Effect of Nordic Hamstring Exercises on the Balance of Knee Muscle Strength in Sprinters

Abstract

Objective: The purpose of this study was to investigate the effect of Nordic hamstring exercises on the balance of knee muscle strength in sprinters. Methods: In this paper, a total of 20 well-trained sprinters were selected as subjects to participate in this experiment, 10 of them were subjected to Nordic hamstring exercise intervention, and the other 10 were treated as control group without any intervention. At different time points before and after intervention, the isokinetic muscle strength and test system were used to analyze the changes of muscle strength of athletes after Nordic hamstring exercise intervention. Results: The H:Q functional ratio changed over time after the intervention: decreased by 0.072 from baseline 24 hours after the intervention, recovered by 0.039 from 24 hours at 48 hours, and recovered by 0.024 from 72 hours at 48 hours. In general, there was a significant decline at 24 hours, and then a gradual recovery at 48 and 72 hours, but a partial recovery was observed overall. Conclusions: After the Nordic hamstring exercise intervention, the H:Q functional ratio showed a significant decline at 24 hours, and then gradually recovered at 48 and 72 hours, but overall partial recovery was observed. It is suggested that the injury risk of sprinters will increase in the short term after intervention, and the injury risk can be avoided by at least 48 hours of recovery.