Anaerobic respiration? FAKE NEWS
I won’t go into details (being a gentleman) but last night I burned a ton of calories over the course of about 3 1/2 minutes.
I doubt there is such a thing as a “fatal rate of burn”. You might kill yourself if you sustain it too long, but that’s going to be true of literally any rate of Calorie burning-- Eventually, if you sustain the burn long enough without replenishing, you’re going to use up all of your body’s energy reserves.
The activities with the top rates are probably going to vary, not in the total amount of Calories consumed, but in the time taken to consume them: Lifting the same weight a little quicker, or the like.
Thinking aloud…
Well, the world record squat is 575kg. If we assume no losses, and just the mass moving over say 2m, we get 2.7 kilo-calories. Seems muscle efficiency is at best 25%, so we get about 10 kilo-calories expended. This is going to be raw ATP. There isn’t enough time for any other process to matter. So oxygen intake or glycogen conversion don’t matter.
So how long to perform a squat? A few seconds. If we say 5, we get ourselves back to that 2 kilocalorie per second number. There may be bursts inside that time that go significantly higher.
(I would expect that there is a lot of energy going into stabilising things as well as just lifting, so this is a lowball number.)
In any activity, after ten odd seconds of effort we are into anaerobic glycogen conversion, and have from say 30 seconds to 2 minutes before we convert to aerobic and become oxygen intake limited. Looks as if during that that time we still get that 2 kilo-calories per second rate. So probably the limit is imposed by our ability to burn ATP.
The OPs question is interesting but imprecise, because it’s subject to various interpretations. It does seem like they understand that, because the question includes “per second, per minute.” They don’t, however, specify whether it should be calories burned per unit of body weight or just total calories period. The body’s mechanisms for converting the energy of chemical bonds into work and heat are going to be different on a timescale of seconds to hours.
Short of feeding a corpse into a hypothetical Mr. Fusion, burning the body is going to release the most energy, total; you can let the fire smolder for hours or dump it into liquid oxygen to get the energy released as fast as possible.
In a living athlete, in the very short term (just a couple of seconds) you’re primarily using up the ATP that you already have lying around before anaerobic or aerobic metabolism can spool up to replace the losses. A weightlifter would fall into this category, but even they don’t use all muscles to full effort. That would a person being electrocuted or in the first seconds of a grand mal seizure, where there is maximal recruitment of muscle fibers over the whole body contracting at maximal effort, not even limited by neurological ‘safety limits’. That kind of power output can’t be sustained, however, but it does probably represent peak calories per second. With the caveat that you aren’t burning glucose or glycogen or fat to do it, just the ATP that was previously produced from the burning of those energy sources, and it’s only for a second or three.
For any time scale longer than that, continued energy output is going to be coming from a combination of aerobic and anaerobic metabolism (strictly speaking, burning ATP is anaerobic, but here I’m referring to anaerobic glycolysis). From an individual athlete standpoint, you want a person with the highest possible V02 max (which measures their maximum ability to deliver oxygen to their tissues and use it there) as well as the highest possible ability to remove and/or tolerate high lactic acid levels in muscle tissue. At the level of a sport or activity for short-term maximum calorie burning, you’d look for an activity that has the athletes with the highest VO2s doing something that uses as many muscles as possible and lasts just long enough for them to run their lactic acid levels to the highest tolerable levels, and then stop, totally blown out.
For my money, that would be an activity like sprint cycling, rowing, or cross country skiing. If you look at lists of record VO2 max for individual athletes, you find a lot of cyclists and skiers but not a lot of swimmers. I believe I saw a number for Michael Phelps that was in the 70’s, which is amazing for a human being but not in the league of a lot of these other guys. My money is on a 1.5 km ski sprint burning more calories than, say, a 400m swim that takes about the same world-record time. That’s because I suspect that the skiers have higher V02 maxes than the swimmers, and both are probably pushing to max exertion including developing lactic acidosis to max tolerable levels. Or maybe we just don’t have data on the swimmers.
This. A significant portion of the work is against gravity.
Drinking too much & then “reverse drinking”, while a good core workout doesn’t burn that many calories. :o
There’s certainly hyperthermia, which is eventually going to kill you unless you can get rid of that excess heat at a faster rate than you’re producing it!
