1. Oh, and if your means of exercise involves any sort of motorized assist, well that throws a HUGE variable into the calculations.

2. I'll try to explain a bit more.

"Calories" is the coloquial term for kilocalorie, aka kcal. Yes, every food "calorie" is actually 1000 real calories. Anyway, one kcal (same as "calorie") is the energy needed to heat one cubic centimeter of water one degree (Celsius). The kcal is a measure of "work" in physics terms and here's the important part: the work needed to move something a certain distance is the same no matter which way or how fast you do it.

So walking one mile does the same "work" as running one mile. As such the calories your body uses to walk or run 1 mile is the same. This is physics.

It follows, therefore, that moving the same distance in a wheelchair or handcycle also requires the same amount of work. So if I push my chair 5 miles or ride my handcycle that same route the "work" and calories burned are the same.

So if you ride your handcycle along side a friend on a regular bicycle and you both weigh the same and your bikes weigh the same and you ride the exact same route then the calories burned are the same. You will absolutely be feeling it more and it will be more difficult, but that's because you're doing the same work with fewer and smaller muscles.

Math wise, work is the integral of force times distance. It takes more force to accelerate a heavy handcycle than it does a lightweight bicycle, so the reality is that the handcyclist of the same weight will burn more calories owing to the heavier bike.

3. Originally Posted by brian
Oh, and if your means of exercise involves any sort of motorized assist, well that throws a HUGE variable into the calculations.
I have a motorized assist on my handcycle. My plan is to replace my current cranks with a power meter crank from Quarq (I have two on racing bicycles from pre-accident, but they're the wrong BCD for the chainrings I'd need today). With power measured at the crank, I will be able to isolate the work that I'm doing vs. what the motor is doing.

4. Originally Posted by Mize
So if you ride your handcycle along side a friend on a regular bicycle and you both weigh the same and your bikes weigh the same and you ride the exact same route then the calories burned are the same. You will absolutely be feeling it more and it will be more difficult, but that's because you're doing the same work with fewer and smaller muscles.
Can you reference any studies that support this?

A 12 cylinder engine and a 6 cylinder engine can each move the same car the same distance, but I imagine they will use a differing amount of fuel to do it.

Originally Posted by Mize
With power measured at the crank, I will be able to isolate the work that I'm doing vs. what the motor is doing.
If you are ONLY using power at crank, then okay. But the software can't separate work like that when calculating it with speed and length of ride. The numbers still aren't accurate.

Again, I'm happy to be wrong about all of this. I just need data and reliable sources that say otherwise.

5. My statements about work required to move things can be found in literally every introductory Physics textbook. Energy and work are interchangeable in physics as they both represent the same thing.

If a 4-cylinder and an 8-cylinder car drive the identical route without stopping the 8-cylinder car will do more work because it is heavier. It is likely also less efficient as the amount of energy lost to simply creating heat will rise with the number of cylinders. Likewise a fat cyclist will have to do more work than a stick-cyclist.

So when a map-based estimate of calories is used they are essentially guessing at the total amount of vertical rise in the route and using your weight. This omits all the inefficiencies like that 8-cylinder creating more heat. It also omits aerodynamic effects. This is where heartrate comes in. Heartrate calories estimates are "better" because they include all the wasted effort from poor form or from stopping often (losing momentum). Heartrate isn't interested in the work required to move the bike, but rather the work that you used. There are many models for heartrate calorie burn but absolutely NONE of them is for wheelchair users. The best way to get that data is to hook wheelers up to a breath analyzer while they workout on a trainer. The breath analyzer looks for chemical byproducts of metabolism and can thereby be used to create a better heartrate model.

With power meters they are directly measuring the torque applied by the user to the cranks. There is no better measure for calculating applied work. They're just really expensive!

6. I am sorry that I did not see this earlier.... Put it to post-holiday blahs....

I don't know of any studies but will do my best to find some. One of my questions is (and maybe you already answered this - my apologies if you did), is what are you trying to accomplish with this. Curiosity? Weight loss? Muscle tone/

ckf

7. Originally Posted by SCI-Nurse
I don't know of any studies but will do my best to find some.

One of my questions is what are you trying to accomplish with this. Curiosity? Weight loss? Muscle tone?

ckf

Thanks, CKF.

