How Jumping Puts Girls At Risk For ACL Injury
Research suggests that the way female athletes jump and land makes their knees more vulnerable to ACL injury. We explain why.
If your daughter plays soccer, she’s four to eight times more likely than her brother to damage the anterior cruciate ligament (ACL) in her knee. Why? After exploring a number of possible explanations, including structural differences in the female knee, ligament size, alignment of the knee with upper and lower leg bones, deficits in muscle strength, and hormonal differences, researchers have identified jumping technique as a critical risk factor for girls.
Studies of the ways girls jump and land have given us the best insight into why these actions make girls’ knees so vulnerable to ligament injury. Overall, the techniques girls use to land are distinct from the techniques boys use, and put more stress on the knee. When girls make contact with the ground after a jump, their form is different in several important ways:
- Girls tend to land on straighter knees, slapping their feet on the ground and putting more stress on knee ligaments.
- When girls land, their knees buckle inward to a greater degree than boys’ knees do. The stress of this buckling is borne directly by the ACL.
- Girls tend to activate their hamstrings later and less often than their male counterparts. Activating the hamstring muscles at the back of the leg helps the ACL to hold the tibia in place, and prevents it from moving too far forward. Without early hamstring activation, a girl’s ACL bears more stress and has less support from leg muscles.
- Girls’ hamstrings are significantly weaker than their quadriceps (the muscles in the front of the thigh). This muscular imbalance, combined with the important role of the hamstring in supporting the ACL, makes girls more prone to knee injury.
There is no magic bullet to prevent ACL injury in female athletes, but programs have been developed that successfully address both muscle strength and athletic technique during the jumping and landing actions that put girls most at risk.
Part of this training focuses on retraining girls how to land after a jump:
- The landing is softened when girls learn to bend their knees more on contact. With bent knees, the force of the landing is absorbed by the leg muscles, instead of by the ligaments and bones in the knee joint.
- Girls are taught to keep their flexed knees directly over their feet as they land, instead of allowing the knees to come together.
- Chest position upon landing is also important. Instead of bending too far forward at the waist or sitting back on their heels, girls are taught to keep their chest over their knees as they make contact with the ground.
Researchers have found that when girls spend warm-up time in a training program that teaches them to land properly, the incidence of ACL injury decreases. This means lower medical costs, more time on the field, and better long-term health for your daughter’s knees: a win-win for everyone.
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