Gait Pattern Alterations during Walking, Texting and Walking and Texting during Cognitively Distractive Tasks while Negotiating Common Pedestrian Obstacles

The original Physical Activity Readiness Questionnaire (PAR-Q) offers a safe preliminary screening of candidates for exercise testing and prescription, but it screens out what seems an excessive proportion of apparently healthy older adults. To reduce unnecessary exclusions, an expert committee established by Fitness Canada has now revised the questionnaire wording. The present study compares responses to the original and the revised PAR-Q questionnaire in 399 men and women attending 40 accredited fitness testing centres across Canada. The number of subjects screened out by the revised test decreased significantly (p < .05), from 68 to 48 of the 399 subjects. The change reflects in part the inclusion of individuals who had made an erroneous positive response to the original question regarding high blood pressure. There is no simple gold standard to provide an objective evaluation of the sensitivity and specificity of either questionnaire format, but the revised wording has apparently had the intended effect of reducing positive responses, particularly to the question regarding an elevation of blood pressure.

The determination of gait events such as heel strike and toe-off provide the basis for defining stance and swing phases of gait cycles. Two algorithms for determining event times for treadmill and overground walking based solely on kinematic data are presented. Kinematic data from treadmill walking trials lasting 20-45s were collected from three subject populations (healthy young, n=7; multiple sclerosis, n=7; stroke, n=4). Overground walking trials consisted of approximately eight successful passes over two force plates for a healthy subject population (n=5). Time of heel strike and toe-off were determined using the two new computational techniques and compared to events detected using vertical ground reaction force (GRF) as a gold standard. The two algorithms determined 94% of the treadmill events from healthy subjects within one frame (0.0167s) of the GRF events. In the impaired populations, 89% of treadmill events were within two frames (0.0334s) of the GRF events. For overground trials, 98% of events were within two frames. Automatic event detection from the two kinematic-based algorithms will aid researchers by accurately determining gait events during the analysis of treadmill and overground walking.

Dual-task studies assessed the effects of cellular-phone conversations on performance of a simulated driving task. Performance was not disrupted by listening to radio broadcasts or listening to a book on tape. Nor was it disrupted by a continuous shadowing task using a handheld phone, ruling out, in this case, dual-task interpretations associated with holding the phone, listening, or speaking, However significant interference was observed in a word-generation variant of the shadowing task, and this deficit increased with the difficulty of driving. Moreover unconstrained conversations using either a handheld or a hands-free cell phone resulted in a twofold increase in the failure to detect simulated traffic signals and slower reactions to those signals that were detected. We suggest that cellular-phone use disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving.