Here’s an article written in Vision Quest’s December 2010 newsletter by Coach Jason Schisler. If you’ve ever questioned increasing cadence, he lays out the science behind doing it.
One of the central components of off-season training is improving your technical skills. On the bike, this includes looking at pedaling economy and potentially increasing cadence. A common mistake among new cyclists, and some more experienced riders as well, is a pedaling cadence that is too low. The aim here will be to offer insight regarding why increased pedaling may be beneficial to your performance and how you can go about spinning faster.
First, it is necessary to understand a bit of the science behind power production at different cadences as well as the related physiology. Physics tells us that power is the result of work divided by time or, in the case of cycling gear, ratio divided by cadence. What this means is that it’s technically possible to produce a given power in any gear on the bike provided the appropriate cadence adjustments are made. As you might imagine, the number of gears in which a given power can be produced efficiently is much smaller.
Laboratory testing attempting to determine the most economical pedaling rate has continually found this rate to occur at 50-60 rpm when viewed in terms of power produced in relation to energy consumed. Interestingly, it is also well established that both amateur and elite cyclists freely choose to pedal at a much higher and less metabolically efficient rate of 80-100 rpm. Although researchers have not been able to reach a consensus, one potential explanation could be the greater contribution of the cardiovascular system at higher cadences.
The heart and lungs that compose the cardiovascular system work nonstop, so while power production is lacking, endurance will not be a limiter. The muscular system, on the other hand, will recruit the minimum number of motor units to complete a task, which always starts with the weaker but more aerobically efficient slow-twitch fibers and progresses to the stronger but anaerobically fueled fast-twitch fibers as slow-twitch fiber capacity is exceeded. Adopting a pedaling rhythm that keeps the force requirements low enough to be sustained primarily by the slow-twitch fibers, and thus the cardiovascular system, can spare fuel in the anaerobic fibers and delay fatigue late in exercise.
Consider our earlier point that a given power can be produced with several different gearing and cadence combinations. For example, let’s take the power required to maintain 20 mph: approximately 200 watts depending on body size, aerodynamic drag and terrain conditions. You could ride at 200 watts in the biggest gear on the bike and cadence would probably be in the range of 40-60 rpm. Conversely, you could also ride at 200 watts in a more moderate gear and 80-100 rpm. In the latter case, you have cut the force requirement of each pedal stroke by half to a load within reach of the slow-twitch fibers, but compensated by producing that force more frequently to maintain overall workload.
Depending on your current preferred cadence, adopting a higher cadence may not immediately result in improved efficiency and delayed fatigue. Faster pedaling will result in increased breathing and heart rate at a given power output as demand on the cardiovascular system increases. The neurological system will also have to undergo some learning to become more efficient at rapidly cycling each motor unit at faster rates. On first attempt, it’s possible to actually fatigue more quickly, and it could take a month or more to adapt to these changes.
The approach to faster and more economical pedaling will not differ significantly from the approach you take to improve power, except that the emphasis will be on cadence rather than workload. Short intervals at high workloads are employed to increase sustainable power on longer duration rides. In the same way, short intervals of high-cadence pedaling will allow you to more easily maintain a high cadence on long rides. Two favorite routines follow:
* Spin-ups: start in a moderate gear at the top of a slight descent. Begin rolling down the hill and, as speed increases, don’t shift but continue to spin the gear faster until you start bouncing on the saddle. Recover and repeat this sequence, trying to smoothly spin a little faster on each attempt.
* High-cadence intervals: during a submax ride, shift 2-3 gears easier than normal and increase cadence to maintain power while maintaining smooth pedaling movements. Stay in this gear for 5-10 minutes and then return to your normal rhythm. Repeat several times over the duration of the ride.
With some patience and practice, you will soon find yourself capable of effectively using a higher pedaling rate. Whether you race on the track, in crits, time trials or triathlon, there are benefits to be gained. Make use of your off-season training to implement these changes and the adaptation should be complete by the spring and you will be ready for more focused work on energy system development.