Expanding the walking fatigability definition in people with multiple sclerosis: An exploratory study

Abstract

Objective: To investigate the relationship of the 6MWT and walking fatigability with different domains of physical activity in pwMS with WF (MS-WF), non-WF (MS-NWF) and healthy controls (HC). Methods: Twenty-two MS-WF (EDSS 4.7±1.1; 15F/7M), 21 NWF-MS (EDSS: 4.9±1.2; 15F/6M) and 21 HC (18F/3M) responded to the international physical activity questionnaire (IPAQ-long version) and performed the 6MWT. IPAQ was calculated in metabolic equivalent of task for moderate, vigorous and total physical activities domains. Total and minute-by-minute distances were recorded in the 6MWT, and the distance walked index from the last minute (DWI 6-1) was calculated for WF. Spearman's rank correlation, separately per group, was used to examine the correlation between IPAQ and total distance on 6MWT and DWI 6-1. Results: Moderate and total physical activities were significantly moderately associated with the 6MWT (MSWF: rho = 0.598, p<0.003 and rho = 0.608, p<0.003, respectively; NWFMS: rho = 0.564, p<0.008 and rho = 0.628, p<0.002 respectively) and the DWI 6-1 (MSWF: rho = 0.524, p<0.012 and rho = 0.461, p<0.031 respectively; NWFMS: rho = 0.441, p<0.045-moderate). No significant association was observed between moderate and total (HC) and vigorous activities (MS-WF, NWF-MS and HC) with the 6MWT and DWI 6-1. Conclusion: Our results indicate that physical activity is similarly associated with walking capacity and WF. The lower levels of physical activity, normally observed among studies in pwMS, could be related to lower walking capacity (i.e., lower performance on 6MWT) and lower capacity to sustain walking performance over prolonged periods (i.e., lower values on DWI 6-1). Improving walking capacity and fatigability may consequently improve physical activity in pwMS and other factors associated as fatigue, quality of life and disability levels.