Electromyography during pedaling on upright and recumbent ergometer

Ergometers are used during rehabilitation and fitness to restore range of motion, muscular strength, and cardiovascular fitness. The primary difference between upright and recumbent ergometers is that the seat and crank spindle are aligned nearly vertically on upright bicycles and nearly horizontally on recumbent ergometers. In addition, recumbent ergometers are characterized by large seats with backrests to provide support for the upper body and are low to the ground, permitting easier access for wheelchair users and individuals with mobility impairments. Despite the great utility of the recumbent bike, it has not been studied with regard to energy costs or muscular output. This is the first study to investigate the differences between two commercial ergometers by analyzing of lower limb EMG in participants who are not habitual cyclers.

Ten non-cyclist males with no history of musculoskeletal lower limb injury pedaled on standard recumbent and upright ergometers. EMG data were recorded from the volunteers' lower limb muscles (rectus femoris, semitendinosus, tibialis anterior, and medial gastrocnemius muscles). EMG signals were normalized to the highest EMG signals recorded for the maximum voluntary isometric contractions (MVIC). The peak normalized EMG value of the studied muscles over the average of the 10 pedal cycles was analyzed.

The differences in average peak muscle activity were not statistically significant for any of the four muscles tested. Pedaling a recumbent ergometer resulted in greater activity in two (semitendinosus and tibialis anterior) of the four muscles studied. Only the rectus femoris muscle demonstrated greater activity during upright pedaling.

There were no differences in the EMG activity of the muscles studied during pedaling on a standard recumbent and an upright stationary exercise ergometer at moderate workload. This increased understanding of muscle activity during pedaling may be useful in the development of new exercise protocols and therapeutic approaches.

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