Age and activity status affect muscle reoxygenation time after maximal cycling exercise

Purpose: The purpose of this study was to determine the interaction of age and habitual physical activity on recovery time of muscle oxygenation following maximal cycling exercise (CycEXmax). Methods: Twelve sedentary middle-aged (50 6), 13 sedentary elderly (66 3), 13 active middle-aged (53 +/- 5), and 20 active elderly (67 5) women participated in this study. We evaluated the peak pulmonary oxygen uptake ((V) over barO(2peak)) during CycEXmax and the half-recovery time of muscle oxygenation (T1/2reoxy time) using near-infrared spectroscopy at the vastus lateralis (VL) during the recovery phase after CycEXmax. Results: T1/2reoxy time was significantly greater in the elderly subjects than in the middle-aged subjects in both sedentary (P < 0.05) and active groups (P < 0.01). T1/2reoxy time of the active group was lower (P < 0.01) than that of the sedentary group regardless of age. Age was significantly correlated to T1/2reoxy time in both sedentary and active groups (in both sedentary and active groups: P < 0.01). The slope of T1/2reoxy time against age in the sedentary group was significantly greater(VL: P < 0.05) than that of the active group. (V) over barO(2peak) showed significant inverse correlation with T1/2reoxy time at the VL in both sedentary and active groups. The slope Of (V) over barO(2peak) against T1/2reoxy time showed no significant differences between middle-aged and elderly subjects. Conclusion: The results of this study suggest that T1/2reoxy time was prolonged with aging, regardless of habitual physical activity levels. However, habitual physical activity may prevent the age-related prolongation in T1/2reoxy time after CycEXmax. (V) over barO(2peak) appears to be one of the major factors determining T1/2reoxy time, not age.