A Very Low Volume of Nordic Hamstring Exercise Increases Maximal Eccentric Strength and Reduces Hamstring Injury Rate in Professional Soccer Players

Abstract

The aim of this study was to determine whether the inclusion of a very low volume (1 set of 3 maximal repetitions) of eccentric-biased Nordic hamstring program of 21 weeks induced an increase in maximal eccentric strength and whether its magnitude was influenced by the compliance rate. The secondary aim of this study was to determine whether this eccentric-biased Nordic hamstring program was effective at reducing hamstring injury rate. Twenty-three professional soccer players formed the experimental group and undertook regular in-season hamstring strength training and monitoring for 21 weeks. Data from 23 players in the immediately preceding cohort (previous year) were included as a control group. The subdivision of the experimental group revealed that the high compliance subgroup (∼13 d between sessions) exhibited higher changes in maximal eccentric strength compared with the low compliance group (∼24 d between sessions; +26.5%; 95% confidence interval, 7.1%–45.9%; P < .001; g = 1.2). Five hamstring injuries (22%) were recorded in the experimental group and 9 (39%) in the control group, corresponding to a nonsignificant 2.7-fold lower risk (P = .12) of suffering hamstring injury in the experimental group. The current study demonstrates that the inclusion of a very low volume of eccentric-biased Nordic hamstring program for 21 weeks induced an increase in maximal eccentric strength (∼15%) in professional soccer players, the magnitude of which depended on the players’ compliance. We also found that this program was efficient (2.7-fold lower risk), although nonsignificant, at reducing hamstring injury rate in professional soccer players.

Performing Nordic hamstring strength testing with additional weight affects the maximal eccentric force measured: do not compare apples to oranges

“…In the original study on the Nordic Hamstring Exercise, Mjølsnes et al 25 proposed that load could be increased by adding speed to the starting phase of the motion 25. Later studies have added weight to the exercise for the same purpose, using the ability to control the final phase of the exercise as a criterion to decide if testing with added weight was needed or not 16–22. Our results demonstrate that the maximal eccentric hamstring force measured in the Nordic hamstring strength test was significantly higher when players performed the test with added weight, regardless of their ability to control the final phase (figure 1 and table 1).…”

“…The intra-rater and inter-rater reliability of this categorisation has not been tested and may be low. It is, nonetheless, an approach that has been adopted by several previous studies to decide which players should train and be tested with added weight 16–22. The analysis of players performing the test with up to 20 kg added weight should be interpreted with care because of low statistical power.…”

“…Some studies have addressed this problem. To ensure that supramaximal intensity is achieved, study participants who were able to control the final phase of the forward falling movement before full extension have performed training while holding weight plates, increasing the weight over the intervention period 16–22. Several of these studies have used the same criterion when testing maximal eccentric hamstring force with Nordic hamstring test devices 17–21.…”

Effect of additional Nordic hamstring exercise or sprint training on the modifiable risk factors of hamstring strain injuries and performance

“…Furthermore, despite Bourne, Duhig [ 1 ] progressing the eccentric intensity with the addition of load–the prescription could have been excessive with high volumes. This is highlighted by Presland, Timmins [ 13 ] and Cadu, Goreau [ 15 ], who have both used low and extremely low session volumes and observed increased in eccentric hamstring strength. Although the literature is contradictory on these low volumes of NHE [ 14 ].…”

“…Although similar volumes of training had small to trivial effects upon eccentric isokinetic hamstring strength and BF LH muscle architecture in elite youth soccer players [ 14 ]. However, contrastingly in elite senior soccer players 1 set of 3 repetitions had a meaningful effect on eccentric hamstring strength [ 15 ], with compliance (or more specifically frequency of stimulus) having a significant role in improvements in eccentric hamstring strength [ 15 ].…”