Treadmill & Fat

very good question-bumping for answer

When you are running, your body burns a combination of fat and carbohydrate for energy. The proportion of fat and carbohydrate burned is a function both ot your aerobic fitness level and the exercise intensity. At very high intensity, such as sprinting up a hill, the body burns almost exclusively carbohydrate. At very low intensity, such as sleeping, it burns almost exclusively fat. At approximately 75% max heart rate it is burning 50% of each.

If the treadmill is not reading from a heartrate monitor you are wearing I do not know how it could possibly be measuring exercise intensity. It cannot be from the speed and incline alone because two people with different fitness levels would be exercising at vastly different intensities at the same speed and incline.

When you are running, your body burns a combination of fat and carbohydrate for energy. The proportion of fat and carbohydrate burned is a function both ot your aerobic fitness level and the exercise intensity. At very high intensity, such as sprinting up a hill, the body burns almost exclusively carbohydrate. At very low intensity, such as sleeping, it burns almost exclusively fat. At approximately 75% max heart rate it is burning 50% of each.

If the treadmill is not reading from a heartrate monitor you are wearing I do not know how it could possibly be measuring exercise intensity. It cannot be from the speed and incline alone because two people with different fitness levels would be exercising at vastly different intensities at the same speed and incline.

???? I think you are mistaking relative intensity for absolute intensity.

The ACSM energy prediction equations for walking and running do not require age, height, fitness level, or gender--or even weight for that matter--to estimate VO2--just speed and elevation.

My understanding (from reading your other posts) is that energy expenditure for a cardiovascular activity for a particular person is dependent on speed, elevation, and bodyweight. So, two persons of equal bodyweight on the same course for the same distance will burn the same amount of calories regardless of fitness level.

However, the % of fat and carbohydrate burned for each of the two people to produce the same amount of energy may be vastly different dependent on the fitness level of each. The lower the workload's % of VO2max, the higher the % of fat and lower the % of glycogen burned to produce energy, independent of speed or elevation.

Is that correct?

Treadmill calorie estimates are often wildly inaccurate as the only data entered is age and weight. It's pretty reasonable to assume that an extremely fit, 6'2" 180lb male would probably be burning fewer calories than a 5'4" 180lb male yet the treadmill would have no way of differentiating the two......

Actually, treadmills are probably the most accurate as there is a known and accepted workload for walking. Weight is the only variable, and most treadmills that count cals allow you to enter your weight.

Also, if you are exercising on the treadmill with the primary purpose of losing weight the only really important number is the total calories burned. The proportion from fat and carbohydrate is only nice to know but not very relevant to overall weight loss.

The proportion from fat and carbohydrate only really becomes important for people training for endurance events and that is trained by by staying in specific cardio zones for long periods of time.

Agreed.

When you are running, your body burns a combination of fat and carbohydrate for energy. The proportion of fat and carbohydrate burned is a function both ot your aerobic fitness level and the exercise intensity. At very high intensity, such as sprinting up a hill, the body burns almost exclusively carbohydrate. At very low intensity, such as sleeping, it burns almost exclusively fat. At approximately 75% max heart rate it is burning 50% of each.

If the treadmill is not reading from a heartrate monitor you are wearing I do not know how it could possibly be measuring exercise intensity. It cannot be from the speed and incline alone because two people with different fitness levels would be exercising at vastly different intensities at the same speed and incline.

Isn't recent diet also a factor in what the body burns? If your working out fasted will your body burn differently than if you work out fed? For lack of better terms...

Also interested to know if/when the body burns muscle for fuel.

Keep in mind that fuel substrate use during exercise is a transient thing. Regardless of what is being used, it has no significant effect on body fat or muscle mass--not independently at least.

There might be some instances where "fasted cardio" is going to drive the RQ more toward the "fat" side of things, but that will make no difference in overall body fat--at least not for the average person. First of all--you don't burn that much fat anyhow, even in a 45-60 min workout. Secondly, the body up- or down-regulates fat oxidation during the following 24 hours, so it all evens out. (Now for someone, say a bodybuilder who is at 5% body fat, there might be a more significant effect--it's not really an area I care about).

