Cadence, power, and muscle activation in cycle ergometry

Purpose: Based on the resistance-rpm relationship for cycling, which is not unlike the force-velocity relationship of muscle, it is hypothesized that the cadence which requires the minimal muscle activation will be progressiv ely higher as power output increases. Methods: To test this hypothesis, sub jects were instrumented with surface electrodes placed over seven muscles t hat were considered to be important during cycling. Measurements were made while subjects cycled at 100, 200, 300, and 400 W at each cadence: 50, 60, 80, 100, and 120 rpm. These power outputs represented effort which was up t o 32% of peak power output for these subjects. Results: When all seven musc les were averaged together, there was a proportional increase in EMG amplit ude each cadence as power increased. A second-order polynomial equation fit the EMG:cadence results very well (r(2) = 0.87-0.996), for each power outp ut. Optimal cadence (cadence with lowest amplitude of EMG for a given power output) increased with increases in power output: 57 +/- 3.1, 70 +/- 3.7, 86 +/- 7.6, and 99 +/- 4.0 rpm for 100, 200, 300, and 400 W, respectively. Conclusion: The results confirm that the level of muscle activation varies with cadence at a given power output. The minimum EMG amplitude occurs at a progressively higher cadence as power output increases. These results have implications for the sense of effort and preferential use of higher cadenc es as power output is increased.