I have read and heard that for every ten pounds of weight lost (assuming the individual had it to lose in the first place, which I do), said individual would increase their pace by 20 seconds per mile, all else being equal (which it rarely is).
With the above stated, I'm 5'8" and when I ran a 25:20 5K ten days ago I weighed about 205 pounds. I figure I have an easy 30 pounds I can lose without negatively impacting my strength, and based upon the above formula, I should be able to run a 22:20 with virtually the same effort, assuming of course I get down to 175. The thing is, given that "all else" is almost never "equal", I have to believe there will also be incremental improvements in strength, stamina, and breathing, which to my way of thinking, should translate to even more improvement in pace.
My goal is to start making some noise in my age group (Men's 55-59) next summer which, based upon the recent race I ran with 5,500 participants, would mean I need to knock my time down to 21:40 just to crack the top 10. If I want to get into the top 3 I would need to burn through a 5K in less than 20 minutes; over 5 minutes faster.
I guess what I'm looking for are any anecdotal stories from y'all regarding how much speed y'all have gained through weight loss brought on by training.
Fat old man PRs:
I have heard similar things but I don't remember if it was 20 secs/mile. I don't have personal experience with it since I didn't lose any more weight after I started racing. But I think you would be better served by revising your training to do things like intervals, tempo runs and possibly hill repeats. Finding a coach or joining a running club might help to get advice on adjusting your training. If you want to look at some online stuff, try http://www.mcmillanrunning.com/.
Good advice; I'm set to join a running club at work this Tuesday (new job as of mid-July), and as for my actual workouts, my "hilly" 8-miler is just that, hilly, very hilly, culminating in a 300+ foot climb mid way through the last mile. When I first ran it in April it was all I could do to slog up the various hills, and barely crawl up the final one; now I attack the mid run hills (err, up anyway, given how technical the trail is, attacking on the downslope would be just asking for my third broken leg, no thanks), and while I wouldn't exactly say I "attack" the final climb, I do work it pretty hard these days. Long story short, that entire run is one long "hill repeat". The 19th century rail-trail I run on over the weekends is flat, the dirt alternates back-and-forth between hard-pack and almost beach sand soft, and it allows for some pretty good speeds broken up by some heavy slogging. Those runs combined with running with the club at work should give me a nicely varied workout scheme.
Fat old man PRs:
When I started this thread a few weeks ago I had just run a 5K on a warm and humid day in 25:20 which equates to an 8:10 per mile pace; I've since dropped my weight from about 205 to 195 pounds, and today (on yet another warm and humid day) I turned in a 1:25:06 time in a very hilly 10 mile road race, which works out to 8:31 miles. Granted my per mile pace went up 21 seconds per mile, but I ran over three times as far; looks like "speed up 20 seconds per mile for every 10 pounds of weight loss" might be pretty accurate.
Fat old man PRs: