Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise

Review written by Sam Spinelli info

Key Points

  1. Previous research claiming the injury preventative effect of the Nordic Hamstring Exercise (NHE) had a number of distinct flaws, over-extending the benefits of the NHE.
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BACKGROUND & OBJECTIVE

Hamstring strain injuries are a costly and challenging injury that affects athletes in many sports, particularly those with a demand on high velocity running (1). Each year, an average football squad will experience 5-6 hamstring injuries each season, which can result in over 80 days of lost time from playing (2). These lost days can result in a significant impact on the athletes and organizations, reduced performance, increased financial burden, and more.

As such, there has been a huge push from managing these injuries after occurring, to trying to prevent them from occurring in the first place. With this change, there has been a big emphasis on finding ways to prevent injuries - enter the Nordic Hamstring Exercise (NHE) (see the video below for a demonstration of this exercise).

NORDIC HAMSTRING EXERCISE https://youtu.be/3UFQSHTWmJc

Over time, more and more research has emerged supporting the NHE. In 2019, Van Dyk et al. completed a systematic review and meta-analysis on the available literature on the NHE and concluded “Programmes that include the NHE reduce hamstring injuries by up to 51%.” (3). This strong statement pushed for individuals to utilize the NHE even more than previously, given the high benefit reported.

To highlight the importance and impact of using appropriate methodology for evidence synthesis, the authors of this review paper revisited the study selection, re-analyzed, and updated the findings of this 2019 meta-analysis.

Hamstring strain injuries affect athletes in many sports, particularly those with a demand on high velocity running.
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Each coach/physio should consider the possible benefits and risks associated with the exercise and decide if it should be implemented with their athletes.

FINDINGS

Unfortunately, this meta-analysis had distinct methodological limitations that made this claim not quite accurate. Firstly, the prior meta-analysis had utilized studies where the NHE was combined with other exercises and was not specifically unique to the intervention group, making it

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