The mix of fuel substrates used during exercise is primarily driven by intensity. However, training style can also have an impact. The ability to "burn more fat" during exercise may not have that much effect on weight loss, but it can affect performance.

The same thing with "muscle" at some point, in long-duration, higher-intensity aerobic exercise, you can see an increase in the % of amino acids used for fuel--basically they are being scavenged for their carbon skeletons. There was a great study done about 15 years ago that first used radioactive isotopes to track substrate usage. This was the study that open eyes about amino acid usage. When I went to school, amino acid contribution to aerobic exercise was considered negligible--so much so that it is not even counted in any of the equations used to estimate percentage of fuel substrate used. I thought I had filed a copy of the study, but I have never been able to find it.

It was from this study and others that were similar that it was determine that endurance athletes needed to increase their protein intake above the RDA--in fact, on a per kg basis, endurance athletes actually needed more protein than powerlifters (mainly because total body mass was so much smaller).

If protein intake is adequate, then people can perform a high volume of aerobic exercise and not lose any lean mass.

I think one of the reasons the "cardio burns muscle" misinformation is so prevalent is that people use different criteria and reference points. In fact, high volumes of steady-state cardio do inhibit gains in muscle mass. To me, that's not the same as "burning muscle" and it is only relevant to those who are trying to maximize gains in muscle mass. For the average person, it doesn't mean anything. You can still gain mass while doing a lot of cardio--you just aren't going to maximize your gains. Unfortunately, the body builder or power lifter is too often used as the standard "reference point" for the general population. So a sedentary, overweight, middle-aged person is warned against "doing too much cardio" because it will burn muscle and make them more fat, which is possibly more bizarre than an NRA news conference.

When you are running, your body burns a combination of fat and carbohydrate for energy. The proportion of fat and carbohydrate burned is a function both ot your aerobic fitness level and the exercise intensity. At very high intensity, such as sprinting up a hill, the body burns almost exclusively carbohydrate. At very low intensity, such as sleeping, it burns almost exclusively fat. At approximately 75% max heart rate it is burning 50% of each.

If the treadmill is not reading from a heartrate monitor you are wearing I do not know how it could possibly be measuring exercise intensity. It cannot be from the speed and incline alone because two people with different fitness levels would be exercising at vastly different intensities at the same speed and incline.

Isn't recent diet also a factor in what the body burns? If your working out fasted will your body burn differently than if you work out fed? For lack of better terms...

Also interested to know if/when the body burns muscle for fuel.

Keep in mind that fuel substrate use during exercise is a transient thing. Regardless of what is being used, it has no significant effect on body fat or muscle mass--not independently at least.

There might be some instances where "fasted cardio" is going to drive the RQ more toward the "fat" side of things, but that will make no difference in overall body fat--at least not for the average person. First of all--you don't burn that much fat anyhow, even in a 45-60 min workout. Secondly, the body up- or down-regulates fat oxidation during the following 24 hours, so it all evens out. (Now for someone, say a bodybuilder who is at 5% body fat, there might be a more significant effect--it's not really an area I care about).

The mix of fuel substrates used during exercise is primarily driven by intensity. However, training style can also have an impact. The ability to "burn more fat" during exercise may not have that much effect on weight loss, but it can affect performance.

The same thing with "muscle" at some point, in long-duration, higher-intensity aerobic exercise, you can see an increase in the % of amino acids used for fuel--basically they are being scavenged for their carbon skeletons. There was a great study done about 15 years ago that first used radioactive isotopes to track substrate usage. This was the study that open eyes about amino acid usage. When I went to school, amino acid contribution to aerobic exercise was considered negligible--so much so that it is not even counted in any of the equations used to estimate percentage of fuel substrate used. I thought I had filed a copy of the study, but I have never been able to find it.

It was from this study and others that were similar that it was determine that endurance athletes needed to increase their protein intake above the RDA--in fact, on a per kg basis, endurance athletes actually needed more protein than powerlifters (mainly because total body mass was so much smaller).

