The purpose of this study was to examine the relationship between the level of subjective muscle fatigue sensation (SMS) and the physiological responses to decreasing force during and after sustained and constant effort static gripping (SSG) at 50, 75 and 100% of the maximal voluntary contraction (MVC). The subjects were 10 healthy males without upper extremity impairments. Each subject performed SSG for 6 min with three target forces. SMS of the forearm by Borg’s CR 10 scale was measured every 30 sec during and after the SSG. The blood lactate concentration (La) and MVC were measured before the SSG and at 0, 4 and 7 min after the SSG. There were no significant differences in the average grip force after 30 sec from the SSG onset between the target forces. The SMS for 75% MVC during the SSG increased markedly, and was the highest at 30 sec after the onset (p < 0.05). Although the La at 4 min was higher than that before the SSG, the La recovered to 80% at 7 min after the SSG, and the SMS recovered almost completely. The cross correlation coefficients between the increasing SMS and decreasing force during the SSG were very high in all conditions (r_xy= -0.819 to -0.979, -0.930 to -0.988, -0.789 to -0.985, for 50%, 75% and 100%, respectively; all coefficients: lag = 0), but the relationships between the recovery ratio of the SMS and that of the maximal grip force at 4 and 7 min after the SSG were low. In addition, the relationships between the recovery ratio of the La and the maximal grip force for 75% MVC were high at 0 and 4 min after the SSG (r = -0.814, -0.744, respectively). In the case of sustained muscle contraction for a long time, there were no significant differences between the target forces for the SMS, La and maximal grip force after SSG, and the degree of muscle fatigue was considered to be similar at each target force. However, the SMS during SSG, especially before the gripping force decreased to the almost steady state, may differ at each target force.

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The acceleration plethysmography (APG) is a useful tool to analyze the heart rate variability (HRV) with the merits of being portable and simple in operation. To use it clinically, ‘stationarity' of the HRV measurements in resting state should be justified as a fundamental premise. Therefore, the purpose of this research was to investigate the stationarity of the short-term HRV derived from APG in resting state in daily life. The sample size was determined on the basis of α=0.05 and β=0.20. The HRV measurements of 44 healthy male subjects were done twice during a one-week period by the APG system. The HRV parameters were examined by the assessments of distribution, equality of the mean and variance and internal consistency reliability. Concerning spectral components represented as proportion, normalized units and the logarithm of the rate of each component, the normal distribution and the homogeneity of variance in two measurements were confirmed. Significant difference was not found between the mean values in two measurements. The internal consistency reliability evaluated by Cronbach's α of 0.6-0.7 was acceptable for every parameter. It is concluded that for healthy young males, the parameters of short-term HRV derived from APG measured in resting state in the same time zone in daily life remain stationary within a certain range regardless of the measurement day.

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Strenous physical exercise like professional load bearing often produces oxidative stress, increasing post exercise Malondialdehyde (MDA) levels. To quantify the cellular dimension/profile of the said stress, nanoscopic observation of the erythrocyte surface was made by Atomic Forced Microscopy (AFM)/Lateral Forced Microscopy (LFM) and correspondingly the average roughness of the surface was measured. An attempt has been made to correlate the antioxidant vitamin mixture supplementation, endurance capacity, allied physiological parameters and blood glucose-6-phosphate dehydrogenase (G-6-PD) level and roughness-MDA correlation and thereby the deduced regression equation as crucial markers of performance related oxidative stress management in professional female load bearers. Three experimental groups A, B and placebo, each consisting of ten female workers (18-21 years old), were chosen. Group A was given 400 mg of vitamin E supplementation daily, while Group B was given a clinical mixture of vitamin E, vitamin C and β-carotene daily in capsular form for a period of 28 days. The exercise- induced hike in the status of serum MDA was found to rise less significantly with vitamin supplementation. Further study showed that the supplementation was instrumental in reducing the basal MDA level. Endurance capacity, determined by bicycle ergometric method, was increased more significantly (p<0.001) in group B than in group A (p<0.01), and first minute recovery heart rate decreased significantly (p<0.05) in both groups. G-6-PD level was shown to increase more significantly (p<0.01) with antioxidant vitamin mixture supplementation than with vitamin E supplementation singly (p<0.05) in professional female load bearers. The regression equation might be instrumental in early detection of oxidative damage in strenuous exercise in manual material handling.

