Relationships between muscle activity and autonomic regulation during cycling with a torque-assisted bicycle.

For customizing the assistance scheme of a torque-assisted bicycle, we estimated physical activity during cycling with ECG and surface EMG for the circuit including a steep uphill section near the middle and compared it with the vehicle data. Using the respiratory-sinus-arrhythmia-related power ratio in the fluctuation of the R-R interval, prRSA and a muscular fatigue index, we classified physical activity into four groups for each trial. Results showed that the assist enlarged prRSA but did not sufficiently support muscular fatigue.