HR/fitness zone vs fat burning confusion

bohdanko
bohdanko Posts: 16 Member
edited December 2024 in Fitness and Exercise
I thought I was doing pretty well alternating about 45 minutes of cardio 3 times a week, getting pretty sweaty and out of breath, with days of interval training, cardio and weights 3 days a week, also getting pretty sweaty and out of breath. Then I started using a HR monitor, and it tells you how much of your workout is spent in a fitness vs. fat-burning zone. In order to stay in my "fat-burning" HR zone, apparently I have to keep my HR under 120. At under 120, I barely feel like I've done anything.

So I started trying to research. This is ridiculous! Everyone is an expert, and there is way too much conflicting information out there! I read the entire 20 pages of cardio vs strength training thread hoping someone would link to something I could trust, but nope.

I know I need strength training for optimal fitness, and I enjoy it. I also enjoy cardio, but not that much at only 60% of my max HR. So my question: Do I really need to stay that low for optimal cardiovascular fitness? Also, can anyone show me some links to trustworthy informatiion about this - not sites that are trying to sell things or pushing a particular diet plan, BTW. I used to know a fair amount about fitness, but it's been probably 10-15 years since I read up, and research changes!

Replies

  • scottb81
    scottb81 Posts: 2,538 Member
    Staying that low is not necessary for cardiovascular fitness. For daily general running you should stay under around 80%. Google "heart rate training for running" and the information is there.

    This site is pretty good http://www.coachr.org/heart_rate_training_for_improved.htm.
  • Azdak
    Azdak Posts: 8,281 Member
    First of all, you have to make sure your HR numbers are accurate.

    That means knowing your maximum heart rate and resting heart rate.

    It's not easy to measure HRmax--an all out test can be risky, is quite uncomfortable, and people who don't push themselves regularly to that level often are stopped by muscle fatigue before they reach max.

    So you can start with an HRmax prediction formula based on age. Google it and you will find plenty.

    The best way to determine training HR levels is using the Karvonen method (AKA "HR Reserve" method).

    1. Determine HR reserve: HRmax -- HRrest = HR Reserve

    2. Multiply HR Reserve by training intensity: For a 60% intensity: HR Reserve X .6

    3 Add HR Rest back to the number calculated in Step 2. That is your "target HR" for a 60% effort.

    Ex: 40 year old with a resting HR of 60.
    HRmax (estimated) = 180 (220-age)
    HR Reserve = HRmax (180) -- HR rest (60) = 120
    60% HR Reserve = HR Reserve (120) * 60% = 72
    60% Target Heart Rate = 60% HR Reserve (72) + HR rest (60) = 132

    Here's the difference if you did not include HRrest and just multiplied HRmax (180) times 60%, you get a Target Heart Rate of 108. Big difference between 132 and 108.

    So now you have estimated a more "accurate" target HR. But you still have to test it out and compare your HR to your perceived exertion. If your 60% Target HR is 132, but you start to exercise, and at a "light" level of effort you see your heart rate is 140, for example, that means your actual HRmax is noticeably higher than the age-predicted HRmax we used. At that point you can either be tested for HRmax, or use perceived exertion and trial and error to get a better sense of your true HR max.

    Now let's address the second question, which is: Do you even need to work at a 60% effort level?

    My answer is: a qualified "yes", but not for the reason you think. You don't need it to stay in a "fat-burning zone" -- that is a myth you should just ignore.

    But, a balanced cardio program should include 1 or 2 endurance workouts per week--not just for losing weight, but for general fitness training. The endurance workouts are a good compliment to interval and high-intensity steady state workouts. Endurance workouts should be done primarily at an intensity that barely gets you breathing harder. If you were to try to count very fast between breaths, it is an intensity that should allow you count "onetwothreefourfivesixseven or eight" between breaths (although overall you might breath more rhythmically than that).

    HRMs are good tools, but you need to ignore ALL the "fat burning" stuff.

    Hope this makes some sense. Your described routine sounds fine. If you want, you could modify 1 of the 45 minute days to a 60min "endurance day" and change one of the interval days to a "tempo" or "higher intensity steady state" day, On that day you either do a approx 25-30 min hard workout of steady-state exercise at about a 75%-80% effort.
  • bohdanko
    bohdanko Posts: 16 Member
    Thanks for the responses and the link. That does help. I kind of figured that going up to 75% or so was okay. My perceived HR does match pretty well with the age-predicted one for my age, I think. I just don't feel like I've accomplished as much if I don't sweat. I will keep going the way I am for now, and if I find my progress lagging, I will try shaking it up. Azdak, I actually was thinking along the lines you mention, with one or two longer, slower HR day, and one or two shorter, more intense effort days.

    Thanks again!
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