The purpose of the present study was to use a previously developed treadmill walking test to determine training-induced changes within and between two groups of untrained men during a six week training period. One group consisted of seven middle-aged (mean age, 41.3 yr), and the second group consisted of seven young adult (mean age, 19.9 yr), men. Heart rates following training were significantly lower at all work intensities for the middle-aged men (p less than 0.005) whilst for the young adults only the 12.5% and 15% (p less than 0.025) work levels were significantly lower. Blood lactic acid concentrations (p less than 0.005), Respiratory Exchange Ratios (p less than 0.05), Ventilatory Equivalents (p less than 0.005) and mean Two Mile times (p less than 0.005) were all significantly lower after training for the older age group but this was not so for the younger adult group. The oxygen cost of the walking test was lower for four of the workloads of the middle-aged, but only for the final workload (p less than 0.005) for the young adults, after training. The performance test did not disadvantage the middle-aged subjects yet the results demonstrated that the test provided a common means of reflecting the training state of the two groups whether the level of activity took place on the treadmill or on the track.