The effect of different aero handlebar positions on aerodynamic and gas exchange variables

Adopting the time trial position (TTP) represents a notable improvement for cycling aerodynamic performance. Aero handlebars are designed to enable the cyclist to adopt a more aerodynamic TTP. However, it is unclear to what realistic extent the aero handlebar configuration affects the aerodynamics and physiological functioning. Thus this study aimed to investigate the effect of aero handlebar alterations on gas exchange parameters and aerodynamics of TTP. Seven male competitive cyclists and triathletes performed submaximal tests on a cycle ergometer at six different TTPs. Oxygen uptake, respiratory exchange ratio, minute ventilation and tidal volume were collected. Using the computational fluid dynamics (CFD) method, the detailed airflow patterns around the cyclist were investigated. The results were analyzed in terms of drag area, velocity and pressure distributions around the cyclist, surface pressure coefficient and wall shear stress magnitude. It was revealed that varying the aero handlebar position significantly influences aerodynamic performance, while maximal values of all the gas exchange variables remained unchanged. Compared to the cyclist's preferred TTP, the frontal area, drag coefficient and drag area were reduced by 4.1%, 4.6% and 8.5%, respectively, when lowering the handlebar position by 5 cm, which overcomes the metabolic costs.