Using the Recovery Phase in Wheelchair Racing to Estimate the Resistance Forces

Abstract

Insight into in-field mechanical power estimation in wheelchair racing is useful for athletes and coaches. A non-invasive method to estimate mechanical power is by using inertial measurement units (IMUs) to estimate the power lost to resistive forces during wheelchair propulsion. During the recovery phase, no propulsive force acts on the athlete/wheelchair combination and therefore, the deceleration of the athlete/wheelchair combination during this phase is caused by the power lost to resistive forces. The aim of this study was to investigate whether using deceleration in the recovery phase for estimation of resistance using IMUs is applicable in wheelchair racing. To approach the instantaneous velocity of the athlete/wheelchair combination and therefore the deceleration during the recovery phase, the kinematics of the wheelchair and the upper body were measured and used for three different methods. The simplest method is to use the velocity of the wheelchair (v_wc), the second method takes the influence of the trunk movement into account (v_com,2seg) and the last method takes the influence of all upper body segments into account (v_com,tot). The results of this study indicate that using v_wc, v_com,2seg or v_com,tot for estimating the deceleration during the recovery phase is not yet suitable to provide accurate estimation of the total resistance compared to drag test based results. This indicates that application of this method of estimating resistance forces in the recovery phase is not as straightforward as initially anticipated. Despite the potential benefits of this approach, the results suggest that refinement of this method or development of a new method is necessary to obtain an accurate estimation of the total resistance.