Page 27 - ISAKOS 2021 Newsletter Volume 1
P. 27

Hamstring Injury Prevention
Andre Pedrinelli, Prof.
Hospital Das Clinicas São Paulo, BRAZIL
The hamstrings are so named because of the way in which European butchers use these muscles to hang the legs of slaughtered pigs in their stores to sell. The hamstring tendons, which are composed of the tendons of the semimembranosus, semitendinosus, and long head of the biceps femoris, are responsible for hip extension and knee flexion.
Hamstring injury is the most common injury in a variety of sports, especially those that require high running speed. It has been the most common injury in professional football for many years, with the annual incidence increasing by 4% in the elite athletes of the Union of European Football Associations (UEFA) between 2001 and 20141. Hamstring injury leads to withdrawal from sporting activities and is associated with frequent recurrence. On average, a team suffers 5 to 6 hamstring injuries per season, which generates a loss of 80 days of sports activities. As such, these injuries have a considerable economic impact, given that the average cost of an injured starting player is 500,000 euros per month2.
Hamstring injury can occur anywhere along the length of the musculo-tendinous unit. While most injuries occur in the proximal portion, at the tendon-muscle transition, avulsion of the tendon origin can also occur, in which case the treatment is typically surgical.
The injury occurs most often during eccentric contraction during a high-speed start or run. The patient frequently reports pain in the posterior thigh region, describing it as a stabbing sensation, which may or may not be accompanied by a “click.” Physical examination may reveal edema, ecchymosis, and even a palpable gap due to the retraction of muscle fibers.
Evaluation and Classification
If avulsion of the tendon origin is suspected, pelvic and hip radiographs on the affected side should be made to assess the integrity of the sciatic tuberosity.
Ultrasonography and magnetic resonance imaging (MRI) are suitable methods for the diagnosis of the lesion; while ultrasonography is a cheaper and more available alternative, MRI has the advantage of being more sensitive and not being operator-dependent.
A wide variety of image classification systems are used to evaluate muscle injuries. For example, the British Athletics Muscle Injury Classification system classifies injuries into 5 grades (Grade 0 to 4), with an additional suffix of a, b, or c indicating whether the lesion is myofascial, tendinous, or intratendinous. Muscle injuries also are commonly classified with the Munich Classification system, which distinguishes direct injuries (bruises and lacerations) from indirect injuries and functional muscle disorders. Indirect injuries are subdivided according to the severity of the structural injury into partial injuries and (sub)total injuries, and functional changes are subdivided into overuse injuries and neuromuscular pathologies. Therefore, this classification system addresses the injury mechanism and distinguishes functional problems from structural injuries, but it does not address the injury site or whether the injury is a new injury or a recurrence.
To fill these gaps, a new classification system was proposed by the medical department of FC Barcelona and Aspetar3. This system is based on the mechanism of injury, the location of the injury and its relationship to the myotendinous junction, the assessment of connective tissue with imaging studies, and whether the injury is new or a recurrence. Recurrence is a very important consideration given that the most important risk factor for a hamstring injury is a previous hamstring injury. Strength is the most important modifiable risk factor, but age, flexibility, level of muscle fatigue, lumbopelvic control, quality of sports movement, range of motion, and position of the player are also risk factors.
When formulating a prevention program, the ideal approach is to use exercises that mimic the load, range of motion, and speed experienced during sports while also correcting the greatest possible number of risk factors. The best results in preventing hamstring injuries have been achieved with use of the Nordic hamstring exercise (NH) hamstring strengthening program and the FIFA 11+ program (which uses the Nordic hamstring exercise along with other exercises). In addition, the Get Set-Train Smarter application (developed by the International Olympic Committee [IOC]) is a valuable clinical tool that can be used for the prevention of sports injuries, with the ability to select the prevention program according to sport or anatomical region.
Nordic Hamstring Exercise
The Nordic hamstring exercise is a double exercise that does not require special equipment. The athlete kneels on a stable and comfortable surface while the partner stabilizes the athlete’s legs, keeping them against the ground.

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