Preventing Hamstring Injuries: Key Factors and Exercises

Hamstring injuries can be a major setback, especially for athletes involved in high-speed running (HSR) sports like soccer, football, or track. Understanding the risk factors for hamstring injuries (HSI) and implementing an evidence-based prevention program can help you stay in the game and reduce the risk of injury recurrence. Let’s dive into the main factors that contribute to HSI and explore exercises proven to help prevent them. 

What Are the Predominant Risk Factors for Hamstring Injury? 

Hamstring injuries don’t happen randomly—there are key risk factors that can increase the likelihood of an injury. These risk factors are divided into non-modifiable and modifiable, helping you identify what you can change to reduce your risk. 

1. Participation in High-Speed Running (HSR) Sports 

High-speed running (sprinting) is one of the most common causes of hamstring injuries. In fact, most hamstring injuries occur in the biceps femoris long head¹, one of the major muscles in the hamstring group. Sports like sprinting, soccer, and rugby involve rapid acceleration and deceleration, which put significant stress on the hamstrings. 

2. Non-Modifiable Risk Factors 

While some risk factors are beyond our control, they are still important to recognize: 

• Previous Hamstring Injury: One of the most significant risk factors is having a history of hamstring injury. Studies show that 25% to 33% of these injuries can recur, and when they do, they often tend to be more severe. If you’ve been sidelined by a hamstring injury before, it’s essential to be even more diligent about prevention. 

3. Modifiable Risk Factors 

The good news is that many risk factors can be managed or improved with targeted training: 

• Low Eccentric Strength: Weakness in eccentric hamstring strength—where the muscle lengthens under tension—has been closely linked to HSI². Building eccentric strength helps the hamstrings better absorb the forces they encounter during running. 

• Fatigue/Fitness: Hamstring muscles are more vulnerable to injury when fatigued. Maintaining good conditioning helps delay fatigue and keeps your muscles performing optimally². 

• Short Fascicle (Muscle) Length: Shorter muscle fibers are more susceptible to strain, particularly during running as injuries happen when the hamstring is lengthening, rather than as it contracts/shortens. Targeted exercises can help lengthen muscle fascicles, reducing the risk of injury². 

• Spike in High-Speed Running: A rapid or large change in high-speed running volume increases risk for hamstring injury as these spikes will induce more strain to the hamstring which then requires additional time to recover in between training sessions³.  

• Lumbopelvic Control/Kinematics: Poor control of the pelvis and lumbar spine can alter the strain on the hamstrings, making them more prone to injury. Core stability and lumbopelvic control are key for injury prevention⁴. 

Evidence-Based Exercise Program for Hamstring Injury Prevention 

A well-designed exercise program can help address these modifiable risk factors. Research supports the following exercises for reducing the risk of hamstring injuries: 

1. Nordic Hamstring Curls 

Nordic hamstring curls are one of the most effective exercises for building eccentric strength in the hamstrings. When included in injury prevention programs, the risk of injury is halved⁵. Additionally, performing this exercise consistently will increase muscle fascicle length, moving your hamstring from “short and weak” to “long and strong.”  

• How to Perform: Kneel on a soft surface, with a partner holding your ankles down. Slowly lower your body forward as far as you can control, then push back up to the starting position. 

2. Hip Extensions (45-Degree) 

Hip extensions at a 45-degree angle have been shown to selectively target the biceps femoris long head more than any other individual exercise, making them an important inclusion in your injury prevention program⁶. 

• How to Perform: Position yourself on a 45-degree back extension bench. Lower your upper body while keeping your back straight, then lift back up until your body forms a straight line. 

Figure 1. Needle electromyography (nEMG) comparing medial and lateral hamstring activation during commonly prescribed hamstring exercises. Hip hinge (HH), lunge (L), bilateral stiff-leg deadlift (SDL), unilateral stiff-leg deadlift (USDL), unilateral bent knee bridge (bKB), leg curl (LC), 45° hip extension (HE), unilateral straight knee bridge (SKB), glute-ham raise (GHR), Nordic (NHE)⁶.  

3. Minimum Effective Dose 

Research has shown that strength AND muscle length changes when performing Nordic hamstring curls are almost identical at a dose of 1x/week with 2 sets of 4 repetitions compared to 2x/week with 5 sets of 10, over a 12-week period, with strength gains slightly favouring the lower volume group. This means you only need to perform these exercises once per week, with 2 sets of 4 repetitions to significantly reduce your risk of hamstring injury⁷.  

4. Why Intensity Matters 

The intensity of these exercises is crucial for achieving meaningful strength gains. Progressive overload is required to achieve the tissue adaptions we need to prevent hamstring injuries, i.e. increased muscle length, and increased hamstring strength. Gradually adding resistance/load to these exercises over time will ensure you are building strength and improving your muscle length, rather than just maintaining it.  

Hamstring Rehabilitation 

While training your hamstrings eccentrically can reduce your risk of hamstring injury, it cannot eliminate the risk. In the event you suffer a hamstring injury/tear, early rehabilitation is paramount. Beginning your rehabilitation within the first 2 days after injury can reduce full, pain free recovery times by up to 3 weeks⁸. Be sure to see a Physiotherapist as soon as possible so you can get on the fast track to recovery.  

Figure 2. Comparison of Early (care initiated within 2 days of sustaining injury) vs. Delayed (care initiated beyond 2 days after sustaining injury)⁸.  

Have you had a recent hamstring injury? Wondering if you are at risk for one? Book now with one of our Physiotherapists to optimize your training and recovery.  

 
References:  

1. 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 Feb;40(2):67-81. doi: 10.2519/jospt.2010.3047. PMID: 20118524; PMCID: PMC2867336. 

2. Pizzari, Tania, Brady Green, and Nicol van Dyk. “Extrinsic and intrinsic risk factors associated with hamstring injury.” Prevention and Rehabilitation of Hamstring Injuries (2020): 83-115. 

3. Duhig, Steven, et al. “Effect of high-speed running on hamstring strain injury risk.” British journal of sports medicine 50.24 (2016): 1536-1540. 

4. Schuermans, Joke, et al. “Deviating running kinematics and hamstring injury susceptibility in male soccer players: Cause or consequence?.” Gait & posture 57 (2017): 270-277. 

5. Van Dyk, Nicol, Fearghal P. Behan, and Rod Whiteley. “Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes.” British journal of sports medicine 53.21 (2019): 1362-1370. 

6. Bourne, Matthew N., et al. “Impact of exercise selection on hamstring muscle activation.” British journal of sports medicine 51.13 (2017): 1021-1028. 

7. Presland, Joel D., et al. “The effect of Nordic hamstring exercise training volume on biceps femoris long head architectural adaptation.” Scandinavian journal of medicine & science in sports 28.7 (2018): 1775-1783. 

8. Bayer, Monika L., S. Peter Magnusson, and Michael Kjaer. “Early versus delayed rehabilitation after acute muscle injury.” New England Journal of Medicine 377.13 (2017): 1300-1301.