A quantification of the treadmill six-minute walk test using the MyWellness Key™ accelerometer

Background: Accelerometers have been suggested to provide additional information during the six-minute walk test which may be useful in evaluating changes in functional exercise capacity. The aim of the study was to identify whether the additional information measured by the MyWellness Key™ (MWK) accelerometer during a treadmill-six minute walk test was related to currently used outcome measures. Method: Fifteen participants (male n=9; female n= 6) performed a self-paced treadmill six minute walk test. Respiratory gas analysis and walking distance were measured whilst wearing the MWK. Results: A significant correlation was established between activity counts and six minute walk distance (r=-0.847, p<0.001) yet not six minute walk work (r=-0.337, p=0.220). Energy expenditure estimated by the MWK was strongly correlated to six minute walk work (r=0.938, p<0.001) but not six minute walk distance (r=0.477, p=0.072). The MWK significantly underestimated energy expenditure (36.73, CI=33.9 - 39.7 Kcal) compared to gas analysis (54.35, CI=46.2 - 61.4 Kcal) demonstrating poor agreement between the two analyses (Bias = -17.61 Kcal, Limits of agreement= -37.4, +2.2 Kcal). Measurement of time spent undertaking light, moderate and vigorous physical activity was not significantly different (p>0.05) between the MWK and gas analysis. Conclusion: Estimated energy expenditure provided by the MWK was strongly correlated to six minute walk work; however, MWK underestimated energy expenditure as measured by gas analysis. The MWK may provide outcome data that supplements that currently provided by the 6MWD for functional capacity assessment during the treadmill 6MWT.