Effect of Nordic hamstring exercise and straight leg deadlift on hamstring fatigue post repeated sprint

The purpose of this study was to investigate whether the nordic hamstring exercise (NHE) or straight leg deadlift (SLD) had greater effect of fascicle length (FL), pennation angle (PA) as well as peak force (PF) following a repeated sprint fatiguing protocol. The NHE uses short muscle contractions while the SLD uses long muscle contractions, the effects each exercise has on the maintenance of peak force following repeated sprints was of interest. Eighteen youth football players playing at a professional Football League 1 club were randomly allocated into 2 groups, NHE and SLD. A pre- test-post- test experimental design was utilised with each participant performing 12 progressive strength sessions over a 6- week period. Each participant performed 15 x 30 meter repeated sprints followed by a Nordbord PF measurement both pre and post training intervention. Both PA and FL were measured by means of ultrasound. The Results state that PF was higher in the SLD group post training intervention (P < 0.05) there was no significant difference in the NHE group. The SLD group also showed a medium effect size d=.55 while the NHE group showed a small effect size d= .24. Mean PA was significantly higher post intervention compared to pre intervention in the SLD group only (P < 0.05), there was also a medium effect size d=.59 while the NHE group showed a small effect size d=.16. Similarly, the FL score was significantly higher post intervention than pre intervention, however, only in the SLD group (P < 0.05) there was also a medium effect size d=.68 while the NHE group showed a small effect size d=.12. The SLD may be an appropriate exercise in order to reduce the effects of fatigue in the hamstrings during repeated sprint activity as well as induce positive architectural changes in the hamstring muscles. The findings in this study offer what may be a novel method for training the hamstrings in order to reduce the effects of fatigue. The findings suggest that this may be an appropriate pilot study for future research.