Tremor is an invisible mechanical vibration observed on parts of the body. It is classified into physiological and pathological tremors. It was reported that an oral dose of alcohol could decrease the amplitude of pathological tremor. Usually, drunken level is estimated by the alcohol concentration in expiration. But, physiological tremor can be used to estimate drunken level easily. In this paper, power spectrum of the physiological tremor of index finger and some reaction time of the pedal operations of imitated car driving were measured every 15 minutes for 3 hours under drinking and non-drinking conditions. Subjects were 10 males aged 20 to 25 years. Under drinking condition, the total power values of tremor from 15 to 180 minutes after drinking were smaller than that of before drinking. It is clear that the influence of drinking could be estimated by the total power of the physiological tremor, even when the significant difference of the influence of drinking on reaction time was not found.
Experiments were conducted to examine the visibility of different floor levels from a stumbling point of view. The test subjects were the elderly and the young, and we compared the difference between the two. We investigated eye movement while they were scanning the different floor levels. The results were as follows: 1) The height of different floor levels and illuminance had an influence on the visibility of different floor levels. Especially, the elderly were easily influenced by them. 2) The eye movements in scanning the different floor levels did not relate to the visibility of them, but were related to the personality of the test subjects. Eye movement patterns of the elderly differed from that of the young. The elderly were scanning mainly the lower part. The eye fixation time of the elderly was longer than that of the young. From the results, it was clarified that there were the difference between the elderly and the young. We could show it by the degree of influence. For example, the influence by the change of environmental condition.
The physiological responses and the magnitude of perceived fatigue (MPF) were estimated from eight healthy men during isometric continuous and intermittent handgrip at 10% maximum voluntary contraction (MVC). The physiological responses involved electromyogram (EMG), heart rate (HR), mean blood pressure (MBP) and forearm blood flow during contraction (FBFC) and relaxation (FBFR). The sequence of tests included three different work patterns: 1) continuous handgrip for 30 min, 2) intermittent handgrip (10 sec contraction +5 sec relaxation) for 45 min, 3) intermittent handgrip (10 sec contraction +10 sec relaxation) for 60 min. These experiments were performed on two different heat loads (25 degrees C and 40 degrees C, H.R. 50%). The results were as follows: 1) The localized muscle fatigue in the forearm was observed during the work periods. 2) The mean frequency of EMG was higher at 40 degrees C than 25 degrees C. 3) FBFR was significantly lower than FBFC at 40 degrees C. 4) MPF and MBP were little influenced by the heat load. 5) MPF correlated well with both HR and MBP.
