Seasonal changes in ambient temperature and day length are thought to modify habitual physical activity. However, relationships between such environmental factors and the daily physical activity of older populations remain unclear. The present study thus examined associations between meteorological variables and the number of steps taken per day by elderly Japanese. Continuous pedometer counts over a 450-day period were collected from 41 healthy subjects (age 71+/-4 years), none of whom engaged in any specific occupational activity or exercise programs. An electronic physical activity monitor was attached to a belt worn on the left side of the body throughout the day. Daily values for mean ambient temperature, duration of bright sunshine, mean wind speed, mean relative humidity, and precipitation were obtained from local meteorological stations. The day length was calculated from times of sunrise and sunset. Based on the entire group of 41 subjects (ensemble average), a subject's step count per day decreased exponentially with increasing precipitation (r2=0.19, P<0.05). On days when precipitation was <1 mm, the step count increased with the mean ambient temperature over the range of -2 to 17 degrees C, but decreased over the range 17-29 degrees C. The daily step count also tended to increase with day length, but the regression coefficient of determination attributable to step count and mean ambient temperature (r2=0.32, P<0.05) exceeded that linking the step count and day length (r2=0.13, P<0.05). The influence of other meteorological factors was small (r2

This study provides Class IV evidence that in patients with bilateral vestibular dysfunction, an imperceptible level of noisy GVS may improve postural stability.

BackgroundCardiovascular disease (CVD) is the leading cause of mortality and morbidity in industrialized countries 1) . In a working population, occupational factors are believed to pose a threat to workers' cardiovascular health. Substantial research has shown that adverse physical and psychosocial work environments and working conditions, such as shift work and excessive workload, are related to CVD. To examine the acute and chronic effects of such work-related factors on the cardiovascular system, cardiac autonomic nervous system activity during work and rest has been assessed by heart rate variability (HRV).Heart rhythm is recorded by electrocardiography. The measured signal shows a series of waves that present electrical events in the four chambers and the conduction pathways within the heart. The time interval between consecutive R waves that correspond to the contraction of the ventricles is called the RR interval (RRI). HRV is a time series of RRIs that fluctuate beat by beat in healthy humans because of time-to-time changes in activities of sympathetic and parasympathetic nerves innervating to the sinus node.HRV is generated in part by periodic inputs of both respiration and blood pressure variability into the medullary cardiovascular centers 2) . These periodic modulations are clearly identified within the power spectrum of HRV as peaks at the respiratory frequency (≈ 0.25 Hz) and at the frequency of the well-known Mayer wave (0.1 Hz) in blood pressure variability 1,3) .Heart rate increases and decreases during inspiration and expiration, respectively. This is mainly caused by the physiological fact that parasympathetic output from the cardiovascular center is inhibited during inspiration 4) . Respiratory rhythm during rest is about 0.25 Hz. Therefore, exposure to occupational toxicants and hazardous environments), psychosocial workload (i.e. job stressors), and working time (i.e. shift work) had been examined and identified as having associations with low HF power. These findings may indicate that research into parasympathetic nervous system activity should be focused to protect cardiovascular health at work. We also propose the use of very low and ultralow frequency HRV components in autonomic research for workers' health.

Vestibular dysfunction causes postural instability, which is prevalent in the elderly. We previously showed that an imperceptible level of noisy galvanic vestibular stimulation (nGVS) can improve postural stability in patients with bilateral vestibulopathy during the stimulus, presumably by enhancing vestibular information processing. In this study, we investigated the after-effects of an imperceptible long-duration nGVS on body balance in elderly adults. Thirty elderly participants underwent two nGVS sessions in a randomised order. In Session 1, participants received nGVS for 30 min twice with a 4-h interval. In Session 2, participants received nGVS for 3 h. Two-legged stance tasks were performed with eyes closed while participants stood on a foam rubber surface, with and without nGVS, and parameters related to postural stability were measured using posturography. In both sessions, the postural stability was markedly improved for more than 2 h after the cessation of the stimulus and tended to decrease thereafter. The second stimulation in Session 1 caused a moderate additional improvement in body balance and promoted the sustainability of the improvement. These results suggest that nGVS can lead to a postural stability improvement in elderly adults that lasts for several hours after the cessation of the stimulus, probably via vestibular neuroplasticity.

The interactions of sex, age, season, and habitual physical activity were examined in 41 male and 54 female Japanese age 65–83 yr, using a pedometer/accelerometer that determined step counts and amounts of physical activity (<3 and >3 metabolic equivalents [METs]) throughout each 24-hr period for an entire year. All 3 measures were greater in men than in women. In women, age was negatively correlated with step count and activity <3 METs, but in men, it was correlated with step count and activity >3 METs. Irrespective of sex or age, all 3 activity variables were low in the winter, peaking in spring or autumn. In the summer, step counts matched the annual average, but durations of activity <3 and >3 METs were, respectively, longer and shorter than in other seasons. These findings have practical implications for those promoting physical activity for older adults.