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this maybe a dumb question but, do you burn more calories if your fit?


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While running, the mind wonders.  So I was wondering if you have 2 people same height & weight but different fitness levels (lets say one pretty fit and one not so much), doing same workout.  Does each burn the same amount of calories?

 

 

16 Replies (last)

same size, same distance, same speed? the fitter person will burn fewer calories, because they don't have to work as hard, and--theoretically, at least--they're more efficient.

Highly subjective :-)  Does the fit person have a lower body fat percentage?  Thus having more muscle and a higher metabolism...

wes- guess i didn't think that deeply about it.  but i guess i'd have fit person w/ more muscle mass.

if i'm reading the question correctly, it's how much each person burns as a direct result of the workout.  the fitter person with more muscle mass would burn more calories overall, but not as a direct result of the run.

that's assuming, of course, that the person is fit from running and not from--say--rock climbing.

the more accustomed we are to any particular activity, the more efficiently we perform the activity, the less benefit we receive from that activity.

You are going to burn (X) number of calories per liter of oxygen you consume.  How much oxygen you consume depends on your VO2Max and the ability of your body to deliver said oxygen to your working muscles.  Fit people will, no doubt, have increased the the quantity and density of capillaries in the body, resulting in a more efficient deliver and utilization of oxygen.

It's a slippery slope :-)

The calories you burn are affected primarily by weight and intensity of the activity. A fit person may find that performing at a particular intensity feels easier than the unfit person, because that intensity is a lower percentage of the fit person's VO2 max, but if they weigh the same, the calorie output will be similar. 

I have not seen any studies that would indicate a substantial difference between two people of the same weight but different BF% levels--so if anyone has, I would definitely be interested in reading them. If you look at energy-prediction equations--like those from the Amer Coll of Sports Medicine--they make no distinction between fitness levels or body fat levels. 

Original Post by wesmckean:

You are going to burn (X) number of calories per liter of oxygen you consume.  How much oxygen you consume depends on your VO2Max and the ability of your body to deliver said oxygen to your working muscles.  Fit people will, no doubt, have increased the the quantity and density of capillaries in the body, resulting in a more efficient deliver and utilization of oxygen.

It's a slippery slope :-)

What you are describing is (partly) the definition of increasing VO2 max. The increased capacity you describe just means that "x" intensity now represents a lower % of VO2max compared to before, not that "greater efficiency" has lowered the intensity. 

Someone running at 6mph is working at ~10METS. Runner A has a VO2max of 12 METs, so that speed represents 83% of their maximum, which is pretty hard. Runner B has a VO2max of 15 METs, so that speed represents 67% of maximum, which is a medium effort. Runner A may struggle at that speed and not be able to last more than 10 min, while Runner B can maintain it for an hour. However, they both are working at 10 METs and both are burning roughly 10 Kcal/kg body wt/hour. 

If Runner A increases VO2 Max to 15 METs, running at 6 mph will now represent 67% of max, just like Runner B. The effort will feel significantly easier. However, it will still be 10 METs and the calorie burn at that speed will stay the same, as long as body weight has not changed. 

If Runner A wears an HRM, and has not changed the setting to reflect the increase in VO2 max, then the HRM will show a decrease in calories burned. I think that is what messes a lot of people up. What they don't realize is that HRMs do NOT measure calories--they only interpret heart rate response as a percentage of HR (and VO2) max. If the parameters are wrong, the HRM will be inaccurate as well. 

Original Post by wesmckean:

You are going to burn (X) number of calories per liter of oxygen you consume.  How much oxygen you consume depends on your VO2Max and the ability of your body to deliver said oxygen to your working muscles.  Fit people will, no doubt, have increased the the quantity and density of capillaries in the body, resulting in a more efficient deliver and utilization of oxygen.

It's a slippery slope :-)

What you are describing is (partly) the definition of increasing VO2 max. The increased capacity you describe just means that "x" intensity now represents a lower % of VO2max compared to before, not that "greater efficiency" has lowered the intensity. 

