The Influence Of An Acute Bout Of Eccentric Exercise On The Hamstrings To Quadriceps Ratio

Abstract

INTRODUCTION: The hamstrings to-quadriceps (H:Q) ratio has been used to assess the muscle balance at the knee joint. An imbalance of the flexor and extensor muscles at the knee joint has been shown to be associated with an increased risk for knee and hamstring related injuries. Eccentric training may potentially influence the (H:Q) ratio as it leads to an acute reduction in muscle force and impaired muscle function in the days following the workout. However, we are aware of no previous studies that have examined the effects of an acute bout of eccentric exercise on the H:Q ratio. PURPOSE: To examine the effects of a single bout of eccentric exercise on the H:Q ratio in recreationally active college age males. METHODS: Eight healthy male individuals (mean ± age = 20.75 ± 2.49 yr) volunteered to participate in the study. Isokinetic peak torque (IPT) of the right leg extensors and flexors were assessed on a Biodex System 2 dynamometer at 60° s-1. IPT was assessed 4 days prior to the eccentric workout protocol and again 24 hrs following the protocol. The eccentric workout consisted of four sets of 10 repetitions for the leg press, leg extension, and leg curl exercises that were performed at 120% of their predetermined concentric one repetition maximum. All exercises were performed on the right leg only. Conventional H:Q ratios were calculated by dividing the highest leg flexion IPT value by the highest leg extension IPT value. A paired samples t-test was used to analyze all data. An alpha of P ≤ 0.05 was used to determine statistical significance. RESULTS: The acute bout of eccentric exercise resulted in a significant decrease in IPT of the leg extensors (-10.93%, P = 0.007) and a non-significant decrease in IPT of the leg flexors (-5.90%, P = 0.138) at 24 hrs post eccentric training. There was no significant difference (P = 0.302) observed in the H:Q ratio following the acute eccentric exercise protocol. CONCLUSIONS: These findings indicated that a single bout of eccentric exercise reduced hamstring and quadriceps isokinetic strength, but did not influence the H:Q ratio. Thus, an acute bout of lower body eccentric exercise appears to not adversely affect muscular balance across the knee joint as measured from the H:Q ratio.