Resumen de Progressive Workload Periodization Maximizes Effects of Nordic Hamstring Exercise on Muscle Injury Risk Factors
Lucas Severo, Mauricio P. Dornelles, Felipe Xavier Lima e Silva, Cesar L. Marchiori, Thales M. Medeiros, Evangelos Pappas, Bruno M. Baroni
This study aimed to investigate the effect of 2 different Nordic hamstring exercise (NHE) training programs (constant workload vs. progressive workload) on multiple risk factors for hamstring strain injury in high competitive level athletes. Twenty-one premier league rugby union players (~26 years) were randomized into 1 of 2 experimental groups and completed an 8-week NHE training program: constant training group (CTG) or progressive training group (PTG). Knee flexor/extensor strength and biceps femoris long head (BFLH) muscle architecture were assessed through isokinetic dynamometry and ultrasonography, respectively, before and after the training programs. Increased hamstring concentric ([DELTA] = 8%, p = 0.004, d = 0.42) and eccentric ([DELTA] = 7%, p = 0.041, d = 0.39) peak torques, as well as H:Q conventional ([DELTA] = 7%, p = 0.015, d = 0.54) and functional ([DELTA] = 6%, p = 0.026, d = 0.62) ratios were observed in the follow-up compared with baseline for the PTG group only. Nordic hamstring exercise training significantly increased BFLH muscle thickness (CTG: [DELTA] = 7%, p = 0.001, d = 0.60; PTG: [DELTA] = 7%, p < 0.001, d = 0.54) and fascicle length (CTG: [DELTA] = 8%, p < 0.001, d = 0.29; PTG: [DELTA] = 10%, p < 0.001, d = 0.35) in both groups. Training adaptations on hamstring peak torque (concentric and eccentric) and H:Q ratio (conventional and functional) "likely favor" PTG, whereas changes in BFLH fascicle length "possibly favor" PTG. In conclusion, only PTG enhanced hamstring strength; both NHE training programs increased BFLH muscle thickness and fascicle length, but progressive training generated greater changes on fascicle length than constant training. Medical/coaching staff should be aware that NHE with adequate training periodization with workload progression to maximize its benefits.