Someone running at 6mph is working at ~10METS. Runner A has a VO2max of 12 METs, so that speed represents 83% of their maximum, which is pretty hard. Runner B has a VO2max of 15 METs, so that speed represents 67% of maximum, which is a medium effort. Runner A may struggle at that speed and not be able to last more than 10 min, while Runner B can maintain it for an hour. However, they both are working at 10 METs and both are burning roughly 10 Kcal/kg body wt/hour. 

If Runner A increases VO2 Max to 15 METs, running at 6 mph will now represent 67% of max, just like Runner B. The effort will feel significantly easier. However, it will still be 10 METs and the calorie burn at that speed will stay the same, as long as body weight has not changed. 

If Runner A wears an HRM, and has not changed the setting to reflect the increase in VO2 max, then the HRM will show a decrease in calories burned. I think that is what messes a lot of people up. What they don't realize is that HRMs do NOT measure calories--they only interpret heart rate response as a percentage of HR (and VO2) max. If the parameters are wrong, the HRM will be inaccurate as well. 

jg,

The more skill the activity requires, the more difference their will be. So, if the activity is cross country skiing, the fitter person that has more balance and coordination will be burning fewer calories at the same speed. Running would see a smaller difference, maybe none if both people had good form (but good form requires core strength/muscle/fitness). On an inclined treadmill, like for a cardiac stress test, the leg speed and coordination required is minimal and the two people would probably burn almost the same calories.

OGR

If you have a heart rate monitor, and go to a gym that has mirrors in front of the treadmills, you can do a revealing experiment:

1)run at a constant speed until your HR has leveled out.

2)try various ways to change your form and see how it affects your heart rate. Don't change the speed setting while you do these tests:

lengthen your stride, along with a decrease in cadence.

shorten your stride, with faster cadence 

hold your arms close to your chest with elbow bent.

keep your arms down low, swinging by your hips.

throw your legs back behind you farther than normal.

etc.

You will see some significant differences, and that range is similar to the differences between people and how their efficiencies differ.

Original Post by oldguysrule:

If you have a heart rate monitor, and go to a gym that has mirrors in front of the treadmills, you can do a revealing experiment:

1)run at a constant speed until your HR has leveled out.

2)try various ways to change your form and see how it affects your heart rate. Don't change the speed setting while you do these tests:

lengthen your stride, along with a decrease in cadence.

shorten your stride, with faster cadence 

hold your arms close to your chest with elbow bent.

keep your arms down low, swinging by your hips.

throw your legs back behind you farther than normal.

etc.

You will see some significant differences, and that range is similar to the differences between people and how their efficiencies differ.

Not really. You seem to be describing exaggerated movements that, depending on how exaggerated they are, might significantly affect the intensity of the activity. However, those exaggerated movements are not related to the much smaller variation in running form that one sees among individuals. 

Changing your form somewhat might result in a transient increase in HR the first couple of times you do it, but the body will quickly adapt. 

For a trained individual, it takes a huge amount of training to realize even tiny improvements in mechanical efficiency. 

Original Post by oldguysrule:

jg,

The more skill the activity requires, the more difference their will be. So, if the activity is cross country skiing, the fitter person that has more balance and coordination will be burning fewer calories at the same speed. Running would see a smaller difference, maybe none if both people had good form (but good form requires core strength/muscle/fitness). On an inclined treadmill, like for a cardiac stress test, the leg speed and coordination required is minimal and the two people would probably burn almost the same calories.

OGR

The fitter person would almost certainly go faster, however. 

In theory, I mostly agree with you about complex movements--i.e. as one becomes more accomplished, energy expenditure will actually decrease for certain submax workloads.

In practice, however, I am not sure there is much practical effect. An untrained person performing a more complex activity might, in theory, expend more energy at a given submaximal workoad compared to a more trained individual (more trained at the same activity) doing the same workload. However, someone who is that inefficient is also going to be very limited as to how much effort they can exert and how long they can do it. And while, technically, as they become more trained and efficient, they will likely burn fewer calories at that same low-level intensity, there is little chance that they would do so, since the greater proficiency would allow them to work much harder. In any case, the "inefficiency" will more than likely be a short-term effect. 

