This article is adapted from a presentation by Emma Draffin, Sports & Exercise Physiotherapist at Complete Physio Richmond, delivered as part of our Hamstring Injuries in Football seminar held last month.
Hamstring injuries are the most common injury in Australian Rules football. That’s been the case since the AFL started recording injury data back in 1992, and it hasn’t changed. Whether you’re playing elite or local footy, hamstring strains cost players time on the field and clubs significant resources.
Understanding the anatomy of the hamstrings, how they get injured, and what the key risk factors are is essential for anyone involved in football, whether you’re a player, coach or clinician. In this article, Emma walks through the fundamentals of hamstring injuries with a specific focus on AFL and AFLW.
Hamstring Anatomy
The hamstring is made up of three muscles, but four muscle heads. We’ve got the biceps femoris, which has the long head and the short head, along with the semitendinosus and the semimembranosus.
The long head of the biceps femoris and the semitendinosus both originate from the ischial tuberosity, sharing a common tendon known as the conjoint tendon. The semimembranosus also arises from the ischial tuberosity, but slightly more superior and lateral. The short head of biceps femoris doesn’t originate from the pelvis. It only crosses the knee joint, arising from the linea aspera on the posterior femur.
In terms of positioning, the biceps femoris makes up the lateral compartment, and the semitendinosus and semimembranosus make up the medial portion.
Function
The semitendinosus, the semimembranosus and the long head of biceps femoris all cross both the hip and the knee joint, meaning they contribute to both hip extension and knee flexion. The short head of biceps femoris only crosses the knee joint.
As a collective, the hamstrings are important in decelerating knee extension during running, stabilising the pelvis during walking, assisting in powerful movements like sprinting and jumping, and helping control trunk position when bending forward.
When the knee is flexed, the hamstrings also contribute to tibial rotation. Lateral rotation via biceps femoris and medial rotation via the semitendinosus and semimembranosus.
Biomechanics – How Hamstrings Get Injured During Running
During sprinting and running, the hamstrings are at the highest risk of injury during terminal swing. As the leg swings forward, the hip is flexed, the knee extends rapidly, and the hamstrings work eccentrically. They’re working to decelerate the knee and prepare the leg for initial contact with the ground.
After initial contact, the hamstrings transition from eccentric to concentric work, contributing to hip extension, propulsion and horizontal force production. They help drive acceleration.
Two Main Mechanisms of Hamstring Strain Injury
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Sprint Type
The most common type of hamstring strain. It occurs during high-speed running, typically in that terminal swing phase. It’s usually the biceps femoris long head that gets injured. It’s a high-speed eccentric overload, that classic “sniper” effect where a player is running at full speed, no contact, and grabs the back of the thigh immediately.
Sprint-type injuries generally have a shorter recovery time.
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Stretch Type
Stretch-type injuries occur during extreme hip flexion with knee extension. Things like high kicking, being forced into the splits, or those contested ground ball situations in football. This mechanism often involves the semimembranosus and sometimes more proximal tendon involvement.
Because of the potential tendon involvement, stretch-type injuries typically have a longer recovery time.
Which Muscles Get Injured Most?
Around 83% of hamstring injuries occur in the biceps femoris, particularly with the sprint-type mechanism. The semimembranosus accounts for about 12%, usually injured in stretch-type mechanisms. The semitendinosus is less commonly affected, at around 5%.
Recurrence rates are also higher in biceps femoris injuries (around 18%), compared to 2% for semimembranosus and semitendinosus.
Hamstring Injuries in AFL
Hamstring strains are the most common injury in AFL football, and have been since data collection began in 1992. In 2020, it accounted for 4.86 new injuries per club. Around 74% of these injuries occurred during matches, with the remainder in training.
Each team averages around seven hamstring strain injuries per season. Recurrent hamstring strains accounted for 26% of all injuries, with 52% of those occurring within two months of the initial injury. Return to play was around 30 days for new injuries and 36 days for recurrent injuries.
AFLW Comparison
Interestingly, hamstring strains are not in the top three most common injuries in AFLW. Knee injuries, ankle injuries and concussion rank higher. AFL men are four times more likely to sustain a hamstring injury compared to AFLW players.
Looking at the 2019 AFLW season, the injury incidence was 1.71 per 1,000 player hours for AFLW compared to 7.85 for AFL men.
There are several possible explanations for the difference. AFLW games are shorter (17-minute quarters compared to 20), there are fewer players on the field (16 compared to 18), and there’s an extra interchange player. Research has found that AFLW athletes typically cover 50 to 70% less high-speed running distance per minute of match play than their male AFL counterparts. Given that high-speed running is a key mechanism for hamstring injury, this likely plays a significant role.
Community Football
In community football, the pattern is similar for men’s and youth competitions. Hamstring strains are very common, alongside shoulder injuries, ankle sprains and concussions. There’s typically a high incidence early in the season, and recurrence rates tend to be higher than at the elite level, likely because community players don’t have access to the same rehabilitation resources as professional athletes.
