Take the 2-minute tour ×
Physical Fitness Stack Exchange is a question and answer site for physical fitness professionals, athletes, trainers, and those providing health-related needs. It's 100% free, no registration required.

So I was wondering if there are formulas to calculate the energy expenditure of common lifts, like deadlifts, bench press, squat etc. I know that every formula could only be an approximation, due to differing technique, execution speed etc.

I was just curious if such formulas exist and if so, how accurate they are.

If they don't exist, why is that? Did just noone care to find out? Is it not feasible due to one of the factors mentioned above (or other factors), if so which?

share|improve this question
    
Cool; I'm usually on the computer, so it's somewhere I would like to patrol often :) –  Kneel-Before-ZOD Mar 26 at 18:37
1  
I have a degree in exercise science, I am not aware of any specific formulae for individual lifts (That's not to say they don't possibly exist, just that I haven't found any). You could measure it if you have access to a lab with direct gas analysis to measure oxygen consumed, but that's about the only way that I'm aware of to get that specific. There are commonly accepted values for weightlifting per hour by body weight, however. –  JohnP Mar 26 at 19:37
    
Thanks for your reply. I knew about the approximated values for lifting per hour and bodyweight, but never really got to trust them, hence the question. Unfortunately, I don't have access to a lab, so I guess I will have to stick with those for now. –  LarissaGodzilla Mar 27 at 7:17
    
@LarissaGodzilla This is something you may be interested in. –  Daniel May 5 at 14:43
    
@Doc: It looks interesting enough, I'll keep an eye on it ^^ –  LarissaGodzilla May 6 at 5:25

3 Answers 3

While work does equal force times distance, the rest of Sergey's commentary is rather absurd. His calculation presumes 1 dimensional motion and forces, people don't move in one dimension first off. Secondly, carrying 100kg involves gravitational force and simply standing still with 100kg on your back will result in increased caloric consumption due to the 981N pushing down on your body and requiring muscle activation to not fall over from carrying the weight (your muscles are contracting and causing mass to move over distance). Additionally there is the calories burned from travel (100kg≈1000N 7700Cal/kg 0.000238845896627 calories/N•m, this equates to about 32.23km to burn 1kg of fat along the x-axis only) This does not account for calories burned in stabilization, calories burned due to metabolic processes such as converting ATP to and from ADP among other things, metabolic efficiency, anaerobic threshold, etc. Also, HIIT cardio and weightlifting also result in excess post-exercise oxygen consumption. Since O2 is a required for cellular respiration (anaerobic exercise doesn't excrete waste effectively until you stop working and permit the respiratory system to blow off CO2, the other other pH regulatory systems don't act fast enough to be relevant) it is the primary indicator of caloric consumption. This effectively means that while lifting weights on it's own doesn't burn as much calories during a workout, they burn more calories post workout (this doesn't count increased caloric consumption due to increased muscle mass.)

Short story: if you're trying to calculate work done based off of your estimated range of motion, you're wasting your time. While the fundamental point of Sergey's post was correct, it left out some pertinent details. As I don't really feel like getting into the physics of all of it in any deeper fashion than I already have, I'll ask that you take my word, as an engineering student, that between the lack of precision of measurement and the sheer amount of calculations required to figure it out would take time that would be better spent working out, resting, eating, or any number of things. So yes, there are formulas that you could use to figure it ou should you have sufficiently precise measurements, but the benefit of figuring it out doesn't even remotely come close to justifying the effort.

share|improve this answer
2  
Yes, I know it would be complicated to calculate all of those factors, but that's not even necessary. For cycling, at the very least, there exists a method to measure the calories consumed (something about measuring oxygen, if I remember right). Doing this for some lifts with some people over some time would provide a close enough approximation of all the complicated effects. Or so I imagine... –  LarissaGodzilla May 20 at 12:02
    
The oxygen method you're thinking of is called indirect calorimetry. While it doesn't require a laboratory setting, a lab is about the only place you'll find the equipment for it outside of a hospital. –  user8691 Jul 28 at 21:02

A= m*a*s;

mass*acceleration*s-distance.

or

A=F*s Force;

http://en.wikipedia.org/wiki/Work_(physics)

I do not think it is very easy to calculate force though. when i do the math i usually estimate force as gravity force and acceleration as Gravitational acceleration.

Why it is not very important is : energy expenditure during the lift is not important (very small compared to daily non exercising expenditure). This is because of small distance of the movement. I once calculated that to burn a kilogram of fat i need to carry 100kg of iron to the distance of 36 kilometers (maybe i am mistaken here but not by too much) which is ridiculous.

This formula is important for aerobics(aka cardio). Moving your body(50 -100kg) over long distance does the trick.

share|improve this answer
    
As for it 'not [being] very important', you're probably right. An hour of all-out workout is estimated at 300kcal, afaik. Still, there are some bodybuilders that work out instead of cardio, which made me think it can't be that little. But seemingly, energy expenditure while lifting really isn't that much. –  LarissaGodzilla Apr 7 at 6:09
    
Bodybuilders do not use cardio much because they use Clenbuterol and AAS to keep muscle mass while cutting. In this circumstances just dieting melt their fat quickly, while leaving the muscles intact. –  Sergey Apr 7 at 18:20

One additional factor that none of the other answers factor in is that power lifting not only requires the energy expenditure to rebuild the muscles after a lift. I don't know exact numbers but your body burns a significant number of calories rebuilding muscles. Add on to that the fact that muscles need to burn calories just to maintain themselves having more muscle means your body will be burning more calories while you go about your life. Long story short actually measuring a Joule or KCal energy expenditure is more or less useless but strength training does lead to a large amount of caloric expenditure both during the activity and after.

share|improve this answer
    
Indeed, that's an additional factor and probably by far the most complicated one to measure. One could use the same respiratory measuring device i mentioned below to determine that factor, although that would take weeks, and at that point it'd just get silly. Ah well, I'll just keep guessing then :) –  LarissaGodzilla Jun 20 at 7:05

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.