Hamstring injuries
Hamstring injuries are the most common soft tissue injuries observed in team field sports and track. The high rate of re-injury (up to one in three) suggests frequent errors in injury management. These errors may include returning to sport too soon, inadequate or unspecific rehabilitation, or a combination of these factors.
Clinicians typically structure hamstring rehabilitation around the injury’s healing phase, such as the stages of inflammation and tissue repair. An alternative approach tailors treatment to the injury mechanism. For instance, injuries from high-speed running and sudden acceleration may require different rehabilitation methods than stretch-related injuries caused by slow, extreme muscle lengthening. However, recent research from British Athletics indicates that rehabilitation outcomes improve when clinicians focus on the anatomical location of hamstring injuries. They propose that treatment should consider the differing responses to loading and healing rates of the affected tissues—fascia, muscle, and tendon—making it essential to identify the injury’s location.
While clinical examination can confirm a hamstring injury, pinpointing the exact anatomical location is challenging. Nonetheless, certain clinical signs can hint at the involved tissue. Sudden or gradual onset pain in the posterior thigh may suggest a myofascial injury, where the athlete generally retains their range of motion and strength despite discomfort. In contrast, those with a sudden onset of pain following high-speed sprints or jumps may have an injury at the musculotendinous junction, characterized by severe pain, weakness, and restricted movement. Intra-tendon injuries, often resulting from high-velocity sprinting or stretching, present with symptoms like limited range of motion, decreased power, and an antalgic gait.
MRI can precisely identify the location and severity of the injury, providing valuable insight for return-to-sport planning. For example, a tendon injury generally requires a longer healing period than a muscle injury due to the time needed for collagen synthesis, remodeling, and safe force transmission. Understanding the specific injury location enables clinicians to develop a suitable rehabilitation plan and communicate realistic recovery timelines to the athlete.
Figure 1: Anatomical representation of hamstring injury location(3)
Principles of hamstring rehabilitation
*Specificity
The hamstring is composed of three distinct muscle portions that share a common origin and work in unison, yet each performs unique actions. The biceps femoris, for instance, is particularly active during acceleration and the terminal swing phase, where it decelerates the leg’s forward motion upon ground contact. As a result, it generates the highest forces during sprinting but is also susceptible to injury during intense active lengthening contractions.
When assessing a hamstring injury, it’s essential to consider the athlete’s previous injury history. Prior damage, such as scar tissue, may impair tissue mobility and increase strain on the musculotendinous junction (MTJ). The semitendinosus experiences the highest lengthening velocities, while the semimembranosus, primarily responsible for generating force during the swing and stance phases, has a more limited capacity for lengthening. Therefore, loading progressions should be carefully tailored to the specific area injured and its role in the biomechanical movement pattern.
Loading
Begin graded running drills as early as 48 hours after a hamstring injury; evidence suggests that early activity does not hinder recovery and may reduce re-injury rates upon return to sport. Progressive running drills should gradually increase in speed toward sprinting and incorporate active muscle lengthening. This approach provides functional loading and conditions the hamstrings to withstand sprinting demands.
Strength & Conditioning
Sprinting generates high eccentric forces within the hamstring muscles, particularly when the leg is outstretched just before heel strike. At this point in the gait cycle, the muscles are at peak length and maximally contracting to decelerate the body, which makes eccentric rehabilitation exercises critical. These exercises help lengthen the muscle’s optimal force-generating range, mimic the hamstrings’ biomechanical function, and reduce load on the damaged tissue.
Hamstring injuries frequently occur late in play or competition when athletes are fatigued. Fatigue reduces functional strength, eccentric torque, and muscle length capacity, making the muscle more prone to injury if it cannot handle the load. To address this, loading the hamstrings under fatigue in rehabilitation prepares the muscle for these conditions. Isometric exercises can build fatigue resistance and produce a “spring-like” response in the tendon while minimizing contractile load. Strength exercises should be done after running drills to develop fatigue resilience.
Tissue-Specific Rehabilitation
1. Fascia
Fascial injuries cause intense pain initially due to rich neurovascular innervations, yet they typically heal quickly. Inflammation and edema initiate repair, with research indicating that half of maximal strength returns within a week and full strength within three weeks. With the muscle-tendon structure intact, rehabilitation can progress swiftly with running drills and general strength training. The focus should be on refining lower-limb biomechanics, such as hip flexion, trunk control, leg coordination, arm usage during rotation, and ground contact.
2. Musculotendinous Junction
Injuries at the musculotendinous junction cause immediate impairment by damaging the muscle’s contractile portion, reducing its force generation. Stretching is typically painful. Rehabilitation should start with low-load, low-volume exercises with a limited range, like isometrics, squats, or step-ups. Progressions should focus on fatigue resistance through higher loads and lower volumes, emphasizing eccentric loading through hip-dominant exercises and advancing to knee-dominant eccentric exercises. Running drills can be introduced once the athlete can walk pain-free, with pain ratings below 3/10, and minimal hamstring stretch.
3. Intra-Tendon
Tendon injuries take longer to heal due to the complex process of collagen synthesis, remodeling, and maturation needed to restore tensile strength. Partial intra-tendon injuries may seem to resolve quickly if the contractile musculotendinous unit remains intact. To align with the physiological timeline for healing, start with isometric exercises and delay eccentric loading for approximately three weeks to avoid premature stress. When introduced, load the muscle at 80% of a one-repetition max, gradually increasing for at least 12 weeks, even if symptoms have subsided.
Fascia
Musculotendinous Junction
Intra-tendon
Healing facts
Fast recovery.Minimal impact on range of movement & strength.Inflammation & edema main factors.
Early recovery 10 days post-injury. Regeneration within ~ 3 weeks.
Apparent fast recovery for low-level loading. Caution for high-level loading for subsequent 4-6 months.
Running progressions
Early.
When walking is pain-free. Keep pain levels <3/10.
From week 1 post-injury, but slower progression over 9 week period.
Strength training progressions
Non-specific to hamstrings. Follow previous strength program.
High-volume, low-load, and progress towards low-volume, high-load. Combine eccentric, isometric, exercises while in a fatigued state.
Begin with isometrics. No eccentric work until 3 weeks post-injury. Continue for more than 12 weeks.
Estimated return to sport
Approx. 3 weeks.
Longer delay. Full eccentric strength required.
6 weeks to 6 months, depending on time taken to generate adequate load.
Sample rehabilitation exercises
Early-stage, low load exercises:
Squats
Step-ups
Hamstring curls (isometric or concentric)
Glute bridges (see figure 2)
Figure 2: Glute bridges
Note: Perform with the foot elevated on a bench for a greater challenge.
Hip-dominant eccentric exercises:
Romanian deadlifts (bilateral or single leg – see figure 3)
Prone hip extension (see figure 4)
Figure 3: Romanian deadlifts
Note: Progress by adding weight and performing as a single-leg exercise.
Figure 4: Prone hip extension exercise
Knee-dominant eccentric exercises:
Nordic hamstring curls
Summary of key points
Hamstring injuries comprise a large number of soft-tissue sports injuries, as well as having a significant re-injury rate.
Hamstring injury diagnosis should be classified by anatomical location for a more specific rehabilitation prescription, as different tissues differ in their healing rates and their response to loading.
Determine as an injury to the fascia, musculotendinous junction, or intra-tendon.
Follow standard principles of hamstring rehabilitation, including running-load management, strength training, and fatigue resistance conditioning.
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