Self-selected exercise intensity can be a useful exercise prescription tool for older adults; however, it is not known if it can elicit improvements in walking and aerobic capacity. In older adults, effects of concentric or eccentric endurance exercise at self-selected walking speed were examined on 1-mile indoor walk performance, predicted maximum oxygen uptake and physiological parameters. Twenty-four older adults (67 ± 4 years) completed 3 × 30 min treadmill walks per week for 12-weeks on level (LTW, n = 11, 0%) or downhill (DTW, n = 13, ﹣10%) treadmill gradient at a self- selected speed, which progressed every 4 weeks. Maximal oxygen uptake was predicted using a 1-mile walk at 4-week intervals with physiological responses recorded using a portable metabolic system. One-mile walking speed increased from baseline following 8- and 12-weeks (12 weeks: LTW: 13% ± 6%, DTW: 14% ± 9%, P < 0.01). Both groups increased predicted maximal oxygen uptake following 8-weeks of walking (LTW: 15% ± 15%; DTW: 23% ± 30%, P < 0.01). At 12-weeks, the 1-mile walk was performed with higher heart rates and minute ventilation (P < 0.01). It is concluded that an exercise programme of concentric or eccentric endurance exercise, at self-selected exercise intensity, is sufficient to elicit similar improvements in maximum oxygen uptake.