2013 年 16 巻 1 号 p. 58-
Purpose: The purpose of the present study was to examine the effects of smoking on muscle oxygenation during localized muscular exercise. Methods: The subjects included 9 young smokers and 9 nonsmokers. Near-infrared spectroscopy (NIRS) was used to assess muscle oxygenation in the right vastus lateralis muscle during 30 repeated maximal isokinetic knee extensions at high angular velocity (300 degrees per sec) and 5 repeated extensions at low angular velocity (60 degrees per sec). Results: During the high angular velocity extensions, the time course of the NIRS parameters were not significantly different between two groups. In contrast, during the low angular velocity extensions, time-related changes in Oxy-Hb･Mb and Total-Hb･Mb were significantly different in the two groups. We also showed that Oxy-Hb･Mb was significantly lower in smokers than in nonsmokers during the latter period of the exercise. Conclusion: These results indicate that the ability to deliver oxygen to active muscles to satisfy oxygen demand in young smokers is limited compared to nonsmokers during isokinetic knee extension at higher torque and low angular velocity.