Abstract
The mental and physical workload (MPWL) due to motorcycle (MC) and automobile (AM) operation were compared quantitatively by means of ECG R-R intervals (RRI). The RRI of 30 MC riders and 20 AM drivers were measured. Eight statistics were derived from RRI; average (RRM), mean coefficient of variance (mean CVR-R), auto regressive variability (ARV), power of high-frequency region (HF), central frequency of high-frequency region (HFF), power of low-frequency region (LF), central frequency of low-frequency region (LFF) and ratio of LF and HF (LF/HF). As a result of factor analysis, three common factors which reflect, “stress level” (represented by mean CVR-R & LF), “parasympathetic tone” (RRM & HF) and “randomness of RRI variability” (ARV) were extracted from these eight statistics. MC riders' stress level gradually increased in accordance with riding distance up to 260-320km, then it started to decrease and parasympathetic tone was enhanced in turn. This phenomenon can be comprehended so as to indicate the difficulty in maintaining attention. On the contrary, AM drivers' stress level increased steadily in accordance with driving distance, but no phenomena thought to affect the maintenance of attention was observed.
