Personal trainers and physical therapists often prescribe squats to their clients. It's a weight-bearing exercise that simultaneously strengthens the quadriceps, hamstrings and gluteal muscles. The National Osteoporosis Foundation recommends weight-bearing exercises as a means of building bone mineral density and preventing osteoporosis, yet despite their efficiency, squats are often associated with knee pain. The research on the subject, however, has been criticized by professional organizations such as the American College of Sports Medicine. These studies failed to account for form, weight load and predisposition to knee injuries.
History
Studies performed in the 1960s contributed to the belief that squats cause knee pain. Investigators alleged that squats overstretched the ligaments that support the knee. This research caused the U.S. Army to ban the squat as a training exercise. The research, however, was biased. Parachutists, whose high impact landings overstretch their knee ligaments, were the subjects of the study. Their knee joint laxity might have resulted from their landing methods, as opposed to the squat.
Theories/Speculation
Trainers and therapists need to determine whether the squat is causing the knee pain, or if knee pain experienced during squats is a symptom of a preexisting problem. Joint laxity, as indicated by the parachutist study, will probably cause knee pain during squats. People who practice contortion-type flexibility exercises such as the full lotus or full split often have overstretched ligaments, which compromises knee stability. Improper knee tracking can also cause knee pain during squats, but this is again a chicken or egg issue. If the muscles and ligaments surrounding the knee joints are over-stretched, the knee will rotate internally or externally, thereby causing inner or outer knee pain.
Cause and Effect
Congenital issues, past injuries and muscular-skeletal diseases may also cause squat-related knee pain. Examples of these conditions are found on the Rubin Institute for Orthopedics website. People who were born with congenital dysplasia, for example, have misshapen kneecaps. Chondromalacia, which is an irritation of the kneecap's under-surface, and arthritis can also cause knee pain during squats.
Prevention/Solution
Postural misalignment, poor form, muscle weaknesses and muscular imbalances can all cause knee pain during squats. People with sway-backs tend to shift their weight toward their heels, which causes the knees to hyperextend. When this happens during the extension phase of a squat, the rear ligaments overstretch and cause pain. Muscular imbalances between the hamstrings and the quadriceps also cause the legs to hyperextend. Likewise, a pelvis that is shifted to one side places more weight on one leg during squats. This may result in incorrect knee tracking. Postural assessment and re-alignment, balancing strength with flexibility and performing extra hamstring strength exercises may prevent squat-related knee pain.
Indicators
If your knees tend to turn outward while performing squats, place a mini ball between your knees. Likewise, if you tend to roll inward, place a resistance band around the outer legs. You don't need to consciously squeeze the ball or press your legs into to the band, but dropping the ball or slackening the band provides feedback about your form.
