To elucidate how aging affects the muscular load required for pulling up pants-style disposable diapers, and why some elderly people cannot pull up the rear of their disposable diapers well, we evaluated the electromyogram (EMG) of 8 young subjects (21.5±1.5 years) and 7 elderly subjects (71.6±6.1 years). EMG was measured for four muscles—biceps brachii, deltoid, brachioradialis, and flexor carpi ulnaris. We evaluated the muscular load during a series of motions for pulling a disposable diaper up at the front and the rear of the body using an EMG-Video Synchronous Split Method. The analysis revealed that the front and the rear integral EMG of elderly subjects were both significantly larger than those of young subjects for all four muscles. For the deltoid and flexor carpi ulnaris muscles, the maximum amplitude of EMG when pulling up the rear of the disposable diapers was significantly larger in the elderly subjects than the young ones. These results suggest that the muscular load involved in pulling up the rear of disposable diapers may increase due to changes in body habitus caused by aging. Since muscular strength decreases with age, it seems likely that the elderly individuals will eventually be unable to pull up the rear of their diapers.

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In Japan, there is a higher incidence of childhood obesity in the Tohoku district than in other areas. It is known that reduced physical activity is associated with increased body weight, but little is known about the physical activity patterns of children in this area. Accordingly, this study was designed to measure the physical activity of 145 children (73 boys and 72 girls) in Hashikami Town, Aomori Prefecture. Physical activity was assessed through a questionnaire as well as through two weeks of pedometer use. Boys spent more time engaging in physical activity than girls did, reporting 9.5 (0.6–22.0) versus 7.0 (1.2–21.5) hours per week [median (range)] (p=0.002). On school days, boys took an average of 13,586±4,386 (mean±SD) steps per day, while girls took 12,248±4,112; on holidays, boys took 9,531±4,557, while girls took 9,419±4,524. There was no significant sex-based difference in the number of steps per day (F=1.197, p=0.276), but both boys and girls significantly reduced the number of steps they took on holidays (F=116.537, p<0.001). In addition, 36 (24.8%) children reduced the number of steps they took by more than 50% on holidays compared to school days. In general, the participants engaged in the internationally recommended amounts of physical activity. Yet their reduced level of physical activity on holidays seems to be a matter for concern, as it is a possible cause of the higher incidence of childhood obesity in this area.

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This study examined the ergonomic effects of a specially made knee supporter containing spiral bone springs aimed at reducing physical stress on the leg muscles during sit-to-stand (STS) and walking. Twelve young females and fifteen elderly subjects performed STS and treadmill walking with and without a specially made supporter, which may be a simple device for aiding STS and/or walking. During STS, electromyography (EMG) was observed from the vastus lateralis of the right leg. The root mean square (RMS) and mean power frequency (MPF) were calculated from the observed EMG. The changing rate of maximal leg acceleration, the third time derivative of the leg position, was also assessed during treadmill walking at a freely chosen stride frequency and speed. A significant decrease in the RMS was observed during STS when wearing the supporter in both groups. A significant increase in the changing rate of maximal leg acceleration was found during walking with the supporter in both groups. MPF significantly increased when wearing the supporter only in the young group. These results showed that the supporter with spiral bone springs reduced physical stress placed on the quadriceps muscles during STS and walking. This ergonomic contrivance will reduce the possible “risk” of stumbling and/or falling in elderly individuals. The reduced physical burden on the quadriceps muscles will also reduce or delay muscle fatigue, which will further result in an increase in the amount of daily physical activities exhibited in physically poor populations.

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No previous study has investigated age-related changes in prefrontal hemodynamics during saccade tasks in a large number of elderly adults. The purpose of this study was to evaluate prefrontal activity related to the performance of anti-saccade in the elderly using near-infrared spectroscopy (NIRS). Ninety-six elderly adults and 22 young adults performed pro- and anti-saccade tasks. Measures included reaction times of both saccades, error rate during anti-saccade, and concentration of oxyhemoglobin (Δoxy-Hb) in the prefrontal cortex during both saccades. Saccade performance, especially error rate, was significantly poorer in the elderly than the young. In the elderly, error rates were widely distributed from 5% to 100%. In about half (48%) of the elderly, error rates were distributed under the mean+3 standard deviations (48%) for the young, and Δoxy-Hb did not differ significantly from that in the young. Elderly subjects whose anti-saccade reaction time was over the regression line (of reaction time in anti-saccade to that in pro-saccade in the young)+2 standard errors showed a strong positive correlation (r=0.79) between Δoxy-Hb and error rate, as did those whose error rate exceeded 48%. In the elderly subjects whose error rates exceeded 90%, Δoxy-Hb was extremely small and deviated greatly from the correlation between Δoxy-Hb and error rate. Based on these findings, we propose a method of evaluating inhibitory function and attention allocation in anti-saccade performance, which is mainly related to the prefrontal cortex, in the elderly, using NIRS.

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We had previously reported on the effect of exposure to light on the human digestive system: daytime bright light exposure has a positive effect, whereas, evening bright light exposure has a negative effect on the efficiency of dietary carbohydrate absorption from the evening meal. These results prompted us to examine whether the light intensity to which subjects are exposed in the evening affects the efficiency of dietary carbohydrate absorption the following morning. In this study, subjects were exposed to either 50 lux (dim light conditions) or 2,000 lux (bright light conditions) in the evening for 9 h (from 15:00 to 24:00) after staying under bright light in the daytime (under 2,000 lux from 07:00 to 15:00). We measured unabsorbed dietary carbohydrates using the breath-hydrogen test the morning after exposure to either bright light or dim light the previous evening. Results showed that there was no significant difference between the two conditions in the amount of breath hydrogen. This indicates that evening exposure to bright or dim light after bright light exposure in the daytime has no varying effect on digestion or absorption of dietary carbohydrates in the following morning's breakfast.

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