Tuesday, January 5, 2010

Raising the stink of increased cycling efficiency: Part Two

In my previous post, I argued that the cardiovascular / aerobic model, with its emphasis on VO2 max is flawed. Two factors (1) muscle type and (2) maximum pumping capacity of the heart are better indicators of performance than V02. The varying VO2s of top runners is evidence: Steve Prefontaine's and Frank Shorter's VO2 maxes differed by 16%, but their mile times differed by only 8 seconds. VO2 is generally correlated with better performance, but athletes with similar VO2s have very different performances. VO2 is also flawed as a measure of long-distance cycling performance because the test is conducted over a short period and does not measure fatigue resistence over longer duration. For example, a bike race.

For training does it matter what the hell we call the X thingee that makes us go / prevents us from going? Does it matter?

In short, yes, there is a difference.

An alternative to the cardiovascular / aerobic model Noakes calls the Biomechanical model. The emphasis is on efficiency. Cycling efficiency is defined as the amount of oxygen used at a given effort. Conley and Krahenbuhl (1980) found that economy is a much more accurate predictor of performance than VO2.

One famously disputed study showed that between 21 and 28 years of age, Lance showed an 8% improvement in cycling efficiency. That is, at a given steady state, his power production improved 8%. The author, Coyle, speculated that Lance's daily 3-6 hours on the bike contributed to the improvement. The testing was conducted in November, however, amid the heyday of EPO. Although its conclusion (that Lance improved because of efficiency improvements, not VO2 max improvements) are important, its conclusions about how Lance achieved his efficiency gains are practically useless.

Notwithstanding the dubious speculation of Coyle concerning Lance, researchers have pretty good evidence that the most significant effect of heavy training is on efficiency. When you ride hard and often you become efficient.

Cycling efficiency has two components: mechanical and biological.

Focus on your pedal stroke to improve mechanical efficiency . Power cranks, single-legged cycling drills, cadence drills--all of these have been recommended as tricks to improve your mechanical efficiency. Stephen Cheung has even examined the importance of balance between the left and right leg (his conclusion here). Bike fit is also a factor (visit the Bike Rack January 9th for a professional fitting).

Biological effiency is a more complex and unknown factor. Furthermore, you can't improve biological efficiency by aligning your knees or by telling yourself to relax or keep your cadence under 130rpms. The goal is to improve whatever it is that takes in oxygen and food and turns it into energy in your legs. The bad news is that there are several models that explain how this happens.

The good news is that even though we don't know exactly how our bodies become more efficient at the biological level, we do know what stimulates increased efficiency. Think of it as a black box with a skunk inside; if you shake the box, you smell the skunk--the smell of the skunk being, in this case, the smell of your increasingly efficient muscles.

Shaking the black box and making the stink...that will be the subject of my next post.

1 comment:

Tim Rugg said...

Bring on the stink.