RESEARCH REPORT POSTER DISPLAY

CARDIORESPIRATORY RESPONSES AND WALKING PATTERN ADAPTATIONS DURING THE 6-MINUTE WALKING TEST IN HEALTHY ADULTS AND ADULTS WITH CHRONIC STROKE. Antunes F^1,2, Brosseau R^1,2, Gagnon D^1-3, Tardif C³, Nadeau S^1,2; ¹École de réadaptation, Université de Montréal. ²Centre de recherche interdisciplinaire en réadaptation (CRIR), Institut de réadaptation de Montréal. ³Hôpital de réadaptation Lindsay

PURPOSE: To study the profile of the cardiorespiratory responses and walking-pattern parameters during the 6-min walking test (6-MWT) in adults with chronic stroke. RELEVANCE: Changes in the walking-pattern parameters of the lower limbs have scarcely been studied during the 6-MWT. PARTICIPANTS: Convenience samples of 10 subjects who had sustained a stroke at least 6 months earlier (mean age ± SD: 61.0±14.1) and 10 healthy controls participated in this study. All participants gave their written consent. The persons with stroke were able to walk without aid over long distances and had a mean self-selected gait speed of 0.76 m/s (±0.34). METHODS: During the test, the subjects carried the Cosmed K4 b2 telemetric portable metabolic measurement system to record the cardiorespiratory parameters (e.g. VO2, VCO2, respiratory frequency, heart rate, etc.). To quantify the gait pattern, surface electrodes recorded the bilateral EMG of four lower-limb muscles. The sagittal hip excursion angles were assessed with flexible electrogoniometers while time-distance parameters were recorded with foot switches. All the gait parameters were acquired by telemetry at a sampling rate of 1200 Hz with the Noraxon Telemyo System. ANALYSIS: Descriptive statistics were calculated and values at each minute of the 6-MWT were obtained by averaging the data over 30-s periods. Data from individuals with stroke and from healthy participants were compared using 2-way ANOVAs with “minutes” of the 6-MWT as the within-subject factor and groups (healthy and stroke) as the between-subject factor. RESULTS: On average, the total distance walked by individuals with stroke during the 6-MWT was 51% lower than by their healthy counterparts (275±173m vs. 566±65m; p < 0.05). They presented a slower gait speed and a decreased hip excursion on both sides. Their stance phase (in %) was respectively greater and lower than that of healthy subjects on the unaffected and affected sides. Subjects with stroke did not use their maximal speed during the test but chose instead to walk at their preferred gait speed. Overall, no adaptation over time was observed in the selected gait parameters or EMG data, which showed relatively constant values for both groups during the 6-MWT. With regard to the cardiorespiratory responses, in addition to differences observed between groups, the values changed significantly during the 6-MWT. For both groups, the major cardiorespiratory adaptations were observed in the first two minutes. The mean energy cost was 40% greater for the participants with stroke. CONCLUSIONS: During the 6-MWT, the cardiorespiratory responses to moderate effort among individuals with stroke were not different from those found in healthy subjects. Moreover, no significant changes were found over time in either group of participants in most of the parameters studied to characterize their gait patterns. IMPLICATIONS: The 6-MWT does not challenge the walking endurance ability in either group: subjects chose to perform the test at a comfortable speed even though they were instructed to “walk from one end of the hallway to the other with the goal of covering the greatest distance possible within a 6-min period”. KEYWORDS: walk, cerebral vascular accident, endurance, energy cost. FUNDING ACKNOWLEDGEMENTS: The project was financed by the Fondation de l’Hôpital de réadaptation Lindsay, the Fonds de la recherche en Santé du Québec (FRSQ) and the Canadian Foundation for Innovation. Dr. Nadeau is a junior II scientist and M. Gagnon, a PhD student, both supported by the FRSQ. The authors thank M. Goyette, D. Marineau and F. Piotte for their assistance. CONTACT: rachel.brosseau@umontreal.ca

ETHICS COMMITTEE: Ethics commitee of Centre de recherche interdisciplinaire en réadaptation (CRIR)