The purpose of this study was to measure the balance of oxygen delivery and oxygen consumption in the working muscle during the incremental cycling exercise. Using near infrared spectroscopy， we monitored the changes in oxygenated hemoglobin and
myoglobin [oxy(Hb+Mb)] of the vastus lateralis muscle (VL) and lateral part of the gastrocnemius muscle (LG) during the exhaustive cycle exercise. Studies were done in healthy five male and one female volunteers while gas exchange parameters were measured. During exercise of relatively low intensity (up to 20%V02max)， oxy(Hb+Mb) increased from resting value in both VL and LG. ln VL，oxy(Hb+Mb) was sustained or decreased slowly between 40 and 50% VO2max，and decreased linearly with the exercise intensity at 50 to 80%V02max. Thereafter，it was sustained up to near 100%VO2max. In LG，on the 0ther hand， oxy(Hb+Mb) remained constant near resting levels during exercise of moderate intensity(40 to 70%V02max). During exercise of higher intensity (above 70% V02max)， there was a rapid drop. These results indicated the difference in the pattern of oxy(Hb+Mb) change between VL and LG muscles during the exhaustive incremental cycle exercise