If you’ve injured your hamstring playing local footy, getting professional guidance early makes a real difference. You can book an appointment at Complete Physio Richmond with one of our sports physiotherapists to get a clear plan in place.
Risk Factors for Hamstring Injury
Non-Modifiable Risk Factors
Previous hamstring injury is the single highest risk factor. There’s strong evidence that if you’ve had a hamstring injury before, you’re more likely to injure it again. A recent hamstring injury (within the last 12 months) further increases the risk.
Age is also a factor. Players over 25 have an increased risk. Being male carries a higher risk (AFL men are four times more likely than AFLW players). A previous lower limb injury of any kind, whether that’s groin, calf, ACL or a previous hamstring strain, also increases susceptibility.
Modifiable Risk Factors
These are the things we can address, and they’re a major focus of both prevention and rehabilitation:
- High-speed running load:
Greater absolute and relative high-speed running distances, particularly acute spikes in load, can increase hamstring strain risk. - Eccentric hamstring strength:
Lower eccentric hamstring strength increases the risk of future strain. Failure to restore eccentric strength after a previous injury is a key concern. Previously injured players often demonstrate only small improvements in eccentric strength across preseason. - Fascicle length:
Shorter fascicle length is associated with increased strain risk. Timmins (2016) found that a short fascicle length of less than 10.56 cm had a significantly increased risk. Nordic hamstring training helps increase fascicle length and reduce injury incidence. - Fatigue:
Research shows that 26% of muscular strain injuries can occur in the final 15 minutes of competition. Neuromuscular fatigue increases susceptibility to injury late in play. - Interchange exposure:
Greater interchange use appears protective against hamstring strain injury, another reason why load management matters.
The Financial Burden
On average, players miss three to four weeks with a hamstring strain injury. In the 2023 AFL men’s season, 14.34 matches were missed per club due to hamstring injuries. In 2012, hamstring strain injuries cost AFL clubs around $40,000 per injury, almost double the early 2000s figure of around $25,000.
Recurrence rates have been declining since 1992, which is encouraging, but the overall burden remains significant.
Assessment and Diagnosis
When assessing an acute hamstring strain, the subjective history is critical. You want to understand the mechanism. Was it a sprint-type or stretch-type injury? What position do they play? When did the injury occur? Did they have to stop immediately, or could they continue for a period? What are their current symptoms? Pain with walking, swelling, bruising, any neural symptoms?
Previous injury history is important. If they’ve had a previous lower limb injury (hamstring, calf, knee), that increases their risk profile.
On objective assessment, you’re looking at observation (gait, swelling, bruising), palpation through the hamstring muscles (biceps femoris long head primarily, but also semimembranosus and semitendinosus), and specific tests including active knee flexion, active and passive straight leg raise, active and passive knee extension.
Progressive loading tests are useful: starting with a double-leg glute bridge, progressing to single leg, then an elevated hamstring bridge, and a prone hamstring curl. These aren’t true strength tests. They’re about seeing what reproduces pain and discomfort.
Importantly, you also want to rule out other causes of posterior thigh pain. Lumbar referral and neural injury can present similarly, and the differential diagnosis is important to get right.
Classification
The traditional grading system uses grade 1 (mild/minor tear), grade 2 (moderate/partial tear) and grade 3 (severe/complete tear). However, more detailed classification systems like the British Athletics Muscle Injury Classification use a 0 to 4 severity scale combined with the site of injury, whether it’s muscular, at the musculotendinous junction, or tendon related. This gives a more nuanced picture, particularly when MRI imaging is available.
Prognosis
Some factors can help guide prognosis and rehab planning. Time to walk pain-free and days to jog pain-free can be strong predictors of return to play. MRI severity alone is not a reliable predictor of return to play. The clinical exam drives decision-making. More proximal injuries, tendon-related injuries and stretch-type mechanisms tend to have longer return-to-play timelines.
For a more detailed look at how we approach hamstring rehabilitation at Complete Physio, see Indi Franke’s article
Key Takeaways
Knowing your hamstring anatomy is really important to differentiate between which muscle head is injured. Understanding the biomechanics of how hamstrings get injured matters. There are two main injury mechanisms, and the type will help guide prognosis and rehabilitation.
Hamstring injuries are very common in men’s footy, less common in women’s footy, but they do occur at both the elite and the local level. Understanding your risk factors helps with preventing recurrence, and having a clear assessment process helps with accurate diagnosis.
You can read more about hamstring strains and how we treat them on our hamstring strain conditions page.
If you’ve injured your hamstring or you’re returning to sport after a hamstring strain, our sports physiotherapists can help.
Book an appointment at Complete, 656 Bridge Road, Richmond VIC 3121.
Call (03) 9882 2020 or book online.
This article is based on a presentation from our Hamstring Injuries in Football seminar. We regularly run professional development events for clinicians. Check our clinician education page for upcoming sessions.
