How does weight affect swim / bike?

Triathlon Forum
1

I’ve read estimates of running times improving 2-3 seconds/mile for each fat pound lost. This seems about right vs my race times as my weight has fluctuated over the last several years while I ran 12 marathons. Currently I’ve lost 30 pounds, but plan to loose 40 more before I complete an IM this fall.

Are there similar improvement estimates on bike speeds and swim times? I have good endurance in the swim and I think my stroke is about right, but it takes me 98 minutes to swim 2.5 miles in the pool. Most swimmers are much faster. and the better swimmers take 16-18 strokes/25yrds. I take 24-26 strokes. I’m hoping as I loose weight my speed will improve, perhaps I’ll slide though the water better, or is it more likely my stroke mechanics are still not right?

Similary, is there anything regarding the affects of weight vs cycling speed?

Thanks

2

the analytic cycling website can give you a good guess of what added weight will do. but that does not take into account

  1. the added weights effect on your total drag
  2. the added weights effect on how strong your leg muscles are.

At some point losing weight might slow you down on a flat course.

3

Weight does not effect swimming. It might even help with the flotation.
Work on your stroke mechanics.

4

Interesting. I have been analyzing this for a while. I was 250 three years ago and just under 200 now on my way to 185. I am 6’1"

No penalty in swimming, IMO. It is all technique and efficiency.
Biking depends on the course. Huge penalty on the run.
Here a real life example. My coach is 6’1" and 167lbs. We are about the same speed in the water.
On the bike, if it is flat we are very close, BUT when we climb, no comparison. We do a hill repeats on a climb that is 550 ft in 1.4 miles. My best time is 9:15, his is 7:45. Same heartrate, same wattage. Weight really penalizes here.

Running is the biggest. He kills me on the run. The longer the run the more he kills me. As I lose more weight I get faster with a lower HR.

5

There is a guy who swims in my master’s program in the 1:10/100yd base lane who is both old and at least 50 lbs overweight. That dude FLIES through the water, and he takes between 10-12 strokes to get across the 25 yard pool.

You need to work on your swimming technique A LOT.

This business of losing weight on the bike slowing you down is rubbish, assuming you’re using exercise to facilitate weight loss, and not meth or a starvation diet.

6

The really really fast swimmers are usually in good physical shape simply as a function of the training loads, but there are plenty of reasonably fast swimmers who you’d have to call fat and that’s being charitable (i’d even go with ‘blubbery’). I swam competitively all through HS and into college, and I’ve gotten whupped more than once by dudes who look like they’d blow a gasket trying to waddle up a flight of stairs.

On the bike, however, you no longer have the buoyancy factor to bail you out. On a flat course, it’s not a big deal since you don’t have to actually lug that extra mass upwards against gravity (although it could still be an issue trying to get low and aero due to gut clearance against the upstroke of your legs), but on a hilly course the weight penalty absolutely will handicap you severely. Unlike the swim, I very rarely get passed on the bike by someone who looks like what I’d call fat (and I only consider myself a little better than MOP).

7

Don’t worry about weight on a swim. Some of the best distance swimmers I know have extra lbs, but it’s how you balance your body in the water that really matters. AKA form/technique. Better swimmers take less strokes because they have a great feel for the water and don’t waste effort. Try swimming tall - that always helps. Good luck

8

blubbery

yeah yeah yeah make fun of the swimming puppy fat.

9

my experience has been that added weight has not had a serious impact in terms of reducing swim and bike times. but i am clearly paying the price on the run. that is slowly changing back.

i think you will find that faster swim times are more a technique issue. forget tracking stroke count for a while. just think smooth. you know it when you are not. become your own wave. punch as small a hole as possible on the way through. visualization techniques work well for the swim if you let them.

