1. INTRODUCTION A person’s motor performance is influenced by the interplay among the individual’s physical characteristics, the task demands, and the environment. When there is a mismatch among these variables, motor performance can be compromised, even during common (well- practiced) tasks such as walking. In the worst case scenario, falls and injury may occur. METHODS & PROCEDURES Participants performed three walking trials in each of eight conditions resulting from combinations of Walking speed: self-selected comfortable pace and fast pace Lighting: normal room light (400 lux) and low light (4 lux) Task demand: single task (walking only) and dual task (walking while performing a mental task requiring serial subtractions by sevens from a randomly assigned three-digit number (Karzmark, 2000). RESULTS Velocity Deborah Bubela, Jeffrey M. Kinsella-Shaw, Alen Hajnal Collaboratory for Rehabilitation Research University of Connecticut, Storrs, CT USA This research was supported by a grant from the University of Connecticut Influences of Dual Tasking, Walking Speed, and Room Lighting on Gait Participants traversed a 4.3 m electronic walkway (GaitRite) that provided kinematic measures of stride and velocity. Verbal responses (from the mental task) were audio-tape recorded. SUBJECTS Twenty young healthy adults (mean age 21 years) and twenty community-dwelling adults over 65 years of age (mean age 79.5 years) volunteered to participate. All individuals were independently ambulatory without assistive devices. DESIGN Dual task and walking speed were randomized within level of illumination which was blocked and counter-balanced over participants. A person’s age is one of the most common individual characteristics that affect movement. Older persons show greater variability in gait and tend to fall more frequently than younger adults during typical activities of daily living (Kressig, 2004). Task demands: Simultaneous performance of physical and mental tasks may negatively influence one or both activities (Beauchat et al., 2003; Melzer & Oddsson, 2004; Pellecchia, 2003) Suboptimal environmental conditions that limit vision are associated with dimin- ished postural stability and increased risk of falls (Kinsella-Shaw, Harrison, Colon-Semenza, & Turvey, 2006). THE PRESENT EXPERIMENT How do commonplace, non-optimal conditions affect a person’s ability to carry out concurrent cognitive and physical tasks (dual tasking)? The contribution of age to the performance of simultaneous cognitive and physical tasks under the demand of moving quickly while walking was assessed under different level of illumination. Variations in lighting and walking quickly are common occurrences that may present potential risks to persons’ upright balance during static or dynamic tasks. Performing multiple tasks in less than optimal conditions (e.g., dim lighting or quickened pace) may have implications for persons’ safety, especially as they age or experience compromised mobility. Increases in stride variability correlates with greater fall risk. Individual’s characteristics: The pace at which a person executes a task may also affect the quality of movement and the intended outcome. Walking speeds greater than comfortable, self-selected pace increase healthy older adults’ risk of falling (Pavol, Owings, Foley & Grabinder, 2001). Environmental Conditions: ANALYSIS 2 (Age) x 2 (Pace) x 2 (Task) x 2 (Illumination) repeated measures Analyses of Variance (ANOVAs) were conducted on: Velocity (cm/s) Percent of Gait Cycle in Double Stance Stride Length SUMMARY A concurrent cognitive task can influence young adult gait when the cognitive task is adequately challenging. The gait of both young and older adults shows the interactive influences of dual tasking, low illumination, and the requirement to walk at a pace greater than comfort level. Percent of Gait Cycle in Double Stance Stride Length Task x Age p =.007 Age x Speed p =.000 Task x Speed p =.004 Task x Age p =.006 Task x Speed p =.000 Task x Age p =.006 Age x Speed p =.003 Task x Speed p =.000 Illumination x Speed p =.089 A concurrent cognitive task slows walking speed, especially for older adults (left), and it restricts the speed increase due to instruction (middle). Younger adults are able to increase their walking pace more than older adults (right). Performing a con-current cognitive task requires that more time is spent with both feet in contact with the ground, especially for older adults (left) and for a faster pace (right). REFERENCES Beauchat, O., Kressig, R.W., Najafi, B., Aminian, K., Dubost, V., & Mourey, F. (2003). Age-related decline of gait control under a dual-task condition. Journal of American Geriatric Society, 51, 1187-1188. Karzmark, P. (2000). Validity of the serial seven procedure. International Journal of Geriatric Psychiatry, 15, 677-679. Kinsella-Shaw, J.M.,Harrison, S.J., Colon-Semenza, C., & Turvey, M.T. (2006). Effects of visual environment on quiet standing by young and old adults. Journal of Motor Behavior, 38, 251-264. Kressig, R.W., Gregor, R.J., Oliver, A., Waddell, D., Smith, W., O’Grady, M. (2004). Temporal and spatial gait features of older adults transitioning to frailty. Gait & Posture. 20, 30-35. Melzer, I., & Oddsson, L.I. (2004). The effect of a cognitive task on voluntary step execution in healthy elderly and young individuals. Journal of American Geriatric Society, 52, 1255-1262. Owsley, C., Sekuler, R., & Siemsen, D. (1983). Contrast sensitivity throughout adulthood. Vision Research, 23, 689-699. Pellecchia, G.L. (2003). Postural sway increases with attentional demands of concurrent cognitive task. Gait Posture, 18, 29-34. Dim illumination results in shorter strides when walking is at a comfortable self-selected pace. At a faster pace, stride length was less affected by illumination level (left). Performing a concurrent cognitive task shortens stride length, especially for older adults (left), and especially for a faster pace (middle). Younger adults increase their stride length more to achieve the fast pace (right). 0 50 100 150 200 Velocity (cm/s) OldYoung Age DualSingle 0 50 100 150 200 Velocity (cm/s) ComfortableFast Pace DualSingle 0 50 100 150 200 Velocity (cm/s) OldYoung Age FastComfortable z 20 22 24 26 28 30 Double Support Percent (%) OldYoung Age DualSingle 20 22 24 26 28 30 Double Support Percent (%) ComfortableFast Pace DualSingle 0 50 100 150 200 Stride Length (cm) OldYoung Age DualSingle 0 50 100 150 200 Stride Length (cm) ComfortableFast Pace DualSingle 0 50 100 150 200 Stride Length (cm) OldYoung Age FastComfortable 0 50 100 150 200 Stride Length (cm) ComfortableFast Pace DimNormal