EFFECTS OF WEIGHT RELEASE ON CARDIOPULMONARY FUNCTIONS DURING TREADMILL WALKING / 体力科学

There are various methods for gait exercise in rehabilitation medicine. These methods are useful for patients to control weight bearing and gait pattern. But they have good points and bad points. The purpose of this study was to determine the effects of weight release on cardiopulmonary function during walking, and to examine the potential of this weight-release method in rehabilitation medicine. Subjects were 15 males who had no cardiopulmonary disease or past illness. They wore a respiratory mask connected with metabolic analyzers and a lifting jacket, and they performed three walking tasks on a treadmill at 4.8 km/hour speed for five minutes. During walking, they were lifted up for the weight release employing 3 different traction forces, by a lifting system (Pneu-Weight, Pneumex, Inc.). The three conditions for traction were adjusted for their body weight percentage : 0% (full weight bearing ; FWB), 25% and 50% body-weight release. Each trial was measured with a metabolic analyzing system and electromyography. There were no significant differences among the three conditions in respiratory parameters such as oxygen uptake and minute ventilation. However, systolic blood pressure significantly decreased in the FWB condition. There were various sorts of changes in the integral electromyogram. For example, gastrocnemius increased and decreased, bicepsbrachii increased without weight-releasing, and increased more with weight-release. During exercise, oxygen uptake corresponded to the amount of muscle activity, and ventilation and heart rate were increased by oxygen requirement increases. These results indicate that weight-release saved muscle activity, and gait patterns were changed to less thrust force. The amount of total muscle activity as a postural adjustment and thrust was unchanged in this gait, but muscles used were altered. In rehabilitation medicine, we should give much thought to these changes. This weight-release walking method is useful, because the load can be adjusted according to the breathing circulation constant.

Effects of drinking on sweating and body cooling during exercise / 体力科学

To examine the effects of water replacement on sweating and body cooling during exercise, We studied the sweat rate, changes in body weight and body temperature during exercise with or with-out drinking various amounts of water. The subjects had been dehydrated or normally hydrated prior to exercise.<BR>1. Rectal temperature increased significantly with body weight loss.<BR>2. Sweat rate during exercise was constant (968-996 g/h) regardless of whether the subjects were dehydrated or hydrated.<BR>3. Body weight loss was negatively correlated with the amount of water intake, but was not correlated with the total amount of sweating.<BR>4. Total heat loss increased with increased water intake, and corresponded to 1345% of heat storage during exercise without drinking.<BR>These results suggest that although water replacement during exercise dose not affect the sweat rate, it has physiological significance in the maintenance of body fluid, and a physical effect in terms of body cooling.

A survey of ambient temperature, drinking, sweating and body temperature / 体力科学

In order to get basic data for preventing heat stroke accident during exercise in a hot environment, we analysed the relation between environmental temperature, and drinking and sweating. We also analyed the effect of water intake on body temperature regulation during exercise.<BR>The environmental temperature started to rise in April, reached the maximumin August, and then decreased. Water intake and sweating increased significantly with increase in WBGT, but there was no correlation between weight loss and WBGT. The rise in body temperature during exercise (0.52±0.080°C) was constant and independent of WBGT. The rise in oral temperature during exercise was affected by the water intake and it was significantly higher when water was not supplied than that with water supply (p<0.001) . Sweat rate was significantly greater when water was supplied than when it was not supplied (p<0.01) .<BR>The above results suggest that the amount of water intake increased with the increase in WBGT, which guarantees the increase in sweating and as a result maintenance of constant oral temperature.<BR>Therefore it is suggested that it is better to supply water during exercise to facilitate evaporative heat loss, which prevent rise in oral temperature.

Influence of warm-up on thermoregulatory responses during exercise / 体力科学

To examine the influence of warm-up on thermoregulatory responses during exercise, heat balance was measured in 5 healthy male students during lhr of exercise at 600 kpm/min work intensity in a climatic room of WBGT (Wet-Bulb Globe Temperature) at 30°C with or without pre-exercise warm-up at the minimum phase (6: 00-7: 00) of body temperature.<BR>There was no significant difference in heat production between exercise with and without warm-up. Evaporative heat loss during exercise with warm-up was 4-8% higher than that without warm-up.<BR>Warm-up did not influence dry heat loss. Body heat storage during exercise without warm-up was 36% higher than that with warm-up.<BR>The slope of the characteristic curve between the sweating response and elevation of rectal temperature during exercise with warm-up was higher than that without warm-up. These results indicate that the increased evaporative heat loss resulting from warm-up is brought about by changes in the sensitivity of the thermoregulatory response.

Circadian variation of thermoregulatory responses during rest in water / 体力科学

To observe possible influences of the biological clock on thermoregulatory responses, heat balance was measured 6 healthy students wearing only trunks during 30 min of immersion in water at a temperature of 21°C in both the rising phase (11: 00-13: 00) and the falling phase (23: 00-1: 00) of body temperature.<BR>Heat production was higher in the rising phase than in the falling phase. Duration of shivering was longer in the rising phase than in the falling phase. Dry heat loss was nearly constant, 163 to 166 W/m<SUP>2</SUP> in both phases. Body heat storage was negative in both phases, but higher in the falling phase than in the rising phase.<BR>The mean body temperature, however, changed to a similar extent in the rising phase and in the falling phase when the circadian temperature variation was balanced.<BR>Analysis of these results implies that the increased shivering in the rising phase is brought about by changes in the sensitivity of the thermoregulatory response.

CIRCADIAN VARIATION OF THERMOREGULATORY RESPONSES DURING EXERCISE IN MALE / 体力科学

Heat balance during 1hr exercise at 450 kpm/min was measured on 5 healthy male students wearing only shorts in a climatic chamber of 13°C and r.h. 60% at the minimum phase (5 : 00-7 : 00), the rising phase (11 : 00-13 : 00), the maximum phase (17 : 00-19 : 00) and the falling phase (23 : 00-1 : 00) of body temperature.<BR>Heat production was nearly constant, 194 to 209w/m2 at all phase both in summer and winter. Evaporative heat loss was lowest at the minimum phase and highest at the maximum phase. In all phases, evaporative heat loss was 14-29% higher in summer than in winter. Dry heat loss was not significantly different summer and winter. Body heat storage was high at the minimum phase, low at the maximum phase and higher in winter than in summer. The threshold rectal temperature for the onset of sweating was lower at the maximum phase than at the minimum phase by 0.65°C in winter and by 0.70°C in summer.

THERMOREGULATION DURING EXERCISE IN HIGH HUMIDITY ENVIRONMENTS / 体力科学

Thermoregulatory responses during one hour pedalling on bicycle ergometer were measured in a climatic chamber of 26°C at various humidity levels. Work intensities were 30, 40, 50, 60 and 70% of Vo<SUB>2</SUB>max. Relative humidities were 30, 60 and 90%.<BR>1) Oxygen intake remained nearly constant at the same work load and was not influenced by humidity level.<BR>2) At work intensities of more than 60% of Vo<SUB>2</SUB>max the elevation of rectal temperature was augmented by increased humidity.<BR>3) The secretion of sweat increased, but the evaporation of sweat decreased with increased humidity, particularly at work intensities of 60% and 70% of Vo<SUB>2</SUB>max.