Hamstring Muscle Injuries in Athletes
Hamstring injuries are most common in sports that require sprinting, such as football, rugby, basketball, and track and field, but hamstring injuries can also occur in sports that do not require significant running and sprinting. The average hamstring injury can cause an athlete to miss out on activity for up to 3 weeks. Torn hamstrings can be much more serious and cause long-term loss of time due to sports or surgery. One troubling aspect of hamstring injuries is the high rate of re-injury in the literature, which ranges from 12% to 30%. The most common type of hamstring injury is a hamstring strain, and the most common type occurs at the musculotendinous junction of the biceps femoris muscle.
In 1992 Worrell and Perrin identified primary predisposing factors for hamstring strains: strength (including strength imbalances in unilateral extensors or flexors), flexibility, and fatigue. The two most common factors in hamstring injury are a lack of adequate flexibility in the hamstrings and strength imbalances (flexor-to-extensor and right-to-left imbalance). The clinical history of a jogging athlete often includes a description of “pull-up” and inability to finish activity. The athlete may also report feeling or hearing a “pop” in the back thigh. If this injury occurs early during an athletic activity (i.e., early in practice), the primary factor can be assumed to be a lack of flexibility, whereas injuries occurring later during the athletic event (training or competition) may be believed to be related to fatigue. In reality, many factors may be involved, including intrinsic factors such as muscle weakness, strength and balance, fatigue, insufficient flexibility, abnormal biomechanics, impaired posture, poor running technique, and psychosocial factors. Extrinsic factors include warm-up and training procedures, fatigue related to excessive activities, inappropriate training, and sport-specific activities. No single risk factor was found to have a significant association with hamstring injury.
If the athlete presents with a primary acute hamstring strain, the examination begins with the athlete pointing a finger at the pain or the “center” of the pain. Often times this will guide a physical examination and lead to a diagnosis. Inspection may or may not show ecchymosis and swelling, depending on the severity and acuity of the injury.
In general, ecchymosis and swelling in the posterior thigh are indicative of a hamstring injury. Inspection and palpation should be performed with the athlete prone and knee in three positions:
- in a comfortable position
- In slight flexion (15 degrees)
- Knees bent (90 degrees flexed)
Light resistance from the heel should be applied as the knee moves toward flexion. Strength and ROM are not usually tested in patients with acute injuries because of pain. In subacute injuries, pain and swelling often diminish the validity of these findings; Ecchymosis and swelling are often present. Several specific tests have been identified that may be strongly associated with prognosis:
Straight Leg Lift Test
This is done in the same way as the typical supine straight leg raise test for back pain, but the athlete is asked to report initial tension or discomfort/stiffness. The degree of hip flexion is measured with an inclinometer or goniometer.
Manual Muscle test
This is not a classic manual muscle test in the sense of rating strength; rather, this test is used to detect pain. A positive test is when pain occurs, and a negative test is one where resistance is applied and pain is not reproduced.
This neural tension test aims to differentiate between soft tissue (eg hamstring) and neurological tissue involvement.
Hamstring Injuries Rehabilitation
The primary goal of a rehabilitation program is to return the athlete to sport at the highest level of function with minimal risk of re-injury. Returning an athlete with a hamstring muscle injury to sports may require the use of multiple rehabilitation strategies consisting of both direct and indirect techniques. The high recurrence rate and chronicity associated with hamstring injuries has placed a significant emphasis not only on the appropriate management of these injuries after they occur, but also on developing and implementing strategies to prevent hamstring injuries. The recurrence rate of hamstring injuries is as high as 12% to 31%, and estimates suggest that about one in three athletes re-injure their involved hamstrings within 1 year of returning to sports. Several factors may contribute to the high recurrence rate of hamstring injuries: (1) persistent hamstring muscle weakness, (2) scar tissue formation resulting in reduced extensibility of the musculotendon unit, and (3) biomechanical and neuromuscular adaptations as a result of the injury.
