Hamstring Tears: Causes and Risk Factors

While almost anyone can injure a hamstring muscle, some people are at greater risk than others. The risk factors for hamstring injuries include: ¹ Orchard J, Marsden J, Lord S, Garlick D. Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. Am J Sports Med 1997;25:81-5. ^{, 2} Engebretsen A, Myklebust G, Holme I, Engebretsen L, Bahr R. Intrinsic risk factors for hamstring injuries among male soccer players: a prospective cohort study. Am J Sports Med 2010;38:1147-53. ^{, 3} Gabbe B, Bennell K, Finch C, Wajswelner H, Orchard J. Predictors of hamstring injury at the elite level of Australian football. Scand J Med Sci Sports 2006;16:7-13. ^{, 4} Thelen D, Chumanov E, Sherry M, Heiderscheit B. Neuromusculoskeletal models provide insights into the mechanisms and rehabilitation of hamstring strains. Exerc Sport Sci Rev 2006;34:135-41. ^{, 5} Gabbe B, Finch C, Bennell K, Waj-swelner H. Risk factors for hamstring injuries in community level Australian football. Br J Sports Med 2005;39:106-10. ^{, 6} Fields K, Bloom O, Priebe D, Foreman B. Basic biomechanics of the lower extremity. Prim Care 2005;32:245-51.

Previous hamstring injury. People who have suffered a hamstring injury in the past are at the greatest risk of future hamstring injuries.

See Symptoms of Chronic High (Proximal) Hamstring Tendinopathy

Muscle weakness and fatigue. If a muscle is weak or fatigued it can alter a person’s biomechanics and may increase risk of injury.

Lack of flexibility. A muscle that is less pliable may be more likely to be injured.

Inadequate warm-up. Muscles that have been warmed up will be more flexible and possibly less likely to be injured.

Muscle imbalance between the hamstrings and quadriceps. The hamstring (back of thigh) and quadriceps (front of thigh) muscle groups must work together. The risk of injury is increased if one muscle group is weaker than the other.

Dehydration. When someone is dehydrated, the muscles can be more prone to cramping and therefore more prone to injury.

Existing lower limb injury. If the body is compensating for another lower-limb injury, it can increase the chances of another injury somewhere else in the same or opposite limb.

Out of all these risk factors, a previous hamstring injury is the most significant risk factor for a recurrent hamstring injury. When compared to healthy individuals, people who have had a previous hamstring injury are 2 to 6 times more likely to suffer a hamstring injury. ⁷ Engebretsen A, Myklebust G, Holme I, Engebretsen L, Bahr R. Intrinsic risk factors for hamstring injuries among male soccer players: a prospective cohort study. Am J Sports Med 2010;38:1147-53. ^{, 8} Gabbe B, Bennell K, Finch C, Wajswelner H, Orchard J. Predictors of hamstring injury at the elite level of Australian football. Scand J Med Sci Sports 2006;16:7-13. Because of this added risk, proper initial management and rehabilitation of an acute hamstring injury may be important to preventing future injury in an active individual.