Effects of cycling cadence on respiratory and haemodynamic responses in trained cyclists

The physiological consequences of cycling cadence selection are poorly understood. Purpose: To determine the impact of cadence on cardiorespiratory and metabolic parameters; perceptual responses; power of breathing (Pb); electromyography of the diaphragm (EMGdi) and leg muscles; and microvascular leg blood flow. Methods: Eleven trained cyclists (10M:1F; age=27±6yrs; V̇O2max=60.8±3.7ml·kg-¹·min-¹) completed four 6-min constant-load cycling trials at 10% below their gas exchange threshold (63±5% peak power) while pedaling at 60rpm, 90rpm, 120rpm, and a freely chosen cadence (FCC, 94.3±6.9 rpm), in randomized order, on an electromagnetically braked cycle ergometer. Ventilatory and metabolic parameters were measured using a commercially available metabolic cart. An oesophageal electrode balloon catheter was used to assess Pb and EMGdi. Surface EMG was placed on four leg muscles predominant in cycling. Blood flow index (BFI) was determined on the same muscles of the contralateral limb using near-infrared spectroscopy and indocyanine green. Perceptual responses were measured using the modified 0-10 category ratio Borg scale. Results: With each increase in cadence there was a corresponding increase in V̇O2 (all pairwise comparisons p0.05). Conclusion: Relative blood flow appears to be closely linked with metabolic activity of the muscle, which was significantly elevated during the highest cadence condition. In combination with the substantial rise in respiratory variables and the Pb, cadence may represent the balance between peripheral and central stressors.Medicine, Faculty ofGraduat