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How To Analyze A Power File

In this Rock Star Triathlete Academy audio, Ben Greenfield speaks with TrainingPeaks chief evangelist Dirk Friel about how to analyze a power file. During the discussion, Dirk reviews the data below.

It is highly recommended that you click on the links for each report below as Dirk walks you through analyzing the power files. You’ll learn what to look for in a power file, how to identify areas that need improvement, and what makes for a good workout and race!



Ironman Kona

Michael Weiss SRM Bike Analysis 2011

File Viewer <–click here to view the file

Did Not Finish Ironman Hawaii. Dropped out at mile 14 of run.

Bike Time: 4:25 (16th fastest among pros)
Average watts: 317w (326np)
79kg= 4.0 w/kg
Average cadence: 89rpm
Average Speed: 25.5mph
Work: 5026kj

Austrian professional triathlete Michael Weiss did not have the race he had envisioned in this year’s Ironman Hawaii. Weiss had a very strong bike and solid run in 2010 which lead to a 13th place finish. However this year’s race ended with exhaustion half way through the run.

Weiss came out of the water in 43rd place (57:21) which meant he had to chase hard on the bike for the first hour in order to catch the first group of 20-some pros. He is a very strong cyclist, but having to make up so much time on the bike certainly didn’t help him finish with a strong run.

Weiss describes his Kona experience as, “I came out of water ~5:30 behind the main pack. I averaged 347 watts in the first hour to close the gap on the chase group. I caught a smaller group for the last 15 miles and settled into a more comfortable pace to recover for the run. Ran the first 10 miles in 1:05hr, but hit the wall around mile 14 where I was unable to recover and withdrew.”

The Numbers Don’t Lie

By looking at his SRM power data in TrainingPeaks you can easily see how hard he chased the first half of the race. For just over 2hrs he averaged 343w, whereas the last 2hrs of the race he averaged 292w. A 50w difference took a lot out of Weiss which certainly showed later on. Not only did he average 343w for the first 2hrs, but he also started out with his first 10-minutes on the bike at 372w average! Wow big time numbers!

Weiss will certainly not ever forget this day and will be back with a vengeance no doubt.

Side note: IMAZ 6 weeks after IM Hawaii Michael rode a 4:24 bike (7th fastest) and he went on to run a 2:59. Finish time-8:21, 8th overall)


Ironman Kona

Shawn Burke- M45-49

Coach – Alan Couzens

Race File (Power-Tap) <–click here to view the file

2011: 10:00:27 (31st place)

Bike 5:15
207w, 218np
1.05 very good VI
86avg cadence
Hawi Climb- 27′ 221W avg

Peak 30′ was on the way back which is impressive. You had energy left in the tank for sure!
avg 223w for 30′ within the last 90′ of the bike.

Overall decoupling was great at 2.3% Power:HR. Very fit and paced it well.
1st half- 210w avg
2nd half- 204w. perfect!

avg 7:59 marathon splits (3:29)
134avg HR

Comparison to 2010 Ironman Hawaii

Time- 10:18:00
Bike- 5:17
195w avg , 211np
Max 30′ was 221w
88avg cadence
131avg HR


Michael Weiss Xterra World Championship Victory at Xterra 2011

File viewer: <–click here to view the file


Wow. holy cow.

-Michael averaged 350w for 1:17! His normalized power for the race was 442w!

Normalized power is a more accurate indicator of the watts he would have held if he rode at a constant pace.
Notice the VI is very different in Xterra vs IMKona (1.26 in Xterra vs 1.03 in Kona). VI is the variability index and shows how steady the effort was. A constant output would equal 1.0 which is almost exactly what Kona was. Xterra however had a much larger wattage range and there was very little consistency within the effort (hence a VI of 1.26)

-He rode 20% above 450w (15 minutes) in Xterra vs 2% (5-minutes) of the time above 450w in Kona

Mountain biking is a lot of accelerations plus a lot of coasting up and down hills. The fastest way to complete a long distance road-TT is a constant effort, vs the fastest way to complete a MTB race is to push the hills really hard andkeepthe momentum up on downhills where there may be very short hills or twists and turns.

-First 42’ had 1780’ altitude gain which translated into 372w, 400np VS the last 34’ with 1800’ loss and 318w, 480np.

Because he could recover so much on the descent the 2nd half he could push the pace on the short hills and turns. I found one 3’ stretch where he did 9 efforts of 10-20” each at 450+ watts, other than that he was coasting. The avg watts was only 192w for that 3’, but the actual physiological affect was well over 450w. Eventhough the avg watts was only 192w for that three minutes his body was going 100%, lactate was high, heart rate was high and the average watts don’t reflect that.

This information is perfect for triathlon coaches to help their triathletes learn more from workouts and races, so if you’re interested in our “Business of Triathlon Coaching” membership option, simply click here to join the Rock Star Triathlete Academy, then review your upgrade options within the membership area! Upgrading to our coach option gets you instant access to learn how to be a better triathlon coach, and is just $10!