10

As to your question about cycling- If you have 40lbs to lose of extra weight and don’t have less than 5% body fat, chances are it will help your speed. It seems swimmers are swimmers as you probably see in your local pool, the fastest ones aren’t always the leanest…

11

to go along with the others… it is the run where the difference is most noticeable.

i have lost around 50lbs and my run is completely different. incomparable. my recovery run speed is now my old race speed! hahah

as for swim and bike?
yep… they have improved slightly… but i don’t think it is related directly due to a lose of fat.

instead the connection is…
weightloss → better recovery, less injuries, improved quality sessions, more training sessions → swim/bike speed increase.

the weightloss has completely changed my training.
i train more now and get more done in the time i train. less injuries, more energy… THAT is where the improved speed on the bike and swim are coming from for me.

of course, going up hills is easier… but then again, i don’t go so fast going down them now! :slight_smile:

12

Thanks for the replies. I guess, except for the run, I am not just going to get faster by just loosing the weight. I had hoped a thinner me might have less drag in the water and have a faster swim, but you’re all right I have seen a few big guys who are very fast swimmers in the pool.

I have one hilly half on May 31st, and I won’t be thin by then so I will be carrying the weight up the hills. Hopefully my hilly training rides for that will develop some strong legs that will help as I get thinner by September for the IM.

13

Everyone seems to be suggesting that extra weight won’t hurt you on the swim. It can definitely help from a momentum standpoint. BUT doesn’t the increase in surface area also slow you down? If someone is 40 pounds overweight they have a lot more surface area and thus drag to overcome in the water, right? Great technique is the key but I seriously doubt that a bunch of extra weight is actually going to help you on the swim even if it hurts you less than on the run.

The same principle will apply to bike aerodynamics. I find that I can hang with a lot of people on a flat course that I could never hang with in the hills. But I also find that as I drop weight my speed increases for the same wattage. Less surface area creating drag. The key is to do lots of hilly rides when you are overweight. That will allow you to keep adding power while also dropping weight. When I do intervals on flat courses I never seem to be able to generate the kind of power I can generate when I get to the hills. If you do a bunch of flat riding you could see your wattage stagnate as you lose weight because it takes less wattage to move you. The added weight can have a long term benefit if you can maintain or increase your power while dropping weight.

14

Being a clydesdale, I have been conducting a long running experiment on this very issue :wink: Here are my findings based on personal experience.

Weight makes no difference in swimming speed. The increased drag arguments are BS, unless your talking about someone who is morbidly obese. (Actually, elite swimmers are generally quite big folks. Michael Phelps is only 5 pounds away from clydesdaledom and he will surely cross over to the dark side withing a few months once he stops swimming full time.) Fat on a swimmer, up to a point, can actually improve bouyancy and it can even elminate the need for a wetsuit, thus saving transistion time. (Fat is not the same as weight but it is where most big triathlon swimmers get their weight from unlike someone like Phelps).

As long as the tri course is flat, weight doesn’t matter much on the bike. Weight is a huge issue in cycling when climbing or accelerating so every ounce matters to a professional road racer but in the steady speed relatively flat time trials that make up most triathlons weight just isn’t much of an issue.

Weight is an absolute killer on the run. Every step involves lifting the body a bit. You just can’t run fast for a long time if you are big.

So, lose weight since it will help you run faster. It will also have a direct affect on speed if the bike course is hilly.

Losing wieght will only help your swim speed if looking better in a swim suit gets you motivated to train more :wink:

15

I think your argument is valid as the swimming speeds increase.
But the OP swims 2.5 miles in 98 minutes. At that pace, surface area probably plays too small a role to measure. In fact, at such a slow pace I would say that the extra bouyancy is helping…and that if the OP were to drop 40lbs of fat tonight…swimming speed tomorrow would be slower.

16

I’m not so sure I agree with the folks who say losing weight won’t help the swim.

When I was a young lad, one of my coaches had us strap a weight belt on and do a series of 50 meter sprints - some with the weight belt on, and some with it off. If I remember right, the belt had 6 lbs of weight on it.

The difference over the course of 50 meters was about a second and a half.

Yes, I acknowledge that strapping a weight belt on probably wreaked havoc on my stroke and body position and is probably more responsible for the slower times than merely the weight - but even so, it takes more energy to move 200 lbs through the water than it does to move 150 lbs through the water.

Sure, if he lost the weight tonight and swam tomorrow, I’m sure his body position would suffer. But if the weight is lost gradually, over the course of several months, and he continues to work on his swim, I would anticipate that he’ll be faster.

