Effect of resistance training on the relationship of quadriceps and hamstring muscles in five-a-side football players: strength and myoelectric activity assessment

Abstract

Introduction: Football 5-a-side is an adapted sport modality geared towards people with visual impairments. Proper physical preparation of athletes is fundamental not only for better sports performance, as well as better overall health. The resistance training (RT) has been used as a component in the overall training routine for increasing muscle strength and hence in preventing injury. Objective: The aim of the study was to evaluate, in a group of 5-a-side footballers, the effect of TR on maximal isometric strength and electrical activity of the quadriceps and hamstring muscles. Methods: A non-controlled clinical trial was conducted with football 5-a-side soccer players. In sectional phase of the study, maximal isometric strength (dynamometry) and surface electromyography of the quadriceps and hamstring muscles were assessed. In the prospective phase of the study, the soccer players were submitted to RT and reassessed after 15 weeks for the same outcome variables. TR occurred at a frequency of three times per week for fifteen weeks with non-linear periodization. The main outcomes considered were: electrical activity through the antagonist / agonist ratio (EMG IT: QUAD) and maximal isometric strength of the quadriceps and hamstrings (muscle deficit index; MDI) muscles. Results: On electromyographic analysis, no statistically significant differences in the EMG IT:QUAD were observed on both dominant and non-dominant side. Regarding the maximal isometric force, significant reductions were observed in MDI of hamstrings (p = 0.04) and quadriceps (p = 0.02) after the training period. Conclusion: Resistance training was effective in reducing the muscle deficit index of the hamstrings and quadriceps. This result is very important because it represents a better muscular balance between the members, which is directly associated with a lower risk of musculoskeletal injury and indirectly to improved sports performance. Moreover, there was no change in the electrical activity of the muscles, which could be related to the time of training adopted in the present study.