Leg death during a ride

More an open question as I’ve not really had this before. Did a club ride out (Mixed XC type) and for the last 20% of the ride my legs seemed to just die on me. This is likely due to the effort being a bit above my solo pace with lots of shortish sharp climbs with some loose and techy bits.
These pushed me a bit with some being max efforts and not many stops, or recovery moments. My fitness seemed ok with my cardio not really too flustered and holding fine but my legs just died towards the end to the point the other gents had to back off on the return run, especially on hills as anything above half ftp seemed to build up high discomfort and I couldn’t hold.

I’m curious what’s going on with it. Is it simply just fatigue and muscle failure from load? Calorie intake was pretty good so hopefully not that, it did not feel like a bonk.
Is this something that can be recovered on the day or did I just burn out my legs present ability and need to recover and keep training them (the long haul).

Sounds like a bonk to me. Can you quantify “pretty good” carb intake? If heart rate was under control, upping your cadence may have shifted your cardio and leg load balance.

Either way, in my experience once the legs are gone, they’re gone for the day.


From everything I have read and from a couple of experiences, bonking is a near full body shutdown that can include dizziness and nausea and can be relieved with ingestion of calories somewhat.

This was literally just my legs seemed to die off to the point any attempt to push on gave severe discomfort that limited me, it wasn’t pain as such. I wasn’t hungry, my heart rate and lungs were under control, everything not my legs felt fine and only slightly worn. If I stopped briefly I got a tiny bit of recovery but nowhere near normal.

I was carrying about 1k+ of calories, mainly carbs. Think I had got through about two thirds coming into the fourth hour of riding. I had breakfast fuelled a couple of hours for about 1k cals prior to riding so should have had enough with my glycogen onboard.

I’m guessing I just blew my legs up then really with no way to recover it on the day? Just need to keep getting stronger then.

How much time did you spend in VO2 max zone and above? Lots of hard spiky efforts will kill your legs regardless of how well you fuel, and there’s not all that much you can do about it on the day other than taking a prolonged stop (and even then you’ll still be fatigued). It’s why people talk about “burning matches” in racing - when you go repeatedly hard at the start of a race (through attacking or just responding) at some point you’ll find your ability to accelerate is just no longer there.

Can be improved somewhat by training those kind of efforts. Raising your FTP also enables you to stay with your mates without digging quite so deep. Or sag climbing where you anticipate the climbs and get to the front before them then gradually drop to the back of the group on the climb. Doing a climb at VO2 instead of anaerobic makes a huge difference to how quickly you tire.


That’s what I hear! :smiley: I’ve never bonked so I can’t say.

It sounds to me like you depleted glycogen during your ride. Maybe you were unable to fuel properly the night before or have the best meal before the ride. So localized muscle glycogen wasn’t topped up…ride effort caused you to utlilize a lot of muscle glycogen…and you started to experience muscle fatigued due to localized glycogen depletion.

I’m just speculating because there isn’t enough information to say for sure. But, ask yourself, did you eat well the night before and the morning of the ride? Just something to think about.

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You’re just not fit for it yet. Endurance pace always feels easy, that’s the point of it. Repetitively going above it is what’s hard. That’s why in races there are repeated attacks. Eventually, some competitors just give out and the group dwindles.

Don’t worry about it and keep training. You’ll get fitter and last longer.


Have you done this ride before? Do you regularly ride that far and that hard? What I find when I go do a big event that is longer and/or harder than I regularly do, is that my legs can just run out of gas. No amount of water, sugar, or salt fixes it (although it can prevent horrible cramping). I know they’ve often said in the podcast that you don’t need to do big rides to train for big rides, and I agree, that’s true, you don’t NEED to, but if you want to do well and enjoy the whole experience, I’m a believer in getting in those long training rides.

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I’m training up for a 100 miler XC event so building and pushing. This I think is the longest I’ve gone with hard efforts so they took me beyond my muscular endurance limit I think. I was also single speeding with them a bunch which hits harder than normal. I’m actually pretty happy despite the fail as I did 3 solid hours out of 4 of riding above my normal pace with basically hard intervals thrown in. I know if I drop 10 to 20% of the hard loading I should be able to go for far longer.

It’s all good information, so cheers all for the feedback, just keep training and getting stronger. I think the only thing I need to figure is how long to rest after trashing my muscles that hard to not ruin the recovery. Did a super easy recovery the day after, avoided the commute miles today so might jump on the trainer tomorrow to see how they feel.

Thanks all.


I’m with cartsman above, too many efforts above threshold, and especially now that you said singlespeed, too much power required.

I don’t think it’s a nutrition issue, its a strength and anaerobic capacity issue. Nothing you can do on the day, just keep training and getting stronger.

The same thing happens to me too, if I go on a hilly ride with my super light climber-type friends, and have to smash it up every hill (and still get dropped while they are pedalling along chatting.)

Obviously, a higher FTP means less work above threshold, so that’d help too, but I think it’s not the main issue here.

That 4th hour is when the fueling you’ve done becomes critical. If you had taken in 700 cals going into the 4th hour, that’s 175g or about 60g/hr… probably plenty for z2, but if you were pushing yourself, you may very well have been running low. 150w for 3 hours is about 1800 calories burned. You’re not pulling as much from your fat stores when you’re putting out more watts, and if your base isn’t well trained you’ll be pulling from the glycogen stores to a greater extent even at lower watts.

Not saying that’s the only reason you had these issues, but I’m taking more carbs / hour when I get into 3+hour rides higher than z2.

“I was also single speeding with them a bunch which hits harder than normal.”

LOL, there’s your answer! A long, punchy ride on a SS will cook your legs. Those hard efforts to get up steep inclines add up. I swap between SS hardtail and geared FS and the SS always leaves my legs more cooked, even if the total effort (estimated TSS from HR) isn’t much different. Those slow cadence climbs are like doing single leg squats over and over and over again.

Probably a bit of calorie deficit going on too. On a harder 4 hour ride, I’ll usually do 1 bottle of Skratch mix, plus a pack or two of gummies (or big bar of some kind, or 5-6 homemade rice balls) per hour.


Doesn’t sounds like a bonk to me.

More details would help like FTP, NP up to that point, duration (to failure and total). But it sounds to me like you just did too much for too long and ran out of energy. Sometimes it can feel like a bit of a wall once your brain flicks that switch and your focus and motivation leaves.

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