training, including the squat exercise, strengthens connective tissue, including muscles, bones, ligaments and tendons. Proper form depends on the style of the squat and the muscles to be conditioned. Bouncing in the bottom position of a squat to help initiate ascent increases mechanical loads on the knee joint and is therefore contraindicated. While squatting results in high forces on the back, injury potential is low with appropriate technique and supervision.
Conflicting reports exist as to the type, frequency and severity of weight-training injuries.
Some reports of high injury rate may be based on biased samples. Others have attributed injuries to weight training, including the squat, which could have been caused by other factors. Injuries attributed to the squat may result not from the exercise itself, but from improper technique, pre-existing structural abnormalities, other physical activities, fatigue or excessive training. The stretch-shortening cycle, characterized by a rapid deceleration of a mass followed almost immediately by rapid acceleration of the mass in the opposite direction is essential in the performance of most competitive sports, particularly those involving running, jumping and rapid changes in direction. A plyometric exercise program which trains the muscles, connective tissue and nervous system to effectively carry out the stretch-shortening cycle can improve performance in most competitive sports.