Effects of physical activity on age-related decline in oxygen delivery to working muscles

The purpose of this study was to determine the age and habitual physical activity on re-oxygenation time in working muscles following maximal cycling exercise (CycEXmax). Twelve sedentary middle-aged (50 +/- 6), 13 sedentary elderly (66 +/- 3), 13 active middle-aged (53 +/- 5), and 20 active elderly (67 +/- 5) were evaluated the half re-oxygenation time (T1/2 reoxy) as an index of oxygen delivery, using near-infrared spectroscopy at the vastus lateralis (VL) and lateral head of the gastrocnemius (LG) after CycEXmax. T1/2 reoxys at VL and LG were significantly greater in the elderly subjects than in the middle-aged subjects in both sedentary and active groups. T1/2 reoxys at VL and LG of the active group were smaller than those of the sedentary group, regardless of age. The results of this study suggest that habitual physical activity may attenuate age-related prolongation in T1/2 reoxy in working muscles although ageing delay T1/2 reoxy in working muscles.