Age-associated changes in power and maximal oxygen consumption (VO_2max) were studied in a cross section of endurance trained cyclists. Subjects (n = 56) performed incremental cycling exercise, during which capillary blood lactate [La^-] was measured. Power output increased by 30 Watts during each 5 minutes stage, with initial power output based on individual ability. When [La^-] was >4.5 mmol·L^-1, subjects were given a 10 min recovery at a power output approximately 50% below estimated power at [La^-]_4mmol. Subjects then performed an incremental test (1 minute stages) to VO_2max. Decline in VO_2max was 0.65 ml·kg^-1·min^-1·year^-1 (r = -0.72, p < 0.01) for males, and 0.39 ml·kg^-1·min^-1·year^-1 (r = -0.54, p < 0.05) for females. Power at VO_2max decreased by 0.048 W kg^-1·year^-1 (r = -0.72, p < 0.01) in males. Power at [La^-]_4mmol decreased by 0.044 W kg^-1·year^-1 (r = -0.76, p < 0.01) in males, and by 0.019 W kg^-1·year^-1 (r = -0.53, p < 0.05) in females. Heart rate at VO_2max (HR_max) showed a weaker correlation with age in males (r = -0.36, p < 0.05). The age-associated changes in maximum aerobic power and sub-maximal power were gender- specific, thus suggesting different age-related effects on the systems which support exercise in males and females.

• VO decreased with age by 0.65 ml·kg·min·year in male, and by 0.39 ml·kg·min·year in female endurance trained cyclists.

• Power at VO decreased with age by 0.048 Watts·kg·year in male endurance trained cyclists.

• Sub-maximal power at a blood lactate concentration of 4mmol·L decreased by 0.044 Watts·kg·year in male, and by 0.019 Watts·kg·year in female endurance trained cyclists.