Biomedical subjects

A Yasukouchi

Publications and source records attributed to A Yasukouchi.

16 recordsLinked to original sources

PubMed1992

Breathing pattern and subjective responses to small inspiratory resistance during submaximal exercise.

Breathing patterns and subjective responses to small resistances were investigated in seven subjects during moderate exercise. Inspiratory resistances of 0.15 (R1), 0.25 (R2) and 0.30 (R3) kPa.l-1.s were tested against control of 0.06 kPa.l-1.s with no added resistance. Subjective responses to small inspiratory resistances were evaluated through whole experiments including periods before and after exercise, herein called SNS. Average SNS significantly increased above the R2 condition. Above the R2 condition, significant changes in the breathing components of volume, flow and timing were also observed during exercise. SNS grew as a power function of peak inspiratory pressure (P(imax)) measured during exercise within such small range of stimulation less than the R3 condition and individual differences in the relationship between SNS and P(imax) were observed. All subjects felt at least some discomfort below the resistance of R3 and two subjects felt it below around R1 condition. It was suggested that breathing pattern was selected to limit peak pressure at the R3 condition by further increasing inspiratory work for a breath and this tendency was reinforced in load-sensitive subjects with longer inspiratory time and lower peak flow rate. We concluded that breathing patterns depend mainly on peak work, especially in load-sensitive individuals, which is likely to be one of the primary determinants of a worker's tolerance to respirators.

Adult↗

PubMed1990

Changes in breathing pattern at loads near perceptual threshold at different work levels.

Five subjects were tested to determine the threshold for detection of an added resistance to inspiration in three tests, one at rest and two with exercise (mild = 50 W; moderate = 100 W) on a cycle ergometer. Changes in the breathing pattern were examined at added resistances near the perceptual threshold. Added inspiratory resistances with a 50% probability of detection were very variable at rest; they decreased significantly from rest (250 Pa.l-1.s-1) to moderate exercise (98 Pa.l-1.s-1) in four subjects. It is suggested that physical exercise may cause discomfort even when workers wearing a respirator do not have any abnormal sensation during sedentary work. Breathing patterns were compared between resistance loaded and unloaded breathing during each test. Decreases in inspiratory peak flow and acceleration of flow early in inspiration were found in resistance loaded breathing in almost all tests and a tendency for tidal volume to decrease was found during moderate exercise only. The ratios of resistance loaded to unloaded breathing for inspiratory time (ti) and total time (tt) tended to be greater in the detected than in the undetected responses at rest and during mild exercise but not during moderate exercise. This would imply that further prolongation of ti and tt in the detected responses was attributable to conscious or subconscious aspects of the resistance leading responses: however, these adjustments in breathing, which reduce frequency, would be less likely to occur as the work rate increases.

Adult↗

PubMed1990

Characteristics of pulmonary diffusing capacity for CO at rest and during exercise.

Characteristic patterns of changes in pulmonary diffusing capacity (DL) at rest and during exercise were investigated and characteristics of normal DL values concerned on sex, age, and ethnic groups were examined by viewing our studies and other reports. The relation of DL and pulmonary capillary blood volume (Vc) was represented as a logarithmic regression at rest and as a linear regression during exercise. The curve relation at rest is considered to show that the increase in Vc mainly reflects the process of transport from pulmonary capillary recruitment to pulmonary capillary dilation. The increasing rate of DL was not decreased during exercise, which seemed to be due to an increase in pulmonary blood flow accompanying exercise. The linear regression was also found between DL and oxygen intake during exercise and the slope was always constant among individuals and among subject groups. The general results concerned with sex difference in Japanese or ethnic difference between Japanese and Caucasians in both sexes could show that DL per stature was greater in males or Caucasians than in females or Japanese in young adults, however, the sex or ethnic difference disappeared in middle or old aged group. DL per alveolar volume which showed no sex or ethnic difference in young adults, was greater in middle or old aged group of females or Japanese than in that of males or Caucasians.

Adolescent↗

PubMed1989

Effect of precooling on heat tolerance of resting men in a hot environment: comparison with seasonal effect on it.

Four healthy Japanese males volunteered as subjects. They were exposed to hot environment of 50 degrees C with 50% relative humidity for 61 minutes immediately after the precooling where they rested in a 10 degrees C for 30 minutes. Their physiological data were compared with that of a previous report (Iwanaga et al., 1983), in which we studied the physiological responses of the same subjects at rest in a 50 degrees C without precooling in summer and winter. After precooling (PC), all the four subjects completed heat exposure for 61 minutes. But without precooling in summer (NC), two of the subjects stopped heat exposure before 61 minutes because of hyperthermia. Rectal temperature (TR) was lower in PC than in NC before and during heat exposure. During heat exposure, TR in PC had risen at the 30th minute, but TR in NC at 20th minute. Whereas there was no difference in heart rate (HR) during heat exposure between summer and winter, in PC HR remained lower than in NC because rising time of HR was prolonged during heat exposure.

Acclimatization↗

PubMed1989