The aim of this study was to investigate the relationship between heart rate variability (HRV) during exercise and ventilatory threshold (VT), using the MemCalc system which is superior in spectral analysis. Nine healthy male subjects with no cardiopulmonary disease performed an exercise test to exhaustion to determine VT on a bicycle ergometer. Low frequency (LF : 0.04-0.15 Hz), high frequency (HF : 0.15-0.40Hz) and LF/HF ratio power spectra were calculated by maximum entropy method (MEM) spectral analysis, using the MemCalc system. In each case, when the subject started exercise, the HF component declined rapidly during the first 30 seconds ; and compared to the resting value, it declined to approximately 5 % at VT. The possibility of using this phenomenon as a criterion for setting intensity of exercise is tinder consideration. The LF/HF ratio showed different patterns of variation among the subjects. A significant linear relationship was seen between the declining rate of the HF component and VT (r=0.93, p<0.001), suggesting a corres pondence between the heart's capability of adjusting to maintained exercise and high endurance capacity.
The purpose of this study was to analyze the body characteristics of university soccer players, especially the hip joint and pelvis where chronic injuries frequently occur among soccer players. Body characteristics of seventy male university soccer players were surveyed by an orthopedic medical check. The Micro FET value (MF) was used as the unique test for the potential stress on the pubic symphysis. MF was defined as the pressure value at which a subject claimed tenderness from compression on the pubic symphysis. Among the various tests of the orthopedic medical check, trunk extension in the prone position and external rotation of the hip joint in the standing position correlated with MF. The same tendencies were observed in soccer players with pubic symphysitis. Results indicate that these three simple tests : MF, trunk extension in the prone position and external rotation of the hip joint in the standing position, can be used as valuable indices for detecting pubic symphysitis in the early stages.
The purpose of this study was to examine how S-R compatibility affected P 300, the stimulusevaluation process and response process. The P 300 component is thought to reflect information processing of stimuli. Previous studies used visual stimuli. In this study, we measured S-R compatibility effects on EMG-RT and P 300 using electrical somatosensory stimuli. Subjects performed the oddball task (Task 1) and the four-choice stimuli response task (Task 2) . They were presented electrical stimuli through ring electrodes on the index and little fingers of both hands and instructed to respond quickly to stimuli. S-R compatibility was decided by position of the stimuli. EMG-RT and P 300 latency for compatible and incompatible conditions were analyzed. For ERP analysis, data of subjects who reacted faster to compatibility ware used. Neither P 300 latency nor amplitude differed significantly between compatibility and incompatibility in Tasks 1 and 2, but for Task 2, latency tended to be prolonged by incompatibility. Therefore, it is thought that S-R compatibility mainly has an effect on response processing. However, judging from the tendency of P 300 latency to be prolonged by incompatibility for Task 2, it was considered that there is the possibility that S-R compatibility influenced P 300 latency, even if using a somatosensory stimulus.
The purpose of this study was to evaluate the validity of two different measures of physical activity under normal living conditions. The 24-hour physical activity diary method (24 HD) and accelerometer (Lifecorder) were analyzed. Total daily energy expenditure (TDEE) and daily varia tion of energy expenditure (EE) were compared employing the two measures in conjunction with the minute-by-minute heart rate method (Flex HR) in middle-aged people with a mean age of 57.9 yr (N =17), and in young people (college students) with a mean age of 23.5 yr (N=11) . The TDEE as measured by the 24HD and Lifecorder was 2576.4±514.7kcal·d-1 and 1973.1±290.2kcal·d-1 respectively. The TDEE as measured by the Flex HR method was 2718.3±625.5kcal·d-1. The TDEE as measured by the Lifecorder method was significantly lower than that of the Flex HR method (p<0.01), The correlation coefficient (r) for the 24 HD and FlexHR measured values for TDEE (kcal/day) was 0.64 (p<0.01), and that for Lifecorder and Flex HR was 0.38. The daily variation of energy expenditure pattern measured by Lifecorder was similar to that of the Flex HR ; 24 HD measurements, on the other hand, were slightly lower than Flex HR measurements during the afternoon period. The 24 HD method was reasonably accurate in the testing. The daily variation of energy expenditure measured pattern by Lifecorder was similar to that of the Flex HR method ; but the fact that the TDEE results were underestimated suggests that the Lifecorder method has merit in the measurement of daily activity patterns. It follows from this that to improve measurement of the TDEE, it is necessary to modify the Lifecorder method of calculating the algorithm,
The purpose of this study was to clarify the interaction between environmental and genetic factors on bone. Using an ultrasound bone densitometer, the stiffness of calcaneus was measured in 52 postmenopausal Japanese women. The VDR gene polymorphism was defined by PCR-RFLP using the endonuclease BsmI. Daily walking steps as a physical activity was measured in these subjects with a pedometer for 7 days and calculated as walking steps per day. Simple regression analysis showed that stiffness was significantly correlated with age, years since menopause, weight, and walking steps. There was no significant association between BsmI VDR genotypes and stiffness. The association between VDR genotypes and stiffness was analyzed in high and low walking steps groups (HW. LW) separated by the mean walking steps in each genotype and we found that VDR genotype had the most significant effect on stiffness (p< 0.01) as indicated by using two-factors (VDR genotypes × walking steps) mixed design analysis of covariance (ANCOVA) with the age, years since menopause and weight as covariates. A significant interaction of VDR genotype with walking steps was also observed (p 0.01) . Stiffness of HW was significantly higher than that of LW in both genotypes (Bb: p<0.01, bb: p<0.05) . Our findings showed that the correlation of walking steps with stiffness by simple regression analysis varied with VDR genotypes, but that the slope in Bb did not differ significantly from that in bb and this result did not change after adjustment for age, years since menopause and weight. From now on, further investigations will be needed to clarify the interaction between VDR genotypes and environmental factors in an effect on stiffness.
The present study was aimed to survey the relation between habitual exercise and the quality of nocturnal sleep. Questionnaires on exercise behavior and sleep were given to 452 male and female university students. The questionnaires included such questions as; on their habitual exercise, the kind of exercise, duration and frequency of doing the exercise, the period of continuation, rating of perceived exertion (RPE) and subjective feeling of their exercise load for health (heavy, suitable, light) . TMIN Life Habits Inventory were conducted to ascertain the quality of sleep. The results of all the students showed that they were more likely to experience insufficient asleep period (64.6%), were not refreshed in the morning (40.0%), found unbearable daytime napping (38.5%) . The student group with habitual exercise (n=237) showed significant “more easily fall asleep” (p<0.05) and “more insufficient asleep period” (p<0.05) tendencies than the group without habitual exercise. Further, three groups divided by their subjective feeling toward their exercise load showed some significantly different quality of sleep. The students who felt that their habitual exercise was “suitable” or “light” showed better sleep, with reference to frequency of mid-sleep awakening and deepness of sleep, as compared with students who felt that their exercise was “heavy” (p<0.05) . These results indicate that suitable or light habitual exercise might facilitate better quality of sleep, while heavy exercise which strongly activate the sympathetic nervous system, pose a risk to disrupt sleep.