EFFECT OF NONCIRCULAR O-SYMETRIC CHAINRING ON MUSCULAR ACTIVATION DURING STEADY-STATE PEDALLING

Abstract

The purpose of this preliminary study was to compare the surface EMG level activity of seven muscles (gluteus maximus, rectus femoris, vastus medialis, tibialis anterior, gastrocnemius medialis and soleus) while pedalling with circular and noncircular ring (OSymetric). Five cyclists rode at 2 power output levels (150 - 200 W) and 3 different pedalling cadences (70 – 90 – 110 rpm) on SRM ergotrainer. Unlike the other muscles, gluteus maximus and vastus medialis were more recruited while pedalling with OSymetric ring (~5-15%) only at the lowest cadence (70 rpm). These neuromuscular behaviours might be related to the increase in time of the power crank sector induced by the O-Symetric design. However, this substantial advantage didn’t appear as benefical for higher crank velocities, probably due to muscle activation-deactivation dynamics.