Mitsuharu Kaya

Role of xanthine oxidase in delayed lipid peroxidation in rat liver induced by acute exhausting exercise

Abstract The aim of this study was to examine whether xanthine oxidase (XOD)-derived hepatic oxidative damage occurs in the main not during but following strenuous exercise. The degree of damage to hepatic tissue catalyzed by XOD was investigated immediately and 3 h after a single bout of exhausting exercise, in allopurinol and saline injected female Wistar rats. Allopurinol treatment resulted in increased hypoxanthine and decreased uric acid contents in the liver compared with the saline treated group, immediately and 3 h after the exercise. Analysis immediately after the exercise showed no changes in hepatic hypoxanthine, uric acid, and thiobarbituric acid-reactive substance (TBARS) contents in the saline treated group, when compared with the resting controls. However, significant increases in uric acid contents in the saline treated livers were observed 3 h after the exercise, relative to the controls. Hepatic TBARS content in the saline treated group were markedly greater than those in both the control and allopurinol treated groups after 3 h of recovery following the exercise. It was concluded that a single bout of exhausting exercise may impose XOD-derived hepatic oxidative damage, primarily during the recovery phase after acute severe exercise.

Differences between the physiologic and psychologic effects of aromatherapy body treatment.

BACKGROUND The wide use of herbal plants and essential oils for the prevention and treatment of diseases dates back to ancient times. However, the scientific basis for the beneficial effects of such plants and oils has not been precisely clarified. OBJECTIVE The purpose of this study was to evaluate the effects of aromatherapy body treatment on healthy subjects. DESIGN We compared the physiologic and psychologic effects of aromatherapy body treatment (E), massage treatment with carrier oil alone (C), and rest in healthy adults. SUBJECTS Seven (7) female and 6 male volunteers participated as subjects. INTERVENTIONS Each subject underwent 3 trials, in which the Advanced Trail Making Test (ATMT) was given as a stress-inducing task before and after 1 of 3 treatments. OUTCOME MEASURES The State Anxiety Inventory (SAI), the Visual Analog Scale, and the Face Scale were used to assess anxiety, feelings, and mood, respectively. RESULTS After the treatments, the SAI score and the feelings of fatigue were decreased, the positive and comfortable feelings were increased, and mood improved significantly in C and E. Furthermore, significant declines in the feelings of mental and total fatigue were maintained even after the second ATMT in E. On the other hand, the cortisol concentration in the saliva did not show significant changes in any of the trials. Secretory immunoglobulin A levels in the saliva increased significantly after all treatments. CONCLUSIONS We conclude that massage treatments, irrespective of the presence of essential oils, are more advantageous than rest in terms of psychologic or subjective evaluations but not in terms of physiologic or objective evaluations. Furthermore, as compared to massage alone, the aromatherapy body treatment provides a stronger and continuous relief from fatigue, especially fatigue of mental origin.

Effects of decreased plasma glutamine concentrations on peripheral lymphocyte proliferation in rats

Abstract The relationship between exercise-induced lowering of plasma glutamine concentrations and proliferation of peripheral lymphocytes was investigated in male Wistar rats. The T-lymphocyte proliferative responses to the mitogen, concanavalin A, were determined by incorporation of radiolabelled thymidine into the DNA in vitro. The rats ran 2 h · day−1, 6 days · week−1 for 4 weeks. Analysis immediately after the final period of exercise showed T-lymphocyte proliferation to be significantly depressed, together with a marked decrease in plasma glutamine concentrations. There were also significant increases in serum corticosterone concentrations immediately after exercise. However, following 24-h recovery, this exercise-induced immunosuppression was not statistically significant when compared with the age-matched control group. In the second experiment, in order to clarify the importance of glutamine for immunological function in vivo, methionine sulfoximine, an effective inhibitor of glutamine synthetase was injected intraperitoneally (12.5 mg · kg body mass−1). Plasma glutamine concentrations were decreased 4 h after the injection, compared with the placebo control group, and this resulted in a significant decrease in the rate of T-lymphocyte proliferation. This treatment had no effects on serum corticosterone concentrations. These results would suggest that the chronic exercise-induced reduction in proliferation of peripheral T-lymphocytes is a transient reversible phenomenon, which returns to normal levels within 24 h of the final training period. It is also conceivable that this exercise-induced immunosuppression is associated with a decrease in circulating glutamine concentrations.