My original point was to warn people that calorie counters can be wildly inaccurate and to take them with a grain of salt. And then to warn people that poor calorie expenditure estimation can lead to overeating and weight gain.

One of my reasons was that I *think* that SCI burn calories at a different rate than ABs. That's what got the larger argument going.

I linked studies showing that calorie counters are inaccurate in general, even with a heart rate monitor. But I can't find any studies about how SCI calorie expenditure compares to AB. Does an SCI that only uses 30% of an AB's muscle mass burn the same calories for the same work?

Mize believes so. I have a difficult time believing that (I got a C- in physics).

This is something I've been curious about for a while and I'd love to have a definitive answer backed by a scientific study.

MIZE:

Originally Posted by Mize
(I have two on racing bicycles from pre-accident, but they're the wrong BCD for the chainrings I'd need today).
What's the BCD and would you sell one and for how much?

Originally Posted by Mize
With power measured at the crank, I will be able to isolate the work that I'm doing vs. what the motor is doing.
Right. I agree that power meter + HRM is a more accurate way to measure caloric expenditure with the caveat that some software will calculate the data differently then others.
But if you have motorized assist, whatever calculations the software uses cannot take distance and speed into account. Right? Because some of that distance and speed is work done by the motor...?

Originally Posted by Mize
My statements about work required to move things can be found in literally every introductory Physics textbook. Energy and work are interchangeable in physics as they both represent the same thing.
I'm going to be annoying here (plus I was bad at Physics as noted above). Can you share any studies or medical articles showing that two people of the same weight will burn the same calories for the same work despite differences in muscle mass?

Everything you said sounds reasonable, but I have a very difficult time believing that two 160lb people - one 30 year old male with 50% body fat and one 50 year old female with 20% body fat - will burn calories at the same rate.

I looked a bit for articles that support this. I tried to prove your point to myself. But I couldn't really find any. But I also couldn't find any articles showing they DO burn calories differently. So I'm at a bit of a loss.

8. Brian, you are correct. Few studies have been done on exercise physiology with people with SCI related to either cardiovascular benefits nor calorie expenditure. The few studies done have shown a significant different between people with different levels of injury engaged in the same exercise (such as pushing a manual wheelchair).

The most accurate studies are metabolic studies which measure oxygen demand and consumption, not calorie burning. This can be expressed in "METs". “MET” is another name for metabolic equivalent; a measure of exercise intensity based on oxygen consumption. More specifically, a single MET is defined as the amount of oxygen a person consumes (or the energy expended) per unit of body weight during 1 minute of rest. METs have been calculated for ABs for a wide variety of activities, and are using often in pulmonary or cardiac rehabilitation programs for ABs. For example, walking at 3.0 miles per hour requires 3.3 METs of energy expenditure and is therefore considered a moderate-intensity activity. Vigorous-intensity activities are defined as 6.0 METs or more. Running at 10 minutes per mile (6.0 mph) is a 10 MET activity and is therefore classified as vigorous intensity.

Keep in mind that things like spasticity burn calories, and muscle movement stimulated by FES also burns calories, so these factors also need to be factored into studies done on various physical activities in persons with SCI.

This study looked only at energy expenditure (METs) in persons with SCI engaged in transfers and ADLs, not exercise such as hand cycling or pushing a manual wheelchair:
http://archive.scijournal.com/doi/ab...tlpi-tscr-site

This one looked only at cardiovascular (pulse, BP, etc.) response to arm ergometer use in people with tetraplegia vs. ABs engaged in the same activity;
http://www.tandfonline.com/doi/abs/1...8.2015.1126939

Here is an interesting study done on energy expenditure with participants engaged in Power (wheelchair) Soccer:
http://www.sciencedirect.com/science...03999316302398

This one looks a interval vs. aerobic exercise related to cardiovascular benefits:
http://www.tandfonline.com/doi/abs/1...8.2016.1260648

(KLD)

9. sunday my wife and I did a ride, only 15 miles but on crushed limestone.. we both have newer garmins and the higher end garmin hr straps.
I burned 589 to her 850. shes much smaller than me.

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