Power File Analysis: IMWI '11 - Scott Roehrborn - KQ
Posted Oct 01 2012 7:15am
A few posts ago, I asked for some power files to analyze and post. I received one from Scott Roehrborn, an ex-teammate of mine from the Gear Grinder team. It's from Ironman Wisconsin 2011, where he qualified for Kona.
To give you a little background on Scott, He's 40, 5'9" and 138 pounds. He has 20+ years of multisport experience with a running background going back to high school cross country and track. He's a self-coached athlete and this was his fifth Ironman, all of them being IMWI. His threshold is 235w.
There weren't a lot of surprises in his file. He did a great job pacing himself, as expected. Typically, when people qualify for Kona, their power files are great examples of pacing.
Taking a quick look at his metrics from the ride, there are a few key things I want to point out. First off is that Scott rode at an Average Power that is 68% of his threshold and his intensity factor was .71. This is on the lower end of recommended zones for Ironman so Scott may have ridden more conservatively than he needed to and left a little time on the table, but that's hard to say for sure. I'd have to see the data on his big training rides because ultimately you need to decide how to ride on race day based on your long rides, plus he qualified for Kona by taking 5th in his age group so it's hard to say he didn't pace himself well. He clearly did. But I see potential for faster bike splits by riding at 72-75% of FTP and an IF of .75-.78. This depends on Scott's bike fitness and how confident he feels he can ride that hard for 112 miles and run well.
Another metric worth pointing out is his VI at 1.04. That's low for the Wisconsin course and a sign of very good pacing. This means he controlled his effort and didn't hit the hills too hard, but also kept his power up on the flats. Basically, he spent a lot of time right around his goal power. VI is NP/AP so you can see his Normalized Power and Average Power are very close.
Sidenote: I read a really good summary of what Normalized Power and Average Power is that I want to share: Normalized Power is how hard you worked, Average Power is how fast you went.
Scott's TSS is 279, which is good. A general rule of thumb is to try to keep it below 300. He burned almost 3200 calories and had a cadence of 93.
When looking at an Ironman power file, one place I like to start is the power zone distribution:
Power Zone Distribution
This is a great example of good pacing. Scott has the majority of his time in his endurance zone (51%) followed by tempo, recovery and very little time at threshold and above. You can get away with more time in the tempo zone, but that depends on your strengths and weaknesses. Strong cyclists will be able to push closer to the top end of the endurance zone and will end up with more time in their tempo zones. This power distribution looks really good.
Power Distribution By 20w Zones.
This is his power distribution broken down into 20 watt zones. A few things to point out - the tallest bar is 160-180w. Scott spent nearly two hours right in that zone, so nearly 36% of the right was right at Ironman power. Another thing that stands out is the 0-20w bar - that's time spent coasting. Scott spent 18 minutes coasting, only 5.5% of the ride. One last thing to point out is how quickly the bars drop off to the right of the tallest bar. This shows little time spent around and above threshold. This is where his low VI came from - very few hard efforts, very little coasting, lots of time right at goal power.
Time Spent Above Threshold
I always like to create this chart, which just shows all time spent above threshold. For Scott, that came to less than 10 minutes. That's very good for a course like Wisconsin with all the short, steep climbs. This shows a lot of patience and discipline on Scott's part.
Power With Threshold and Trend Line
In the chart above, blue is power, red is threshold, green is the power trendline. Here you can easily see how little time Scott spent above threshold and how he doesn't have any sustained efforts at or above threshold. His power trends downward slightly, which isn't bad. That's pretty typical. You can see he basically maintained even power throughout the entire ride.
If you're unfamiliar with Quadrant Analysis, the horizontal line is Scott's threshold. The vertical line is threshold cadence. The line you need to be most concerned with here is the horizontal line, the division between quadrants I&II and III&IV. It might be hard to read, but the big thing to point out in the quadrant analysis is how little time Scott spent in quadrants I and II (the top two quadrants). Those two quadrants really zap your strength and glycogen. For an Ironman, you want your power in quadrants III and IV. The way to accomplish this is to limit your time above threshold (recurring theme if you haven't picked up on that yet :)
Nutrition: I always like to take a look at nutrition because I think one of the big advantages of having a power meter is that you get accurate calorie information (KJ = Calories burned). A lot of people get hung up on calories vs. body weight or how many calories they think they can take in per hour, etc. I like to compare calories taking in vs. calories burned. I've had good luck replacing around 40% of calories burned. (Gordo Byrn recommends replacing 50% of calories burned ). Scott took in 1400 total calories on the bike (250 per hour), which was a mix of Carbo Pro and 4 Espresso gels with caffeine. He burned 3,176 calories so he replaced about 44% of the calories he burned.
Overall, this file is a great example of how to pace yourself well and set up a good run. Obviously, it takes a certain level of fitness to KQ, but one of the biggest keys to qualifying is proper pacing on the bike. A lot of people throw their races away in the first two hours on the bike because they lack the discipline and patience to hold back. Scott held back and was rewarded with a ticket to the big island.
One last sidenote: Scott rode a 50/34 compact crank with a 12/27 cassette and said it was perfect (I ride a 50/34 compact with 11-25 cassette).
Scott is racing Kona in a couple of weeks, and if he can pace himself this well again I think he'll have a good race. Good luck in Kona, Scott. Thanks for sharing your power file.