- Acute phase (2 to 4 days) focuses on controlling inflammation and regaining early movement
- Subacute phase with isolated hamstring strengthening and painless stretching
- Remodeling phase with continued hamstring strengthening and addition of eccentric muscle strengthening
- Functional period in which jogging, running, sprinting, functional training and sport-specific training are added.
- These rehabilitation phases take into account the time elapsed since injury; however, specific interventions and progress should be determined by the athlete’s condition.
Acute Hamstring Injuries Rehabilitation
Acute hamstring injuries result in pain and disability, manifested by reduced ROM, decreased strength, and decreased functional abilities. The initial focus of rehabilitation of hamstring injuries should be to minimize the acute effects of the injury and promote tissue healing. Management of acute hamstring injuries begins with an emphasis on indirect interventions to reduce associated inflammation and pain while promoting tissue healing and protecting scar formation. Interventions include low-intensity therapeutic exercise, modalities, medications, and protection.
The injured limb is protected by modified ambulation. If tolerated, full weight-bearing ambulation is allowed, using shorter steps to protect injured tissue from excessive stretching. Crutches can be used for ambulation if symptoms are more disabling and weight bearing needs to be limited.
Ice or Cryotherapy is used to reduce pain and inflammation. It can be used acutely. Ice should be applied to the injured area several times a day. The duration of the treatment depends on the methods used (ice pack, ice massage, etc.), but it usually takes 10 to 20 minutes for ice to be effective.
Non-steroidal anti-inflammatory drugs are often used to control pain and inflammation in the first days following an acute hamstring injury. However, there is controversy regarding this widely accepted approach, due to its lack of proven benefit and a potentially negative effect on muscle tissue recovery. Analgesics with less associated risks are an alternative to NSAIDs.
Intramuscular Corticosteroid Injection
The use of corticosteroid injections for the treatment of hamstring muscle injuries is highly controversial, primarily because of the temporal association with tendon or facial rupture. However, a retrospective study found no adverse effects when using intramuscular injections of corticosteroids to reduce the inflammatory response and limit loss of playing time in athletes with severe, discrete intramuscular or myotendinous hamstring injuries. This suggests that intramuscular injections of corticosteroids can accelerate an athlete’s return to sports without increasing the risk of relapse.
Rehabilitation protocols for acute muscle strains have traditionally focused on isolated muscle stretching and strengthening. Sherry and Best (2004) reported a significant reduction in recurrence rates in individuals with hamstring injuries when a progressive agility and trunk stabilization program was used. The program emphasized early movement and coordination of the pelvis and trunk muscles, suggesting that enhanced neuromuscular control of the lumbopelvic region allows the hamstrings to work at safe lengths and loads during athletic movement, thereby reducing the risk of re-injury. Exercises and movements to promote neuromuscular control should be performed in a protected ROM to minimize the risk of damage to healing tissue. If the athlete feels pain, the intensity should be reduced until painless contraction is achieved. In addition, low-intensity step exercises should be performed, including sideways, forward and backward stepping, single-leg stance exercises, and lumbopelvic isometric exercises such as prone bridging, supine bent knee bridging, and side bridging. Eccentric hamstring strengthening should be included when sufficient tissue regeneration has occurred to allow the muscle to withstand the greater forces caused by such contraction. In addition, emphasis should be placed on stretching the hamstring muscle to restore the normal flexibility of the healing tissue. Finally, as the athlete approaches symptom-free function and strength and neuromuscular control improves significantly, therapeutic exercises that integrate postural control and high-demand sport-specific activities can be implemented.
Soft Tissue Mobilization Techniques
Loss of muscle flexibility, in part due to connective tissue scarring, is a feature of hamstring injuries. The theoretical benefit of techniques such as various types of massage and enhanced soft tissue mobilization is to limit the residual effects of scar tissue formed early in the remodeling process, resulting in increased soft tissue extensibility. Scar tissue formation can cause changes in muscle-tendon properties that can alter the mechanical environment, affect muscle fiber stretching, and thus contribute to the risk of recurrence.
