The effects of vibration foam roller applied to hamstring on the quadriceps electromyography activity and hamstring flexibility

This study investigates the effect of vibration foam roller (VFR) applied to the hamstring, on the quadriceps electromyography (EMG) activity and hamstring flexibility. A total of 16 subjects were randomly assigned to either the VFR group (n=8) or the nonvibration foam roller group (NVFR, n=8). The two groups applied the foam roller or the VFR to the dominant hamstring, at a rate of 40 times per min, for a total of 200 times in 5 min. The primary outcome was to measure hamstring extensibility using the sit and reach test. The EMG activity of the dominant rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) was measured as the secondary outcome. Results indicate a significant increase in the sit and reach distance after the intervention in both groups, as compared to preintervention. The sit and reach difference between VFR and NVFR show no significant difference after the intervention. Significant increases were observed after intervention in the %maximum voluntary isometric contraction (%MVIC) of VL, VM, and RF in the VFR group, and RF in the NVFR group, as compared to the preintervention values. Furthermore, %MVIC values of VL and RF, but not the VM muscle, were significantly different between the two groups. These findings suggest that regardless of vibration, the application of foam roller to hamstring may exert a positive effect on hamstring flexibility. Furthermore, these results indicate that the application of foam roller with vibrations causes more EMG activation in the antagonists.