Takashi Komura

Wearing a cooling jacket during exercise reduces thermal strain and improves endurance exercise performance in a warm environment.

The aim of the present study was to investigate the effect of wearing a cooling jacket on thermoregulatory responses and endurance exercise performance in a warm environment. Nine untrained male subjects cycled for 60 minutes at 60% VO2max (Ex1) and then immediately exercised to exhaustion at 80% VO2max (Ex2) in 32.0 ± 0.28C and 70–80% relative humidity. Four separate conditions were set during exercise: no water intake (NW), water intake (W), wearing a cooling jacket (C) and the combination of C and W (C1W). Rectal temperatures (Tre) before Ex1 were not different between the 4 conditions, whereas at the end of Ex1 Tre of C1W was significantly lower than the C and W (p < 0.05). Mean skin temperature (Tsk) was significantly lower in C and C1W than the NW and W during Ex1. Heart rate of C and C1W were significantly lower than the NW and W, and rating of perceived exertion (RPE) in C1W was lower than in the other conditions. Exercise time to exhaustion was significantly longer in C1W than in the other conditions (NW < W, C < C1W; p < 0.05), whereas Tre at exhaustion was not different. Our results indicate that the combination of wearing a cooling jacket and water intake enhances exercise endurance performance in a warm environment because of a widened temperature margin before the critical limiting temperature is reached and also because of decreased thermoregulatory and cardiovascular strain.

Combined effects of pre-cooling and water ingestion on thermoregulation and physical capacity during exercise in a hot environment

Abstract The aim of the present study was to determine the combined effects of pre-cooling and water ingestion on thermoregulatory responses and exercise capacity at 32°C and 80% relative humidity. Nine untrained males exercised for 60 min on a cycle ergometer at 60% maximal oxygen uptake ([Vdot]O2max) (first exercise bout) under four separate conditions: No Water intake, Pre-cooling, Water ingestion, and a combination of pre-cooling and water ingestion (Combined). To evaluate the efficacy of these conditions on exercise capacity, the participants exercised to exhaustion at 80% [Vdot]O2max (second exercise bout) following the first exercise bout. Rectal and mean skin temperatures before the first exercise bout in the Pre-cooling and Combined conditions were significantly lower than in the No Water and Water conditions. At the end of the first exercise bout, rectal temperature was lower in the Combined condition (38.5 ± 0.1°C) than in the other conditions (No Water: 39.1 ± 0.1°C; Pre-cooling: 38.7 ± 0.1°C; Water: 38.8 ± 0.1°C) (P < 0.05). Heat storage was higher following pre-cooling than when there was no pre-cooling (P < 0.05). The final rectal temperature in the second exercise bout was similar between the four conditions (39.1 ± 0.1°C). However, exercise time to exhaustion was longer (P < 0.05) in the Combined condition than in the other conditions. Total sweat loss was less following pre-cooling than when there was no pre-cooling (P < 0.001). Evaporative sweat loss in the Water and Combined conditions was greater (P < 0.01) than in the No Water and Pre-cooling conditions. Our results suggest that the combination of pre-cooling and water ingestion increases exercise endurance in a hot environment through enhanced heat storage and decreased thermoregulatory and cardiovascular strain.

Relationship between physical characteristics and physiological responses during maximal arm cranking in paraplegics.

The purpose of this study was to elucidate the main physical factor(s) affecting cardiorespiratory responses during maximal arm cranking exercise in patients with paraplegia. Peak oxygen uptake (peak VO2), peak pulmonary ventilation (peak VE) and peak heart rate (peak HR) were measured during maximal arm cranking exercise in 28 Japanese male patients. A cluster analysis was applied to the data for peak VO2, peak HR and peak VE, and then the subjects were classified into four groups (A, B, C and D). Group A showed high peak VE and peak HR and low peak VO2, Group B low peak VO2 and high values for other parameters, Group C the greatest physiological values for all measurements among the groups and, in contrast, Group D showed low peak VO2 and the lowest peak VE and peak HR among the groups. The subjects in Group C had low level of spinal cord injury and were sports participants. On the other hand, duration since injury was not related to the cardiorespiratory responses during maximal arm cranking. These findings indicate that the effects on these responses of years since injury are subordinate to those of the level of spinal cord injury and training.

Exercise-Induced Temperature Changes in the Tympanic Membrane and Skin of Patients with Spinal Cord Injury

The kinetics of thermoregulation mechanisms were observed in patients with spinal cord injury (SCI) during exercise. Five patients with paraplegia (T4–T12/L1) due to spinal cord injury underwent arm cranking exercise after 60min of rest in the sitting position. The exercises were conducted with incremental increases (5 watts/min) in external workload starting at 0 watts (50rpm). They were performed in a climato-therapeutic chamber at 25°C and a relative humidity between 50%–60%. The patients were worked to exhaustion. Tympanic membrane (Tty) and the skin (Tsk; head, arms, chest, thigh, and shin) temperatures were measured at rest and during exercise. Results of the measurements showed that Tty in the SCI group was lower both at rest (36.15°–36.65°C) and during exercise (36.15°–36.70°C) than in the healthy control group. Tsk were also lower at all measured sites. The differences in the temperatures were especially marked at sites where dermal sensation was impaired such as the thighs and shins. It is concluded that the lower temperatures were due to disturbances in the input of thermal information to the thermoregulatory nucleus as well as the generation and modification of output command signals and responses with regard to the regulation of temperature which were caused by the spinal cord injury.

Development of Pressure Sores in Active and Inactive Persons with Spinal Cord Injury

To investigate the benefits of sports participation on the prevention of pressure sores, a questionnaire was mailed to 668 men and women with spinal cord injury. The questionnaire was designed to clarify the effects of physical activity and lifestyle on the development of pressure sores. Usable questionnaires were received from 466 persons, representing a response rate of 70%. Thirty-eight percent were quadriplegic and 62% paraplegic, with incomplete injuries accounting for 26% of the combined group. About half of the 466 subjects reported the development of pressure sores during their wheelchair life. There was a clear tendency for the subjects with severe and frequent spasms of their legs to have no pressure sores. Forty percent of the subjects (active subjects) participated in sports regularly, including basketball, tennis, table tennis, swimming, and road racing. When the development of pressure sores for the 5 years before sports participation was compared with the 5-year period after commencement of sports participation, no significant difference was noted. Thus, whether sports participation has a positive benefit in the prevention of pressure sores in paraplegics and quadriplegics could not be determined from the present study.