Effects Of Electrical Muscle Stimulation With Voluntary Pedaling Exercise On Skeletal Muscle Morphology And Function

Abstract

PURPOSE: This study was to examine the effects of EMS while voluntary pedaling exercise for 8 weeks on the morphology and function of skeletal muscles. METHODS: Fifteen college age students (19-24) were randomly divided into EMS group; EMS only (n = 7) and EMS-EX group; EMS with voluntary pedaling (n = 8). They completed EMS training for 8 weeks (two times per weeks). The EMS group was performed EMS in a seated position, and the EMS-EX group was performed EMS with voluntary pedaling at 40-50 rpm with a very low load (0.5% of body weight) for 20 minutes, respectively. EMS was applied to the quadriceps muscle with the stimulator. The stimulator current waveform was set at a frequency of 50 Hz with a pulse width of 250 μs for both groups. Also, the stimulation intensity (mA) was set to the maximum intensity (23 to 60 mA) that they could tolerate for each session. We measured knee extension isometric and isokinetic strength (angular velocity60,120,180 deg/s), muscular endurance as skeletal muscle function, rectus femoris muscle thickness and thigh circumference as skeletal muscle morphology before and after 8 weeks of training. Each parameter was statistical analyzed by paired t-test were completed to identify any significant between-groups (p < 0.05). RESULTS: Knee extension isometric and isokinetic strength tended to increase after EMS training in both groups. But there was no difference in the changes between the two groups, the rate of increase in muscle strength in the EMS-EX group tended to be higher than that in the EMS group. Total work capacity and first 1/3 work capacity as muscular endurance were significantly increased in both groups(p < 0.05), but final 1/3 work capacity increased only in the EMS-EX group(EMS group; 99.3 ± 12.0%, EMS-EX group; 103.4 ± 9.5%) after EMS training. Rectus femoris muscle thickness of both group were significantly increased after EMS training (EMS group; 112.3 ± 5.6% and EMS-EX group; 111.7 ± 11.7%, p < 0.05). And thigh circumference in EMS-EX group was significantly increased after EMS training (p < 0.05). CONCLUSIONS: These results suggest that EMS would be induce increased isometric and isokinetic muscle strength and muscle hypertrophy. Furthermore, EMS training while voluntarily pedaling may be more effective than EMS alone in improving morphology and function of skeletal muscle.