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.