Metabolic and blood flow responses to single leg emphasis cycling compared to single and double leg cycling

Single leg emphasis cycling (SLEC) has the potential to be beneficial in the rehabilitation setting; however, the metabolic responses to it are unknown. Thus, the current investigation sought to evaluate the metabolic and blood flow responses of SLEC compared to traditional double leg cycling (DLC) and single leg cycling (SLC). This was a within-participant randomized controlled trial where 12 recreationally active participants completed three different cycling modalities (DLC, SLC and SLEC) at 20%, 35% and 50% of power associated with DLC ${\dot{V}}_{O_2\mathrm{peak}}$ (P_α). Gas exchange ( ${\dot{V}}_{O_2}$ and ${\dot{V}}_{C{O}_2}$ ) was monitored continuously during exercise and rating of perceived exertion (RPE) for the active leg and whole body (WB) was recorded in the last minute of each stage, and blood flow was recorded in the femoral artery immediately following each stage using Doppler ultrasound. Despite similar ${\dot{V}}_{O_2}$ across the three conditions, carbohydrate oxidation was greater during SLEC compared to DLC at 20%, 35% and 50% (P ≤ 0.047) but, lower than SLC at 35% and 50% P_α (P ≤ 0.011). Similarly, blood flow was greater during SLEC compared to DLC at 20%, 35% and 50% (P ≤ 0.010), but lower than SLC at 35% and 50% P_α (P ≤ 0.008). There were no differences in WB or leg RPE between SLEC and DLC across all intensities. The current investigation suggests that SLEC could be an alternative and applicable cycling modality for individuals to increase local metabolic stress for similar levels of exertion and whole-body metabolic demand.