Interactions between cadence and power output effects on mechanical efficiency during sub maximal cycling exercises

Area of Science:

• Exercise Physiology
• Biomechanics
• Sports Science

Background:

• Cycling efficiency is crucial for performance.
• Understanding the interplay between cadence and power output is key to optimizing cycling.
• Previous research has explored these factors individually, but their interaction requires further investigation.

Purpose of the Study:

• To investigate the interactive effects of cadence and power output on cycling gross efficiency (GE).
• To determine the cadence that maximizes efficiency (CAeff) at different power outputs.
• To analyze how variations in cadence and power output influence energy expenditure.

Main Methods:

• Fourteen healthy subjects completed constant power output tests at 40, 80, 120, and 160 W.
• Within each power output test, cadence varied across five bouts from 40 to 120 rpm.
• Gross efficiency (GE) was calculated as the ratio of mechanical energy to energy expenditure, measured over the final ten respiratory cycles.

Main Results:

• Gross efficiency (GE) demonstrated a peak at each power output, corresponding to a specific cadence maximizing efficiency (CAeff).
• GE generally increased with power output across all cadences, approaching a theoretical maximum.
• Significant interactions were observed: the influence of cadence on GE diminished linearly with increasing power output, while the impact of power output on GE grew exponentially with higher cadences.

Conclusions:

• Cycling efficiency is significantly influenced by the interaction between cadence and power output.
• Deviations from the optimal cadence (CAeff) reduce efficiency more substantially at lower power outputs.
• Higher cadences lead to greater increases in cycling efficiency with rising power output, primarily due to altered energy expenditure patterns.