The ECW/TW ratio increases in the lower leg with age. The results suggest that the expansion of ECW relative to ICW and the LV masked actual muscle cell atrophy with aging.

This study evaluated the validity of the total energy expenditure (TEE) estimated using uniaxial (ACCuni) and triaxial (ACCtri) accelerometers in the elderly. Thirty-two healthy elderly (64-87 years) participated in this study. TEE was measured using the doubly labeled water (DLW) method (TEE(DLW)). TEE(ACCuni) (6.79 +/- 1.08 MJ day(-1)) was significantly lower than TEE(DLW) (7.85 +/- 1.54 MJ day(-1)) and showed wider limits of agreement (-3.15 to 1.12 MJ day(-1)) with a smaller correlation coefficient (r = 0.703). TEE(ACCtri) (7.88 +/- 1.27 MJ day(-1)) did not differ from TEE(DLW) and showed narrower limits of agreement (-1.64 to 1.72 MJ day(-1)) with a larger correlation coefficient (r = 0.835, P < 0.001). The estimated intensities of light activities were significantly lower with ACCuni. Greater mediolateral acceleration was observed during 6-min walk tests. The results suggest that ACCtri is a better choice than ACCuni for assessing TEE in the elderly.

Global warming is increasingly recognized as a threat to the survival of human beings, because it could cause a serious increase in the occurrence of diseases due to environmental heat during intermittent hot weather. To assess the direct impact of extremely hot weather on human health, we investigated heat-related deaths in Japan from 1968 through 1994, analyzing the data to determine the distribution of the deaths by age and their correlation to the incidence of hot days in summer. Vital Statistics of Japan, published by the Ministry of Health and Welfare of Japan, was the source of the heat-related mortality data employed in this study. Meteorological data were obtained from the District Meteorological Observatories in Tokyo and Osaka, the two largest cities in Japan. Heat-related deaths were most prone to occur on days with a peak daily temperature above 38 degrees C, and the incidence of these deaths showed an exponential dependence on the number of hot days. Thus, even a small rise in atmospheric temperature may lead to a considerable increase in heat-related mortality, indicating the importance of combating global warming. Furthermore, half (50.1%) of the above-noted deaths occurred in children (4 years and under) and the elderly (70 years and over) irrespective of gender, indicating the vulnerability of these specific age groups to heat. Since a warmer climate is predicted in the future, the incidence of heat waves will increase, and more comprehensive measures, both medical and social, should be adopted for children of 4 years and younger the elderly to prevent heat-related deaths in these age groups.

We examined the effect of increased plasma osmolality (P(osm)) on cutaneous vasodilatory response to increased esophageal temperature (T(es)) in passively heated human subjects (n = 6). To modify P(osm), subjects were infused with 0.9, 2, or 3% NaCl infusions (Inf) for 90 min on separate days. Infusion rates were 0.2, 0.15, and 0.125 ml.min-1.kg body wt-1 for 0.9, 2, and 3% Inf, respectively, which produced relatively similar plasma volume expansion. Thirty minutes after the end of infusion, subjects immersed their lower legs in a water bath at 42 degrees C (room temperature 28 degrees C) for 60 min after 10 min of preheating control measurements. Passive heating without infusion (NI) served as time control to account for the effect of volume expansion. P(osm) (mosmol/kgH2O) values at the onset of passive heating were 289.9 +/- 1.4, 292.1 +/- 0.6, 298.7 +/- 0.7, and 305.6 +/- 0.6 after NI, 0.9% Inf, 2% Inf, and 3% Inf, respectively. The increases in T(es) (delta T(es)) at equilibrium during passive heating (mean delta T(es) during 55-60 min) were 0.47 +/- 0.08, 0.59 +/- 0.08, 0.85 +/- 0.13, and 1.09 +/- 0.12 degrees C after NI, 0.9% Inf, 2% Inf, and 3% Inf, respectively, which indicates that T(es) at equilibrium increased linearly as P(osm) increased. delta T(es) required to elicit cutaneous vasodilation (delta T(es) threshold for cutaneous vasodilation) also increased linearly as P(osm) increased as well as the delta T(es) threshold for sweating. The calculated increases in these thresholds per unit rise in P(osm) from regression analysis were 0.044 degree C for the cutaneous vasodilation and 0.034 degree C for sweating. Thus the delta T(es) thresholds for cutaneous vasodilation and sweating are shifted to higher delta T(es) along with the increase in P(osm), and these shifts resulted in the higher increase in T(es) during passive heating.

Bioelectrical impedance analysis (BIA) is used to assess skeletal muscle mass, although its application in the elderly has not been fully established. Several BIA modalities are available: single-frequency BIA (SFBIA), multifrequency BIA (MFBIA), and bioelectrical impedance spectroscopy (BIS). The aim of this study was to examine the difference between SFBIA, MFBIA, and BIS for assessment of appendicular skeletal muscle strength in the elderly. A total of 405 elderly (74.2 ± 5.0 yr) individuals were recruited. Grip strength and isometric knee extension strength were measured. Segmental SFBIA, MFBIA, and BIS were measured for the arms and upper legs. Bioelectrical impedance indexes were calculated by squared segment length divided by impedance (L2/Z). Impedance at 5 and 50 kHz (Z5 and Z50) was used for SFBIA. Impedance of the intracellular component was calculated from MFBIA (Z250-5) and BIS (RICW). Correlation coefficients between knee extension strength and L2/Z5, L2/Z50, L2/RICW, and L2/Z250-5 of the upper legs were 0.661, 0.705, 0.790, and 0.808, respectively (P < 0.001). Correlation coefficients were significantly greater for MFBIA and BIS than SFBIA. Receiver operating characteristic curves showed that L2/Z250-5 and L2/RICW had significantly larger areas under the curve for the diagnosis of muscle weakness compared with L2/Z5 and L2/Z50. Very similar results were observed for grip strength. Our findings suggest that MFBIA and BIS are better methods than SFBIA for assessing skeletal muscle strength in the elderly.