The Effect of Nordic Hamstring Exercise Intervention Volume on Eccentric Strength and Muscle Architecture Adaptations: A Systematic Review and Meta-analyses

Abstract

Background Although performance of the Nordic hamstring exercise (NHE) has been shown to elicit adaptations that may reduce hamstring strain injury (HSI) risk and occurrence, compliance in NHE interventions in professional soccer teams is low despite a high occurrence of HSI in soccer. A possible reason for low compliance is the high dosages prescribed within the recommended interventions. The aim of this review was to investigate the effect of NHE-training volume on eccentric hamstring strength and biceps femoris fascicle length adaptations. Methods A literature search was conducted using the SPORTDiscus, Ovid, and PubMed databases. A total of 293 studies were identified prior to application of the following inclusion criteria: (1) a minimum of 4 weeks of NHE training was completed; (2) mean ± standard deviation (SD) pre-and post-intervention were provided for the measured variables to allow for secondary analysis; and (3) biceps femoris muscle architecture was measured, which resulted in 13 studies identified for further analysis. The TESTEX criteria were used to assess the quality of studies with risk of bias assessment assessed using a fail-safe N (Rosenthal method). Consistency of studies was analysed using I 2 as a test of heterogeneity and secondary analysis of studies included Hedges' g effect sizes for strength and muscle architecture variables to provide comparison within studies, between-study differences were estimated using a random-effects model. Results A range of scores (3-11 out of 15) from the TESTEX criteria were reported, showing variation in study quality. A 'low risk of bias' was observed in the randomized controlled trials included, with no study bias shown for both strength or architecture (N = 250 and 663, respectively; p < 0.001). Study consistency was moderate to high for strength (I 2 = 62.49%) and muscle architecture (I 2 = 88.03%). Within-study differences showed that following interventions of ≥ 6 weeks, very large positive effect sizes were seen in eccentric strength following both high volume (g = 2.12) and low volume (g = 2.28) NHE interventions. Similar results were reported for changes in fascicle length (g ≥ 2.58) and a large-to-very large positive reduction in pennation angle (g ≥ 1.31). Between-study differences were estimated to be at a magnitude of 0.374 (p = 0.009) for strength and 0.793 (p < 0.001) for architecture. Conclusions Reducing NHE volume prescription does not negatively affect adaptations in eccentric strength and muscle architecture when compared with high dose interventions. These findings suggest that lower volumes of NHE may be more appropriate for athletes, with an aim to increase intervention compliance, potentially reducing the risk of HSI.

The Training of Short Distance Sprint Performance in Football Code Athletes: A Systematic Review and Meta-Analysis

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Effects of eccentric training at long‐muscle length on architectural and functional characteristics of the hamstrings

“…This effect size was selected as recent meta-analytical review revealed that the eccentric hamstring strengthening results in large increases (effect sizes >1.0) in eccentric hamstring strength and BFlh fascicle length. 16 All participants self-reported as being recreationally active (>3 hours of physical activity per week). The inclusion criteria were the ability to descend actively to at least 50% of the full range of motion during the standard NHE.…”

The influence of maturation on the reliability of the Nordic hamstring exercise in male youth footballers

“…When used longitudinally, eccentrically biased training can provide a range of benefits including enhanced concentric and eccentric strength, change of direction ability, sprint and jump performance, and decreased injury incidence . Moreover, a recent meta‐analysis concluded that the Nordic hamstring exercise (NHE) can induce positive changes in muscle architecture and strength . Notwithstanding the performance‐related benefits, the NHE has the ability to reduce hamstring injuries by up to 51% in a sample of 8459 athletes and is advocated within youth soccer injury prevention programs .…”

“…24 Moreover, a recent meta-analysis concluded that the Nordic hamstring exercise (NHE) can induce positive changes in muscle architecture and strength. 25 Notwithstanding the performance-related benefits, the NHE has the ability to reduce hamstring injuries by up to 51% in a sample of 8459 athletes 26 and is advocated within youth soccer injury prevention programs. 27 This is particularly important when considering that hamstring strains account for 12% of injuries among 17 top fight European soccer teams 28 and is considered the most important injury risk factor.…”