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Bmi

Discussion in 'Beginner Freediving Q&A' started by Tobias Bernhard, Apr 3, 2018.

  1. Tobias Bernhard

    Tobias Bernhard New Member

    Local Time:
    3:53 AM
    another newby on this site with a question: Is there an ideal BMI for a freediver. I noticed some of the greats are burly and some are skinny. I am a BMI 20 starting to freefall at 20 meters or so with no neoprene. Is it wise to lower my BMI further?
     
  2. HLanger1955

    HLanger1955 Member

    Local Time:
    5:53 PM
    Guess below BMI 20 your're going to be underweight. I've some doubts whether this is wise. My BMI is somewhere around 21, but already with this I tend to feel rapidly cold in the water..
     
  3. Tobias Bernhard

    Tobias Bernhard New Member

    Local Time:
    3:53 AM
    Yea cold is a problem. Fiji summer temp is often close to 30c so we mostly dive in rashies only. even with that after 30 min my breath-hold is affected.
     
  4. SubSub

    SubSub Well-Known Member

    Local Time:
    5:53 PM
    BMI doesn’t have so much to do with your body’s floatation. I have a higher BMI and need less weight than most of the skinny dudes.

    What makes a body more or less boyant btw?
     
  5. Bill McIntyre

    Bill McIntyre San Clemente, CA Staff Member Supporter Forum Mentor

    Local Time:
    8:53 AM
    I agree and can give a personal example. When I was in my early 20s I sank like a rock in fresh water and there was a period when I barely sank in salt water. When I went through US Navy scuba school at Pearl Harbor, part of the syllabus was a free ascent from 100 feet. Everyone else just stepped out of the lock and drifted up while blowing bubbles so as not to embolize. They had to let me swim up. I was a pretty muscular kid then as shown in this photo.

    Now at age 79 I'm at about the same body weight but I float like a cork. Why? Because I replaced a lot of that muscle tissue with fat. My BMI must be the same, but it doesn't tell you much about my buoyancy.

    I'm not going to show you a current photo without a shirt on. :) ulua.JPG
     
    daforg and Cetaceous Maximus like this.
  6. Davos

    Davos Member

    Local Time:
    11:53 PM
    I think we can (pretty much) ignore BMI altogether. It's a terrible measure of body composition.
    That said, using body fat calipers to measure body comp is quite easy and reliable. I'd wager that 14-20% body fat is ideal for most freediving, but as it's quite lean getting cold is possibly a factor.


    Sent from my iPhone using Tapatalk
     
    daforg likes this.
  7. Davos

    Davos Member

    Local Time:
    11:53 PM
    I should note, that is for men. For women you could aim for 18-25%(women should generally be higher than men, but the result will be a similar composition... I just can't recall the exact difference off hand)


    Sent from my iPhone using Tapatalk
     
  8. HLanger1955

    HLanger1955 Member

    Local Time:
    5:53 PM
    BMI ic certainly a thumb rule. However, going to the original question - perhaps it tells you that going below 20 is not so preferable, and you are probably not well advised to go above 25. Then there is percentage of fat, muscles, bones, age and other. But this needs a physician to judge..
     
  9. daforg

    daforg New Member

    Local Time:
    1:53 AM
    I have to agree with those that have stated BMI is not a useful indicator for buoyancy. For example my BMI is 24.8, which is the upper range of normal, borderline overweight. However, measured with calipers my bodyfat is in the 12-14% range, I just have some muscle on my frame relative to my height. For reference I don't have much buoyancy, it doesn't take a lot to get me sinking like a stone.