So even if we could show that there was a greater rate (e.g. Kcal/min) of calorie burn for an untrained vs trained individual at a given workload, the difference in duration that both could achieve and the very low workload level that the untrained person is limited to, makes this idea useless as a "strategy" for weight loss.  

Which is why, while programs like P90X might be OK workout routines, the theoretical underpinning of that program (i.e. "muscle confusion") is pure nonsense. 

Original Post by azdak:

Original Post by oldguysrule:

If you have a heart rate monitor, and go to a gym that has mirrors in front of the treadmills, you can do a revealing experiment:

1)run at a constant speed until your HR has leveled out.

2)try various ways to change your form and see how it affects your heart rate. Don't change the speed setting while you do these tests:

lengthen your stride, along with a decrease in cadence.

shorten your stride, with faster cadence 

hold your arms close to your chest with elbow bent.

keep your arms down low, swinging by your hips.

throw your legs back behind you farther than normal.

etc.

You will see some significant differences, and that range is similar to the differences between people and how their efficiencies differ.

Not really. You seem to be describing exaggerated movements that, depending on how exaggerated they are, might significantly affect the intensity of the activity. However, those exaggerated movements are not related to the much smaller variation in running form that one sees among individuals. 

 

My movements in this experiment weren't exaggerated at all and were within the normal variation between runners, but my word choice ("significant") was a bad one. It should have been something more like "small but definitely measurable." My point was actually that there wasn't much difference between people, calorie wise, but that you could do the experiment and see about how big those differences might be. On the other hand, in races, being a bit more efficient than the next guy can end up making a big difference in a long race where people bonk. 

 

 

Original Post by oldguysrule:

Original Post by azdak:

Original Post by oldguysrule:

If you have a heart rate monitor, and go to a gym that has mirrors in front of the treadmills, you can do a revealing experiment:

1)run at a constant speed until your HR has leveled out.

2)try various ways to change your form and see how it affects your heart rate. Don't change the speed setting while you do these tests:

lengthen your stride, along with a decrease in cadence.

shorten your stride, with faster cadence 

hold your arms close to your chest with elbow bent.

keep your arms down low, swinging by your hips.

throw your legs back behind you farther than normal.

etc.

You will see some significant differences, and that range is similar to the differences between people and how their efficiencies differ.

Not really. You seem to be describing exaggerated movements that, depending on how exaggerated they are, might significantly affect the intensity of the activity. However, those exaggerated movements are not related to the much smaller variation in running form that one sees among individuals. 

 

My movements in this experiment weren't exaggerated at all and were within the normal variation between runners, but my word choice ("significant") was a bad one. It should have been something more like "small but definitely measurable." My point was actually that there wasn't much difference between people, calorie wise, but that you could do the experiment and see about how big those differences might be. On the other hand, in races, being a bit more efficient than the next guy can end up making a big difference in a long race where people bonk. 

 

 

Sounds like I misinterpreted your descriptions. As usual in these types of discussions, we start from different positions but, as we elaborate our ideas, end up pretty close. 

My main point is that, when starting a new activity, mechanical inefficiencies range from transient to short-term. Just like the training curve itself, beginning exercisers will see the biggest improvement in just a few sessions, intermediate exercisers will see steady, but much less improvement over  the following months, and experienced exercisers will have to do huge amounts of training to see any improvement at all. 

Original Post by azdak:

My main point is that, when starting a new activity, mechanical inefficiencies range from transient to short-term. Just like the training curve itself, beginning exercisers will see the biggest improvement in just a few sessions, intermediate exercisers will see steady, but much less improvement over  the following months, and experienced exercisers will have to do huge amounts of training to see any improvement at all. 

great. but the OP's question wasn't about longitudinal results, was it?

Original Post by pgeorgian:

Original Post by azdak:

My main point is that, when starting a new activity, mechanical inefficiencies range from transient to short-term. Just like the training curve itself, beginning exercisers will see the biggest improvement in just a few sessions, intermediate exercisers will see steady, but much less improvement over  the following months, and experienced exercisers will have to do huge amounts of training to see any improvement at all. 

great. but the OP's question wasn't about longitudinal results, was it?

A good thread eventually takes on a mind of it's own. 

See #6 for my original answer to the OP's original question. 

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