Estimation of mechanical power and energy cost in elite wheelchair racing by analytical procedures and numerical simulations

Abstract

The aim was to compare the mechanical power and energy cost of an elite wheelchair sprinter in the key-moments of the stroke cycle. The wheelchair-athlete system was 3D scanned and then computational fluid dynamics was used to estimate the drag force. Mechanical power and energy cost were derived from a set of formulae. The effective area in the catch, release and recovery phases were 0.41 m 2 , 0.33 m 2 and 0.24 m 2 , respectively. Drag increased with speed and varied across the key-moments. The catch required the highest total power (range: 62.76-423.46 W), followed-up by the release (61.50-407.85 W) and the recovery (60.09-363.89 W).

Estimation of an Elite Road Cyclist Performance in Different Positions Based on Numerical Simulations and Analytical Procedures

“…The scans were obtained by a Sense 3D scanner (3D Systems, Inc., Canada) and saved in the Sense Software (Sense, 3D Systems, Inc., Canada). The geometries were edited and converted to CAD models in Geomagic studio software (3D Systems, USA) (Forte et al, 2018b).…”

“…D is the main RF in cycling and is related with the cyclist positions and increases with speed (Gross et al, 1983;Kyle and Burke, 1984;Defraeye et al, 2010a;Debraux et al, 2011). The effective surface area (ACd) results from the multiplication of surface area (A) and coefficient of drag (Cd) (Forte et al, 2015(Forte et al, , 2018b and it is a mainstream procedure to assess cyclists' aerodynamics (Zdravkovic et al, 1996;Grappe et al, 1997;Candau et al, 1999;Defraeye et al, 2010a;Beaumont et al, 2018). Positions with smaller surface areas may also lead to less D. However, the body shape and equipment's design may affect the fluid flow and aerodynamics (Schlichting and Gersten, 2016).…”

The Aerodynamics and Energy Cost Assessment of an Able-Bodied Cyclist and Amputated Models by Computer Fluid Dynamics

“…Knowing drag and rolling resistance, Equation (2) enables the assess of the energy cost (i.e., energy expenditure per unit of distance) [14].…”

“…In Equation 2, Ec is the energy cost, CR is the rolling coefficient, m the body mass of the bicycle-cyclist system, g the gravitational acceleration, v the mean velocity over the race, ρ the air density, A is the surface area and CD the drag coefficient and η the gross efficiency. The assumed gross efficiency of cyclists is 20% [29] and CR 0.00368 [14].…”

“…Thus, racing will be as intense as the energy expenditure. It is possible to assess the energy expenditure and energy cost by a set of analytical procedures that encompass the measurement of drag and rolling resistance [14,15]. Rolling resistance is dependent on the mass of the bicycle-cyclists system, gravitational acceleration, rolling resistance coefficient and velocity, whereas, drag is dependent on the speed, fluid density, drag coefficient and object/system surface area [16].…”