ABSTRACT

　Purpose: This study aimed to examine the effects of electrical stimulation in hypoxia on arterial stiffness and glucose metabolism. Methods: Seven healthy male adults participated in experiments of four different protocols (i.e., rest in normoxia (NR), rest in hypoxia (HR), electrical stimulation in normoxia (NES), and electrical stimulation in hypoxia (HES)) in random order on separate days. Throughout a 40-min measurement, the subjects breathed normoxic (20.9%O₂) or hypoxic (15.3-15.5%O₂) gas via a facemask connected to the oxygen generator. Also, in NES and HES, a 20-min electrical stimulation of 4Hz was conducted in a lower limb in the latter 20-min of the measurement. Results: During electrical stimulation, heart rate and oxygen uptake in NES and HES increased, compared with each baseline. However, no significant difference was observed in the heart rate between NES and HES. Conversely, oxygen uptake during electrical stimulation was significantly lower in HES than in NES. Interestingly, CAVI, which is an index of arterial stiffness, significantly reduced, and the reduction in CAVI was significantly greater in HES than that in NES. In addition, lactate concentrations and respiratory exchange ratio were significantly higher in HES than the other three trials. Conclusion: These findings suggest that electrical stimulation in hypoxia can induce both greater reduction in arterial stiffness and increase in glucose metabolism than those in normoxia.

DESCENTE SPORTS SCIENCE Vol.38/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE