PezCycling News - What's Cool In Pro Cycling : Sit or Stand: Tradeoffs in Efficiency?

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Sit or Stand: Tradeoffs in Efficiency?
Varying our positions on the bike is required in order to adapt to different terrain or riding situations, or simply to give our body a break from being stuck in the same position and stressing the same muscles. While we know that standing is great for giving us more power, what are the effects on metabolic demand and efficiency?

Boy You’ve Got to Carry That Weight…
When we think of weight-bearing exercises, the first and most obvious one is running. That’s because, in addition to propelling yourself forward, a lot of energy is required simply to keep yourself upright and stabilize yourself. Added to that is the impact force from landing on your feet each stride. It’s the combination of the two that makes for a much higher heart rate, metabolic rate, and overall stress when running compared to cycling, and which helps explain why Lance felt the NY Marathon was tougher than any ride he did during his cycling career.

Cycling is mostly a non-weight bearing activity, and the bicycle is a highly efficient machine especially because it removes the impact forces and also because the cycling position cradles our body and minimizes the need to support our own weight for the large part. However, there are times where we have to support a good deal of our body weight, and that’s when we’re standing. Whether it’s on the flats, the hills, or in a sprint, we are no longer supporting weight on the saddle, and have to rely on our muscles more to keep ourselves upright.

Sit or Stand: Tradeoffs in Efficiency?
Of course, this is why standing typically costs more energy, but it’s also the leveraging of more of your body weight over the pedals, along with the recruitment of additional muscles, that produces the higher power outputs possible when standing as opposed to sitting. This is one of the main reasons why we’re generally taught to keep the standing to a minimum and when you need extra power, such as initiating an acceleration (e.g., sprint, breakaway) or when you need the extra power while climbing. Wind resistance is also higher while standing due to the larger surface area you’re exposing.

I have written extensively on efficiency in various forms over the past couple of years on Toolbox, and that’s because it is the single biggest pathway to increasing the power output you can lay out on the road. To refresh your memory, check out the article on Lance’s improvements in pedaling efficiency from 1993 through his first Tour victory. So this begs the question: while standing may provide more power and also cost more energy, is there a difference in the efficiency (gross efficiency defined as power output : energy consumption) between standing and sitting?

To the Books
You know where I’m heading with this – straight to the library. Doing so is always such a humbling experience, because I almost always come across one of those “why the heck didn’t I think of doing this?” experiments that have me kicking myself.

This time around, it’s a French research group from Montpellier that’s making me making me black and blue from the kicking (1). The experiment itself is ridiculously simple: have fit cyclists ride for 6 min at 75% VO2max in the following conditions:
1. flat (velodrome) in a seated position (done twice).
2. 5.3% gradient hill in a seated position (done twice).
3. 5.3% gradient hill in a standing position.

Seated position consisted of riding in the drops. Standing position was done with the hands on the hoods.

Subjects also did a 30s all out sprint in three conditions over the same day:
1. on a stationary indoor bike (Wingate test, a standard anaerobic power test).
2. seated on a slightly ascending road.
3. standing on a slightly ascending road.

Thanks to the improvements in technology, the researchers were no longer constrained to the lab and could take this study out onto “real” terrain and on the subjects’ own bikes, increasing the applicability of the study. Namely, each subject’s bike was equipped with a SRM “Pro” crankset to determine power output. To measure energy consumption, subjects carried a small and highly portable Cosmed metabolic cart, weighing about 1 kg or less.

Data analysis consisted of calculating “gross efficiency” (power compared to energy consumption). 100% would mean that every bit of energy was converted from chemical to mechanical energy and producing forward motion. This is pretty much an impossibility, and humans are typically 20-25% efficient, with the remainder of the energy converted to heat energy. Also calculated was “economy,” or the amount of power produced per each litre of oxygen you breathed in. Typical values are about 4-5 kJ of mechanical energy per litre of oxygen.

Just the Facts
Very simple and nicely designed study. What were the results?

• Subjects were 8 highly-trained cyclists, including 2 professionals riding 20-30,000 km/y. the others were elite junior or national-level cyclists.

• As expected, power was not different across the different positions, because subjects were required to keep a similar 75% VO2max workload. Wattage was about 290 W for the 6 min, not easy!

• Also as expected, heart rate was about 8 bpm higher when standing compared to seated uphill. Ventilation was also higher, though no differences were seen in oxygen consumption. Cadence was similar at just under 60 rpm in both conditions.

Most importantly to answering our question, no differences were found in either gross efficiency (~22.5%) or economy (4.7 kJ of power per L of oxygen).

• In the 30s tests, maximum and mean power were much higher in the standing than seated positions (mean power of ~820 and 650 W, respectively), despite similar cadences and blood lactate values.

Summary
For the large part, the findings of this study are not major surprises, nor were there any surprises intended to begin with. The ability to produce higher power when sprinting and standing is fairly evident, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, and the interesting nugget of information is that there were no differences in efficiency or economy while standing or seated.

This means that, while standing is a bigger stress on our aerobic and cardiovascular system, it does not necessarily mean a decrease in efficiency itself. So standing is not going to disproportionately cost more energy to perform, when you factor in the greater power you are generating. Applying this information to the road, you are NOT “wasting” energy by standing.

The caveat, however, is that practice is required to build good form and technique while standing, and likely especially so when you start becoming tired and fatigued. I remember during my graduate days at Simon Fraser University, I would often practice my technique by standing up the entire 5 km of the 8% hill up to campus.

Another caveat is that all of the subjects in the study were young, lean, and light, averaging 67 kg. If you’re a bigger rider, the efficiency equation might remain tilted in favour of sitting. Regardless, practice remains a vital component of good technique, so keep mixing up your workouts and remember that technique and efficiency remains the key to maximizing cycling performance!

References

1. Millet, G. P., C. Tronche, N. Fuster, and R. Candau. Level ground and uphill cycling efficiency in seated and standing positions. Med Sci Sports Exerc. 34:1645-1652, 2002.




About Stephen:
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University, with a research specialization in the effects of thermal stress on human physiology and performance. He can be reached for comments at stephen@pezcyclingnews.com.
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