Document Type : Original Articles


1 Department of Physical Education and Sport Sciences, Islamic Azad University, Bojnourd Branch, Bojnourd, Iran

2 Department of Medical Physics and Radiology, School of Medicine, North Khorasan University of Medical Sciences, Bojnurd, Iran



Background: Strength training has been commonly used as an intervention to improve neuromuscular activity within the synergic and/or agonist-antagonist muscles. This study aimed to evaluate simultaneous electrical activity of quadriceps and hamstrings muscles after strength eccentric training versus concentric training.
Methods: This study was an experimental study with a between-group comparison design. 26 male participated in two groups (eccentric training group and concentric training group). Maximal knee extension force, and bipolar surface electromyography (EMG) signals from quadriceps and hamstrings muscles were simultaneously recorded pre- and post- concentric and eccentric strength training. After EMG pre-processing for noise reduction, EMG signals were evaluated in two groups by time and frequency analysis. Nine EMG features (six time features and three frequency features) were analyzed in two groups pre- and post-training by statistical analysis.
Results: the results showed that the maximal voluntary isometric contraction (MIVC) of quadriceps muscle were significantly increased in both groups from pre- to post-training (P< 0.05). Moreover, eccentric training resulted in greater increase in time features of EMG for quadriceps and hamstrings muscles as compared to concentric training (P< 0.05). All frequency features showed significant changes in pre-test and post-test for eccentric training group (P< 0.05). However, no significant difference was observed in the frequency features in the post-test compared to the pre-test in the concentric training group (P>0.05).
Conclusion: based on our results, the great changes in time and frequency features of quadriceps and hamstring EMG were observed using eccentric training. So, eccentric strength training could be more effective to trigger neuromuscular activity within the agonist and antagonist muscle simultaneously.