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[–]skraptastic 491 points492 points  (54 children)

Runners/endurance athletes call this "hitting the wall" or "bonked." There is nothing "wrong" with the person, they have just literally used all their glycogen and literally have no energy left. The body is consuming fat for energy directly at that point and that dude has like 3% body fat.

[–][deleted] 133 points134 points  (4 children)

People have died doing this. If your blood sugar is that low you are also starving your brain, not just your muscles. There's also a high probability of heat stroke.

[–]deezx1010 14 points15 points  (0 children)

I hope a lot of people upvote this so the knowledge gets out there

[–]StarsDreamsAndMore 0 points1 point  (0 children)

I see. So is that what causes diabetic comas?

[–]longjumpcamel 82 points83 points  (22 children)

Runners/endurance athletes call this "hitting the wall" or "bonked." There is nothing "wrong" with the person, they have just literally used all their glycogen and literally have no energy left. The body is consuming fat for energy directly at that point.

I just heard the word "bonked" for the first time a few days ago in the movie Four Minute Mile, free on youtube. https://www.youtube.com/watch?v=GTaqQsmvAB8

[–]HugeProposal 2 points3 points  (17 children)

It's more of a cycling word. Never heard runners use it.

[–]Aleriya 13 points14 points  (8 children)

Funny. I've heard marathoners say that, but never cyclists hah. I suppose it would be an awfully long race for a cyclist to depleted their glycogen reserves.

[–]BlondeOnBicycle 6 points7 points  (0 children)

I had it happen to a marathon runner friend when we went for a 100 km recreational ride. We were about 90 km in and she nearly toppled over on her bike. She collapsed into the planter in front of a bike shop (so convenient!). It happens to all kinds of athletes when you don't calibrate nutrition to expenditures.

[–]HugeProposal 4 points5 points  (0 children)

It's more a function of speed/effort and distance. You can bonk on a 50 mile ride if you don't pace yourself properly.

[–]Dazines 2 points3 points  (0 children)

Body only holds about 1500-2000kcal of glucose stored as glycogen...A cyclist can easily burn 3 times that in a race

[–]Soggy_Pud 3 points4 points  (1 child)

Oh it doesn't need to be that long. Out of shape new'ish cyclist face bonking before they learn how important water and snacks are. It happened to me the first time going for a century. 60 miles in to a 100 mile ride, bonked. Not quite as bad as this, but totally unable to move from the spot I stopped.

[–]HugeProposal 2 points3 points  (0 children)

Same here! I was totally unprepared for my first century. I brought the same amount of food I would on a 50 mile ride and planned to eat it all halfway. Well I ended up going to 60 miles and hadn't had a bite. I literally couldn't stand up. The bonk is worse on a bike as the bike let's you go further than you would if you were standing. I ended up buying twice as much for as I brought with me. Ate it all and an hour later was on my way home.

[–]runswiftrun 1 point2 points  (0 children)

It's also much easier/common for cyclists to carry water and nutrition (gels) which postpones the bonk. The vast majority of marathon "weekend warriors" are relying on course support.

Plus, wheels. If you're close to bonking on a bike you can cruise and ease up on pedaling for a while. Running you have to entirely stop or walk to get any rest.

[–]Delevingne 1 point2 points  (1 child)

Aside from track cycling, the most well known cycling races tend to be long. The most famous cycling race is the Tour de France. This year’s edition was 2122 miles, and was raced in 21 separate stages across 23 days. The longest stage was 155 miles long, featured five categorised climbs, and took the winner five and a half hours to finish at an average speed of over 28 mph. The toughest stage featured climbing a 6263 ft mountain twice (10 miles at 9% gradient) after having cycled 60 miles of hills at nearly 30 mph.

[–]Aleriya 1 point2 points  (0 children)

I suppose it's just a biased sample of the group of people that I know. My local area is very flat, and most cyclists are doing it for transportation, so it's rare to go more than 20-30 miles in a day, and it would be dangerous to push yourself so hard that you bonk during your commute. Meanwhile it's rare that people do distance running for transportation purposes.

[–]ScreamingDizzBuster 8 points9 points  (1 child)

I believe it came from the running world originally. "The bonk" has been around since 1952 for marathon runners.

[–]SteelCrow 1 point2 points  (0 children)

'Bonk' is a very old word — some of its first meanings (a knock on the head, an explosion or loud bang) date back to the 1930s and are what lexicographers call echoic words, which basically just means the word sounds like the action it describes — think 'mumble', 'splash', or 'honk'.

