Hamstring Injuries & the Nordic
It is well documented that acute hamstring muscle strains are the most common type of injury in sports involving repeated bouts of sprinting – particularly soccer and Australian Rules football (1). Hamstring muscle injuries are said to account for 12% to 16% of all injuries within the sport of soccer. Hamstring injuries also have a high recurrence rate (2). The recurrence rate is 22% within the first 2 months after the injury was first reported (2). It is for this reason that the prevention of initial and recurrent hamstring strains has been investigated and implemented for numerous years (1).
Why the “hammie”?
The hamstrings experience the most force during the late swing phase of a walking/running and this force increases with speed (2). It is the deceleration of the knee as it straightens during sprinting that most commonly causes injury (2). From looking at the cause of hamstring injuries – researches have worked out what training should help prevent these from reoccurring or occuring in the first place. The proposed manner of doing this is via increasing eccentric strength of the hamstring muscles (2). This is best achieved by lengthening the hamstrings while they contract under load (2). The “Nordic” The Nordic hamstring exercise (NHE) involves two players, one holding the heels/lower leg of the other while the they use their hamstrings to slowly lower their body down as low as they can until bracing and catching themselves before they hit the floor.
A 2011 study analysed the effects the nordic hamstring exercise had on lowering the incidence of hamstring injuries in soccer (2). The study took amateur, semi-professional and professional players from the top 5 Danish football leagues and after applying their methodology, resulted in a total of 461 players in the intervention group and 481 in the control group (2). The intervention group completed NHE as per table 1.
The 10 week period that the intervention was completed was during the mid season break – however the recording of hamstring injuries was undertaken from the second half of the season and first half of the next season (2).
Results showed that the group (461) that underwent the Nordic training protocol had a total of 15 hamstring injuries compared to the control group (481) that had a total of 52 hamstring injuries (2).
Another study involved 32 professional football (soccer) teams with 16 using the NHE training protocol and the other 16 not. Prior to the NHE being applied to the intervention group – there were no statistical differences between the number of players, playing or training exposure time or the amount of hamstring injuries in the past (1).
After the intervention period 18 hamstring injuries were recorded in the control group and 6 in that performed NHE throughout the study period (1).
Why the NHE works
The reasoning behind the effectiveness of NHE can be explained by previous biomechanical analyses (1). Hamstring injuries typically occur in the latter phase of knee swing. Essentially, at this phase of sprinting – the hamstrings are performing an eccentric contraction in a lengthened position (1).
This also supplies reasoning as to why the higher the velocity of sprint – the greater the hamstring force is and the more likely the injury (1). Ultimately meaning the following:
- “The risk of hamstring injury during high-speed running is associated with inadequate eccentric strength of the hamstrings.” (1).
- The NHE has been identified as one of the most, if not the most, effective and accessible way to improve the eccentric strength of the hamstring muscle group.
The NordBord
The NordBord is an effective tool at measuring an individual’s eccentric hamstring strength. The NordBord is also useful at comparing side to side to strength scores in newtons. This helps determine if the tested individual is at risk of a hamstring injury or injury recurrence. POGO has a NordBord onsite with clinicians using it regularly as part of the assessment and rehabilitation of clients of various athletic abilities.
For more information on the NordBord see: https://www.pogophysio.com.au/blog/hamstring-strength-testing-the-nordbord/
To summarise
Injuries to the hamstring are the most common non-contact injury in sports such as soccer, american football, rugby, australian football, baseball and cricket (3). Hamstring injuries require extensive rehabilitation (greater than a month) and have a high recurrence rate of 12-33% (3). A systematic review and meta-analysis looked at the current research related to the use of NHE in hamstring injury prevention and concluded the following: “Teams utilizing the NH exercise alone or in combination with injury prevention programs could reduce hamstring injury rates up to 51 % in the long term compared to the teams that do not.” (3). This information has valid potential to be used in various footballing codes or sports, and can be used for any level from social to professional.
Alec Lablache
POGO Physiotherapist
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References:
- van der Horst, N., Smits, D., Petersen, J., Goedhart, E. A., & Backx, F. J. G. (2015). The preventive effect of the nordic hamstring exercise on hamstring injuries in amateur soccer players : A randomized controlled trial. American Journal of Sports Medicine, 43(6), 1316-1323. doi:10.1177/0363546515574057
- Petersen, J., Thorborg, K., Nielsen, M. B., Budtz-Jørgensen, E., & Hölmich, P. (2011). Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: A cluster-randomized controlled trial. The American Journal of Sports Medicine, 39(11), 2296.
- Al Attar, Wesam Saleh A, Soomro, N., Sinclair, P. J., Pappas, E., & Sanders, R. H. (2017). 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 Medicine (Auckland, N.Z.), 47(5), 907-916. doi:10.1007/s40279-016-0638-2
- Vald Performance (2015). NordBord hamstring testing system (VIDEO). Retrieved from https://www.youtube.com/watch?v=FjEyIaPCDnc
