Is it? I’ve heard some people throw it around as a reason for their struggles in swimming… is it a legit thing? I have my doubts…?
Is it? I’ve heard some people throw it around as a reason for their struggles in swimming… is it a legit thing? I have my doubts…?
You mean they sink? No, it’s not really a thing. Pretty much every elite-level swimmer, and most male swimmers, will sink to the bottom. Hell, I’m hardly elite and I sink like a rock.
Keeping your legs and body up is an active technique thing, not a passive floating thing.
Is it true, though, that a swimmer with a higher BMI would not ‘sink’ as much as a lower BMI/more muscular swimmer?
Haha, literally the first Google result:
http://web.csulb.edu/~emyrw/T3/lessons/Hydrodynamics.html
I Googled “do fat people…†and it autofilled it to “floatâ€.
Is it true, though, that a swimmer with a higher BMI would not ‘sink’ as much as a lower BMI/more muscular swimmer?
Sort of, but that doesn’t mean that the “more muscular /low BMI “ swimmer is going to ride lower in the water when swimming, or that riding a little lower is a bad thing.
Side note: BMI isn’t really the relevant metric. Ignore BMI. Body density is. A swimmer who carries a lot of muscle mass is going to have a high BMI and high density. A fat swimmer is going to have high BMI and lower density.
Is it true, though, that a swimmer with a higher BMI would not ‘sink’ as much as a lower BMI/more muscular swimmer?
To an extent, yes.
In diving (scuba) then typically the fatties need to wear more weights to get neutral buoyancy.
Of course in swimming its not just about the buoyancy, but also what position would be stable - the centre of lift is in the body / chest area. Whereas centre of mass is lower. So that ‘tips’ the legs down and chest up unless doing something active to counter it (as JasoninHalifax says)
Is it? I’ve heard some people throw it around as a reason for their struggles in swimming… is it a legit thing? I have my doubts…?
You mean they sink? No, it’s not really a thing. Pretty much every elite-level swimmer, and most male swimmers, will sink to the bottom. Hell, I’m hardly elite and I sink like a rock.
Keeping your legs and body up is an active technique thing, not a passive floating thing.
I think it It helps though. Back when I was doing triathlons and trying to learn to swim, I was lean and sank like a stone, that along with my ineffectual kick gave me an awful position in the water.
Now I’m fat and I can’t imagine my kick is any better given that I haven’t done anything to improve it over the last 20 years since I quit triathlon, and I actually feel half way decent when I swim a lap or two in the pool in the summer.
Haha, literally the first Google result:
http://web.csulb.edu/~emyrw/T3/lessons/Hydrodynamics.html
I Googled “do fat people…†and it autofilled it to “floatâ€.
That’s funny.
I do think adipose helps people to float. Heck, my uncles used to always tease me because they could just lie on their backs in the pool and float, while I would always end up with water up my nose.
I’d also guess that most triathletes have muscular legs which leads to feeling like the legs are sinking.
Is it? I’ve heard some people throw it around as a reason for their struggles in swimming… is it a legit thing? I have my doubts…?
Goggins seems to think so.
Haha, literally the first Google result:
http://web.csulb.edu/~emyrw/T3/lessons/Hydrodynamics.html
I Googled “do fat people…†and it autofilled it to “floatâ€.
That’s funny.
I do think adipose helps people to float. Heck, my uncles used to always tease me because they could just lie on their backs in the pool and float, while I would always end up with water up my nose.
I’d also guess that most triathletes have muscular legs which leads to feeling like the legs are sinking.
Yes, I could never float when I was younger. Now I float just fine.
its a scientific fact that fat floats whereas muscle sinks
what this means for your swimming is less clear. if you look at most elite swimmers, they’re hardly fat and have plenty of muscle yet it doesn’t seem to hurt their swimming
however if you’re like me and have long lean muscle legs then that is bad (especially when combined with a typical triathlete’s poor kick)
a bit of fat around the hips can be quite beneficial to body position
Swimming is the act of not sinking. To what extent forward motion and speed is involved is another thing altogether.
Forward speed is about lots more than buoyancy or any kind of muscle density. If you’re having issues keeping your legs up when you swim, it has less to do with “negative buoyancy†than just adaptations to training. Don’t let legs sinking while not moving be an indicator of anything.
In a relative sense, anybody swimming in an Ironman or any triathlon is much closer to the FOP and top swimmers than almost anyone else. If you’re looking for a reason that your swimming posture is not as horizontal as the very best swimmers, it has to do with what goes on in the legs of long-term swimmers. As they move forward, the best (freestyle/front crawl) swimmers’ legs are horizontal. This has to do with the ROM around the ankles and hips.