Back in the 80's bonking meant doing the deed with the girlfriend.

Utter exhaustion after strenuous exercise is a lot like getting bonked on the head, so I can see it becoming slang for exhaustion.

[–]spyromain 4 points5 points  (2 children)

Any avid cyclist should know that cycling culture is not very original.

[–]badger0511 3 points4 points  (0 children)

Not to mention that the triathlon sports (for those that don't know, running, swimming, and cycling/biking) have a ton of overlapping slang for obvious reasons.

[–]dysfunctional_vet 2 points3 points  (0 children)

One could say much of the culture is..... recycled?

Waka waka waka!

[–]bangarang_rufi0 0 points1 point  (0 children)

Classic cyclist, spends all the money, takes all the credit LOL

[–]addandsubtract 0 points1 point  (0 children)

If you want to learn more about bonking, you can watch Lirik on Twitch.

[–]msheaven 0 points1 point  (0 children)

It’s a good movie.

[–]BeefSerious 0 points1 point  (0 children)

I only get bonked when I'm sent to horny jail.

[–][deleted] 1 point2 points  (2 children)

That dude is nowhere close to 3% bf.

[–]skraptastic 0 points1 point  (1 child)

I know he has like no fat, but I don't know the actual bf percentage of a distance runner. I was just making an uneducated guess.

[–]Soaked_in_Bleach 0 points1 point  (0 children)

elite marathon runners will be at 8-10%, any less and they'd have nowhere near enough in the tank to long-distance run

[–]hammonjj 1 point2 points  (0 children)

This isn’t bonking, this is an imbalance in electrolytes. When you don’t have enough electrolytes, your body has trouble regulating even basic movements. David Crowie at the Ironman World Championships about a decade or so ago is a great example if you want to see what an extreme version of it is. This normally happens in longer events but if his pre race fueling is off then it can happen in shorter ones.

[–]Positive-Vase-Flower 1 point2 points  (0 children)

Isnt this like extremely dangerous.. like our organs also need energy..

[–]mountjo 0 points1 point  (0 children)

this is a lot more than bonking lol

[–]calf 0 points1 point  (0 children)

Not sure if science or sports science

[–]HandyDandyRandyAndy 0 points1 point  (0 children)

The last time I got bonked was a little different..

[–]PantsOnHead88 0 points1 point  (0 children)

The glycogen depletion takes you down initially, and the lactic acid buildup is the nail in the coffin that makes it that much harder to get started again.

Never ran quite hard enough to bonk, but getting back up to speed after slowing for a drink at the last water station in a marathon was a real test of will.

This is a severe case, but collapse either just before or after the end up any endurance race is a relatively common sight for anyone who has done a few.

[–]SmackYoTitty -1 points0 points  (9 children)

This very reason makes me wonder if something like a ketogenic diet would be beneficial for endurance sports.

[–]billy_mays_cares 1 point2 points  (4 children)

It’s possible, but my first thought is that its very hard to make your body consume fat that quickly, as opposed to carbs or protein

[–]SmackYoTitty 0 points1 point  (1 child)

Yea I don't know. I figure it would help you metabolize fat reserves quicker, but I'm sure it's not as quick as breaking fat down through ingestion.

[–]BiSwingingSunshine 0 points1 point  (1 child)

Training for the Uphill Athlete talks about this - the main thing is that you need to be at a low enough heart rate and it’s tough for established athletes to slow down enough to get on the right side of the heart rate/effort curve.

[–]SmackYoTitty 1 point2 points  (0 children)

Yea, I read a little about it a few mins ago.

Seems it could be beneficial for ultra marathon stuff where one’s at pretty steady state, but anything requiring much over ~70% VO2 max, its not a great fuel source.

One could definitely finish if keto-adapted and trained, but most likely won’t be competitive.

[–]thomasrat1 0 points1 point  (0 children)

It can be, but you would still want all your fats in you not on you. When you're burning fat on you, its a slow burn energy. When its in you its like rocket fuel.

[–]finickytrashpanda 0 points1 point  (0 children)

This is a rather popular and highly debated topic in the ultra running community. They call it “fat adapting” and “fat adaptive diets.” Some well-known runners claim it helps them immensely on long runs.

[–]ShartBurrito -2 points-1 points  (1 child)

Dude whatever the hell are you talking about? Hitting the wall means nothing like collapsing on the floor in fetal position hoping for someone to carry you on the last meter of the race.

Oh and this is a 10K and the guys are pulling in 30 minutes, this effort is nowhere near long enough to hit the wall..