Active Drag As a Criterion for Evidence-based Classification in Para Swimming

Introduction: Paralympic classification should provide athletes with an equitable starting point for competition by minimizing the impact their impairment has on the outcome of the event. As swimming is an event conducted in water, the ability to overcome drag (active and passive) is an important performance determinant. It is plausible that the ability to do this is affected by the type and severity of the physical impairment, but the current World Para Swimming classification system does not objectively account for this component. The aim of this study was to quantify active and passive drag in Para swimmers and evaluate the strength of association between these measures and type of physical impairment, swimming performance, and sport class.

Methods: Seventy-two highly trained Para swimmers from sport classes S1 to S10 and 14 highly trained nondisabled swimmers were towed by a motorized winch while the towing force was recorded. Passive drag was measured with the arms held by the side; active drag was determined during freestyle swimming using an assisted towing method.

Results: Active and passive drag were higher in Para swimmers with central motor and neuromuscular impairments than for nondisabled swimmers and were associated with severity of swim-specific impairment (sport class) and maximal freestyle performance in these swimmers (r = -0.40 to -0.50, P ≤ 0.02). Para swimmers with anthropometric impairments showed similar active and passive drag to nondisabled swimmers, and between swimmers from different sport classes.

Conclusions: Para swimmers with central motor and neuromuscular impairments are predisposed to high active drag during freestyle swimming that impacts on their performance. It is recommended that drag measures be considered in revised classification for these swimmers, but not for those with anthropometric impairments.