Preventing Hamstring Injury in SprintersHamstring injuries are common in sprinters. If we can find specific reasons for this, injuries to elite sprinters may be avoided. In this research, the relationship between hip and thigh muscle strength to hamstring injury was studied. The scientists conducting this study looked for imbalances and deficits in muscle strength between the quadriceps and the hamstrings.
They chose 30 men who were elite track and field sprinters. All had participated in athletic championships. One member was even on the 2004 Olympic relay team. Muscle strength was measured using a special tool called a dynamometer.
Eccentric and concentric muscle testing was performed at three speeds (60 degrees per second, 180 degrees per sec, and 300 degrees per second). There was a one-minute rest between each speed.
Eccentric refers to lengthening of the muscle from a shortened position. Concentric is the opposite: the muscle is shortening as it contracts. The muscle testing mimicked the function of the hamstrings during the late swing phase and early contact phase of sprinting.
The athletes were all trained on how to use the dynamometer before testing began. Each athlete had a 10- to 15-minute warm-up period before testing. Knee and hip muscle strength were both measured in the standing position. To avoid injury, the strength testing was not done on the same day for both the knee and the hip motions.
After testing, the athletes were observed for a full year. Number of practices and meets was recorded for each athlete. The occurrence of a hamstring injury sustained during sprinting was also recorded. A hamstring injury was defined as one that caused a break in training or competition for at least a week.
They compared the preseason muscle strengths between the sprinters who had a hamstring injury and those who didn't. Measurements were compared between the right and left legs for the injured and uninjured groups.
The results showed weakness of the muscles in the injured leg. But the weakness was only present at the slowest speed. The specific muscle contractions affected were concentric for hip extensors and eccentric for knee flexors. Strength ratios between hamstrings and quadriceps muscles were also seen. The authors think the change in hamstring strength accounted for the ratio differences.
The conclusion of this study was that it may be possible to prevent hamstring injuries in elite sprinters. The first step is to test for pre-season muscle strength. Use this information to identify anyone with differences from side to side.
Unilateral weakness of the hamstring muscle as a hip extensor and knee flexor is a red flag. A strength training program to correct the muscle deficit and imbalance may help. There may be other key factors that could make a difference. Further studies are needed to look for other areas that might contribute to hamstring function and injury.
Yusaku Sugiura, MS, et al. Strength Deficits Identified with Concentric Action of the Hip Extensors and Eccentric Action of the Hamstrings Predispose to Hamstring Injury in Elite Sprinters. In Journal of Orthopaedic & Sports Physical Therapy. August 2008. Vol. 38. No. 8. Pp. 457-464.
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