The body does not always achieve a steady state and is more often kept in a nonsteady state. It is important not only in terms of physiological anthropology but also in its application to rehabilitation and training to clarify whether oxygen transport or utilization is the limiting factor in oxygen uptake in the nonsteady state. Hypotheses concerning the limiting factor in oxygen uptake have their own rationales, and it is still controversial as to which is actually responsible. The limiting factor in oxygen uptake may vary according to exercise conditions. Under certain conditions, oxygen transport would be responsible for limiting the oxygen uptake, and under others, oxygen utilization or both oxygen transport and utilization would be responsible. These conditions differ according to the type of exercise (e.g. step exercise vs. cycling, 1eg vs. arm exercise, and dynamic vs. static exercise), posture, recruited muscle fibers, and other experimental conditions. Considering that oxygen uptake is regulated by coupling among respiration, circulation, and metabolism, it may be possible that interactions among these functions vary in a complicated manner according to exercise conditions, which may require a different limiting factor in regulating oxygen uptake.
The purpose of this study was to determine differences in body size, composition and structure between three somatotypes of Japanese college-aged women. The study sample consisted of 30 sedentary female college students between 18 and 20 years of age. Ten subjects had an endomorphic ectomorph somatotype (mean weight 41.95 kg), 10 had an endomorph-ectomorph somatotype (mean weight 47.12 kg) and the remaining subjects had a mesomorphic endomorph somatotype (mean weight 55.37 kg). The mean heights for these groups did not differ significantly. The mesomorphic endomorph group had a higher gross weight and a higher percentage of all adipose variables than the other two groups, though these measurements were not significantly different between the endomorph-ectomorph and the endomorphic ectomorph groups. The mean lean body weight (LBW) for the mesomorphic endomorph group was significantly larger than that of the other two groups. The endomorph-ectomorph group had the next largest LBW, and the mean for the endomorphic ectomorph group was significantly smaller than that of the other two groups. Inversely, mean values of LBW/weight(WT), LBW/total adipose tissue weight (TATW) ratio and total body water/WT were significantly lower for the mesomorphic endomorph group than for the other two groups. Furthermore, the ratios of internal adipose tissue to weight (IATW)/WT and subcutaneous adipose tissue to IATW (SATW)/IATW did not differ significantly between groups. In conclusion, college-aged women of different somatotypes within the same age and height range varied in body composition. Consequently, the notion of a small frame is incorrect. An accurate assessment of the human body's composition may provide a valuable insight into the ideal weight for optimal physiologic function.
This study investigated the association between peak oxygen uptake (peak Vo2) during arm cranking exercise and respiratory function in paraplegics. Fourteen male paraplegics were recruited for the present study. The subjects were grouped according to the level of injury into the HL (Th3-Th8) and LL (Th11-L3) group. Prior to the maximal test, pulmonary function, including vital capacity (VC) and residual volume (RV), was measured in the sitting position. Mean peak Vo2 in the LL group (1662 ml·min-1) was significantly greater than that in the HL group (1357 ml·min-1), corresponding to 82% of that in the LL group (P≤0.05). In respiratory function, the HL group showed marked restrictive impairment of ventilatory function. That is, VC and RV were significantly lower in the HL group than in the LL group (P≤0.05). The reduction in VC and RV is related to the degree of loss of control in respiratory functioning muscle mass. However, there was no clear-cut correlation between respiratory function and peak Vo2 expressed as a function of body mass (ml·kg-1·min-l). In addition, a multiple linear regression analysis revealed that RV and VC were not associated with peak Vo2 (ml·min-1) in contrast to the importance of body mass. It seems reasonable to conclude from these results that respiratory function is not an important factor in determining peak Vo2 in the paraplegic.
