Tuesday, March 25, 2008

Numbers in Power

I've been skiing and riding pretty hard all winter. Lots of hard days, lots of long endurance days. But when I give up half my riding hours to skiing some weeks, I pause to wonder how much cycling fitness I give up. I'm quite confident the skiing keeps the core cardio engine in peak shape. Skiing 50k in three hours in the mountains is harder than any hilly 5 hour training ride I do. But skiing is a lot about upper body, something I utterly lack going into winter and barely begin to build by the time snow melts in spring. Upper body is of dubious value to a cycling climbing specialist. It might be lean muscle mass, but not in the places you want. Ever see pictures of elite cyclists with their jerseys off? They don't carry any excess baggage up top. I might gain only a pound or two of muscle over the 4-5 months I roller ski and skate ski, but I also may lose a little leg muscle mass. Skiing is so much less leg specific. It does not tax your quads nearly as much as cycling does.

So I've been getting some good training rides in lately. I feel good on the bike, seem to be riding strong relative to my peer group. I've done a couple benchmark intervals recently, and results were mixed. One was up Pead Hill in Wilton, the other Chestnut Hill in Amherst. Now this time of year, I tend to not ride a good bike, and it still remains cold, necessitating bulky clothing layers. Cold air is more dense too, creating additional resistance to forward motion. So it is really hard to quantitatively judge fitness based on these efforts, as I don't have an established bench mark like 23 lb bike, 32F temp, three layers of clothing on, etc. So how does one go about establishing a fitness benchmark?

With a power meter of course. I finally broke down and put the Power Tap wheel back in my Dean El Diente road bike. I use this bike for most of my road racing. I wasn't particularly recovered from my big volume/intensity weekend, but today was a good one for a long, hard training ride. Tomorrow looks like snow, yet again. So on my lunch break I planned to hit Chestnut Hill and Mt Uncanoonuc, a 35 mile loop with 2500-3000ft of climbing.

Triathlete Dan started with me, although I rode him off my wheel at one point trying to get my legs going. It takes about 30 minutes of hard paced riding to get to Chestnut Hill from work. I was well warmed up when Dan split off to continue his flat "tri friendly" route. After soft pedaling two more miles to base of climb, I started the interval.

Chestnut Hill gains most of its nearly 600ft vertical in the first mile. Then there is a long, gradual grade section very exposed to any wind that turns into a steep-ish punch to the townline sign at the summit. I held good power on the steep part, and as usual, struggled to maintain power on the flat part. Then while already on the verge of puking, I big ringed it up the finishing pitch. Extremely unpleasant, but very effective psychological training. I tell myself I can always hurl AFTER I hit the lap button at the top.

So my time was a so-so 9:05 minutes. That is actually quite good for March, but well off my PR of 8:14. So if I simply used my stopwatch to gauge my fitness, I'd say I lost much since last August when I did 8:14, maybe as much as 10%. But the PT tells a different story. You see, I was bundled up in full winter gear today (+32F at ride start), had modest headwind on the exposed part, and took two large water bottles along for the long ride. My power was 5.2W/kg for over 9 minutes. That is not a PR either, but it is within 2% of PR power for this climb, and almost certainly the highest power I've pushed in March. I can climb this hill much faster in better conditions at lower power. It is hard to sort out all the variables to arrive at a true fitness number.

Typically, my weight drops over the next few weeks, and my power goes up. This puts my W/kg at threshold in a very good pre-season position. I will continue to train with the Power Tap, but my main reason will be to re-align perceived effort with what I am actually doing. On a hill like Chestnut, it is so easy to go into it too hard. Any measly seconds you picked up at the bottom are paid back with big interest payments later in the climb. It is very well established that optimal time trail efforts are steady power. In practice, you almost need to shoot for negative time splits, and you'll still find you went out too hard. This can apply to non-TT scenarios too, such as in road races. Occasionally, I find myself "out there." How do you pace yourself? You go don't go any harder up the hills than you do going down them. That is the best way to put minutes on the field.

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