Working out your Workout Calories

RossUK88

Hey,
I hit the gym 5 times a week but mainly for lifting weights, do a bit of a warm up and a 10-20 minute spot on the treadmill/crosstrainer/rower and then go back for a 10 minute cooldown.
Obviously on these machines there are rough guidelines to what calories are burnt but with weight lifting i can get quite a sweat on, especially on the bigger movements. I was wondering if i wore my HRM for the entire time i was in the gym and just input those calories at the end rather than just adding my cardio and no weight training? I this the right thing to do?

Also in regards to TDEE I've use'd a calculator and its coming out at about 2630 so -10% gives me 2367 a day, which to me seems a little high if I'm wanting to lose weight (MFP gives me 1800 less exercise) i suppose if i hit 500 calories in a workout they would be the same. Bit of a noob with this as my mind set has always been go the gym and just lift heavy things. I guess its more of a trial and error thing, I will be using the gym comp comp analyzer every 2 weeks from now to see whats working and what isn't but im trying to shed this last 5-7% body fat.

Cheers

vorgas

HRMs are not at all accurate for weight lifting.

First thing to understand: HRMs do not measure calories burned! They measure Heart Rate.

Second thing to understand: Your HR can change for any number of reasons. Caffeine, fear, adrenaline, excitement, etc.

Next thing to understand: A faster beating heart does not burn significantly more Calories. You can check this yourself by sitting perfectly still and hold your breath as long as you can. Repeat over and over. Watch your HR soar. Are you burning more calories? No. What if you burn 100 calories in a walk, then repeat the walk the next day immediately after having 3 cups of espresso. Are you burning more calories? No. Well, your HRM will say you did.

Important bit about HRMs: They use a calculation based on the volume load from steady state aerobic exercise to estimate the calories burned.

Volume load: When doing aerobics, your HR rises to move a greater volume of oxygen through your body. When you lift weights, your HR rises while blood vessels constrict to increase the blood pressure in the appropriate area. This is called Pressure Load. You can see this for yourself by examining someone on an elliptical at 85% max HR and someone lifting weights at 85% max HR. The person on the elliptical will be flushed and gasping for breath. The person lifting weights will have veins popping out all over the place and will just have slightly elevated breathing. Pressure load is not volume load. Your heart is beating faster for a different reason with weights than with aerobics. So, the calorie formula is no longer accurate.

Steady state: When you are doing aerobics, you are constantly moving with very little rest, and you are moving large portions of your body. When you lift weight, you are often not using your whole body, and taking longer rests. So, it's not accurate.

Aerobic exercise: Aerobic exercise is when your body mixes oxygen and fat to produce energy. This happens when the energy requirement is low. Lifting weights is anaerobic exercise. That means it uses the glycogen stored in the muscles for energy. Different energy source from aerobics (what most people call cardio), so the formula is inaccurate. (This is a simplifed explanation, the reality is a little more complicated, but the effect is the same).

To recap: The three important factors in determining a calorie burn from HR are all using different things. There is NO WAY for it to be even remotely accurate. Ditch the HRM for weights.

RossUK88

Now that is an amazing answer, thanks for the details; alot to think about there.
Do you tend to log your weight lifting into MFP? I'm just trying to gain as accurately as I can what I'm burning in the gym so I am able to eat them back.

Cheers

vorgas

I do log my weight lifting.

The amount of energy required to lift a weight is a known constant. It's 0.00032 Calories per pound per foot. Of course, our bodies are horribly inefficient, so we burn quite a bit more than that in order to move that weight.

And, obviously, not all lifts are created equal A free weight squat uses more energy than a smith machine squat which uses more energy than an inclined leg press.

The only lifts I do are compound lifts (squats, deadlifts, bench press, snatch, etc), so I am comfortable estimating at 20 calories used for every calorie applied, bringing it to 0.0064 Calories per pound per foot.

I'm usually doing lifts that are about 2 feet of movement each, so 0.0125 calories per pound.

I usually throw in 10 to 20 extra calories for racking/reracking weights, the protein needed to rebuild the muscle damage, etc.

After several months of doing the math this way, my gains/losses are about where I expect them, so it's close enough for me.

skippygirlsmom

good info