Lower physical activity levels in old age are thought to contribute to the age‐related decline in peak aerobic and anaerobic power. Master athletes maintain high levels of physical activity with advancing age and endurance or power training may influence the extent to which these physical functions decline with advancing age. To investigate, 37‐90‐year‐old power (n = 20, 45% female) and endurance (n = 19, 58% female) master athletes were recruited. Maximal aerobic power was assessed when cycling two‐legged (VO2Peak2‐leg) and cycling one‐legged (VO2Peak1‐leg), while peak jumping (anaerobic) power was assessed by a countermovement jump. Men and women had a similar VO2Peak2‐leg (mL/kg/min, P = 0.138) and similar ratio of VO2Peak1‐leg to VO2Peak2‐leg (P = 0.959) and similar ratio of peak aerobic to anaerobic power (P = 0.261). The VO2Peak2‐leg (mL/kg/min) was 17% (P = 0.022) and the peak rate of fat oxidation (FATmax) during steady‐state cycling was 45% higher in endurance than power athletes (P = 0.001). The anaerobic power was 33% higher in power than endurance athletes (P = 0.022). The VO2Peak1‐leg:VO2Peak2‐leg ratio did not differ significantly between disciplines, but the aerobic to anaerobic power ratio was 40% higher in endurance than power athletes (P = 0.002). Anaerobic power, VO2Peak2‐leg, VO2Peak1‐leg, and power at FATmax decreased by around 7%‐14% per decade in male and female power and endurance athletes. The cross‐sectional data from 37‐90‐year‐old master athletes in the present study indicate that peak anaerobic and aerobic power decline by around 7%‐14% per decade and this does not differ between athletic disciplines or sexes.