6533b828fe1ef96bd12890bb

RESEARCH PRODUCT

A new method to calculate external mechanical work using force-platform data in ecological situations in humans: Application to Parkinson's disease

subject

description

Abstract Background and aim To 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 ( W EXT ). Large platform systems surpass other currently used techniques. Here, we describe a calculation method for force-platforms to calculate long-term W EXT . Methods Each force-platform (2.46 × 1.60 m and 3.80 × 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 W EXT ) 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 W EXT 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. Results Values of W EXT with the oscillating pendulum showed that the system was accurate and reliable. During the squatting exercise, the average measured W EXT was 0.4% lower than theoretical work. W EXT 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. Conclusions This method has numerous applications for studying physical activity and mechanical work efficiency in physiological and pathological conditions.