ENERGY EXPENDITURE DURING RUNNING CALCULATED FROM CINEMATOGRAPHIC DATA
AbstractThis paper outlines a method of measuring energy expenditure and presents experimental results in horizontal running. Unlike research and experiments in the past decade whereby the energy expenditure was calculated based on oxygen intake and with athletes directly connected to equipment in the laboratory (e.g. Howley, E.T. and Glover, M.E. (1974); Morgan, D.W. eta1 (1989), measurement can now be undertaken independent of such a procedure. Our method involves filming and computer processing combined with anthropometric data. It is similar to the method of Aleshinsky's (1986), with the difference that we use the full 3D approach instead of being restricted to a planar motion. First we obtain cinematographic data (coordinates) of 18 landmarks of the human body by using 3 video cameras (50 Hz PAL system) and a Peak Performance system. A conversion software is used to translate these coordinates into Euler angles and base coordinates. It also calculates for each parameter a spline of the 5th order which serves as input for the next step. With the help of the commercial software SDS of Solid Dynamics, France, we animated a mathematical model (Hanavan model with segments based on anthropometric data of the athlete) according to movements in the film. Eight male sports students were filmed individually running at a speed of 4 to 5mls. In addition, four ran at a speed of 8 to 9mls. In each run a complete stride-circle was analyzed. Results of our calculations agreed with those given by the researchers who used the energy expenditure values reported by researchers who used the oxygen-intake method. At the lower speed, power per kg body mass was equal to 13.6 W/kg(v=4 m/s) and 17.0 W/kg(v=5 m/s), whereas the oxygen-intake method (corrected for oxygen consumption when standing quietly) yielded results of 14.7 and 18.5 W/kg. In addition, we were able to measure that the higher speed and the results revealed a dramatic increase of the power from 28 to 43 W/kg. In conclusion our method not only opens up the possibility of on-the-spot measurements for general motion (no restriction to aerobic movements), but that energy expenditure can be given as a function of time.
Modelling / Simulation