Hamstring Strain Rehabilitation Protocol (Heiderscheit et al. 2010)
- Prevent scar tissue development
- Minimize atrophy
- Apply ice 2-3 times a day
- Stationary bike × 10 min
- Side step × 10 min, 3 × 1 min, low to medium intensity, painless pace and stride
- Stepping in place 2 × 1 min
- Prone body bridge, 5 × 10 seconds
- Supine body bridge, 5 × 10 sec
- Eyes-open-closed progressive single limb balance, 4 × 20 seconds
Progression Criteria to the Next Stage
- Painless normal walking step.
- Painless very low speed running.
- Painless isometric contraction against submaximal (50%-70%) resistance during prone knee flexion (90 degrees) manual strength test.
- Regain pain-free hamstring strength by starting in the midrange and progressing to a longer hamstring length.
- Improve neuromuscular control of trunk and pelvis with progressive increase in movement speed.
- Apply ice for 10-15 minutes after workouts.
Exercises (5-7 times a week)
- Stationary bike × 10 min
- Side step × 10 min, 3 × 1 min, moderate to high intensity, painless pace and step
- Grapevine × 10 min, 3 × 1 min, moderate to high intensity, painless pace and stride
- Boxer Shuffle × 10 m, 2 × 1 min, low to medium intensity, painless speed and stride
- Rotating body bridge, hold both sides for 5 seconds, 2 × 10 reps
- Walking supine bent knee bridge, 3 × 10 reps
- Trunk rotation, opposite hand-foot touch and T-lift, lunge gait with 2 × 10 steps for each leg
- Single leg balance with forward sloping trunk and opposite hip
- Extension, 5 × 10 seconds per limb
Progression Criteria to the Next Stage
- Pain-free full strength (5/5) (90 degrees) during prone knee flexion
- Manual power test
- Painless back and forth jogging, moderate intensity
- Asymptomatic (no pain or tension) during all activities
- Normal concentric and eccentric hamstring strength throughout the full range of motion and speed.
- Improve neuromuscular control of trunk and pelvis.
- Integrate postural control into sport-specific movements.
Therapeutic Exercises (4-5 days a week)
- Stationary bike × 10 min
- Side shuffle × 30 m, 3 × 1 minute, medium to high intensity, painless speed and stride
- Grapevine jog × 30 m, 3 × 1 min, medium to high intensity, painless pace and step
- Boxer shuffle × 10 m, 2 × 1 min, medium to high intensity, painless speed and stride
- Forward-backward accelerations, 3 × 1 min, start at 5 m, progress to 10 m, then 20 m
- Rotating body bridge with dumbbells , holding both sides for 5 seconds, 2 × 10 reps
- Supine single-limb chair bridge, 3 × 15 reps, slow to fast
- Single-limb balance windmill touches with dumbbells, 4 × 8 reps
- Lunge walk with trunk rotation, opposite hand dumbbell toe touch and T-lift , lunge walk with 2 × 10 steps for each leg
- 1.Side stepping
- 2.Forward stepping
- 3.Backward Stepping
- 4.Single leg stance
- 5.Prone bridging
- 6.Supine bent-knee bridging
- 7.Side shuffling
- 8.Side bridging
- 9.Grapevine jogging
- 10.Rotating body bridging
- 11.Boxer shuffling
- 12.Lunge walking with trunk rotation
- 13.Forward/ Backward accelerations
- 14.Supine single limb chair bridging
- 15.Manuel resist eccentric strenght
- 16.Single leg stance windmill touch
- 17.Hamstring stretch
- 1. Askling CM, Heiderscheit BC. Acute hamstring muscle injury: types, rehabilitation, and return to sports. Sports Injuries. 2013
- 2. Croisier J, Forthomme B, Namurois M, et al. Strength imbalances and prevention of hamstring injury in professional soccer players. A prospective study. Am J Sports Med. 2008
- 3.Mendiguchia Jurdan, Brughelli Matt. A return-to-sport algorithm for acute hamstring injuries. Physical Therapy in Sport. 2011
- 4.Heiderscheit BC, Sherry MA, Silder A, Chumanov ES, Thelen DG. Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention. J Orthop Sports Phys Ther. 2010;40(2):67-81. doi:10.2519/jospt.2010.3047