Lower extremity muscle activities during cycling are influenced by load and frequency

The purpose of this experiment was to investigate the effects of frequency and inertia on lower extremity muscle activities during cycling. Electromyographic (EMG) data of seven lower extremity muscles were collected. Sixteen subjects cycled at 250 W across different cadences (60, 80, and 100 rpm) with different loads (0, 0.5, 1.0, 1.5, and 2.0 kg) attached to distal end of their thighs. Load and cadence interactions were observed for the offset of the biceps femoris (BF), the active duration of the rectus femoris (RF), and the peak magnitudes of the vastus lateralis (VL) and the tibialis anterior (TA). Cadence effects were observed in the onset of the gluteus maximus (GM), RF, BF, VL, and TA; the offset of the GM, RF, BF, VL; the duration of the BF and TA; the peak magnitude of the RF and gastrocnemius (GAS); and the crank angle at which the peak magnitude was achieved of the BF, GAS, and soleus (SOL). Load effect was observed from the onset of RF and SOL, the offset of RF, the duration of SOL, and the peak magnitude of BF. These results indicate that inertial properties influence the lower extremity muscular activity in addition to the cadence effect.