Visual simple and choice reaction time (RT) tests were administered to 64 male and female volunteers 23 to 59 years of age. One half of the subjects were runners involved in rigorous training programs averaging 42 miles per week. The other half of the subjects were sedentary adults. Eighty simple and 100 choice reaction time trials were given with a variable foreperiod ranging from 400 to 1100 msec. Five catch trials were given in both simple and choice reaction time conditions. The results indicated that there was a gradual decline in RT performance as age increased. However, this trend was not evident in the trained group. Reaction time remained constant with age within the trained group. It was concluded that a high state of cardiorespiratory training may prevent cognitive decrements in performance with age.