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The purpose of this study was to investigate whether Typus Melancholicus (TM) personality can be used to explain some individual differences related to the degree of athlete burnout and the features of its process, based on a comparison between TM and non-TM groups. For this purpose, we conducted a questionnaire investigation administered to Japanese university athletes using the Depression-related Personality Trait Scale, Athlete Burnout Questionnaire, Daily and Competitive Stressor Scale, and Modified-COPE, and collected 1,086 samples. The results revealed that although there were no differences in the degrees of burnout, there were different features in the burnout process that depended on whether he/she had TM features.

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Farmers handle heavy workloads, often in awkward postures and experiencing some work related problems. Farmers perceive them as no more than inevitable consequences of farming activities. Although many problems can be prevented or reduced by simple and inexpensive modifications to work, these problems are increasing among farmers. The main focus of the paper was to investigate workload and awkward postures among strawberry farmers and suggest possible solutions to overcome the identified problems. Questionnaires, direct observations and intertwining methods were used to collect the data. Low-level strawberry beds and long working hours were recognized as critical factors that led to farmers’ health problems including suffering from low back pain, heavy fatigue, unsteady feeling after work, etc. There was a substantial increase in fatigue in busy seasons compared with slack seasons. When compared with the other workers such as office, technical, sales and blue-collar workers, female farmers’ general fatigue level was considerably high. Findings indicated that strawberry farming was a stressful occupation and farmers were strained under heavy workload, monotonous and repetitive work and poor working conditions with frequent fatigue symptoms and severe influence on health.

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The basic problems of bed-fence-covers in hospitals were listed for preventing relevant accidents based on the investigation into actual conditions in a hospital in Kawasaki City. There were many elderly aged patients with dementia, higher brain dysfunction or psychosis in the hospital. They sometimes fell into the gaps of bed-fences, resulting in serious accidents. It was due not only to the structure of the bed-fences, but also to the characteristics of patients. Therefore the authors listed up the problems concerning the accidents to recognize them; (i) as physical conditions, (1) they could not move by themselves because of paralysis or decrease of fitness, (2) they could not feel when they were pinched by the gaps because of decrease of sense, (3) they moved irregularly or violently without their intention, and (ii) as mental conditions, (1) they took dangerous behaviors because of dementias, (2) they could not control their behaviors because of higher brain dysfunctions, (3) they could not control their feelings and moved violently because of mental disorders. The authors intend to develop safer bed-fence-covers to prevent these accidents for the elderly patients.

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Old-aged patients, especially when they cannot keep stable sitting postures on wheelchairs, may get hurts seriously by falls. Preventing fall accidents is one of the most important subjects for keeping ADL of old-aged persons. We investigated the fall accidents related to from wheelchairs that occurred in a hospital ( Asao General Hospital of Rehabilitation), and tried to make a new type of safety belts for old-aged wheelchair users based on the investigation. The results of trials using the product was evaluated by the care givers. The number of fall accidents in the hospital amounted to 226 cases within a year. It is noticed that the patients removed their belts by themselves intentionally or unintentionally, which is the most important point of the accidents. The evaluators of new belts were 91 care givers. The evaluation items were (1) the convenience for caregivers to fasten and remove the belts, (2) the ability of holding the patient on the wheelchair, (3) the safeness to prevent the fall from wheelchair (including the disability of removing a belt by the user), (4) the appearance when the usually used belts and the new belts were used, and only for the new belts, (5) the hygienic aspect and (6) the utility of the pocket. The new belts got better marks than the usually used belts. We intend to further improve the trial product (new belt) to be safer, more effective and more comfortable, based on the evaluation.

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