Anatomy and Biomechanics of Injury

Running along the back of our thigh, the hamstring starts at our ischial tuberosity and attaches to our lower leg bone. When it contracts, it helps to extend our hip and bend our knee. Because the hamstrings cross both the hip and knees joint, they are known as biarticular muscles. Biarticular muscles are more likely to strain because they can be placed under stretch at both joints. Hamstring strain injuries occur during moments of high demand on the muscle in its fully lengthened position (hip flexed and knee extended), such as sprinting or quickly stretching when we kick, brake, or lunge. The long head of the biceps femoris is the most commonly affected, responsible for around 80% of strains to the region (1).

 Risk Factors

Several factors increase our risk of sustaining a hamstring strain, some of which we can and cannot address. Non-modifiable factors include a previous hamstring strain or knee injury and being an older athlete. Other factors that we can address include our hamstring length and strength (2).

Treatment

While rest and ice may be our initial thought, we can start rehabbing the injury the next day without any delay in our recovery time or increased risk of worsening the injury (4). Allowing up to 4/10 symptoms during exercise is similarly safe and allows for improved recovery (5).

While treating a hamstring strain and reducing our risk of another, we want to move from the “quadrant of doom” to the opposite corner. The best way to go about this is to use eccentric exercises, or strengthening exercises that simultaneously lengthen the hamstring. Askling et al employed a protocol in professional Swedish soccer players and had great results (6). Their eccentric protocol includes the following three exercises:

The Extender: While lying on your back, hold and stabilize your thigh of the injured leg with the hip bent to approximately 90 degrees. Slowly extend your leg to the point just before symptoms. 

The Diver: Stand with your full weight on your injured leg and slowly tip/dive forward, stretching your arms forward while extending your opposite leg behind you. Try to keep your pelvis level.

The Glider: Stand upright with your legs slightly split with all your body weight on your injured leg in front. Using a slider, perform a backwards gliding motion and stop just before symptoms are felt.

Outside of this protocol, it is important to select exercises that address both actions of the hamstrings (hip extension and knee flexion) in a fully lengthened position.

Romanian deadlifts are a great option for a hip dominant movement while seated hamstring curls are better for knee dominant strengthening. Try leaning forward on the machine to work through more of a lengthened position. One should also ease back into jogging and sprinting gradually, making sure to respect symptoms and monitor for more than 4/10 pain.

Hamstring Strain Prevention

We know that a previous hamstring strain can increase our risk for another, so once an athlete has recovered, we can include additional interventions to reduce our risk and maintain our progress.

Athletes who are in-season, short on time, or don’t have access to weight equipment can easily implement Nordic hamstring curls into their routine (7). Peterson et al found that adhering to the following protocol reduced strain risk by 70-85% in soccer players (8):

Aside from the Nordic hamstring exercise, another intervention to help us prevent strains is high speed running. Despite being one of the more common mechanisms of injury, studies have found that consistent high speed running is actually protective against injury (9, 10) as long as we do not suddenly progress our training too quickly (11).

Malone et al found that injury risk was increased for athletes who had too little or too much exposure to high speed running (12). They found that a moderate exposure to higher velocity training was protective.

Distance needed for benefits varies by sport, but they found that this group of elite soccer players had their best results when completing a weekly average of 700-750 meters of high speed running (at least 80% of max speed) and 200-350 meters of sprinting (>96% max) (13). This should be gradually built up to and broken into a couple running sessions sprinkled throughout the week.

Final Thoughts

By strengthening our hamstrings in lengthened positions with adequate resistance and sprinting frequently, we can address our symptoms, reduce our risk of reinjury, and stay on the pitch.

At Sapphire Physical Therapy, we use a battery of tests to assess your readiness for return to sport and are happy to help you navigate your hamstring injury and return to activities. Give us a call to set up an appointment!

Written by Benjamin Blakely PT, DPT, CSCS

References:

1. Gronwald T, Klein C, Hoenig T, et al. Hamstring injury patterns in professional male football (soccer): a systematic video analysis of 52 cases. British Journal of Sports Medicine 2022;56(3):165-171. doi:10.1136/bjsports-2021-104769

2. Green B, Bourne MN, van Dyk N, et alRecalibrating the risk of hamstring strain injury (HSI): A 2020 systematic review and meta-analysis of risk factors for index and recurrent hamstring strain injury in sport. British Journal of Sports Medicine 2020;54:1081-1088.

3. Timmins RG, Bourne MN, Shield AJ, et al Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (soccer): a prospective cohort study. British Journal of Sports Medicine 2016;50:1524-1535.

4. Vermeulen R, Whiteley R, van der Made AD, et alEarly versus delayed lengthening exercises for acute hamstring injury in male athletes: a randomised controlled clinical trialBritish Journal of Sports Medicine 2022;56:792-800.

5. Hickey JT, Timmins RG, Maniar N, et al. Pain-Free Versus Pain-Threshold Rehabilitation Following Acute Hamstring Strain Injury: A Randomized Controlled Trial. J Orthop Sports Phys Ther. 2020;50(2):91-103. doi:10.2519/jospt.2020.8895

6. Askling CM, Tengvar M, Thorstensson A. Acute hamstring injuries in Swedish elite football: a prospective randomised controlled clinical trial comparing two rehabilitation protocols. Br J Sports Med. 2013;47(15):953-959. doi:10.1136/bjsports-2013-092165

7. Al Attar WSA, Soomro N, Sinclair PJ, Pappas E, Sanders RH. Effect of Injury Prevention Programs that Include the Nordic Hamstring Exercise on Hamstring Injury Rates in Soccer Players: A Systematic Review and Meta-Analysis. Sports Med. 2017;47(5):907-916. doi:10.1007/s40279-016-0638-2

8. Petersen, J., Thorborg, K., Nielsen, M. B., Budtz-Jorgensen, E., & Holmich, P. (2011). Preventative effect of eccentric training on acute hamstring injuries in men’s soccer. The American Journal of Sports Medicine, 39(11), 2296-2303. doi:10.1177/0363546511419277

9. Mendiguchia J, Conceição F, Edouard P, et al. Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players. PLoS One. 2020;15(2):e0228283. Published 2020 Feb 11. doi:10.1371/journal.pone.0228283

10. Van den Tillaar R, Solheim JAB, Bencke J. Comparison of Hamstring Muscle Activation During High-Speed Running and Various Hamstring Strengthening Exercises. Int J Sports Phys Ther. 2017;12(5):718-727.

11. Duhig S, Shield AJ, Opar D, Gabbett TJ, Ferguson C, Williams M. Effect of high-speed running on hamstring strain injury risk. Br J Sports Med. 2016;50(24):1536-1540. doi:10.1136/bjsports-2015-095679 too much HSR increases HSI risk.

12. Malone S, Roe M, Doran DA , et al. High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football. J Sci Med Sport 2017;20:250–4.doi:10.1016/j.jsams.2016.08.005

13. Malone S, Owen A, Mendes B, Hughes B, Collins K, Gabbett TJ. High-speed running and sprinting as an injury risk factor in soccer: Can well-developed physical qualities reduce the risk?. J Sci Med Sport. 2018;21(3):257-262. doi:10.1016/j.jsams.2017.05.016