Race Times and Weight

So....I thought I would post about "racing weight", as I think this has a pretty big impact on performance.

Disclaimer:  The last thing I want is to create any body image issues for anyone, or to encourage  ANY unhealthy habits - the goal with this post is only an honest discussion around how body weight can affect running race times.

I've always been a relatively light weight guy.  "Back in the day" when I was in my 20's and racing bicycles I weighed around 135 (at 5' 9").  This made me pretty good at  climbing hills, but I couldn't sprint for crap (not enough anaerobic strength).  My only chance for a good placing was to find courses with big hills, closer to the end the better.   Cyclists know that going uphill is a power to weight calculation, but on flat roads drafting is a bigger factor (much, much bigger than when running).

When I starting running earlier this year I weighted 152 (in my late - 40's).  Not that heavy, and I was in decent shape.  After a few months of running, my weight went down to 148.  That's what I weighed in my first 5k in May, 2015.  I finished in 21:09.  In June, weighing about the same, I ran 20:47.

I got interested in seeing if I could run faster, so over the summer I ran more, did some track workouts, and lost some weight.  The weight loss was not based on a strict diet; more about higher mileage and "eating more healthy".  In August I ran a 5k in Leesburg VA on a little bit hilly course in 19:51; I weighted 142.  Then, in September I ran a 5k at the Dulles Airport on one of the runways.  PERFECTLY flat course, my time was 19:12 - I weighted 140.    20 years after my cycling days, I'm within 5 lbs. of my "racing weight"

So...my 5k PR came down almost 2 minutes and I lost 8 lbs.  I'm a new runner, so dropping 2 minutes in a 5k over 4-5 months is not that exceptional (I think).   But, how much of this is due to my weight loss vs. training?  I've heard every lb. is 2 seconds/mile.  So 8 lbs is about 50 seconds over a 5k (rough math).  Plus I changed shoes from NB Zante (8 oz) to NB RC5000 at 3 oz.  I think this gave me a few more seconds advantage....this could be debated...but the RC5000 do make me "feel" faster.

Overall I think about 1/2 my performance improvement is from weight loss and 1/2 from training.   I figure if I get my weight down to 135 (like the good old days) I could take another 30 seconds off my 5k time without being any better conditioned.  Now....do I want to do this?  I dunno.  I got to 140 fairly easily, without strict dieting.  But my weight loss stopped there.  Not sure I want to sacrifice that much more to lose another 5 lbs.  My new training plan has my weekly mileage climbing from 30 to 45, so the weight might come off just due to that....

So....am I over emphasizing weight loss in my  performance?  I see a lot of people work very hard on their training and provide specifics on their daily workout in blogs and elsewhere, but very little information on how weight change might have helped or hurt their recent race results.  All the very fast pros discuss their weight...at least I know they seem to work to be at a "race weight" for them on their key races...and they're all pretty light people.

A lot of people are working hard to make PRs, and it seems weight would be part of the effort to achieve faster times....unless of course you're already at your best racing weight....but I don't see much discussion around...

As I mentioned at the top - this is only a discussion around HOW weight would affect race performance, not that anyone SHOULD lose weight. 


Comments/discussion....welcome.