APPLIED HUMAN SCIENCE Journal of Physiological Anthropology Oxygen Kinetics in Response to Impulse Work

There have been several studies on the kinetics of . oxygen uptake (VO2) responding to impulse work (Bakker et al., 1980; Hughson et al., 1988; Swanson, 1990; Whipp and Ward, 1991), and it has been demonstrated . that VO2 is composed of two components (phase I and phase II). With regard to these components, Hughson et al. (1988) have suggested that phase I reflects an immediate increase in pulmonary blood flow and phase II reflects . tissue VO2. However, this inference is derived only from . an analysis of VO2 kinetics and not from correspondence to the oxygen consumption in working muscles. It has recently become possible to noninvasively and continuously measure the kinetics of O2 in working muscles due to the development of near-infrared spectroscopy (NIRS) (Chance et al., 1992; Kuwamori et al., 1995; Homma et al., 1992). In this study, by comparing the change in deoxygenated hemoglobin (deoxy Hb) in the working muscle using NIRS during . impulse work with the change in VO2, we reexamined the hypothesis proposed by Hughson et al. (1988).