Feasibility of whole-body gait kinematics to assess the validity of the six-minute walk test over a 10-m walkway in the elderly

Background: The six-minute walk test (6MWT) assesses the functional exercise capacity and its impairments due to chronic cardiorespiratory and/or musculoskeletal conditions, particularly in the elderly. The clinimetric properties and clinical utility of the 6MWT are well-described, but little is known about the gait kinematics during this test. This study evaluated the feasibility of a study protocol based on whole-body gait kinematics to assess the validity of the 6MWT over a 10-m walkway in the elderly. Methods: Eight elderly healthy participants (7 women, aged 61-77 years) underwent the 6MWT over a 10-m rectilinear walkway. The data were collected using infrared cameras and a spherical marker covered with retroreflective tape firmly attached to a helmet worn by the participant during the 6MWT. Results: The total distance measured by the assessor was significantly smaller than both its kinematics (P=0.012) and model-predicted (P=0.017) counterparts. The total distance measured by the kinematics was also smaller than the predicted one (P=0.025). A large bias toward underestimating the 6MWD, as measured by the assessor (mean=-32, SD=6.3 m), was observed along with a high determination coefficient (R-2=99.2%). Most of the participants presented a negative trend for the average speed as a function of half-turns. Discussion: Analysis of whole-body gait kinematics is feasible using motion capture systems and can be used to assess the validity of the 6MWT over a 10-m walkway in the elderly. The 6MWD, as measured by the assessor, underestimates the actual covered distance in the 6MWT but not the functional exercise capacity. (C) 2018 Elsevier Ltd. All rights reserved.