Decreased energy expenditure during prolonged sub-maximal exercise in a warm environment

Abstract The purpose of this study was to investigate the influence of a warm environment on thermoregulation and energy expenditure during sub-maximal prolonged exercise in humans. Six healthy male subjects cycled for 120 min at an intensity of 60% maximal oxygen uptake (Vo2max) at three environmental temperatures (10°C, CT; 20°C, MT; and 30°C, WT). Although oxygen uptake at WT showed a significantly lower value compared to those at MT and CT, no significant differences of respiratory exchange ratio were observed among the three environmental trials. A remarkable decrease in total energy expenditure during the 120-min exercise at WT was observed in comparison with those at MT and CT (p<0.05). Changes in rectal temperature, mean skin temperature, and mean body temperature at WT were significantly higher than those at both MT and CT. Although increases in mean body temperature from rest every five minutes during exercise were not different among three environmental temperatures, mean energy expenditures every five minutes at WT were lower compared with those at MT and CT (p<0.05). These results suggest that the increase in energy expenditure for physical exertion is substantially reduced during prolonged sub-maximal exercise in a warm environment. This acute alteration in the energy metabolism may contribute to inhibition of excess heat production and enable prolonged exercise in a warm environment.

Zucker obese rats are sensitive to weight-reducing effect and insensitive to orexigenic effect by cold exposure

Abstract Male Wistar and Zucker (lean and obese) rats at 7 weeks of age were divided into three groups: warm-acclimated (25°C for 11 weeks), cold-acclimated (10°C for 11 weeks), and deacclimated (10°C for 9 weeks and 25°C for 2 weeks) groups. The rate of increase in body mass (BM) was lower in obese rats as compared to lean rats. Cold-acclimated Wistar and Zucker lean rats exhibited greater food intake, compared to warm-acclimated rats. Food intake did not increase in obese rats exposed to cold. Obese rats are sensitive to weight-reducing effect and insensitive to the orexigenic effect by cold exposure.

Adaptive changes in brown adipose tissue in Wistar rats, Zucker lean and obese rats

Abstract (1) Male Wistar, and Zucker (lean and obese) rats aged 7 weeks of age were divided into three groups; warm acclimated (25°C for 11 weeks), cold acclimated (10°C for 11 weeks), and deacclimated (10°C for 9 weeks and 25°C for 2 weeks) groups. (2) Density of lipid droplet in brown adipose tissue (BAT) of obese rats was the greatest and that in lean rats was less than that in Wistar rats. (3) Mass of brown adipose tissues (BATM) per body mass (BM) was greater in obese rats than lean rats. (4) Marked weight-reducing effect observed in obese rats during cold acclimation is partly resulted from greater BATM/BM.

Comparison of tympanic membrane temperatures measured by contact and noncontact tympanic thermometers during prolonged exercise in the heat

Abstract We examined the agreement between the tympanic membrane temperature (Tty) measured by a contact tympanic thermometer (Contact-Tty) and the Tty measured by a noncontact tympanic thermometer (Infrared-Tty). In addition, we also evaluated the usefulness of an assessment of core body temperature using a noncontact tympanic thermometer during prolonged exercise in the heat. Seven healthy male subjects cycled for the same four experimental trials at 50% peak oxygen uptake for 90 min in the heat (32°C ambient temperature, 50% relative humidity and 26.6°C wet bulb globe temeprature). The correlation coefficient between both temperatures was strong, 0.89 ( p

Diurnal effects of prior heat stress exposure on sprint and endurance exercise capacity in the heat

