If you have ever strained a hamstring muscle before, you are not alone! Hamstring strains are one of the most common acute musculoskeletal injuries. These strains tend to occur in high speed running activities, and also during a kicking motion.
Athletes who participate in track and field, soccer, and football are especially prone to these injuries. About a third of athletes who suffer from a hamstring strain will experience a re-injury within a year of returning to their sport. The greatest risk for this injury is in the first two weeks after returning to playing their sport, and often this re-injury may be more severe than the initial injury. Even with these high rates of injury and reoccurrence, there are some steps you can take to reduce that risk!
There are a few reasons the prevalence of hamstring injuries and reinjury are so high. The hamstrings are the group of muscles that make up the back of the thigh, consisting of the biceps femoris, semimembranosus, and semitendinosus. During the running gait, the job of the hamstrings is to control the leg during the terminal swing phase. In this phase, the hip is flexing, and the knee is extending by eccentrically decelerating the leg. This eccentric lengthening of the hamstring causes the greatest stretch of the muscle during this phase, which is why having enough eccentric strength is crucial to preventing injury. The best evidence supporting decreased hamstring injury is incorporating these types of exercises. A few examples of these would be swiss ball hamstring curls, bridging up with feet on a swiss ball and then with control, slowly rolling the ball out away from the hips and back in. Another example is a Nordic Hamstring Curl, where you start on your knees and slowly lower your chest to the ground, using your hands as much as needed for control and to help push you back up to the starting position.
Many athletes have an inequality between the strength of their hamstrings and the flexibility of their quadriceps and their hamstrings. As important as it is to have good eccentric strength of the hamstrings, it is useless if there is reduced flexibility in the muscles as well. While you are running, in the terminal swing phase, one leg is out in front of you while the other leg has just pushed off the ground behind you. If your quadriceps on the back leg are inflexible, you are risking a strain on the opposite side hamstring. Tight quadriceps will cause the hips to tilt forward on both sides, causing excessive stretch to the hamstring on the leg that is swinging out in front. This is especially crucial in avoiding reinjury, because following a strain, scar tissue will develop in the muscle which can cause the hamstring to be stiffer and less responsive. If the ability of the hamstring to stretch is shortened, it will weaken the muscle and cause the opposite of what the athlete needs. Therefore, it is very important to improve the extension of the hamstrings and the flexion of the quadriceps through stretching.