FitBit Cardio Zones
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Psychopasta
Posts: 37 Member
Hello 'Pals,
I use a FitBit for heart rate and step counting along with MFP for nutrition. FitBit defines different cardio zones, such as Fat Burn, Cardio and Peak. My question: is there real science behind these zones? As I'm trying to lose weight, why would I want to get out of the Fat Burn zone and get into anything higher (and harder)?
I use a FitBit for heart rate and step counting along with MFP for nutrition. FitBit defines different cardio zones, such as Fat Burn, Cardio and Peak. My question: is there real science behind these zones? As I'm trying to lose weight, why would I want to get out of the Fat Burn zone and get into anything higher (and harder)?
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Let me explain a bit better what I'm thinking. I have a ~4 mile trail near where I Iive. If I walk my dog, it takes ~1 hour and I'm in the 'fat burn zone' for the whole trip. If I jog it takes say 40 mins and I'm in the cardio zone. If I use a bike it's maybe 20 mins and I'm in Cardio/peak. It's the same total distance and calory burn, roughly speaking.
So is dog-walking better for weight loss than biking? It's the exercise time and intensity that varies. Am I better off doing lower intensity for longer, or does this heart-rate-zone stuff not really matter?1 -
There is real science behind the zones - but for cardio training reasons - not for weight/fat loss.
Also, the application to you specifically is NOT scientific, even if you wanted to use it for specific types of cardio training.
They start out with same tired 220-age to estimate HRmax, and then go from there. Huge bell curve, more chance of being out by 8 bpm than within. Also, doesn't always drop as fast as age progresses, especially if doing some cardio.
You do want to get out of the mis-named Fat Burning zone (for ages was called the Active-Recovery HR zone, name gives a clue for it's use) in order to burn more total calories and fat calories.
But it's great if you had a lifting workout day before and sore muscles.
You burn a higher % of calories from fat in that zone. But less calories. It also doesn't incorporate the day as a whole.
My own figures from a VO2/HR max test.
HR 127 - 10.99 cal/min - 51.8% fat usage.
Now lets go up into that upper aerobic zone.
HR 157 - 15.09 cal/min - 27.9% fat usage.
So for an hour each:
659 cal - 342 fat, 317 carb.
905 cal - 253 fat, 652 carb.
So while that 1 hr may look good for fat burn, consider the day as a whole now.
More carbs burned means after your next meal, carbs are going to be sent to refill liver/muscle stores they were pulled from.
Your next meal going to have 652 carbs?
This could take 2 meals.
Once that is done, insulin drops, back to fat burning sooner than if you only burned 317 carbs.
So first assuming the calorie burn based on HR is decently accurate (close enough to compared to other methods) - your comparison of 3 methods leading to same calorie burn, but different amounts of time and intensity - only has a bearing on your cardio goals and time available.
The higher intensity can be useful to get the body strong for hard efforts - chasing after a dog that got off leash in the woods.
The lower intensity can be useful if you have a goal of doing 5-10K's and need to train the fat burning system.
But as far as weight loss and fat loss - doesn't matter.
Calorie deficit does (which puts you into that post-meal fat-burning time sooner than if not dieting).
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