So what happens if you keep pushing to finish an interval when the body can't deliver anymore?

Was struggling on Kaweah after an FTP re-test/bump, next to last interval got bad enough I had to keep my eyes closed to finish it and even then I started to get dizzy/the kind of effect one gets from lifting too hard when the world starts collapsing into one dot. Not bad but it was there. Doesn’t seem like anything bad happened, in fact I did a bunch more stuff later that day and was totally fine.

Anyway, that got me thinking – what is our fuse/protection from doing damage to the body during near-FTP intervals, given a person that has the mental strength to keep going? Faint? Simple inability to push the pedals hard enough?

If you ask David Goggins he’ll tell you when you’re at that point you’re only at 40% of your potential :smiley:


For pure endurance effort, sure, but I’m specifically talking about shorter, FTP level intervals. Which I kinda doubt the 40% rule applies.

Goggins, is there any evidence that he can coach anyone but himself? Is there a method? He’s certainly an inspiration but from what I can tell, he’s no Wim Hof.

HA! Yeah he’s a maniac, but I love how crazy he is!!

I think you will just pass out. You can quite often see it in marathon runners, or iron man event like runners who push it too far. The body just automatically shuts down, a build in kill switch to prevent you from killing yourself.

So I guess if you didn’t pass out then you still had something in the tank. So, train harder :stuck_out_tongue:


Yea, rowers are notorious for this passing out.

exactly, not sure we can actually get to that point!

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Doesn’t this sort of thing happen at either much higher effort levels (e.g. 1 500 to 10 000m runs), or much longer events where pure exhaustion comes into play (marathons, ironman, etc)? I suspect unless you’re in a really peculiar condition (very tired, fasted, high temperature, etc), you would just fail to keep going rather than pass out in a threshold effort which by definition lasts an hour or less.

Fainting towards the end of an interval. It happens to me on occasion. But if you finish it, you finish it, I tell myself, no pain no gain. Lifting mantra and discipline applied here

Sounds like your FTP is too high? 86 TSS for an hour should be doable, thats 86% of your FTP.

But to address ur question. people fed horses strong drugs to dull the pain and then they raced them as hard as they could. the horses ended up ripping the tendons from the bones and ended up having to be put down.

Not sure what would happen before then though, without drugs you would probably faint or throw up. doesn’t sound very pleasant.

Yeah, I’m gonna be the dissenting voice and say that if you feel faint / dizzy at any point in any workout, you should stop. Regardless of how often it might happen at the pro level, or in other sports, I’m strongly of the opinion that dizziness / fainting is a last-ditch defense mechanism of your body, trying to get you to stop right now.

Has this ever happened before? What is your typical “rev-limiter” (e.g. gagging)?

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Side note: Closing your eyes might have been the cause of dizziness. I definitely lose sense of balance and feel weird/dizzy if i close my eyes during hard workout. Mostly cause my brain is thinking I’m moving and have to balance like on a real bike. Same thing used to happen on treadmills.

Short intervals my legs simply shut down.
By that stage my heart and lungs feel like they are going to explode and although I haven’t vomited I have been right on the edge of doing so either collapsed on the bars or lying on the floor - not really a dismount, more of a collapse into a heap

Those guys have taken their glycogen stores to zero which is why they get loopy. It’s not muscle fatigue from a 2+ hour event.

I think in an interval you’d eventually cramp, or your cardiovascular system will give out and you’ll just have to stop.

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You can’t hurt yourself expect for the whole falling off your bike thing, which you could maybe bang your head on the way down from the trainer.

You also should probably not being doing such hard workouts too often as you’re definitely be accumulating a lot of fatigue. This type of push might help you periodically, perhaps you’re pushing through a plateau, but won’t serve you if you are doing it that often.

This all said I’ve never felt like I was being exhausted so much during a ‘near-FTP’ interval. I’ve felt a little light headed after finishing some very hard, short intervals well above FTP. If you are feeling like this after a threshold workout you should consider re-testing, you might be above your FTP. Especially if you find that you have trouble on your next hard workout.

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