The effect of different intensities of eccentric and concentric contraction on the pattern of the quadriceps synergistic muscles activity

Selective muscle strengthening of quadriceps synergistic muscles is important to improve muscle performance specially to prevent Patella- femoral syndrome. Therefore, the aim of this study was to investigate the pattern of the Vastus medialis and Vastus lateralis activity in response to the intensities of super maximal eccentric and submaximal concentric contractions.

12 healthy men students randomly selected (21±2 years, 173±12 cm, and 71±8 kg) from University of Bojnord.  Electromyography activity of quadriceps muscles was measured during contraction by using electromyography system. To evaluate the date, the Multivariate variance (MANOVA) and post hoc test (TUCKY) were applied at p˂0.05.

The data analysis was demonstrated the electromyography activity of Vastus medialis and Vastus lateralis were significantly increased with an increased work load during the eccentric contraction rather than concentric contraction which suggests that progressive resistance training using super maximal eccentric contraction is more effective than submaximal concentric contraction to create the neuromuscular adaptations.

Furthermore, it was observed a significant interaction between muscle type and contraction intensity for muscle electromyography activity. Since, during the submaximal contraction, the EMG activity of Vastus medialis was significantly higher than Vastus lateralis, while it was not the case during super maximal contraction, which could indicate the possibility of selective muscle strengthening of Vastus medialis in sub-maximal intensity to prevent patella-femoral syndrome.