Using a HRM - fat burning zone

Very curious as well. I was trying to figure this out today!

Bumping for curiosity too!

This has been mentioned a lot here, the last thing I remember someone saying is that you will burn more calories at the higher heart rate, but the percentage of fat lost will be less. I'd rather push it harder too, it helps the fitness.

GG

I just got my first HRM (Polar FT40) as I wanted to get a better idea of how many calories I am burning at the gym.

Now in my cardio sessions I like to really 'go for it' - fast and hard listening to energising music. Usually 95% of my workouts were in the 'fitness zone'

On my HRM there is a little heart symbol which shows which zone you are in, fat-burning zone on the left, or fitness zone on the right. Here's what the manual says:

Fatburn (heart symbol is on the left side of the line)
In fatburn zone, training intensity is lower, and the source of energy is mainly fat. Therefore, fat burns efficiently and your metabolism, mainly fat oxidation, increases.

Fitness (heart symbol is on the right side of the line)
In fitness zone, training intensity is higher and you are improving your cardiovascular fitness i.e. strenghtening your heart and increasing blood circulation to muscles and lungs. The main energy source is carbohydrates.

If your aim is to lose weight, training sessions need to be 30-60 minutes or longer in the fat burn zone. The longer the duration the more calories burned, especially from fat. The percentage of burnt fat calories will appear in a summary after the session.
For improving your cardiovascular fitness, aim to train in the fitness zone three or four times a week for 20-40 minutes per session. The fitter you are, the more training (more often and longer duration) is required for fitness improvement.

Having read that tonight I did a much much slower workout and pretty much stayed in the fat-burning zone (max 121bpm for fat-burning zone). I was so bored and hardly even broke into a sweat. In one hour I only burned 383 cals.

I've done a bit of Googling on this topic and there are lots of sites saying that this is all a big myth and generally exercising and just getting the heart-rate up is all that matters.

What do you guys think? Am I better off going to the gym and going at the faster pace which I prefer, or persisting with doing some SLOW cardio in order to burn fat and lose weight more effectively?

BTW I will be doing a spin class tomorrow where my heart rate can go up to 184bpm, this is much more my speed! :laugh:

Depends on what your goal is. If you need to strip some fat off, don't go above 75% of your THR. The best way to get a more accurate number on what that looks like at 75% equals this: 220 - age x 75% + resting heart rate (example: 220 - 50 = 170 x 75% = 127.5 + 70 = 197.50. Usually I have clients stay in the 65% THR for fat loss. When you get to 80% you are looking at anaerobic training which does not pull from the fat cell, in fact it will start taking muscle tissue for the expediture which is why carb loading a bit is important before the session, again it depends on your goal. Message me if you want, I can get into deeper one on one.
Peace.

bumpity-bump for sure.

I'm curious about this too. When I go for a brisk walk or do a walking DVD at home, my average heart rate is in the 140s and I'm always in fitness mode. When I do my walking Wii game, I average in the 120s and am in fat burning mode most of the time. But the intensity is pretty low.

Why not do both throughout the week and optimize your results?

The "fat burning" advice looks at only one part of the picture--it is a common shortcoming when people try to give exercise and weight loss advice.

One of the biggest mistakes that people make--whether it's "fat burning" or "muscle burning" is to assume that what happens during an exercise session is somehow a unique and discrete event that is not affected by what happens metabolically the other 23 hours of the day.

The "fat burning" theory falls apart in two ways. First of all, the difference in actual "fat burned" between a "fat-burning" and a "non fat-burning" workout is only about a half ounce at most. But the main reason the "fat burning" theory is invalid is because, after 24 hours, total fat oxidation is the SAME, regardless of the amount of fat burned during exercise. In other words, fat oxidation over 24 hours is affected by what happens during the exercise session--if you "burn more fat" during exercise, you burn less the rest of the day, and vice versa.

People need to constantly remind themselves that body fat loss results from long-term lifestyle changes and primarily from maintaining a consistent negative calorie balance. The primary role of exercise is to help maintain the calorie deficit and to conserve lean mass. What happens during the workout itself is mostly irrelevant.

This issue is also confused by the fact that there is a lot of variation in heart rate response to exercise and many people (most?) do not have their HRMs set up properly. They follow the default settings for their age and gender, which may be off by 20-30 beats/min in over 20% of the population. If the HRM calculates your HRmax at 180, for example, and your actual HRmax is 200 with a resting HR of 60, all of your "zone" settings will be way off.

So, people get hit with a double whammy: they are not only trying to follow an outdated concept ("fat burning zone"), but their HR settings are way off so that instead of working in the 60% "fat burning" range, they might only be at 40%--no wonder it seems so easy!

Now, having said this, I would also caution against going to the other extreme of pushing high intensity all the time. Not only does this increase your risk of injury and overtraining, it can also make your training unbalanced. There is a role for some endurance training in your routine--it can actually help improve your ability to do HIIT.

A balanced approach is best--you might tinker with the volume, but overall, I always recommend that you train for fitness, and eat for weight loss.

Hope this helps.