Snapshot evaluation of fatigue using heart rate variability and superimposed M-waves of myoelectric signals during skiing exercise

We simultaneously measured the heart rate (HR) and myoelectric (ME) signals during a skiing exercise for a whole day. To realize a snapshot evaluation of fatigue for this long-term exercise, biosignal processing should be designed to estimate the target factors from biosignals and to deal with biosignals measured at a restricted condition. We accumulated the power spectrum of the HR time series within the target frequency bands determined by the results of wavelet analysis. On the other hand, the evoked potential approach was used for evaluating muscle fatigue via ME signals. The accumulated power spectrum of the HR time series changed periodically during skiing and ski-lift riding. Furthermore, a muscle fatigue index and the features of the HR time series became prominent towards the final trial of the day. As a result, we could investigate fatigue at the required times based on the relationship between the time-varying behavior of HR time series and the muscular fatigue index, during long-term skiing exercise