Monday, August 14, 2006

Body weight and speed

I just saw this calculator on another blog (sorry, I've lost track of where!// Update! Neoprene Wedgie is my source! Thanks for the link!) and I thought it was interesting to play with:

Predicted effect of weight change on running speed

It seems to use a factor of 3 seconds per pound of body weight per mile; whereas I've always heard that the difference is 2 seconds per pound of body weight per mile. And it only gives you information for plus or minus 4 pounds. But interesting, nevertheless!!!

Free speed with weight loss. Simple physics.

Let that be an incentive to me as I work off another ten big ones before Ironman Florida!


Mojo said...

But.. Is all weight equal? Like muscle versus fat?

Muscle weighs more than fat, right? If you are carrying more muscle than a skinny but fattier person, will they still be faster?

nancytoby said...

They're pretty much faster than me no matter what. :-)

It depends.

If you're an elite marathon runner, a pound of muscle that's not leg muscle is probably going to slow you down just as much as a pound of fat.

Not that any of us are elite marathon runners.... but 115 pounds is heavy for a world-class female marathoner. Put it that way.

jeanne said...

god almighty. that's all i have to say about that!
can we go back to talking about your triathlon? Please???

j. said...

fascinating. and fun. and according to my calculations, if i can somehow get my weight down to 32 pounds, i've got a good chance of qualifying for Kona. helllooooo South Beach!

21st Century Mom said...

I am so gratified that 4 pounds barely buys me a minute off a 10K - why bother - bwhahahahaha!!!

You IM people floor me - I just don't know how you do it but you rock!

the Dread Pirate Rackham said...

Yes, yes yes - and cyclists are the same. Floyd Landis is 5 inches taller than me but outweighs me by 10lb, and look what he can do...Uh huh, there's a realistic comparison.

The disclaimer on that site is clear - this is an unrealistic estimate.

Here's a question for you: what weighs more -- a pound of muscle or a pound of fat?

THEY WEIGH THE SAME! And here's the kicker - a pound of muscle will WORK while a pound of fat will just follow you along for the ride. Also, a pound of muscle will sit there and burn fat -- while you sleep!

Sometimes, when you lose weight you lose your power. Ask any wrestler.

Ask Lance Armstrong.

Weight is an almost meaningless number. I'm serious. Throw away your scale, get some body comp work done. You don't know what you're actually doing with your body until you have that data. And read my latest post - I've gained 5lb in the last 3 months, and it's all been converted to power.

Muah hwa hwa POWER!!!

Sorry to rant - you know I luv you...

Robin said...

Very cool calculator. It is certainly motivating me to loose teh weight I put on during summer injury season. ;) and then some.

jbmmommy said...

So do you think I can lose 10 pounds before my first race on Saturday? At least I know I'm faster than I was 40 pounds ago that will have to be good enough.

Iron Pol said...

First, you probably saw that on Neoprene Wedgie's blog.

Second, while there are definitely time gains to be made with weight loss, that is hardly the motivation for most. It is, however, a cool side effect. You train to get faster. As you train, you do get faster. And you lose weight. As you lose weight, you get even faster.

But for me, I just want to get better. A better swimmer. It might mean faster, or maybe just easier and more confident. A better biker might mean faster, or just more relaxed, leaving more for the run. And on the run, better might be just dealing with fewer injuries.

Either way, losing the weight is cool.

Lynne said...

More incentive, more to think about... Nancy, you are awesome!!!

nancytoby said...

Thanks for the correct link, Iron Pol! Actually, since I've been more motivated to lose weight to improve my triathlon performances rather than change how I look (not that it isn't nice, it's just secondary for me right now) it's been easier for me to modify what I eat. I'm not sure I understand the psychology of that, but that's been my experience lately.

And yeah, Rackham, I do track my body fat via Tanita and body measurement estimates - I just don't like to post about THOSE numbers! And Tanita is so imprecise and variable it makes me crazy.

the Dread Pirate Rackham said...

Nancy - I know what you mean about the stupid Tanita numbers, it's very frustrating. I can see a couple-percent difference day to day, and I have seen a 6% difference between what the impedence monitor tells me and what the calipers tell me (that's 6% in my favor).

Personally, I see no shame in anyone's bodyfat, especially if you are working to change it. For the record, I started at 30 something percent - and it was very scary for me!

BTW - did you know not to measure yourself right after a heavy workout? Your electrolytes can screw up the impedence apparently.

I still think the bodyfat thing is a better indicator of what changes are going on in your body than a scale. The thing to look for is the Delta (change) in the readings. Here's an article that illustrates my point.

I think you're doing great, and I will always encourage you to reach your performance goals. I guess my point is, my personal experience says don't get frustrated just yet!

TX Runner Girl said...

Good to know! I have been working on losing my last 10 lbs of post-baby weight and have often wondered abou this. Great blog! I can't wait to read more about your triathalon!

Mister P. said...

Of course there's always the flip side... If you are happy with your run times, you can use the site to calculate "how many pounds am I free to GAIN and still run a good pace?" Enjoy that extra scoop of ice cream!

Dawn - Pink Chick said...

So if I lost like 80 pounds I might run a 10k in under an hour...hmmmmmmmmm. Pass the cottage cheese, please.