ANN ARBOR, Mich.---Research suggests that training programs for females to restore balance between hamstring and quadriceps muscles to better support knee joints could help reduce the disproportionately high number of ACL tears in female athletes.
A new study shows that the amount of preparatory muscle action in the muscles spanning the knee joint prior to landings is associated with knee positions that are considered at risk for ACL rupture, said Riann Palmieri-Smith, lead author and assistant professor at the University of Michigan Division of Kinesiology.
The ACL is one of the four major ligaments of the knee, and women are 2-8 times more likely to tear this ligament than men are while playing the same sport, said Palmieri-Smith.
The U-M research suggests that training programs which promote balanced activity of the inner (medial) and outer (lateral) thigh muscles might help protect the ACL.
This preparatory muscle action helps to control the relationship of the shank relative to the thigh. When the shin bone is positioned outward compared to the thigh bone, it results in a knock-kneed posture, Palmieri-Smith said. This position is referred to as knee valgus, and increased knee valgus (more knock kneed) has been shown to be linked to ACL injury risk, said Palmieri-Smith, who is also affiliated with U-M's new Sport Injury Prevention Center.
Think of a person who jumps and lands with knock knees (knees turned in) as opposed to a person who lands with minimal or no side-to-side angle at the knee (thigh and shank aligned). The person who lands with their knees turned in too much appears, based on previous research, to be more likely to tear their ACL.
The U-M study showed that when women are preparing to land from a jump they tend to activate the muscles of the outer (lateral) thigh more than the muscles of their inner (medial) thigh, and that this pattern of muscle activity was associated with a larger
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University of Michigan