Recall that the FS kick is a) not the major source of propulsion, and b) a whip-like movement powered by the hips and “cracked†at the tips of the toes. No matter how muscular or lean the legs are, they will sink more if there is not a good ROM at the hips and ankles that can makes the kick work. Anyone who hasn’t had MANY hours in the pool will have tight ankles. Life-long runners will have these to an even greater extent.
Advice: to work on ankle and hip flexibility, use fins a lot.
Jason and OP,
I have shared this many times here on ST with basically zero response.
In a nutshell bc it gets long to explain. So I may leave something out.
In my time at the OTC in the springs we developed a testing protocol to help us determine this information on all of the US elite atheltes (yes phelps and others) as well as the all the JR camps and college kids that came through over the years.
We called it the COM DEN test. We followed a fairly regimented procedure to ensure some consistency during testing to see different responses. This test basically killed two birds with one stone.
What we did was ask the swimmers, in a rested state (pre workout) to ease into the pool and get positioned in front of the camera. We then asked them to fill their lungs and swim toward the bottom of the pool where I (or another swimmer) would help to position them flat on their bellies on the bottom. They were asked to keep their air in and once positioned, remain in a semi rigid state (arms by sides). Once they were released we asked them to just float to the surface.
For the sake of this post, we studied HOW they came off the bottom and you would be surprised at just how different people come off the bottom. This helped us to understand their COM. (how close was it relative to their center of buoyancy (lungs).
The DEN or density, was determined by how quickly they came to the surface. And we found that by simply timing them.
What was really interesting was that over time, we developed the ability to predict athletes KEY events without knowing who they were. Just doing this test and having seen them walk on a pool deck prior.
(we did a ton of other measurements as well but no need to get into that)
MY OVER REACHING point is… UNLESS you do this type of test and find out where you are on a COM DEN scale, it’s hard to know how to specifically train for your events.
And so yes, normally, with older triathletes, they tend to have low COM (leg density which isn’t just muscle tissue btw or lack of adipose tissue) and generally high density issues to deal with. What this means is that the POTENTIAL for someone with LOW COM and HIGH DENSITY to be a good distance swimmer is only achievable by training at a higher turnover rates. This is to limit the downtime between connections with the water bc they lose momentum so quickly. And so…
And so… to take an AOS who wants to do triathlons and will typically exhibit low com and high den, using a metric like stroke count or distance per stroke is not beneficial in anyway to performance.
All the best,
DaveD
How does observing how athletes walk on the deck figure into the analysis?
Out of my whole post you pick the most anecdotal note in there.
From general observation. If you’ve been around swimmers your entire life of all age ranges… similarities develop
Fair play. I should have deleted that part.
Daved
I am curious - please elaborate. I understand it’s anecdotal. I just wonder how I fit in.
Is it? I’ve heard some people throw it around as a reason for their struggles in swimming… is it a legit thing? I have my doubts…?
Here’s a scientific explanation of relative buoyancy.
Help me understand this. Would a low COM mean basically the swimmer floats up on a significant tilt, like lungs/head go up and legs lag? High COM mean flatter rise?
I have intermittently taken lessons from a local high school coach. She was starting from the basics, so she just wanted me to float face down which I tried to do, but I sculled a bit and kicked a bit to stay on the surface. Her response: no, I just want you to float. So I got in position on top of the water and stopped doing anything active… and sunk straight to the bottom. Like a stone. And stayed there until I had to breathe. She wanted to see it again. So we repeated the exercise. She told me that she had never seen someone sink like that.
In the CoM DENS test above I would be very interesting because I would just stay on the bottom. I do not float. I swear this to be true.
Daved-
Thanks so much for sharing this technical information with us —I seriously enjoyed reading it.
Beyond that however please know that you’ve done a great service to the slowtwitch community. You see, Slowtwitchers are always looking for an excuse why we are not awesome in the swim, bike, or run. It has to be a technical reason, though. For the bike it’s been “I couldn’t get the bike that fit my exact fit coordinates†or “erg mode really just sucks on the trainer it actually makes you worse.†For the run it’s like “all the alpha/vapor/speed fly shoes were sold out so that’s why I couldn’t run fast.†Up to now now we’ve been lacking the technical excuse for the swim. But thanks to you we have an technical excuse ready (TER) for the swim: “my COM & DEN is all screwed up.†So thanks. We will not have to go and swim now because we pre TER not to.