This is an excerpt from Cutting-Edge Cycling by Hunter Allen & Stephen Cheung.
Standing Versus Seated Pedaling
The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.
Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.
Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.
Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.
Read more from Cutting-Edge Cycling by Hunter Allen and Stephen Cheung.