I do not own a power meter, and I found that they are somewhat expensive so I bought a mid-range smart trainer which provides me with my power numbers. Being obsessed with these numbers, I do all of my high-intensity workouts (excluding endurance and sprints) indoors on the trainer. Does this mean that my FTP could be lower outdoors, and could doing all my training indoors hinder my outdoor performance?
Thanks
Usually people do better numbers outside. You could struggle indoor due cooling, dehydration or other factors - this could impair your performance inside but usually not outside.
When it comes to steady power in long duration they are close after some time, shorter power is better outside due bike movement and inertia (1 min efforts and particularly sprint). If you improve indoors you will improve outdoors.
What can you struggle with is holding your power on flats vs climbs (it is way easier on the climbs). But still your FTP will be the same or higher outside.
I am doing 99% or training inside and when I go outside is a little different due inertia, bike movement etc. So for example my HR is usually a little bit higher outside but the RPE lower.
If riding exclusively/mainly indoors, I would make sure to supplement with some core work.
Sitting in a static position for hours on end (when compared to the more dynamic movement experienced outside) does nothing for the small, but very important, muscles!
I second everything @jarsson said.
Feels easier to hit the numbers outdoor. Also have a bit higher HR outdoor, guess because you have to keep the bike upright, using just a bit more muscles.
Your FTP is your FTP. It is a physiological state. That being said, you may be able to do more or less power outside vs inside. When people say they have a higher outside FTP, it just means that they can produce more watts for whatever reason. But the body doesn’t magically change outside.
I think I’d phrase this as: you need a few outdoor rides for your body to adapt neuromuscularly. These days, smart trainers can do a pretty good job of simulating the feel of pedaling IRL. However, they still aren’t 100% the same, especially all the little stabilizer muscles you don’t think about when you’re outdoors but you’re using them all the same. I’d assume that a rocker plate gets you a bit closer still.
That said, this year was my first with a smart trainer. The adaptation process seemed to be a lot easier compared to the bad old days with dumb trainers and DVDs!
Everyone is different, personally I’ve found doing all my training in Erg mode will impact outside performance. Mixing inside and outside riding fixes most of it. Doing all my training outside produces best results. The results have been clear since I bought Kickr four years ago.
Making inside more like outside helps - turn off Erg, ride in standard/level mode or better yet sim mode in Zwift using bike computer to guide me on intervals, and do my own warm up and cool down.
The reasons appear to be partly mental (easier to go hard outside) and how my body responds (better with a little anaerobic/sprinting every ride). Those are educated guesses, all I know for certain is that training outside makes me fastest.