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 Post subject: Calories burned weight liftingPosted: Sat Jan 26, 2013 11:23 pm
 Apprentice

Joined: Sun Dec 23, 2007 9:14 pm
Posts: 153
After being teased a few times by my friend because I treat myself to a vanilla bean latte after workout on Saturdays, I finally decided to crunch the numbers.

1 calorie =4.18J=4.18Nm

For a dumbell press horizontal bench
range is 20inches
total weight is 100lb
10 reps

That's 2260J = 540calories output.

But I assume the human body is not 100% efficient. So what efficiency factor should I apply to arrive at the calories consumed to result in 540 calories output?

Funny thing when I was researching in the internet. Most website simply ask you for your body weight, the exercise performed and the time duration to calculate the calories.

http://www.fitclick.com/calories_burned ... ench+Press

These websites think that lifting 1lb for 15 minutes is the same as lifting 100lbs for 15minutes. Can anybody explain?

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 2:30 am
 Veteren Member

Joined: Tue Oct 19, 2010 1:12 pm
Posts: 2406

100 lbs * 32.15 ft/sec/sec * 20/12 * 10 = 53,585 ft-lbs
* 0.000323832 kilocalories per ft-lb.

I think this is correct presuming 100% efficient
I would not give great odds though that it is correct. Its been yrs.

Calories in food on Amercian labels is in kilocalories

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 5:48 am

Joined: Wed Sep 14, 2011 1:40 pm
Posts: 1142
Location: Lapland, Finland
Counting the calories burned while exercising is in my mind, pointless and unuseful. The real fat burning effect isn't as simple to count on calories as some newton calculations.

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 7:05 am
 Deific Wizard of Sagacity

Joined: Thu Apr 24, 2008 7:20 pm
Posts: 4424
too many variables to consider

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 7:25 am
 moderator

Joined: Thu Feb 07, 2008 7:11 am
Posts: 7503
Location: Kudjip, Papua New Guinea
Besides, you shouldn't be drinking things like vanilla bean lattes anyway. You're contributing to the further decline of civilization as we know and love it. Drink manly coffee.

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Our greatest fear should not be of failure, but of succeeding at things in life that don't really matter.--Francis Chan

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 7:27 am
 moderator

Joined: Thu Feb 07, 2008 7:11 am
Posts: 7503
Location: Kudjip, Papua New Guinea
And, yeah. There's no way that 10 reps of bench burns 500 calories. We'd all wither away to nothing.

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Our greatest fear should not be of failure, but of succeeding at things in life that don't really matter.--Francis Chan

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 10:24 am
 Deific Wizard of Sagacity

Joined: Thu Apr 24, 2008 7:20 pm
Posts: 4424
Jungledoc wrote:
Besides, you shouldn't be drinking things like vanilla bean lattes anyway. You're contributing to the further decline of civilization as we know and love it. Drink manly coffee.

that's rich coming from the fabulous baker boy

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 12:24 pm
 Veteren Member

Joined: Tue Oct 19, 2010 1:12 pm
Posts: 2406
Jungledoc wrote:
And, yeah. There's no way that 10 reps of bench burns 500 calories. We'd all wither away to nothing.

that's what motivated me to respond. I knew there was soemthing wrong with the calculation, even thoetretically
and of course, who knows or cares what the actual in life is

now go make me a croissant

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 12:36 pm
 Apprentice

Joined: Sun Dec 23, 2007 9:14 pm
Posts: 153
Oscar_Actuary wrote:
100 lbs * 32.15 ft/sec/sec * 20/12 * 10 = 53,585 ft-lbs
* 0.000323832 kilocalories per ft-lb....

You don't need to multiply by 32.15 since lbs is already a force.

100lb x 20in = 166.67ft-lb
(1 ft-lb = 0.323831554 calorie)
53.97 calories x 10 reps = 539.7 calories

Oscar_Actuary wrote:

Calories in food on Amercian labels is in kilocalories

Maybe that's why dieters can't get their act together. When burned 17.4kcal, they think they burned 17,400 calories and can't understand why a vanilla bean latte with only 340 calories.

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 12:40 pm
 Apprentice

Joined: Sun Dec 23, 2007 9:14 pm
Posts: 153
Jungledoc wrote:
And, yeah. There's no way that 10 reps of bench burns 500 calories. We'd all wither away to nothing.

Check my calculations. I could do it in metric and come out with the same results. This is in real calories, as in real scientific units, not the kcal crap.

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 12:41 pm
 moderator

Joined: Sat Mar 10, 2007 5:44 pm
Posts: 6498
Location: Halifax, NS
tostig wrote:
Jungledoc wrote:
And, yeah. There's no way that 10 reps of bench burns 500 calories. We'd all wither away to nothing.

Check my calculations. I could do it in metric and come out with the same results. This is in real calories, as in real scientific units, not the kcal crap.

Right, so 539.7 real calories = .5397 Calories as we normally measure food energy.

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Let thy food be thy medicine, and thy medicine be thy food.~Hippocrates
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Thanks TimD

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 1:36 pm
 Veteren Member

Joined: Tue Oct 19, 2010 1:12 pm
Posts: 2406
Tostig,

You also left out Time. "Energy" relates to Ft-lbs, or Nm only when you consider in in terms of Force.
Right?

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 2:01 pm
 Apprentice

Joined: Sun Dec 23, 2007 9:14 pm
Posts: 153
Oscar_Actuary wrote:
Tostig,

You also left out Time. "Energy" relates to Ft-lbs, or Nm only when you consider in in terms of Force.
Right?

Time would go into power calculations. Calories and Joules (or Nm and ft-lbs) are energy measurements.

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 2:04 pm
 Veteren Member

Joined: Tue Oct 19, 2010 1:12 pm
Posts: 2406
tostig wrote:
Oscar_Actuary wrote:
Tostig,

You also left out Time. "Energy" relates to Ft-lbs, or Nm only when you consider in in terms of Force.
Right?

Time would go into power calculations. Calories and Joules (or Nm and ft-lbs) are energy measurements.

I'll have to agree with that. Early research lead me astray

So, we're back to 0.539 food calories, aka kilo calories.
clearly we are burning more, but much less that 540.

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 Post subject: Re: Calories burned weight liftingPosted: Sun Jan 27, 2013 2:07 pm

Joined: Wed Sep 14, 2011 1:40 pm
Posts: 1142
Location: Lapland, Finland
I think this hasn't really been thought through here. First off, no system really uses actual CALORIES. We use KCAL, which are kilocalories. But people refer to them as calories, maybe for convenience. I have serious doubts that ten reps of some exercise (lasting roughly under 30s) burns 500s. Given the fact that an average person has a resting metabolism of 2500kcal +/- a couple of hundred calories PER DAY. You'd add 500kcal of energy need with only one set? Think again.

After that, you haven't taken into account the time under tension. How does your math compare ten reps of barbell shrugs or limited ROM squats to 5s pause bench press or clean&jerk. What about the amount of muscle tissue involved? How much more calories do squats burn than biceps curls?

And this doesn't even cover the physiological effects resistance training has (The energy-metabolism, hormonal actions, protein synthesis, and \$h1t.)

Calories don't matter.

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Physical Preparedness Coach
Co-Owner of UniFit Oy.

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