Hamstring injuries are a common occurrence in athletics, representing the most common cause of lost training and playing time in running-based sports.1 Hamstring injuries also have a fairly high recurrence rate, with 1 in 5 athletes re-injuring their hamstring after the initial injury.1 These injuries typically occur during high speed running and sprinting, as commonly seen in field sports such as soccer and American football.
Return to sport times vary by individual, with some athletes returning within a matter of days and some athletes taking multiple months to get back. The time it takes to return to sport is influenced by a multitude of factors beyond just physical characteristics, but this article will focus on loading and strengthening the hamstrings.
From Compliance to Resilience
Part of the rehab process with any muscle injury is, at some point, to apply load directly to the muscle to stress the specific tissue and create adaptations to facilitate healing and better prepare the system to encounter the stresses of sport. One exercise that has gained a lot of popularity in the realm of hamstring injuries is the Nordic hamstring exercise. One meta-analysis found that utilizing the Nordic hamstring exercise alone or in combination with injury prevention programs could reduce hamstring injury rates in soccer players by up to 51% compared to teams that did not include it.2Utilizing the Nordic hamstring exercise alone or in combination with injury prevention programs could reduce hamstring injury rates in soccer players by up to 51%. Click To Tweet
A key component of these interventions, however, is compliance; meaning, we actually have to do the interventions to get the effect. One study found compliance of above 50.1% of performing exercises targeting the hamstrings had a positive effect on future hamstring injury, and when compliance was above 75.1%, this resulted in a further risk reduction of future hamstring injury.3 This is another reason why the Nordic hamstring exercise can be so beneficial: because it is easy to implement and has been shown to be effective.
With any rehab, we aim to get back to the individual’s goal activity—which in the context of a hamstring injury is often a sport that involves sprinting such as soccer or American football. Is the Nordic hamstring exercise enough to finish up rehab and send the athlete back to their sport? Or is there more that can be done?
Where Sprinting Comes In
One study assessed hamstring muscle activity and force production in various exercises compared with sprinting. Exercises including the Nordic hamstring exercise and isometric upright hip extension were similar in force production to sprinting, but they were not able to reach similar EMG activity of the hamstrings as the ones induced by sprinting.4 None of the exercises tested, including the Nordic hamstring exercise, induced >60% of the maximal hamstring EMG activity compared to maximal sprinting.4
Another study compared a Nordic hamstring group, a sprint group, and a control group that just participated in regular soccer activities. Both the Nordic and the sprint group showed improvements in hamstring (biceps femoris specifically) fascicle length with better adaptations noted in the sprint group; the sprint group also improved in both sprint mechanics and performance, whereas the Nordic group did not.5 Maximal sprinting activities appear to be the best way to achieve high muscle activity in the hamstrings and allows neuromuscular adaptations to occur during sprinting.Maximal sprinting activities appear to be the best way to achieve high muscle activity in the hamstrings. Click To Tweet
When we start to search online, it is hard to know if we should “just do Nordics” or sprint to reduce the risk of sustaining a hamstring injury, but we do not have to dichotomize this. Both can be incorporated along a progression to ultimately return athletes back to high speed sprinting and sport. The Nordic hamstring exercise is a key component of hamstring injury rehab and injury risk reduction, but it appears that sprinting may provide other benefits as well:
- Hamstring muscle activity; sprinting appears to be the exercise that loads the hamstrings the most and therefore is essential to incorporate into the return to sport process after a hamstring injury.
- Due to the nature of hamstring injuries, which are typically locomotive in nature (or performed while the athlete is running), sprinting is a task-specific, locomotive intervention to strengthen the hamstrings and also work on neuromuscular control during high-speed running.
- Sprinting is specific to the athlete’s goal to return to their sport and is an integral component of performing in their sport.
- Performing sprints in the return to sport process can address potential psychosocial barriers such as fear of re-injury during sprinting, as this is likely the action that led to their injury, and it helps them maintain their identity as an athlete by performing high speed running during the rehab process.
Beyond the Sprints
While this article is very pro sprinting, what it is not is anti-Nordics or any other hamstring strengthening exercises. Exercises like bridge variations, hip extensions, RDLs, and Nordics are key components of hamstring injury rehab. It is beneficial to utilize the Nordic hamstring exercise as a bridge for hamstring strengthening/loading, but it is essential to incorporate sprint work which integrates hamstring strength into locomotion to adequately prepare the athlete for return to sprinting and return to field/court sports that require sprinting.
As a loading progression for the hamstrings during the rehab process, we want to start with lower threshold exercises within an athlete’s capacity during the process of their hamstring injury. The extent of the hamstring injury will determine the athlete’s starting point during rehab. Thus, a thorough assessment should be performed to individualize the program to the athlete and the context of their unique injury.The extent of the hamstring injury will determine the athlete’s starting point during rehab. Click To Tweet
A simple, general progression for loading the hamstrings would initiate with upright hip extensions and double leg bridge exercises with the knees bent and progress to double leg bridges with less knee flexion to bias the hamstrings. From there we can progress into single leg bridges to increase loading on one side. Then we can progress into Nordics and RDLs to increase the intensity and magnitude of loading on the hamstrings. And finally, we can then initiate a return to sprinting program with shorter distance accelerations first and increase the intensity, volume, and distance of the sprints to reach higher velocities and load the hamstrings further. There are other appropriate interventions and components to incorporate into a full, holistic program, but that is beyond the scope of this article.
Physical therapists, athletic trainers, strength coaches, sport coaches, and anyone who is working with athletes after a hamstring injury must not end the rehab without exposure to sprinting or we will likely continue to see high re-injury rates with hamstring muscle injuries.
Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF
1. Bourne MN et al. An Evidence-Based Framework for Strengthening Exercises to Prevent Hamstring Injury. Sports Med (2018); 48: 251-267.
2. Al Attar WSA et al. 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: 907-916.
3. Ripley JN et al. The Effect of Exercise Compliance on Risk Reduction for Hamstring Strain Injury: A Systematic Review and Meta-Analyses. International Journal of Environmental and Public Health (2021); 18, 11260.
4. Prince C. et al. Sprint Specificity of Isolated Hamstring-Strengthening Exercises in Terms of Muscle Activity and Force Production. Frontiers in Sports and Active Living (2021); 2:609636.
5. Mendiguchia J. et al. Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players. PLoS ONE (2020); 15(2): e0228283.