ABSTRACT Active individuals often perform exercises in the heat following heat stress exposure (HSE) regardless of the time-of-day and its variation in body temperature. However, there is no information concerning the diurnal effects of a rise in body temperature after HSE on subsequent exercise performance in a hot environnment. This study therefore investigated the diurnal effects of prior HSE on both sprint and endurance exercise capacity in the heat. Eight male volunteers completed four trials which included sprint and endurance cycling tests at 30 °C and 50% relative humidity. At first, volunteers completed a 30-min pre-exercise routine (30-PR): a seated rest in a temperate environment in AM (AmR) or PM (PmR) (Rest trials); and a warm water immersion at 40 °C to induce a 1 °C increase in core temperature in AM (AmW) or PM (PmW) (HSE trials). Volunteers subsequently commenced exercise at 0800 h in AmR/AmW and at 1700 h in PmR/PmW. The sprint test determined a 10-sec maximal sprint power at 5 kp. Then, the endurance test was conducted to measure time to exhaustion at 60% peak oxygen uptake. Maximal sprint power was similar between trials (p = 0.787). Time to exhaustion in AmW (mean±SD; 15 ± 8 min) was less than AmR (38 ± 16 min; p < 0.01) and PmR (43 ± 24 min; p < 0.01) but similar with PmW (24 ± 9 min). Core temperature was higher from post 30-PR to 6 min into the endurance test in AmW and PmW than AmR and PmR (p < 0.05) and at post 30-PR and the start of the endurance test in PmR than AmR (p < 0.05). The rate of rise in core temperature during the endurance test was greater in AmR than AmW and PmW (p < 0.05). Mean skin temperature was higher from post 30-PR to 6 min into the endurance test in HSE trials than Rest trials (p < 0.05). Mean body temperature was higher from post 30-PR to 6 min into the endurance test in AmW and PmW than AmR and PmR (p < 0.05) and the start to 6 min into the endurance test in PmR than AmR (p < 0.05). Convective, radiant, dry and evaporative heat losses were greater on HSE trials than on Rest trials (p < 0.001). Heart rate and cutaneous vascular conductance were higher at post 30-PR in HSE trials than Rest trials (p < 0.05). Thermal sensation was higher from post 30-PR to the start of the endurance test in AmW and PmW than AmR and PmR (p < 0.05). Perceived exertion from the start to 6 min into the endurance test was higher in HSE trials than Rest trials (p < 0.05). This study demonstrates that an approximately 1 °C increase in core temperature by prior HSE has the diurnal effects on endurance exercise capacity but not on sprint exercise capacity in the heat. Moreover, prior HSE reduces endurance exercise capacity in AM, but not in PM. This reduction is associated with a large difference in pre-exercise core temperature between AM trials which is caused by a relatively lower body temperature in the morning due to the time-of-day variation and contributes to lengthening the attainment of high core temperature during exercise in AmR.

Air velocity influences thermoregulation and endurance exercise capacity in the heat

This study examined the effects of variations in air velocity on time to exhaustion and thermoregulatory and perceptual responses to exercise in a hot environment. Eight male volunteers completed stationary cycle exercise trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30 °C and 50% relative humidity. Four air velocity conditions, 30, 20, 10, and 0 km/h, were tested, and the headwind was directed at the frontal aspect of the subject by 2 industrial fans, with blade diameters of 1 m and 0.5 m, set in series and positioned 3 m from the subjects chest. Mean ± SD time to exhaustion was 90 ± 17, 73 ± 16, 58 ± 13, and 41 ± 10 min in 30-, 20-, 10-, and 0-km/h trials, respectively, and was different between all trials (P < 0.05). There were progressive elevations in the rate of core temperature rise, mean skin temperature, and perceived thermal sensation as airflow decreases (P < 0.05). Core temperature, heart rate, cutaneous vascular conductance, and perceived exertion were higher and evaporative heat loss was lower without airflow than at any given airflow (P < 0.05). Dry heat loss and plasma volume were similar between trials (P > 0.05). The present study demonstrated a progressive reduction in time to exhaustion as air velocity decreases. This response is associated with a faster rate of core temperature rise and a higher skin temperature and perceived thermal stress with decreasing airflow. Moreover, airflow greater than 10 km/h (2.8 m/s) might contribute to enhancing endurance exercise capacity and reducing thermoregulatory, cardiovascular, and perceptual strain during exercise in a hot environment.

Influence of passive hyperthermia and diurnal variation on exercise performance and cognitive function in the heat

Both aerobic and anaerobic exercise performances have a diurnal variation. As commonly reported in previous studies, circadian rhythm in exercise performance is low in the morning and peaks in the evening. It has been demonstrated that hyperthermia before exercise attenuates subsequent exercise performance in the heat. However, combined effects of passive hyperthermia and the time-of-day on both aerobic and anaerobic exercise capacity and cognitive function in the heat have not been evaluated. Therefore, the aim of this study was to examine the effects of passive hyperthermia and circadian rhythm on aerobic and anaerobic exercise performances and cognitive function after exercise in the heat.