How to use the Elevation Corrected Power chart in WKO4

One of the many benefits of WKO4 is the ability to create your own custom charts and graphs. You can make these as simple or as complicated as you like, and you can experiment with new ideas or find out if there is a correlation or trend you can learn from. But you don’t have to create a custom chart or know calculus, because there are many charts to choose from inside the Chart Library. You get to benefit from the brain power of super scientists and mathematicians like Dr. Andrew Coggan.

One of the charts Dr. Coggan created is the Elevation Corrected Power chart. We've known for years that the power you can generate at elevation is a lot less than the power you can generate at sea level. How much less depends on your elevation, your unique physiology, and a host of other factors, and Dr. Coggan has created a chart that considers these factors and, using the computing power of the WKO4 software, calculates what our power at elevation would be if we'd been at sea level.

At the 2015 USA Pro Challenge in Colorado, all of the riders were impacted by the elevation in one way or another. Australia-based Team Drapac rider Lachlan Norris proved to be one of the top riders, placing 6th overall. The team did what they could to prepare for the USA Pro Challenge before the race, but every rider is different, and altitude can be very difficult to deal with. After the race, Norris and the team shared his data with us to show what his power would have been had he been racing at sea level, which gives us a perfect example of how to use Dr. Coggan's chart.

Norris’s Elevation Corrected Power

Norris had many good rides during the week and came to the USA Pro Challenge on the heels of a stellar win on the final stage of the Tour of Utah. In Figure 1, Norris’ Average Power for Stage 2 was 187 watts and his sea level corrected average was 205 watts. Stage 2 had a combined climbing of 9,697 ft. The stage started from 6,800 ft., climbed to 9,000 ft. twice, and then finished at 10,000 ft. at Arapahoe Basin. The most dramatic difference between the two came in the first hour of the race as Lachlan climbed from 7,000 ft. to 9,500 ft. His Average Power for this section was 297 watts, but the sea level equivalent power was 342 watts.

figure-1_lachlan_stage_2_not_annotated

In Stage 4, from Aspen to Breckenridge, there was a tremendous difference in the sea level equivalent power and the actual power. In the first climb of the day over Independence Pass, topping out at 12,000 ft., Norris’ actual power average for the climb was 298 watts, but his Sea Level Corrected (SLC) was 328 watts. Notice in Figure 2, that the higher and higher he climbs, the more there is a discrepancy between his actual power and SLC. Near the top of Independence Pass, his actual power is nearly 60 watts lower than SLC.

figure-2_independence_pass_lachlan_not_annotated

In Stage 6, the peloton rode at some of the lowest elevations of the USA Pro Challenge and as a result, Norris’ power was very similar to what it would have been at sea level. For the entire stage, his actual power was 208 watts and his SLC was 218 watts, so a mere 10 watts different. Now, remember this might be the case for you, and everyone reacts differently to riding at elevation, but for Norris, 10 watts isn’t much. Clearly, he rides very well at elevation!

figure-3_stage_6_fort_collins_not_annotated

The Elevation Corrected Power Review Pack is a great tool in WKO4. Check it out in the WKO4 Chart Library and let us know what you think!

 

This article was written by Hunter Allen. You can read the original blog post here.

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