Kazuki Shirakawa

Learn More
The aim of the present study was to compare the frequency of oxygenation determined in the vastus lateralis by near-infrared spectroscopy (NIRS) in light exercise with that at rest. A subject rested in a recumbent position for 5 min and changed body position to a sitting position on a cycle ergometer for 9 min. Then exercise with low intensity (work rate of(More)
The aim of the present study was to compare the oscillations of oxygenation in skeletal muscle between early and late phases in prolonged exercise. During prolonged exercise at 60 % of peak oxygen uptake (V(.)o(2)) for 60 min and at rest, oxygenated hemoglobin/myoglobin (Hb/MbO(2)) and total Hb/Mb (THb/Mb) were determined by near-infrared spectroscopy in(More)
The purpose of the present study was to examine 1) whether O(2) uptake (VO(2)) oscillates during light exercise and 2) whether the oscillation is enhanced after impulse exercise. After resting for 1 min on a bicycle seat, subjects performed 5-min pre-exercise with 25 watts work load, 10-s impulse exercise with 200 watts work load and 15-min post exercise(More)
We investigated ventilation (V . E) control factors during recovery from light impulse-like exercise (100 watts) with a duration of 20 sec. Blood ions and gases were measured at rest and during recovery. V . E, end tidal CO 2 pressure (PETCO 2) and respiratory exchange ratio (RER) were measured continuously during rest, exercise and recovery periods.(More)
Many studies have failed to show that pre-sleep exercise has a negative effect on sleep onset. However, since only a moderate level of physiological excitement was observed at bedtime in these studies, it remains unclear whether a larger magnitude of physiologic excitement present at bedtime would disrupt sleep onset. This study compared the effects of(More)
PURPOSE We have reported that in the thyroid, there is a linear correlation between iodine concentrations and CT values. However, the slope of the regression line was about three times as large as that in KI solutions. We investigated the factor(s) contributing to the increment of the slope of the regression line in the thyroid. METHOD Solutions of NH4I(More)
The purpose of the present study was to examine how oscillation of tissue oxygen index (TOI) in non-exercising exercise is affected during high-intensity and low-intensity exercises. Three exercises were performed with exercise intensities of 30% and 70% peak oxygen uptake (Vo(2)peak) for 12 min and with exercise intensity of 70% Vo(2)peak for 30 s. TOI in(More)
It was hypothesized that an oscillation of tissue oxygen index (TOI) determined by near-infrared spectroscopy during recovery from exercise occurs due to feedback control of adenosine triphosphate and that frequency of the oscillation is affected by blood pH. In order to examine these hypotheses, we aimed 1) to determine whether there is an oscillation of(More)
We investigated ventilation (V(.)E) control factors during recovery from light impulse-like exercise (100 watts) with a duration of 20 s. Blood ions and gases were measured at rest and during recovery. V(.)E, end tidal CO(2) pressure (PETCO(2)) and respiratory exchange ratio (RER) were measured continuously during rest, exercise and recovery periods.(More)