The interaction between cycling cadence and substrate utilization in trained cyclists
Date
2021
Authors
Dippold, Victoria Mary Grace, author
Fahrner, Scott, advisor
Bell, Christopher, committee member
Hickey, Matthew, committee member
Orton, Christopher, committee member
Journal Title
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Abstract
Currently, the optimal pedaling rate for road cycling endurance performance is not very well understood. It is known that muscle fiber recruitment patterns vary between low and high cadence rates. However, it is unclear whether different muscle fiber recruitment patterns stimulate different substrate utilization patterns between low and high cycling cadences. PURPOSE: We investigated if pedaling at a higher cadence at a submaximal work level results in a higher proportion of fat oxidation compared to cycling at the same intensity at a low cadence. In addition, we aimed at studying the optimal cadence for endurance road cycling and why well-trained and professional cyclists tend to pedal at higher rates. METHODS: Participants were trained, competitive cyclists and/or triathletes (VO2 max 60.4 ± 7.1 ml/kg/min, aged 24 ± 2.5 years, n = 11) living in Fort Collins, CO. All were training at least 8 hours per week and had participated in a competitive event in the past two years. Baseline testing consisted of a maximal consumption test (VO2 max test) that started at a low work level (50 – 100 watts) and increased by 25 watts every three minutes until exhaustion after which a verification bout was performed. From the VO2 max test, the first ventilatory threshold (VT1) was determined for each participant and served as the power output used during the cadence protocol that followed on a separate day. The cadence protocol entailed seven stages each lasting six minutes in length with a four-minute recovery period in between. Work rate remained constant during the cadence protocol while a different cadence was assigned randomly to each stage (60, 70, 80, 90, 100, 110 and freely chosen cadence (FCC)). RESULTS: Cadence had a significant effect on HR (estimated slope = 0.2634, SE = 0.032, p < 0.001), VO2 (estimated slope = 0.098, SE = 0.012, p < 0.001), RER (estimated slope = 0.0007, SE = 0.0001, p < 0.001), as well as absolute (estimated slope = 0.012, SE = 0.001, p < 0.001) and relative percentage of CHO utilization (estimated slope = 0.2696, SE = 0.053, p < 0.001. Cadence did not have a significant effect on absolute fat utilization, but it did have a significant effect on the relative percentage of fat utilization (estimated slope = -0.2283, SE = 0.053, p < 0.001. VO2, HR, and VE were minimized at 70 rpm while carbohydrate utilization was minimized at 60 rpm. FCC was found to be 89.8 rpm. Pairwise comparisons with FCC showed significant mean differences with respect to HR and VO2 between FCC and 70, 100, and 110 rpms as well as significant mean differences with respect to CHO utilization between FCC and 110 rpms. CONCLUSION: The increase in energy expenditure at higher cadences is not counterbalanced by a significant increase in fat oxidation, thereby resulting in a carbohydrate penalty at higher cadences. FCC is not solely chosen to limit metabolic cost or optimize substrate utilization. An optimal pedaling cadence may be one that allows the cyclists to maintain the highest wattage desired without a considerable amount of muscular fatigue while minimizing the consequent increased metabolic cost and CHO penalty.
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Subject
carbohydrate penalty
freely chosen cadence
cadence
substrate utilization
cycling