Weight and impact on pace.

Training Advice/Discussion

1 year ago 01/08/2023 11:25am EST

Are there any definitely published studies about impact of weight on pace/effort?

I ran 47/1:50/3:45 about 7 years ago and then have intermittently run since. My racing weight was 152 lbs at 6’. I decided to start running again in September. At the time, I was 205 lbs, a mix of a dad bod and putting on a lot more muscle. I’m at 182 lbs now.

My pace for runs was around 8:30/mile for 3-ish miles when I started back up. I just ran a 12.8 mile long run at 6:48/mile with about 1800’ of gain in the run and a progressive tempo with my last 15 minutes at 5:31 pace, so I’m getting fit, I’m still just heavy. My plan is to race a half marathon in June. I’ll run 45 miles this week and hopefully be able to have a couple of months above 60 per week before that half.

How much impact is the extra 30 lbs having on me now? My goal is to weigh 160 on race day. Most of it is diet which I’m finally cleaning up.

1 year ago 01/08/2023 2:52pm EST

re: GottaDropSomeLBS

1.5-2 secs a mile per pound of fat

1 year ago 01/08/2023 4:06pm EST

re: Kvothe

Per pound of non-essential weight. So extra muscle would be included.

1 year ago 01/10/2023 4:14am EST

re: Shoe Fetish

Shoe Fetish wrote:
Per pound of non-essential weight. So extra muscle would be included.

How is that quantified?

1 year ago 01/10/2023 4:21am EST

re: GottaDropSomeLBS

How old are you (you say you haven't ran for 7 years)?

Because I'm pretty sure cost/reward ratio of 'extra muscle' changes as you get older.

1 year ago 01/10/2023 7:43am EST

re: GottaDropSomeLBS

Unfortunately weight has a significant influence on running performance.

The cost of transport for running is about linear. If you have excess fat and get rid of it by 5% (100kg -> 95kg) you would get 5% faster. However, losing only fat is unrealsitic below BMI=25 (normal weight for men), so for lean and normal weight persons this calculation is not correct.

And for the kids, having too low of weight is also unhealthy and hinders your performance. So there is a sweetspot.

1 year ago 01/10/2023 8:52am EST

re: GottaDropSomeLBS

GottaDropSomeLBS wrote:
How much impact is the extra 30 lbs having on me now? My goal is to weigh 160 on race day. Most of it is diet which I’m finally cleaning up.

As mentioned already, the 2s per pound is a rule of thumb. But at some point, you hit diminishing returns for lots of reasons. So 30 lbs could be as much as a minute per mile.

If you can run 6:48 pace now, and you drop 22 lbs, I would guess you can be at least 15s/mile faster. You have the potential to be waaay faster based on PRs, but you're only human, so it's going to take some training time at faster paces to adapt and improve.

1 year ago 01/10/2023 11:15am EST

re: GottaDropSomeLBS

I'm not going to look for any published studies (you could, if no one mentions them). But, it's basic physics that excess weight will be an issue. but note that I said "excess" weight. If you're dropping fat and maintaining your muscle strength, you have to be faster with the same conditioning. but if you start dropping the muscle you need to stay fast, then I wouldn't bet that less weight will make you faster.

1 year ago 01/10/2023 3:12pm EST

re: GottaDropSomeLBS

1kg muscle or fat not used in running is about 5 sec per km on a 5km horwill estimated, untill bmi goes towards normal/underweight. After that the effect goes down and can be negative.

The easiest way is to focus on bodyfat % while not lifting execessive weights, just sport specific exercises like hill runs/ injury prevenention.

12% is a good target, but 15-18% will already give good results if you are not super pumped up from bodybuilding.

1 year ago 01/10/2023 4:03pm EST

re: lexel

lexel wrote:
Unfortunately weight has a significant influence on running performance.
The cost of transport for running is about linear. If you have excess fat and get rid of it by 5% (100kg -> 95kg) you would get 5% faster. However, losing only fat is unrealsitic below BMI=25 (normal weight for men), so for lean and normal weight persons this calculation is not correct.
And for the kids, having too low of weight is also unhealthy and hinders your performance. So there is a sweetspot.

If I gain 10 pounds, how much of that is muscle and how much is fat?

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