The Impact of Cycling Cadence on Respiratory and Hemodynamic Responses to Exercise

Purpose The physiological consequences of freely chosen cadence (FCC) during cycling remains poorly understood. We sought to determine the effect of cadence on the respiratory and hemodynamic response to cycling exercise. Methods Eleven cyclists (10M:1F; age=27±6yr; V[Combining Dot Above]O2max=60.8±3.7ml·kg-1·min-1) completed four, 6-min constant-load cycling trials at 10% below their previously determined gas exchange threshold (i.e., 63±5% peak power) while pedaling at 60, 90, and 120rpm, and a FCC (94.3±6.9rpm), in randomized order. Standard cardiorespiratory parameters were measured and an esophageal electrode balloon catheter was used to assess electromyography of the diaphragm (EMGdi) and the work of breathing (Wb). Leg blood flow index (BFI) was determined on four muscles using near-infrared spectroscopy (NIRS) with indocyanine green dye injections. Results Oxygen uptake (V[Combining Dot Above]O2) increased as a function of increasing cadence (all pairwise comparisons, p0.05). Conclusions High cadence cycling at submaximal exercise intensities is metabolically inefficient and increases EMGdi, Wb, and leg muscle blood flow relative to slower cadences. Corresponding Author: Jordan A. Guenette, Ph.D. UBC Centre for Heart Lung Innovation Room 166 – 1081 Burrard Street Vancouver, British Columbia, Canada, V6Z-1Y6 Email: jordan.guenette@hli.ubc.ca No conflict of interest, financial or otherwise, are declared by the authors. The results of the present study do not constitute endorsement by the American College of Sports Medicine. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. This work was funded by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC). RAM was supported by a postgraduate doctoral scholarship from the NSERC. AHR was supported by a NSERC Alexander Graham Bell Canada Graduate Scholarship. RAM and AHR were also supported by four-year doctoral fellowships from the University of British Columbia. JAG was supported by a Canadian Institutes of Health Research Clinical Rehabilitation New Investigator Award and a Scholar Award from the Michael Smith Foundation for Health Research. Submitted for publication November 2018. Accepted for publication February 2019. © 2019 American College of Sports Medicine

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