17

I have good endurance in the swim and I think my stroke is about right, but it takes me 98 minutes to swim 2.5 miles in the pool.
Tough love time: your swim technique is terrible. The possible reason you have “good endurance” in the swim is that you aren’t actually swimming (i.e., exerting any force against the water).

18

This topic piqued my interest, so I did a little Googling and found this summary of a study about fat and swimmers:

http://www.pponline.co.uk/encyc/0346.htm

…

To see if feasting and fattening is really a good idea for swimmers, scientists at the University of Miami artificially increased body fat levels by 2 per cent or more in a group of 10 male and female swimmers who had been swimming competitively for at least three years. ‘Fatness was enhanced by fitting latex pads under a spandex triathlon suit in the swimmers’ adominal, hip, thigh, chest, back, and buttock areas. Microscopic balloons were added to the latex so that the pads had the same density as actual body fat. Male swimmers attached a total of 3.3 pounds of artificial fat, while females donned an extra four pounds. Each athlete swam a 50-yard freestyle race as fast as possible, with and without the pads.

While the latex pads did improve flotation, they also slowed the swimmers down considerably. The athletes could rip through their 50-yard sprints in about 26.6 seconds without the added ‘fat’ but required around 27.4 seconds with the additional fat on board. Thus, each additional pound of fat slowed 50-yard swim times by approximately .2 seconds.

   Why did added 'fat' slow performance, even though it improved buoyancy? While supplemental fat can reduce friction drag, it can actually expand something called 'form drag,' which is determined by the dimensions of a swimmer's body. Specifically, as a swimmer fattens up in the abdomen, thigh, and buttock areas, swirling eddy currents form around these protruding areas and can slow swimming velocity appreciably.

A second kind of drag - ‘frontal surface resistance’ - can also make it harder for corpulent swimmers to get through water. Frontal surface resistance is a function of how much body you actually have. If you have a big body, you have more frontal resistance, because there’s more body to push against the water (‘more front for the water to confront’). Instead of slipping through the water like a torpedo, you constantly bump into it. As water crashes against your large surface, it slows you down. Thus, even though fat helps by getting you out of the water, the part of a fatty body which remains in the water impedes progress. Perhaps the ideal free-style swimmer would have a fat back and sides but a slim anterior, while a backstroke specialist would have a paunchy tummy and flat buttocks.

…

Also, the Miami study doesn’t necessarily mean that fat is always bad for swimmers. The swimmers in the Miami research were not bone thin; males possessed 11-per cent body fat while females checked in at 21 percent. It’s possible that thinner swimmers might have actually benefited from increased body fat. The idea would be that an ultra-slim swimmer might slip too far down in the water column, hiking frontal drag to performance-hampering levels. Also, given the prevalence of eating disorders in athletes, it’s unwise to put pressure on swimmers to lose large chunks of weight. The bottom line is that we don’t yet know the true impact of body fat on swimming performance - or which level of fat produces the fastest times.

There’s some bonus information in there about wetsuits and triathlon times (summary: wearing a wetsuit makes you 7% faster).

I’m sure this isn’t the last word on the subject, but it does suggest that a little more fat does mean a little more drag - never mind moving more mass through the water. And it jibes with my own anecdotal experience.

19

My weight has yo-yo’d a bit over the years. I am faster when I am lighter but for me I am certain it is primarily due to the fact that I tend to lose weight as my training load increases and I am just in better shape when I am lighter.

If I lose 10 pounds I am X% faster in all three disciplines. I attribute the improvement to be 10% caused by just losing some mass (the biggest boost comes in running) and 90% due to the fact that I lost those 10 pounds by training harder so I am in better shape.

It’s good to burn off as much fat as you can. Not just because you are getting some energy savings but because the act of losing the weight through increased training improves your engine.

20

Ah, but the study was 50m sprints. My theory is that at slower speeds (say slower than 2mph) that the increased surface area plays a smaller and smaller role. Actually, I would expect that resistance increases exponentially with speed and not linearly so make sure to take that in to account.
For something longer like a typical triathlon swim performed by a MOP triathlete it may not be an issue…and in that kind of swimmer, the increased buoyancy is a bigger boon than for a well-trained swimmer like in this study.