How to interpret new FTP
I did my last NOS FTP test outdoors today. It was my first time ever doing an outdoor FTP test. I never had a good place to do this, but where we currently live, I am 1.5 miles from a flat road , extending 30 or so miles, bike lane and no traffic lights and light traffic. I did my 25' WU indoors on the trainer and then 20' FTP test outside. The reason for doing this is that heading east on that road ( only direction in which you can go to avoid lights and traffic), there is usually a head wind, so the way back I usually have a tailwind. I did not want to WU into the head wind and then be flying on the way back. I thought that may throw off my results.
20' NP was 294 watts, which puts my new and PR FTP at 279 watts. However that is outdoors. I have read in previous threads that outdoor FTP is generally 5-10% higher than on the trainer. My 'trainer FTP' is 258 watts. According to the the 5-10% estimate, that would put me somewhere in the 271- 284 watt range outside. My FTP of 279 watts is 8% higher than indoors, which puts my right in that range. Here is my ride on Garmin Connect: http://connect.garmin.com/modern/activity/674169992
How do I interpret this? I won't know for sure unless I test indoors, but from this result can I assume my indoor FTP would probably be about the same, maybe a 1-2 watt increase?
A couple of observations. Physically it was easier to do this outdoors. Usually around the 17-18 min mark on the trainer I start getting dizzy and it is probably because of less oxygen indoors, higher temps, harder for the body to regulate core temperature. I did not have this outdoors, however the fatigue on my legs, HR, and RPE felt about the same indoors and outdoors. Mentally I thought it was much harder to do this outdoors. Not having TR show you targets and watching sports or whatever to distract yourself makes it harder to keep pushing yourself. I was definitely doing more self talk and was having to dig deep to keep telling myself to keep pushing it.
Comments
"How do I interpret this?" It is what it is. There is no rhyme or reason for differences between outdoors and indoors FTP. Some people are higher, some lower, some the same, usually within a range of +/- 15%. We can speculate all day on the possible reasons for this, but in the end it doesn't matter. The primary use of your FTP is to guide your training and racing. So your outdoor FTP is what you'll use when training outdoors, and in those races you have coming up over the next several months.
"Can I assume my indoor FTP would probably be about the same...?" No. If you train indoors in the future, and you want an accurate baseline to guide that training, you;ll be best served by doing another indoors FTP.
One thing you don;t mention, is whether you used the same bike indoors and out. I assume you used a TT bike outdoors; if you were on a road bike, then the FTP obtained will NOT be useful for races in which you;ll be using a TT bike. IOW, FTPs are specific for location (in vs out), bike, and character of test (e.g., different trainers will have different FTPs, different Power meters will produce different results, different courses - hill vs flat - will produce different results, etc.)
Go back to the first principle - the use of the test is to guide training and racing. Therefore, the conditions of the test should replicate as closely as possible the conditions in which you'll be training and/or racing. Don't try to compare an FTP from one set of conditions to another - there's no point, it will just confuse your training and racing.
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