Dual task performance in older adults: examining visual discrimination whilst treadmill walking at preferred and non-preferred speeds

This study examined visual discrimination performance in a sample of older adults before, during and post treadmill walking at preferred walking speed and preferred walking speed +20%. Nine adults (6 females and 3 males) aged 60–77 years (mean age = 67.1 ± 5.7 years) undertook three trials each lasting 15 min, rest, walking at preferred speed and walking at preferred speed +20%. Pre, during and post each condition, participants undertook measures of visual–cognitive performance. There were no significant main effects or higher order interactions for condition (rest, vs. walking preferred speed, vs. walking preferred speed +20%) or time (pre, during, post) (all P > 0.05). There was a significant condition X time interaction for response time (P = 0.014, partial ɳ2 = 0.352). Post hoc analysis indicated that response times were significantly faster during exercise at preferred speed compared to pre exercise at preferred speed (P = 0.042). Response times were significantly slower during walking at preferred speed +20% compared to pre exercise (P = 0.002) and to post exercise (P = 0.012). Response times were significantly faster during PSW compared to during rest (P = 0.05), during PSW compared to during PSW20 (P = 0.001) and significantly slower during PSW20 compared to during rest (P = 0.001). Post PSW20 response times were significantly slower than post PSW (P = 0.04). These results suggest that visual discrimination performance is facilitated when walking at preferred speeds but walking at 20% faster than preferred speed significantly impedes visual discrimination in older adults.