Dual task performance in older adults: Examining visual discrimination performance 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 ɳ(2)=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.