Why do my legs stop spinning while doing intervals?

Sometimes when I am doing VO2 max intervals, my legs just stop spinning. I just cannot restart, I do a few rotations and then they stop. Then I can only do light spin and cannot mentally make them work hard again. This usually happens in the end of a session. I do three or four intervals OK, then this happens. What is this? Is it overtraining, lack of motivation, nervous system issue?

Amber did a deep dive a few podcasts ago about subconscious responses to things your body perceives as a threat. Quick clip link below. Recently I have had the same issue, BTW.

I am sorry, this looks like a link to TrainerRoad playlists. Do you mean the one #285, about choking? If so, this does not look like the right answer. I do not feel nervous for any reason, I just feel like my body can complete the intervals, I do not even feel tired, but some neurotransmitters just stop firing.

So it sounds like you are aware of this as a mental issue and so possibly the following advice isn’t helpful, but I’ll mention it just in case:

Are you riding in ERG mode? If so, you may be entering the “Spiral of Death” with the trainer. Since slower cadences require more resistance to equal the same power output, if you start to spin too slowly, the trainer will keep adding more and more resistance until it is basically impossible to turn the pedals. The solution is to keep your cadence high and to begin raising your cadence before the start of the interval to stay ahead of this resistance switch. For VO2 max stuff, you’ll probably want to be at a cadence of at least 100, maybe even 110 or higher if you can handle it.