Running form and hamstring injury

Introduction

Hamstring strains and tears are among the most common and troublesome injuries in sport, particularly in high-speed running activities such as Australian rules football, rugby, and soccer. These injuries not only cause time lost from play but also carry a high recurrence rate. The underlying reasons behind hamstring strain injuries (HSIs) are multifactorial, in this blog I focus specifically on how limited strength and poor running form can be potential causes to hamstring injuries. By understanding the epidemiology, strength demands, and mechanics linked to hamstring function, clinicians and athletes can better target prevention and rehabilitation strategies.

Anatomy and Function of the Hamstring 

Within the body there are 3 separate hamstring muscles – the semitendinosus, semimembranosus and the biceps femoris which consist of two different compartments called the short head and the long head. These three muscles cross both the hip and the knee joint, meaning they have a function at both joints. All 3 muscles work in bending the knee and assist in bringing the hip back into extension.

Epidemiology and Data of Hamstring Strain/Tear

Hamstring injuries are consistently the most common soft tissue injury in elite sport, especially in the AFL. According to the 2021 AFL Annual Report, clubs averaged 6.5 hamstring injuries per season, with 24.5% of those injuries being recurrent. This highlights the existing and common issue of hamstring injuries with a high recurrent rate.

Recent data from a 2024 study published in the Journal of Orthopaedic & Sports Physical Therapy reported that across 773 HSIs in 424 AFL players, there was a recurrence rate of 25%. Even more concerning, 52% of athletes re-aggravated their hamstring injury within two months of the initial occurrence. These statistics demonstrate both the burden of HSIs in elite sport and the critical importance of effective rehabilitation and maintenance post rehabilitation to reduce recurrence risk.

Strength and Hamstring Strain/Tear

Strength, particularly eccentric hamstring strength, plays a pivotal role in both injury risk and recovery. The hamstrings function both concentrically (shortening) when bending the knee and eccentrically (lengthening) when controlling to straighten the knee. Eccentric control is critical during high speed runningl, as a strain/tear can happen for two main reasons, number 1 being the load undertaken in the muscle is exceeding its capacity, and number 2 being the muscle is getting stretched beyond its capacity. Before planting  your foot into the ground when running, the hamstrings work in controlling the knee as it straightens, and if there is a lack of eccentric control, there is the risk of the hamstrings stretching beyond its capacity and getting injured.

Another reason why a strain/tear can occur is during eccentric load and acceleration when sprinting, a high load is placed on the hamstrings, and this load can exceed the capacity of the hamstring.

Therefore, it is important to consider regional strength differences within the hamstrings. The proximal hamstrings (near the hip) and distal hamstrings (near the knee) contribute differently to running mechanics. Weakness in eccentric weakness, may predispose athletes to overload during sprinting. Strength imbalances not only increase the risk of initial injury but also impair the ability to fully rehabilitate and withstand the demands of return-to-play.

Mechanics and Hamstring Strain/Tear

Biomechanical factors also contribute significantly to hamstring injury risk. During running, the hamstrings work like a pendulum, especially during the backward swing of the leg. As the hip extends and the knee moves toward terminal swing, the hamstrings must rapidly transition from lengthening to shortening to prepare for ground contact.

Excessive hip extension (pushing the leg back), often associated with an anterior pelvic tilt, can increase hamstring length and strain during this phase. This altered pelvic position places the hamstrings at a mechanical disadvantage by stretching this group of muscles, forcing them to work harder eccentrically while lengthened, an environment strongly linked to injury occurrence (Poudel & Pandey 2023).

Overstriding can be another factor that can increase risk of hamstring injury. Overstriding is when you are swinging your leg too far forward, and by doing so this is causing your leg to straighten whilst your hip is flexing forward (hip flexion). This straightening action at the knee and excessive hip flexion is increasing the stretching force in your hamstring, and if it stretches at that velocity that exceeds the hamstrings capacity, a hamstring strain/tear can occur.

Conclusion

Hamstring strains remain a significant burden in elite sport, particularly within the AFL where incidence and recurrence rates remain stubbornly high. These injuries are influenced by a combination of epidemiological risk, eccentric and regional hamstring strength deficits, and biomechanical factors such as excessive hip extension and anterior pelvic tilt. For physiotherapists and coaches, addressing these elements through targeted strength training, biomechanical assessment, and progressive rehabilitation is crucial. By integrating these principles, athletes can better prepare their hamstrings to tolerate the high demands of sport and reduce the likelihood of reinjury.

References

Australian Football League. (2021). AFL Annual Report 2021. AFL  https://resources.afl.com.au/afl/document/2022/03/10/76a16be1-6439-4020-af33-1cac86639f7e/2021-AFL-Annual-Report.pdf

Breed, R., Opar, D., Maniar, N., & Pizzari, T. (2024). Epidemiology of Hamstring Strain Injuries in Elite Male Australian Football Players: An Analysis of 773 Injuries Over 7 Seasons. JOSPT Open, 2(4), 1–8. https://doi.org/10.2519/josptopen.2024.0359

Poudel, B., & Pandey, S. (2023, August 8). Hamstring Injury. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK558936/