Training and Racing with a Power Meter

here's what I wrote and the figure that I attached (MFQA = multi-file quadrant analysis, AEPF = average effective pedal force, CPV = circumferential pedal velocity, F-V = force-velocity):

"(It is clear from reading various forums that many people still have difficulty distinguishing between strength and power, and hence truly understanding the determinants of performance in different cycling events. This post is another attempt to clarify matters. The analysis is really mostly just a repeat of what I posted to my personal webpages a number of years ago now, but using "cleaner" data from someone whose abilities and racing tactics are more typical than mine.)

The attached pic is a MFQA of a couple of ~1.25 h circuit/criterium races that my wife, Angie, did here in Missouri during her brief comeback in 2007. I'll get to the meaning of the solid and dashed red lines in a moment, but first, a little background about the two races, both of which included some "big ring" hills.

The 1st race (in Washington, MO) was a local P/1/2/3 event with only a handful of starters. One rider attacked right off the line, which quickly whittled the field down to just three, and then two. My wife then rode with this other woman until sprinting it outat the end. Since the field was so small and the race effectively tactically "neutralized", Angie's IF ended up being only 0.86, but with a VI of 1.17 due to the terrain.

The 2nd race (in Winghaven, MO) was a much more competitive P/1/2 NRC race, with (IIRC) approx. 40 starters. About one-fourth of the way through, Angie attacked for some KOM points and ended up riding by herself until the halfway mark. After getting caught by the field, she switched into "prime hunter" mode to try to lock up the KOM prize (a large basket of wine and other goodies worth more - to us, anyway! - than the 1st place prize). One rider slipped away with just over a lap to go to take the V, but the rest of the places were determined during an uphill field sprint. Since this race was more competitive and Angie rode more aggressively, her IF ended up being 0.94 (but 1.1 during her Andy Warhol time), with a VI of 1.22.

Now on to the lines I've added to the MFQA, and the point of this post: I chose these files because we had performed some carefully-standardized F-V testing on the Velodyne both when she first started training again (in February of that year) and a few weeks after the 2nd race. The results of the 2nd tests are shown by the solid red line, which depicts the maximal AEPF she could generate at any given CPV (while seated - more on this later). Since power is equal to force by velocity, each point also corresponds to the highest power she could generate at that CPV (cadence), with her maximal power of 742 W being produced at a CPV of 1.82 m/s (103 rpm). OTOH, the Y intercept of this relationship - labeled as "AEPF @ CPV = 0" - is, *by definition*, her maximal strength (which at the time was just over 800 N).

As you can see on the graph, at no time did she even come close to generating this much force during either of the two races (despite the sprints they entailed). Ispo facto, her strength was not a limiting factor to her performance. This is point #1 of this post.

More interesting, though, is to examine how close any of the points came to her AEPF-CPV line, as this illustrates the extent to which she was limited by her maximal *power* at that particular CPV/cadence. Again as shown on the plot, in the first race there are <10 points where her AEPF approached or even slightly exceeded (presumably due to standing, higher motivation when racing, and/or measurement error) the limit depicted by the dashed line. Although not evident from this plot, examination of the file reveals that this occurred during the final sprint. This is, of course, what you might expect, at least/especially given the way the race played out (i.e., more like a match sprint than a hectic field sprint where the pace is high for quite some time). Interestingly, though, despite giving it "full stick" to initiate the sprint, she failed to gap her competition, and only won the race because her anaerobic capacity ("speed endurance"). That is, she won the race not by sprinting faster, but by sprinting longer.

There were more moments during the 2nd race during which her AEPF fell close to the dashed line, but still only about 20 (at 1 s recording) in all. IOW, despite the repeated attacks, sprinting for KOM points, etc., during only ~20 s of the entire 1+ h race was she really utilizing all of her maximal power. The rest of the time, she was either not giving it "full stick", or was too fatigued at any particular moment to be able to marshall up all of the power her muscles were capable of generating when fresh. Upon examining the file, it turns out that those 20 points all occurred during a KOM sprint about three-fourths of the way through the race, which ultimately did not determine the outcome - in fact, rather ironically what decided who won and who finished 2nd that day was the power that *wasn't* produced when no one responded as the eventual winner rolled off the front.

So, what is my point #2? It is that while, unlike maximal strength, maximal neuromuscular *power* IS often a determinant of how a bike race plays out, this isn't *always* true. In fact, careful examination of multiple files using this approach shows we are far more often limited by how much power we can deliver *at that moment*, versus how much power we can produce when completely rested. Or, to put it somewhat more pithily:

"It's an aerobic (metabolic) sport, dammit!"

Andy Coggan"