The effects of the thermal conditions of the dressing room and bathroom on the physiological responses during bathing were assessed. Six female students participated in this experiment. Three climate chambers were used as a living room, a dressing room and a bathroom. The living room was thermoneutral and maintained at 25°C, while the thermal conditions of the dressing room and bathroom were as follows: (A) cold (10°C), (B) cool (17.5°C) or (C) thermoneutral (25°C). The subjects wore standard clothing (0.65 clo). Heart rate (HR), blood pressure, rectal (Tre) and skin temperature, and subjective thermal sensation were recorded. 1) Marked increases in systolic blood pressure (SBP) after undressing and redressing in the dressing room and during washing were observed under the cold conditions. 2) A significant negative correlation was found between the dressing room temperature and increased SBP compared to before bathing (r=-0.684, p<0.01, n=18). 3) After exposure, mean skin temperature (Tsk) showed marked differences among the three conditions despite the rest taken under the same thermal conditions. 4) A significant negative correlation was found between Tsk and the increase in SBP of after undressing relative to that before bathing (r=-0.695 p<0.01, n=18). These findings suggested that 25°C was the most appropriate temperature for the bathroom and dressing room, since the increase in blood pressure was minimum and subjective thermal sensation was neutral (neither cool nor warm) to warm under this thermal condition, and 17.5°C at which the increase in blood pressure was within the physiological fluctuation range (±10 mmHg) is the minimum tolerable temperature.
A surface array electrode was used to investigate muscle fiber conduction velocity (MFCV) and EMG power spectrum during voluntary isometric contraction of m. biceps brachii. The mean power frequency (MPF) and the total power (TP) at various locations of the muscle were obtained from the power spectrum. MFCVs at various locations of the muscle were measured directly using the averaging method. The values of MPF, TP and MFCV were identified with respect to the electrode locations on the m. biceps brachii. MPF was shown as high near the end-plate and low near the tendon of the muscle during contraction of 40% of isometric maximum voluntary contraction (MVC). TP showed low value near the end-plate and the tendon of the muscle fiber and different values at different location setting electrode during voluntary isometric contraction. TP at each location on the muscle surface increased when the contraction levels increased in the contractions range of 20 to 60 % MVC. MFCVs showed a high value near the end-plate and the tendon of the muscle during the contraction of 40% MVC. These results indicated that MPF, TP and MFCV at different locations on the muscle were different along the length of the muscle fiber.
Thermophysiological responses and clothing microclimate under the influences of different underwear materials were compared during walking and recovery in the cold. Two kinds of underwear were used: two layers of cotton underwear with two-piece long-sleeved shirt and long-legged trousers (C), two layers of polypropylene underwear with two-piece long-sleeved shirt and long-legged trousers (P). In addition, the subject put on a two-piece ski suit of 100% polyester including 100% polyester padding. Seven adult females served as subjects in this study. The test was done in a climatic chamber at an ambient air temperature of 2°C, a relative humidity of 65% and an air velocity of 0.14 m·s-1. The subject walked on a motor-driven treadmill with a 6 km/h speed for 30 min followed by 60 min recovery. Rectal temperature, skin temperatures, clothing microclimate (temperature, humidity), metabolic heat production and heart rate were measured. Furthermore, subjective ratings on thermal sensation, sweating/shivering sensation, clothing wettedness sensation and skin wettedness sensation for whole body were asked. The major findings are summarized as follows: 1) Mean skin temperature was not significantly different during walking, but it was significantly higher in P than in C during the recovery. 2) The absolute humidity of innermost layer and outermost layer were not significantly different during walking, but it was significantly higher in P than in C during the recovery. 3) Clothing microclimate temperature of innermost was not significantly different during the first half of walking, but it was significantly higher in C than in P during the second half of walking and significantly lower in C than in P during the recovery. Clothing microclimate temperature of outermost was not significantly different during walking, but it was significantly higher in P than in C during the recovery. 4) Metabolic heat production for the last 10 min during recovery tended to be higher in P. 5) The degree of skin wettedness sensation and clothing wettedness sensation for whole body was significantly higher in P during walking and recovery. Thus, it was concluded that two kinds of underwear with different properties to moisture could influence, not only clothing microclimate, but also physiological parameters like skin temperatures and metabolic heat production in the cold differently.
Surface electromyogram (EMG) was recorded in m. biceps brachii during the contractions of 20, 40 and 60% of maximum voluntary isometric contraction (MVC) in twelve healthy male subjects, using surface array electrodes. The distribution of muscle fiber conduction velocity (MFCV) was found directly using the averaging technique and the cross-correlation function technique. MFCVs in the region of 20-45 mm measured from end-plate denoted constant value of about 4 m/s in 20% MVC, while MFCVs in the region around end-plate and tendons showed about 10 m/s in 20% MVC. The values of MFCV depended on the contraction levels of muscle. The model for the generation of MFCV which considered the ensemble of muscle fibers with the shape of a cone was proposed. The theoretical values of MFCV by the muscle fiber ensemble model (MFE model) proposed in the paper showed in good agreement with the experimental results.
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