The long turbo sessions, I prefer to call them sessions rather than rides, are mind altering. This was my experience on my virtual IoW ride.
The first hour or so is just like a normal go on the trainer. You're in a familiar place doing the usual thing but at a slightly less frenetic pace, knowing I would be there for a while I took it easier to begin with. The second hour is just an extension of the first. You get into the rhythm of the slightly lower intensity and trundle along to the music or video or whatever you are doing in addition pushing the pedals round.
The third hour you start to pick up on the little niggles of your riding position. You begin to stand up more frequently as the sit bones start to irritate you. Your hands start to give you grief so you start moving them around a lot more. You start to feel as though you want to hop off the bike for a pee, but fear that you will not want to get back on, so soldier on.
The fourth hour was where it went dark for me. The ' I'm gonna complete this ' mentality kicks in and you body really starts to moan at you. The hands hurt, the feet hurt, the sit bones hurt, the back starts to poke at you to remind you it's there. My legs surprisingly didn't hurt much, but I was not racing, just trundling along. The last 15 minutes was where I went a little loopy.
The end is near and I was fearing a bsim crash taking all my hard work with it. I wanted it to be over. I had kept myself fed and well watered so I needed the loo. The choice of riding position is by now a 30 second relief point, hoods 30 seconds, stand 30 seconds, bar top 30 seconds, upright 30 seconds and so on. the last k's arrive and you are counting down the centimeters until the finish. Done
.
With it over and done with you wonder what you have just done and try to switch off the pain of various parts. You get off the bike and stagger to wherever you need to go, for me it was the loo.
I was left wondering if I'd want to do that again. IRL riding gets you somewhere that virtual riding doesn't. But virtual riding allows you more options in the manner in which you attempt the longer rides. It just takes a while to work out if it was worth the effort you put in. In my case I think it was as I now had the knowledge of longer rides than I had attempted previously. I just know that I can do them now and although difficult the sense of achievement is immense. I just need to get IRL rides done more often now
TL;DR Long trainer sessions hurt various parts and you wonder why you did it.