Optimal Weight and Running Speed

[Sasha Pachev]

Hobie Call ran a low 17 5 K with 30 lb vest. His weight is 142lb, I believe. He would have run a low 15 or maybe a little under without it. Rough approximation from that experiment could be t_orig * ((weight + extra_weight)/weight)^0.95, so 8:00 mile = 480 seconds for a 150 lb runner who picks up extra 25 lb becomes 480*((150+25)^0.95)=555 seconds or 9:15 per mile. If you want to do the computations, just substitute the parameter names (like t_orig or weight) with numbers and paste it into Google search box.

However in practice it all depends on the nature of the excessive weight. How is it distributed and how does it affect your biomechanics? Does its presence create a metabolic/blood flow/heart power/etc inefficiency of some kind?

I think it is a mistake to focus on weight alone. Excessive weight is only one of the many symptoms of the lack of fitness, and in some cases it may not be present. Sometimes increases in fitness can be accompanied by a weight gain, or a weight loss can happen along with the loss of fitness. One of my training partners dropped from 135 lb to 125 lb at first when he stopped training, then got back up to 145 lb, for example. Apparently, the body responded first by losing the muscle mass, and only then began to accumulate fat at a fast rate.

So short answer - if you lack the fitness and feel heavy, the fix is a good balance of training, eating, and sleeping. The fitness will improve, and the weight will arrive at its optimal point.

[Jeff Linger]

I think that one thing that hasn't been addressed in this conversation yet is the distribution of weight in terms of 'simply weight (adding vests)' and 'how weight is distributed in terms of fat'. Men who gain weight tend to gain it viscerally (it accumulates around the organs, compressing in on them). Women gain it it below the skin, but not so much around the organs (forgot the word for it, subcutaneously I think). My guess is that in terms of performance, men's performance would actually decrease more with excess weight versus women (speaking relatively here) in terms of strict weight gain. Visceral fat is burned easier than subcutaneous fat I believe. When the effect of weight gain is considered and its impact on the various running systems, I don't think one can simply strap on weight and equate it to weight gain in terms of performance. The runner with a vest is still a more fit runner than the runner who has gained weight. In other words, it is not just the weight that's a factor. For various reasons I've struggled over the last few years to 'get back to where I was'. The end result is has been about 10-20 pounds weight gain (I'm down to about 10 now). I used to run home from work with my work stuff on my back (about the same 10 pounds I have now). I can say that running with the backpack, despite the sloppy weight swing that effected my cadence, was much easier and faster. The fat weight gain impacts so many other systems that are not impacted when simply running with added weight that doesn't belong to you, so to speak.