Publication date: Available online 7 June 2016
Source:Gait & Posture
Author(s): Vincent Gigot, Virginie Van Wymelbeke, Davy Laroche, Thomas Mouillot, Agnès Jacquin-Piques, Matthieu Rossé, Michel Tavan, Laurent Brondel
Background and aimTo accurately quantify the cost of physical activity and to evaluate the different components of energy expenditure in humans, it is necessary to evaluate external mechanical work (WEXT). Large platform systems surpass other currently used techniques. Here, we describe a calculation method for force-platforms to calculate long-term WEXT.MethodsEach force-platform (2.46 x 1.60 m and 3.80 x 2.48 m) rests on 4 piezoelectric sensors. During long periods of recording, a drift in the speed of displacement of the center of mass (necessary to calculate WEXT) is generated. To suppress this drift, wavelet decomposition is used to low-pass filter the source signal. By using wavelet decomposition coefficients, the source signal can be recovered. To check the validity of WEXT calculations after signal processing, an oscillating pendulum system was first used; then, 10 healthy subjects performed a standardized exercise (squatting exercise). A medical application is also reported in eight Parkinsonian patients during the timed “get-up and go” test and compared with the same test in ten healthy subjects.ResultsValues of WEXT with the oscillating pendulum showed that the system was accurate and reliable. During the squatting exercise, the average measured WEXT was 0.4% lower than theoretical work. WEXT and mechanical work efficiency during the “get-up and go” test in Parkinson's disease patients in comparison with that of healthy subjects were very coherent.ConclusionsThis method has numerous applications for studying physical activity and mechanical work efficiency in physiological and pathological conditions.
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