Experts, Explain it to me like I'm 5

LYL353

I need someone to give me the MHR for Dummies break down. I've read plenty on the web so I don't need links and such... I need an EXPERT to explain it to me like I'm completely stupid.

From what I understand MHR (max heart rate) is roughly 220-age. *I* would think that being at the max for the longest possible time would be the most effective for weight loss. However, what I have read has not been the case. Most websites recommend about 60% of the maximum to burn the most fat. This just doesn't make sense to me.

I get that it's a ratio measurement. The math is solid... I just don't get the WHY/why not of it all. Also, if roughly 50% (at the "fat burn" MHR%) of the calories burned are from fat, where are the other calories that are burned coming from?

Any takers?

zipa78

LYL353 wrote: »

*I* would think that being at the max for the longest possible time would be the most effective for weight loss.

It sure is. I just don't know of anyone who can hill sprint at maximum effort for one hour at a time. Most people will manage a few seconds, maybe a minute or two if you are in good shape.

BusyRaeNOTBusty

No one CAN maintain that max heart rate for more than 30 or 40 seconds (maybe less). It's just not possible.

And yes, when you work out at 50-60% you body uses more fat as fuel. Think of it as a car with 2 tanks, one is fat (stored and what you eat), one is the carbs (stored and what you eat). If you work out at 60%, while you are working out you use more from the fat tank, and less from the carb tank. If you work out harder you start to use more carbs. BUT lets say you worked out hard, used a lot of carbs, but at the end of the day you burned more calories in general due to that hard workout, eventually more comes out of the fat tank anyway. As long as you are at a deficit, it doesn't matter if you are in "fat burning zone" while you exercise.

lhippen

I don't believe I qualify as an expert, but as someone who regularly uses a heart rate monitor during exercise I feel fully qualified to assert that no one can exercise at 100% of their true maximum heart rate for more than one minute at most except maybe very well-trained elite athletes. (To even get near maxHR I would need to warm up, then run very hard for at least ten minutes and then sprint all out for another minute, and only for a few seconds at the end will I get up to full maxHR.) So regardless of where the calories are coming from, maxHR will never help you burn many calories because you cannot do it long enough to burn but a small number.

As to where the other calories burned are coming from, it is simply carbohydrate molecules and protein molecules that are also stored/existing in your muscles along with the fat molecules.

LYL353

My question was not if it is possible. My question is why does it work the way it works.

QuietBloom

60% max to burn the most fat is bunk. There is no such thing as a 'fat burning heart rate zone'. You will either incur a deficit or not, it doesn't really matter how you get there.

fearlessleader104

Here is what I would tell a 5 years old kid
Go to bed

ninerbuff

Explanation to a 5 year old: Because that's just how it works.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

LYL353

The "funny guy," huh?

bwogilvie

Your maximum heart rate is the fastest that the old ticker can go. It appears to be limited by the flexibility of the heart walls and your nervous system's ability to stimulate the heart. There may be some neurological limits there too, because if the heart stops working, so do you.

The 220-age formula has no scientific basis. There are more accurate formulae that have been developed since then, but they still have a lot of variance in the study populations. The only accurate way to determine your personal MHR is a stress test. Believe me, it's not a lot of fun. When the formulas predicted mine should be somewhere in the 175-185 range, my test showed that mine was 192.

If you are exercising for weight loss, you need to strike a balance between the effort that burns the most calories per minute and the effort that burns the most calories over the course of the whole workout.

Sure, at MHR you can burn a lot more calories per minute (maybe 20 calories/minute for a trained 150 lb. male), but you'll be doing that for a couple minutes at most. That's not a lot of calories. You simply cannot exercise at your maximum heart rate for more than a very brief period.

At the other extreme: Walking at 3 mph you can walk all day, but if you weigh 150 lb., you'll only burn 4 calories per minute. So walk for 4 hours, burn 960 calories. Not too shabby, but who has 4 hours a day to exercise?

The same 150-lb. person running at an 8:00/minute mile (7.5 mph) might burn 13 calories per minute. To burn the same number of calories you'd burn in 4 hours of walking would require "only" an hour and 15 minutes of running. I put "only" in quotation marks because, if you've run 9.25 miles in an hour and a quarter, you know what it requires.

The 60% of maximum figure that is often recommended is kind of conservative, depending on your fitness and your tolerance for punishment. On my last one-hour run, I averaged 85% of my MHR. That was not exactly a walk in the park, but it wasn't too hard either.

The 60% figure is sometimes justified by the fact that, around that intensity, the greatest proportion of calories burned in exercise comes from free fatty acids. That might be true, but if you're exercising harder, the total calories from fat will be higher even if the proportion is lower.

