It's squatting - the performance of knee bends while holding a weight on the shoulders. Squatting is one of the most important parts of Olympic weightlifting and power-lifting training programmes, and many coaches in a variety of sports believe that squatting is the supreme way to build strength in the upper parts of the legs.

In a way, all of this fuss about squatting is pretty strange, since almost nothing has been known about the forces passing through the hip and knee joints during squatting exercise, nor has much been known about the exact activities of the 'quads' and hamstrings during squats.

In addition, although squatting is a fairly safe activity, there have been some reports of serious knee injuries during squatting workouts. And since the actual forces on the joints and leg muscles haven't been known, squatting's value as part of the rehabilitation process for injured athletes has been unclear.

Fortunately, scientists in the Departments of Anatomy and Kinesiology at the Karolinska Institute in Stockholm, Sweden, have recently determined exactly what happens to the legs during squatting sessions. Eight burly young national-class Olympic weightlifters took part in the research. Average body weight was 180 pounds, mean age was 19, and typical one-repetition maximum during squatting exercise was about 230 pounds.

Each squatting exertion was a 'high-bar' squat, with the weight bar centred across the shoulders just below the seventh cervical vertebra (the first knob one feels when passing the hand down the back surface of the neck). For every squat, the actual weight used was 65 per cent of an athlete's one-repetition maximum.

The subjects tried four different knee-flexion angles while squatting: (1 ) knees flexed to just 45 degrees, (2) knees flexed to 90 degrees, (3) knees flexed more amply so that the back surfaces of the thighs were actually parallel to the floor, and (4) knees flexed fully (the deepest-possible squat). The first two squats - 45 and 90 degrees - are actually just partial squats, with athletes remaining in a semi-standing position and the buttocks only slightly lowered toward the floor. Among coaches, there's considerable controversy about which form of squatting is actually 'best' for athletes.

Video-taping and electromyography were used to determine joint forces and muscle activity. As it turned out, the 45- and 90-degree squats did a poor job of activating the quads and hamstrings, compared to the parallel and deep squats. However, the former two squats also produced fairly low forces at the knee and hip joints, so the 45- and 90-degree squats are probably excellent exercises for athletes who are attempting carefully to recover from leg injuries.

Surprisingly, there was no difference in muscular activity between the parallel and deep squats, even though coaches tend to recommend the latter. The total times required to perform parallel and deep squats were also similar, so neither exercise provides more total work for the leg muscles per training session.

Although the parallel and deep squats produce equivalent amounts of muscle activation, the parallel exercise is better for athletes who have suffered from knee problems, since it produces less strain on the knees. Athletes with hip problems probably should rely on 90-degree squats, since both parallel and deep squats upgrade hip-loading forces significantly.

Overall, squatting does a great job of activating both the quads and hamstrings, especially if one uses parallel or deep squats. Parallel squats are as good as deep squats at working the muscles and better than deep squats for limiting the risk of knee injuries.

'Joint Moments of Force and Quadriceps Muscle-Activity During Squatting Exercise,' Scandinavian Journal of Medicine & Science in Sports, vol. 3(4), pp. 244-250, November 1993


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