If protein intake is adequate, then people can perform a high volume of aerobic exercise and not lose any lean mass.

I think one of the reasons the "cardio burns muscle" misinformation is so prevalent is that people use different criteria and reference points. In fact, high volumes of steady-state cardio do inhibit gains in muscle mass. To me, that's not the same as "burning muscle" and it is only relevant to those who are trying to maximize gains in muscle mass. For the average person, it doesn't mean anything. You can still gain mass while doing a lot of cardio--you just aren't going to maximize your gains. Unfortunately, the body builder or power lifter is too often used as the standard "reference point" for the general population. So a sedentary, overweight, middle-aged person is warned against "doing too much cardio" because it will burn muscle and make them more fat, which is possibly more bizarre than an NRA news conference.

Great stuff, as usual. Thank you.

When you are running, your body burns a combination of fat and carbohydrate for energy. The proportion of fat and carbohydrate burned is a function both ot your aerobic fitness level and the exercise intensity. At very high intensity, such as sprinting up a hill, the body burns almost exclusively carbohydrate. At very low intensity, such as sleeping, it burns almost exclusively fat. At approximately 75% max heart rate it is burning 50% of each.

If the treadmill is not reading from a heartrate monitor you are wearing I do not know how it could possibly be measuring exercise intensity. It cannot be from the speed and incline alone because two people with different fitness levels would be exercising at vastly different intensities at the same speed and incline.

Isn't recent diet also a factor in what the body burns? If your working out fasted will your body burn differently than if you work out fed? For lack of better terms...

Also interested to know if/when the body burns muscle for fuel.

Keep in mind that fuel substrate use during exercise is a transient thing. Regardless of what is being used, it has no significant effect on body fat or muscle mass--not independently at least.

There might be some instances where "fasted cardio" is going to drive the RQ more toward the "fat" side of things, but that will make no difference in overall body fat--at least not for the average person. First of all--you don't burn that much fat anyhow, even in a 45-60 min workout. Secondly, the body up- or down-regulates fat oxidation during the following 24 hours, so it all evens out. (Now for someone, say a bodybuilder who is at 5% body fat, there might be a more significant effect--it's not really an area I care about).

The mix of fuel substrates used during exercise is primarily driven by intensity. However, training style can also have an impact. The ability to "burn more fat" during exercise may not have that much effect on weight loss, but it can affect performance.

The same thing with "muscle" at some point, in long-duration, higher-intensity aerobic exercise, you can see an increase in the % of amino acids used for fuel--basically they are being scavenged for their carbon skeletons. There was a great study done about 15 years ago that first used radioactive isotopes to track substrate usage. This was the study that open eyes about amino acid usage. When I went to school, amino acid contribution to aerobic exercise was considered negligible--so much so that it is not even counted in any of the equations used to estimate percentage of fuel substrate used. I thought I had filed a copy of the study, but I have never been able to find it.

It was from this study and others that were similar that it was determine that endurance athletes needed to increase their protein intake above the RDA--in fact, on a per kg basis, endurance athletes actually needed more protein than powerlifters (mainly because total body mass was so much smaller).

If protein intake is adequate, then people can perform a high volume of aerobic exercise and not lose any lean mass.

I think one of the reasons the "cardio burns muscle" misinformation is so prevalent is that people use different criteria and reference points. In fact, high volumes of steady-state cardio do inhibit gains in muscle mass. To me, that's not the same as "burning muscle" and it is only relevant to those who are trying to maximize gains in muscle mass. For the average person, it doesn't mean anything. You can still gain mass while doing a lot of cardio--you just aren't going to maximize your gains. Unfortunately, the body builder or power lifter is too often used as the standard "reference point" for the general population. So a sedentary, overweight, middle-aged person is warned against "doing too much cardio" because it will burn muscle and make them more fat, which is possibly more bizarre than an NRA news conference.

Thank you! I try to rotate my use of the treadmill, I increase the speed and lower the incline and vice verse. I tempt to burn more cal when I increase the incline 6% and speed 3.5. Once again THANK YOU!!!