This has been something I've wondered the last few years. I used to be a college swimmer, fit and trim, but the 10 years since then I've drank my fair share of beer and ate plenty of cheeseburgers. Just curious what peoples' take is on how much the extra baggage really effects swim races.
I don't really fit the swimmer mold anymore. I'm 31, 6'2", and 270lbs with a huge beer gut. I got some strange looks since the meet i was in recently was a USAS meet and I outweighed my competition by 100lbs in many cases. My first race in about 5 years i went 23.4 in the 50y free. I didn't expect to be that fast at this weight but at the same time I almost wonder if the added intertia is helping me more on the start and turns. Followed it up with a low 52 in the 100y free but I had a horrible reaction on the start and incorrect pacing. I think if i raced again today that'd be deep in the 51 range. For reference, typical non-taper times for me in college were in the low-mid 22 range at just a tick over 200lbs but I was obviously a lot stronger, younger, and doing a TON more yards at the time, that's why it makes me wonder just how much the weight is actually holding me back.
How much time do you think I stand to drop if i were 50lbs lighter? Could it be a measurable difference or something just slight? I guess I ask that to see if it'd be worth my while to drop that much weight quickly by dieting in addition to the swimming i'm doing. I don't really like dieting, and i generally eat what I want, when i want. Not gorging myself at every meal doesn't really seem to fit into my lifestyle :blush: Anyone have a similar story? "I dropped XX lbs and went XX seconds faster because of it."
Maybe it's an immeasurable, but I thought I'd ask for opinion anyway. I'm hoping it doesn't turn into a "to diet or not to diet" discussion though.
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Former Member
Lindsay,
I have been thinking about your comments since you made them.
Form drag is proportional to your forward facing profile
True, but it does not appear to be that simple. Assume fmracing had a 36" waist when he swam 21.7 and has a 42" waist now swimming a 23.4, but than being rounder, he is in just as good of shape now as he was at his peak.*
If his waist is the largest cross section, and it is a circle, his cross sectional area increased by 40%. Since he is in just as good as shape now as he was when he was swimming 21s, he should have trouble breaking 30s.
A skinny swimmer could have a higher drag coefficient compared to a fat swimmer and this could offset the increase in cross sectional area.
At 200 lbs vs 270 lbs, the surface area of fmracing's skin increased by 16%**. If skin friction is the primary source of drag, then he should not be able to break 25.
If the arms are considered separately, the arms of a fat person vs a skinny person are still pretty similar, and if they are the primary drag causers, that would explain why fast fat people can exist. They still have to overcome form drag of their increased girth, the skin friction from their increased surface area, but primarily they are dealing with drag caused by their arms which minimizes the impact of the former causes of drag.
* My assumptions are very conservative. When more realistic assumptions are made, the difference becomes more pronounced.
** Mosteller's formula for estimating surface area hypertextbook.com/.../IgorFridman.shtml
I think that the velocity profiles posted by Budd Termin do a pretty good job of disproving that you only accelerate off the start and walls, there's a fair bit of acceleration in each stroke cycle.
This is correct, I was oversimplifying.
Lindsay,
I have been thinking about your comments since you made them.
Form drag is proportional to your forward facing profile
True, but it does not appear to be that simple. Assume fmracing had a 36" waist when he swam 21.7 and has a 42" waist now swimming a 23.4, but than being rounder, he is in just as good of shape now as he was at his peak.*
If his waist is the largest cross section, and it is a circle, his cross sectional area increased by 40%. Since he is in just as good as shape now as he was when he was swimming 21s, he should have trouble breaking 30s.
A skinny swimmer could have a higher drag coefficient compared to a fat swimmer and this could offset the increase in cross sectional area.
At 200 lbs vs 270 lbs, the surface area of fmracing's skin increased by 16%**. If skin friction is the primary source of drag, then he should not be able to break 25.
If the arms are considered separately, the arms of a fat person vs a skinny person are still pretty similar, and if they are the primary drag causers, that would explain why fast fat people can exist. They still have to overcome form drag of their increased girth, the skin friction from their increased surface area, but primarily they are dealing with drag caused by their arms which minimizes the impact of the former causes of drag.
* My assumptions are very conservative. When more realistic assumptions are made, the difference becomes more pronounced.
** Mosteller's formula for estimating surface area hypertextbook.com/.../IgorFridman.shtml
I think that the velocity profiles posted by Budd Termin do a pretty good job of disproving that you only accelerate off the start and walls, there's a fair bit of acceleration in each stroke cycle.
This is correct, I was oversimplifying.
