Biology subjects

Riveros-Matthey, C. D.

Publications and source records attributed to Riveros-Matthey, C. D..

3 recordsLinked to original sources

bioRxiv2024

Cycling Cadence Selections at Different Saddle Heights Minimize Muscle Activation Rather Than Energy Cost

Unlike walking and running, people do not consistently choose cadences that minimize energy consumption when cycling. Assuming a common objective function for all forms of locomotion, this suggests either that the neural control system relies on indirect sensorimotor cues to energetic cost that are approximately accurate during walking but not cycling, or that an alternative objective function applies that correlates with energy expenditure in walking but not cycling. This study compared how objective functions derived as proxies to 1) energy cost or 2) an avoidance of muscle fatigue predicted self-selected cycling cadences (SSC) at different saddle heights. Saddle height systematically affected SSC, with lower saddles increasing SSC and higher saddles decreasing SSC. Both fatigue-avoidance and energy-expenditure cost functions derived from muscle activation measurements showed minima that closely approximated the SSCs. By contrast, metabolic power derived from VO2 uptake was minimal at cadences well below the SSC across all saddle height variations. The mismatch between the cadence versus muscle activation and the cadence versus metabolic energy relations is likely due to additional energy costs associated with performing mechanical work at higher cadences. The results suggest that the nervous system places greater emphasis on muscle activation than on energy consumption for action selections in cycling.

evolutionary biology↗

bioRxiv2023

An in-silico investigation of the effect of changing cycling crank power and cadence on muscle energetics and active muscle volume

This study used musculoskeletal modelling to explore the relationship between cycling conditions (power output and cadence) and muscle activation and metabolic power. We hypothesized that the cadence that minimized the simulated average active muscle volume would be higher than that which minimized the simulated metabolic power. We validated the simulation by comparing predicted muscle activation and fascicle velocities from select muscles with experimental records of electromyography and ultrasound images. We found strong correlations for averaged muscle activations and moderate to good correlations for fascicle dynamics. These correlations tended to weaken when analyzed at the individual participant level. Our study revealed a curvilinear relationship between average active muscle volume and cadence, with the minimum active volume being aligned to the self-selected cadence. The simulated metabolic power was consistent with previous results and was minimized at lower cadences than that which minimized active muscle volume across power outputs. Whilst there are some limitations to the musculoskeletal modelling approach, the findings suggest that minimizing active muscle volume may be a more important factor than minimizing metabolic power for self-selected cycling cadence preferences. Further research is warranted to explore the potential of an active muscle volume based objective function for control schemes across a wider range of cycling conditions.

bioengineering↗

bioRxiv2022

The effects of crank power and cadence on muscle fascicle shortening velocities, muscle activations and joint-powers during cycling.

Whilst people typically chose to locomote in most economical fashion, during cycling on a bicycle they will, unusually, chose cadences that are higher than metabolically optimal. Empirical measurements of the intrinsic contractile properties of the vastus lateralis (VL) muscle during submaximal cycling suggest that the cadences that people prefer (i.e., self-selected cadences: SSC) allow for optimal muscle fascicle shortening velocity for the production of knee extensor muscle power. It remains unclear, however, whether this is consistent across different power outputs where SSC is known to might be affected. We examined the effect of cadence and external power requirements on muscle neuromechanics and joint powers during cycling. VL fascicle shortening velocities, muscle activations and joint-specific powers were measured during cycling between 60 and 120rpm (and the SSC), while participants produced 10%, 30%, and 50% of peak maximal power. VL shortening velocity increased as cadence increased but was similar across the different power outputs. Although no differences were found in the distribution of joint powers across cadence conditions, the absolute knee joint power increased with increasing crank power output. Muscle fascicle shortening velocities increase in VL at the SSC as pedal power demands increase from submaximal to maximal cycling. It therefore seems highly unlikely that preferred cadence is primarily driven by the desire to maintain "optimal" muscle fascicle shortening velocities. A secondary analysis of muscle activation patterns revealed that minimizing muscle activation is likely more important when choosing a cadence for given pedal power demand.

physiology↗