And to answer the final question: the calories that don't come from fat come from carbohydrates: glycogen stored in muscles (which can usually, by itself, fuel up to 2 hours of moderately intense exercise in a fit athlete), liver glycogen (which fuels the brain), and any ingested carbohydrates. If you're exercising beyond your aerobic (lactate) threshold, accumulated lactate that can no longer be metabolized aerobically by being reduced to pyruvate will circulate in the blood, where it can serve as fuel for those parts of the body that aren't working crazy fast. In extremis, your body will start breaking down proteins, but that's really only in long-distance endurance events when you've exhausted other sources.

Basically, though, it doesn't matter how many calories burned during exercise come from fat. As long as you're in a calorie deficit, your fat stores will provide the energy that ingested food doesn't provide. In my last one-hour run, I burned around 820 calories. Probably 40% of those calories came from my fat stores. But I was at a 500-calorie deficit that day, so all 500 calories that I didn't eat ultimately came from fat stores—if not during the run, then over the next several hours.

dougpconnell219

Just go as balls to the walls as you can, the rest will sort itself out.

LYL353

Fabulous explanation. Thank you for taking the time to reply to me. I can't say I understood it all in the first read but it made more sense than anything else I read online with my Google searches.

You are awesome. Thanks again.

bwogilvie wrote: »

Your maximum heart rate is the fastest that the old ticker can go. It appears to be limited by the flexibility of the heart walls and your nervous system's ability to stimulate the heart. There may be some neurological limits there too, because if the heart stops working, so do you.

The 220-age formula has no scientific basis. There are more accurate formulae that have been developed since then, but they still have a lot of variance in the study populations. The only accurate way to determine your personal MHR is a stress test. Believe me, it's not a lot of fun. When the formulas predicted mine should be somewhere in the 175-185 range, my test showed that mine was 192.

If you are exercising for weight loss, you need to strike a balance between the effort that burns the most calories per minute and the effort that burns the most calories over the course of the whole workout.

Sure, at MHR you can burn a lot more calories per minute (maybe 20 calories/minute for a trained 150 lb. male), but you'll be doing that for a couple minutes at most. That's not a lot of calories. You simply cannot exercise at your maximum heart rate for more than a very brief period.

At the other extreme: Walking at 3 mph you can walk all day, but if you weigh 150 lb., you'll only burn 4 calories per minute. So walk for 4 hours, burn 960 calories. Not too shabby, but who has 4 hours a day to exercise?

The same 150-lb. person running at an 8:00/minute mile (7.5 mph) might burn 13 calories per minute. To burn the same number of calories you'd burn in 4 hours of walking would require "only" an hour and 15 minutes of running. I put "only" in quotation marks because, if you've run 9.25 miles in an hour and a quarter, you know what it requires.

The 60% of maximum figure that is often recommended is kind of conservative, depending on your fitness and your tolerance for punishment. On my last one-hour run, I averaged 85% of my MHR. That was not exactly a walk in the park, but it wasn't too hard either.

The 60% figure is sometimes justified by the fact that, around that intensity, the greatest proportion of calories burned in exercise comes from free fatty acids. That might be true, but if you're exercising harder, the total calories from fat will be higher even if the proportion is lower.

And to answer the final question: the calories that don't come from fat come from carbohydrates: glycogen stored in muscles (which can usually, by itself, fuel up to 2 hours of moderately intense exercise in a fit athlete), liver glycogen (which fuels the brain), and any ingested carbohydrates. If you're exercising beyond your aerobic (lactate) threshold, accumulated lactate that can no longer be metabolized aerobically by being reduced to pyruvate will circulate in the blood, where it can serve as fuel for those parts of the body that aren't working crazy fast. In extremis, your body will start breaking down proteins, but that's really only in long-distance endurance events when you've exhausted other sources.

Basically, though, it doesn't matter how many calories burned during exercise come from fat. As long as you're in a calorie deficit, your fat stores will provide the energy that ingested food doesn't provide. In my last one-hour run, I burned around 820 calories. Probably 40% of those calories came from my fat stores. But I was at a 500-calorie deficit that day, so all 500 calories that I didn't eat ultimately came from fat stores—if not during the run, then over the next several hours.

ninerbuff

LYL353 wrote: »

The "funny guy," huh?

Okay I'll make it easy. Physical activity of any type will ALWAYS burn glycogen first and foremost. The harder you work, the more glycogen you burn. You then go to burning fat, but for most, that's a pretty long workout (1 hour or more of intense exercise).
Fat is EXCLUSIVELY burned (100%) at rest. One burns more fat sleeping for 8 hours, than doing 1 hour of even moderate cardio.
Best bet is to do what you can with good effort, eat a calorie deficit, and get substantial rest. Be consistent with it and fat will get lost.


A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

bwogilvie

ninerbuff wrote: »

Fat is EXCLUSIVELY burned (100%) at rest.

Except for the brain, which needs glucose (or, in extremis, ketones) to function.

But yes, as long as you're in a calorie deficit, it really doesn't matter what percentage of fat exercise burns. Ultimately, the deficit will come from fat stores. Unless you're a special snowflake to whom the laws of physics don't apply