Working hard in a hot, humid atmosphere should do the trick. Or, if you’re not into hard labor, you could chew down on some dinitrophenol!
Surprised nobody has mentioned playing hockey. There’s a reason a shift only lasts about 2 minutes. I’ve done concrete, masonry and hot tar roofing in the past. I’ve never felt as intense a workout than after a shift.
The ultimate (heh) burn for me is Ultimate with its constant running all up and down a soccer-sized field. It’s the only time I’ve actually had my heart hurt from the exertion (which was over 20 years ago so no worries.)
But it won’t be the rate that will kill you. Take Francis Vaughan’s 10-Calorie weightlifting, for example. He assumed that the total lift would take 5 seconds, for a rate of 2 Calories per second. But what if instead you did the same lift in 2 seconds, or 1? Then you’d have 5 or 10 Calories per second. If a superhuman were able to do the same lift in a millisecond, they’d have a rate of 10,000 Calories per second. But it’s still all just 10 Calories, about enough to raise your body temperature by a tenth of a degree Celsius, hardly hyperthermic.
You’re assuming some straight-line relationship between weight lifted and calories expendited per second. Seriously, Chronos, I know you’re much smarter than that!
And, may I remind you, humans succumbing to hyperthermia through overly exhaustion is a pretty well established fact.
ninja’d
2,4-Dinitrophenol was used as a diet aid back in the 1930s. It works by short circuiting the proton gradient used in oxidative metabolism forcing the body to produce ATP by the much less efficient anaerobic pathway. Alas, this results in a lot of energy lost as heat and a strong risk of hyperthermia, at times fatally so.
So take some DNP while swimming in a cold pool for maximum calorie burn per second?
Upthread mentioned being electrocuted or epileptic seizure. Just want to throw out there, just because it’s similar and a “sports” thing, is the goosing up of muscles with electric current–I’m not sure what this is called and if it’s legal, or the Russians did it legally, but first, or something.
Also, FWIW and not worth its own OP, I had my self a fine-old electrocution/seizure, ECT treatment. This was way after the Cuckoo’s Nest muscular-convulsions also over; under anesthesia I think externally your finger twitches a little. OTOH, my brain is not muscle. Much.
I agree with you! Skating up and down a full sheet of ice will gas even the best players after 1 minute. At maximum effort this definitely has to be a contender.
Anything more than 10 minutes has to be some high altitude athlete in an ideal environment exerting NRG somehow…probably playing hockey.
For a brief period of time, perhaps Olympic lifting.
Lovely. So we see power of up to 4.8kW for lifting. That gets us to 1.1 kilo-calories per second input into the moving mass. Again, assuming a 25% efficiency for the muscles we get 4.4 kilo-calories per second chemical energy expended as a lower bound.
These expenditures are scheduled across different muscle groups during the lift, so we might be able to get higher for some contrived activity, but the skill and fine tuning of the lift needed at this level would suggest that it might be hard to manage.
You guys beat me to it! Powerlifting definitely has to be the answer for the per-second limit. That’s because powerlifting is all about peak force exerted, which requires equivalent energy from your body, which comes from calories.
Calories can be equated to newton-meters, with 1 nm = 0.0002388 food calories. You can watch Behdad Salimi powerclean 232kg ~1.8m distance in 1 second here:
(sorry for the url, html linking is broken for some reason for me)
(He’s 6 foot 6, so that’s about 1.8m)
232 * 1.8 * 9.8 = 4092 newton meters = 1 calorie expended over 1 second.
Then you can apply some efficiency calculations like Francis Vaughan has done and get your answer.
But this arguably must be very close to at least the per-second limit, because powerlifting is the definition of maximal force exerted over (relatively) minimal times, and these are the achievements of world-class athletes specialized in the sport. So the limit proposed of 1.1 calories per second from Octopus’ cite is likely very close to the theoretical maximum per-second limit for human physiology as it exists today.
Ive read from a couple of different sources that the most expensive thing your body can do calorie wise is to thermoregulate. Michael Phelps’ infamous 12,000 calorie diet wasn’t because of all the exercise he was doing, but because he spent 8 hours a day in an 80 degree pool, and his body had to burn fuel to maintain its 98.6 degrees.
Wasn’t that 12000 calorie diet thing debunked as an urban legend? I could have sworn it was.
By Phelps himself.