Muscles injuries to the hamstring are any strain or tear of the muscles or tendons of the hamstring group. These injuries occur fairly often among athletes, and make up a significant percentage of sports-related musculoskeletal injuries. Return to the sport may occur in a couple of weeks, or may never occur.
The hamstring is made of three muscles in the posterior thigh. Those muscles include the semimembranous, biceps femoris and the semitendinous. When you are trying to understand hamstring muscle injuries, you should consider that there are many important muscles, nerves and blood vessels in the posterior thigh. If the hamstrings are injured, some of those structures may also be injured.
Hamstring muscle injuries occur often among athletes, but the frequency of injury ranges from 8% to 50% (elite soccer players) depending upon the sport played.
The actions of the hamstring are primarily to flex the knee and extend the hip, with the biceps femoris contributing to rotation of the hip externally and the other two muscles contributing to internal rotation of the hip. When running, walking, or changing direction while moving quickly, the hamstring group has a large role. While moving, the hamstrings coordinate with other muscles involved in movement of the hip and knee, and injury to any of these key muscles will affect other muscles involved in movement.
There are many risk factors for hamstring injury. Some of these risk factors can be modified and some cannot. There have not been many large studies that have tried to determine the risk factors or ways to reduce the risk of an injury. However, it appears that those risk factors that can be modified include the following:
• Increased volume of training
• Muscle fatigue
• Failure of the hamstring to flex
• Weak hamstrings
• Failure to warm-up adequately
• Posture that affects the pelvis
• Running or abruptly changing direction
• Weakness in the region of the low back and pelvis
• Muscle fatigue
• Failure of the hamstring to flex
• Weak hamstrings
• Failure to warm-up adequately
• Posture that affects the pelvis
• Running or abruptly changing direction
• Weakness in the region of the low back and pelvis
There are several risk factors that cannot be modified. These are increased age, prior injury to the hamstring or other muscles of the leg, as well as origin of African or Aboriginal descent. However, the most frequently cited risk factor is a history of previous hamstring injury. Most repeat injuries occur within two months of return to the sport but the risk remains up to three times the risk of an athlete without prior hamstring injury, up to a year after initial injury.
If the hamstrings are not flexible, they run an increased risk of injury. Although the flexibility of the hamstrings should be flexible, a lack of flexibility of the quadriceps, which acts in opposition to the hamstrings, and the muscles that flex the hips should also be flexible in order to reduce the risk of hamstring muscle injury.
Those athletes who can flex their knees greater than 50 degrees had a lower likelihood of injuring their hamstring. However, decreased flexibility in the muscle group that flexes a hip results in an increase of hamstring injury. Weaknesses of the hamstrings when compared to the quadriceps results in a greater risk of injury, because the hamstrings slow down the leg when running and kicking. Those athletes with stronger quadriceps may require more strength in the hamstrings to slow down the action of the lower leg.
Muscles are often dependent upon each other to coordinate movement, and the hamstring is inter-related to muscles that extend the spine and the hips. An injury to another muscle group may become injured or tight, which places additional strain on the hamstrings. Abnormalities of posture can cause hamstring dysfunction, and weakness in the low back and pelvis may result in poor alignment of the joints, abnormalities of posture and movement.
Age is a risk factor for hamstring injury, possibly because the muscles’ cross-sectional area is reduced, which may result in the ability of the muscles to bear weight before failure. Age may also cause degeneration of the lumbar spine, causing nerve impingement on the nerves that serve the hamstrings, causing degeneration of the muscle fibers and leading to injury.
Various sports, particularly those that involve running at high speeds or rapid acceleration and deceleration are more likely to cause hamstring injuries. Because ballet dancing involves extreme movements of the knee and hip joints, ballet dancing is another cause of hamstring injury.
Those who suffer hamstring injuries may feel the sudden onset of pain in their posterior thigh; feel a pop or warmth at the injury site. Running is a high-speed mechanism of hamstring injury and stretching is a low speed mechanism of injury.
During the evaluation of a possible hamstring injury, the physician will inspect the are, feel the muscle, assess the range of motion and strength, note any abnormal gait, inspect the hip and leg region for bruising, swelling, defects in the muscle, and any tenderness, particularly at the attachment of one of the three muscles that make up the hamstrings to the bone. Strength is tested, and the limb is rotated, as is the range of motion of the knee. If there is change in sensation or strength, a neurologic test should be performed. If the diagnosis is not clear, the entire back and hip area should be examined.
Usually the biceps femoris is the most commonly injured muscle, and the closer to the pelvis the injury is, the longer the recovery time will be. Low speed injuries strain the semimembranosus muscle more often, with the tendon closer to the pelvis, which requires a longer recovery time. Both musculoskeletal imaging and MRI provide detailed information. In the case of avulsion injuries, plain radiographs may be useful.
Most hamstring injuries can be managed conservatively with rest and physical therapy, but some types of injuries require surgery for best results and an orthopedic surgeon should be consulted. The area should be rested, with ice packs, compression and elevation. Acetaminophen or ibuprofen usually provides good relief of pain. Injection of steroids is not recommended for treatment of acute injuries to the hamstring. Physical therapy may help treat the muscles, with training in agility and strength exercises for the trunk and hamstring. Gradual increase in exercise is recommended.
Green Apple 
Recent Comments