Strength Exercise Calories

I think this is a good idea. Somebody bench pressing 2x their body weight is going to be burning a lot more than someone doing lunges with 2lb dumbells, time doesn't really work for strength training

sounds like you are overthinking things.

eat food
pick up heavy things
repeat

I have just been entering the total time including rest for almost a year now and it seems to be sort of accurate. Its not a lot. It gives me 214 cals per hour. Im sure its not that accurate on heavier days like legs but it all evens out over the long run. A lot of lifters dont even worry about those calories because its not much.

I don"t log my strength training calories. I set my activity to "exercises 3 times a week" (lightly active?)
And I do my strength training 3 times a week and don"t log it.

And I'm not sure how accurate these calculators are anyway. If I am lifting for an hour I imagine it would be in the neighborhood of 400 calories for a full body workout.

I think this is a good idea. Somebody bench pressing 2x their body weight is going to be burning a lot more than someone doing lunges with 2lb dumbells, time doesn't really work for strength training

Calories burned are based on heart rate and someone working a large muscle group like their legs is going to burn more calories than someone doing a benchpress wether it is done with 5LB weights or none at all. That being said I wear a HR monitor when I do strength training and I burn around 250-300 calories an hour and this is with a warm up that is about 10 minutes of cardio and a cooldown which is about 10 minutes of good stretching. As noted above on days you work on your legs you are going to burn more than on days you work your arms simply because your CV system has to work harder to supply bigger muscles (legs) with blood than smaller muscles (arms).

You want answers?
I want the math!
You can't handle the math!
Did you order the ridiculous explanation?
You're goddam right I did!

1 calorie = 4.2 Joules.
What is a Joule? It is the unit of measurement when determining work. Remember that Work = Force * Distance.

So how much Force is needed to move a weight (and what is it's midichloria... arggh gurgle)? Force is measured in Newtons. One Newton is the force required to accelerate a mass of one kilogram at a rate of one meter per second squared. Given that it seems you live in the states, you might ask how much that is in Fig Newtons. Or pounds. Lets go with pounds. One Newton will move 2.2 pounds 3.2 feet in one second (roughly).

You would think that it would now be fairly simple to calculate calories from moving a weight around. But, don't forget you are on earth. Which exerts 9.8 Newtons of it's own. So on the way up, you have to add your Newtons to that, and on the way down you have to subtract your newtons from that.

Are ya bored yet? Are your eyes all glazed over trying to follow this? I mean, really, you could just take it as said that it's tragically stupendously difficult to calculate calorie burn from lifting weights because of all the variables. Weight. Distance. Speed. Positive resistance. Negative resistance. Calories burned from supporting muscles being activated. I mean WOW, right?

But lets continue. You wanted the answers. The good news is we can do a pretty good estimate a little more simply. I just wanted to make sure you understood all the variables involved.

The basic newton LIFTING weight is (Lbs / 2.2) * 9.81. The division by 2.2 is to convert pounds to kilograms, and the 9.81 is the Newtons exerted by the earth. Because of the wonderfulness of math, we can just go ahead and divide 9.81 / 2.2 and come up with approx 4.5 (I know it's lower than that, but it's a small amount here. Plenty of rounding errors to go around).

So how many Newtons to lift a weight? Pounds * 4.5.
What about setting it down? Hard to say exactly, because it depends on how much gravity you're chopping off, but generally speaking it takes 2 seconds to come down a distance that would take the weights one second to fall freely, so lets cut the newtons in half. Pounds * 2.25.
This means the total Newtons to raise and lower the weight is Pounds * 4.5 * 2.5. Heck, lets just round that to 10.

Now it's back to our second formula. The one about Work. Work = Force * Distance. Lets just figure that you're moving the weights about 2 feet, or .6 meters. So Work = Pounds * 10 * .6 which is the same as Work = Pounds * 6.

But it doesn't stop there! Oh no. Remember that we gotta convert this back to calories, so you would divide this number by 4.2 (from the original formula). So calories = (Pounds * 6) / 4.2. Lets knock this down and divide 6 by 4.2 and get 1.4 or:
calories = Pounds * 1.4.

Right now you're either drooling or thinking I'm an idiot. That would mean lifting 100 pounds would burn 140 calories! What a pile of stupid I must be! Not exactly. The real deal is that the Calorie (capital C) we use in food and our bodies is actually a kilocalorie. That's 1000 calories (lower case c). So we gotta slide that decimal point 3 places to the right, or .0014. Aww heck, we've been doing so much rounding, lets call it .002.

That's the caloric output needed. Your body isn't very efficient at generating that. It may take more than twice as many calories to actually do that. So lets round it up .005

And while we're at it, lets add in the reps and sets.
Calories = Pounds * Sets * Reps * .005
So if you lifted 100 pounds for 3 sets of 10 you would get 100 * 3 * 10 * .002 = 15 Calories.

And now it gets fun! Because squatting 100 pounds free weights uses more muscles than squatting 100 pounds in the smith machine which uses more muscles than bench pressing 100 pounds which uses more muscles than pulling up a 100 lb weight on a cable system. So there's some adjustment there as well.

A quick search for METs and weight lifting shows a range of 3.0 to 6.0 for most free weight lifts. That means this number could be up to twice as high for the big compound exercises.

Lets figure a typical workout session of 300 reps averaging out to 100 pounds each would be 150 to 300 calories output. So basically less than 1/4 pound.

So like robin52077 said:
eat food
pick up heavy things
repeat

Hope that helps

Just use the MFP estimation under cardio, search "strength training". It's good enough. Many of my successful friends (the ones that add individual workouts vs using TDEE) use the MFP numbers and it works fine. Any method is riddled with inaccuracy, at least this one is consistent and uncomplicated.

Right now you're either drooling or thinking I'm an idiot. That would mean lifting 100 pounds would burn 140 calories! What a pile of stupid I must be! Not exactly. The real deal is that the Calorie (capital C) we use in food and our bodies is actually a kilocalorie. That's 1000 calories (lower case c). So we gotta slide that decimal point 3 places to the right, or .0014. Aww heck, we've been doing so much rounding, lets call it .002.

-I love your reply but isn't your math off here? isn't 140c = .14C? not 0.0014?