Age-related Differences in the Influence of Cognitive Task Performance on Postural Control Under Unstable Balance Conditions

Background: Poor multitask performance is commonly used as an indicator of age-related changes in attentional capacity. An inability to allocate sufficient attention to postural control under multitask conditions is thought to be a contributing factor to the risk of falling in older adults. This study examined age-related differences in the influence of cognitive task performance on postural sway and muscle activity on unstable balance conditions. Methods: Thirty healthy younger adults (22.2 ± 1.5 years of age, 15 men and 15 women) and 27 healthy older adults (71.3 ± 3.4 years of age, 13 men and 14 women) participated in the study. Participants performed a reaction time task under three conditions during standing on a compliant foam surface: holding a glass full of sand (control task), holding a glass of water (dual-manual task), and performing a control task while simultaneously performing a verbal fluency task (dual-cognitive task). Results: Both younger and older adults had a longer reaction time for the dual-cognitive task compared to the other two tasks (p < 0.01). Older participants exhibited decreased lower limb muscle activity and increased anterior–posterior trunk acceleration during the dual-cognitive task, while these effects were not observed in younger adults. Conclusion: Increasing attentional demand by implementing a cognitive task concomitant with a balance task had a greater influence on postural control in older compared to younger adults

Physical Activity during Winter in Old-Old Women Associated with Physical Performance after One Year: A Prospective Study

Background. The aim of this study was to evaluate whether the decline of physical activity during winter influences physical performances (after 1 year) in old-old women. Methods. Fifty-three Japanese women (mean age: 78.4 ± 3.2 years) participated in this study. Data of physical activity was collected by using an accelerometer at baseline and 3-month follow-up, and participants who decreased step counts in this period were defined as declining groups. We measured grip strength, knee extensor strength, total length of the center of gravity, hip walking distance, and maximum walking speed to evaluate physical performances at baseline and 1-year follow-up. Repeated-measures analysis of variance determined the difference in physical performance between declining groups and maintenance group with maintained or improved step counts. Results. Daily step counts for 22 older women (41.5%) decreased during winter. A statistically significant interaction effect between group and time was found for maximum walking speed (F(1,50)=5.23, p=0.03). Post hoc comparisons revealed that walking speed in the maintenance group significantly increased compared with baseline (p=0.01); the declining group showed no significant change (p=0.44). Conclusion. Change of physical activity during winter influences the physical performance level after 1 year in community-dwelling old-old women, particularly its effect on maximum walking speed