# Weight Lifting - Calorie Calculations is it just W=F*d?

Hi All,

I have successfully lost 30kg using Trainer Road and a self-built meal planning app.

I am now turning my attention to weight lifting and I want a way to accurately workout my calories burnt for wieght lifting workouts.

I figued that you can workout the Work done through W=Fd and this would be similar to a cycling power meter P=Fv.

Does a the TrainerRoad workout calorie calculation, like other calorie calculation using a power meter, take into account any other physiolical factors is it it just using E=P*t (where energy is power multiplied by time?)

Iâ€™m considering building a data base of calorie burned for every rep for a bunch of preloaded movements, based on length of arms or movement in the workout, and then be able to calculate accurately how much calories I burnt for a workout of x, y and z exercises.

Anyway if anyone outthere is also a physics/diet nerd then thanks in advance!

Cheers,

J

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A quick googling found this link:

Basically work is force times displacement, or range of movement, so it is theoretically easy to calculate. Force is easy to determine but displacement could be a bit more challenging to determine.

Btw, do your self a favor and use the metric systemâ€¦

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The vast majority of the energy from lifting doesnÂ´t come from overcoming gravity but from regenerating all kinds of tissue and returning your body to homeostasis. Dont try to calculate that.
Try macrofactor to adjust your energy intake according to body weight trends, that will be way more precise over time.

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Of course, but the equivalent to measure work with a power meter when cycling is to calculate work during weight lifting as explained.

Calorie expenditure is a different thing.

And he seems to be after that different thing:

and then be able to calculate accurately how much calories I burnt for a workout of x, y and z exercises.

Epic thanks legends!

Yes I had wondered about the energy consumed in rebuilding muscle - that is far to complicated - I guess there is probably a factor to for when looking at adaptions to cycling workouts also.

In terms of distance for the W=F*d I just assumed 0.45m as a rough estimate for the distance of a cable pull machine (I know that is highly inaccurate but to start with) and for body weight movement I used body height and then calculated arm length based on that (again inaccurate but for initial prototype enough)

Thanks for the link! I got half way through building the model prototype -

Strength Workout Planner

I might let it sit for a bit and come back to it later.

Thanks for the input guys!

Oh and also @TomasIvarsson metric system is the only systemâ€¦ who has time for inches and yardsâ€¦

Iâ€™d be hesitant to use an estimation of caloric expenditure during strength training analogous to kilocalories/kilojoules in cycling.

Thereâ€™s some decent literature on in, but unless you have a metabolic cart, ultimately youâ€™ll always be estimating with a hefty grain of salt. I found the model that was derived in this study interesting however: Predicting Energy Expenditure of an Acute Resistance Exercise Bout in Men and Women

Great job on the transformation so far! Keep getting after it and learning in the process. Love the work and resourcefulness.

Part of what determines Calorie burn when cycling is an individualâ€™s Gross Metabolic Efficiency (GME). For most people, typical GME ranges from 20-25%.

1 Calorie (kcal) is 4.184 kJ. Since most people are 20-25% efficient at using that energy (75-80% of that energy is burned off as heat), this boils down to a 1:1 ratio as you can see below:

1 Calorie Ă— 25% = .25 â†’ .25 Ă— 4.184 kJ = 1.045 kJ

For practical reasons, most cyclists approximate this to: 1 kJ to 1 Calorie.

Thatâ€™s how TR calculates your Calories burned when you view your workouts. You can dive deeper in these articles if youâ€™re interested:

Hope that answers your question regarding how TR calculates this metric â€“ feel free to let us know if you need a hand with anything else!

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