What is it about weight loss that improves performance?

I believe that the lighter you get, the more apt you are to get beat up bullies (bullies like to beat up on skinny nerds). So, you tend to run faster to get away from the bullies.

look up some stuff on VO2 max and running economy that should point you in the right direction of some literature that can properly explain it to you.

Erm, surely it's just because you have less to carry and therefore can run easier?

Try going for a run with 5lb dumbells in each hand. Then run the same route without them. Which is easier?

That's not really accurate. Dumbbells would throw your momentum way off. A more accurate representation would be wearing a 10lb. sack on your back that moves just like you do. Still harder, but not as much as with dumbbells. That would just be dumb.

OP is asking WHY weight makes a difference, not IF it makes a difference.

To be precise the OP is asking why weight LOSS improves performance.

Laws of physics. Although there is no formula for predicting improvement from weight loss, because you have to learn a longer stride to get the benefits.

So a 3% loss of fat should give you a 3% improvement in pace in a long run (where wind resistance is negligable)but that improvement will only happen if your stride length/rate improves 3% with the same endurance ability.

A couple of reasons. One, it is less mass that you have to push down the track. Two, there is less of you that is going to require blood to be shunted to, so much more efficient and economical. There's other reasons too. Look it up. GOOOOOOOOOgle

Well, it largely depends on what kind of weight you lost, and how you lost it. I guess we usually speak of unwanted extra fat. I think the best way to look at it is from a first year physics point of view.

Weight loss reduces the energy requirement to move your body over a certain distance.

The same force applied to a lighter mass, will produce higher acceleration, resulting in faster speed.

Weight less doesn't necessarily contribute to improved aerobic capacity, or improved running economy, but they can all result from increased training, coincidentally.

If the weight loss comes about from training, this will also improve muscle strength, cardio-vascular fitness, running form, heat dissipation, and maybe 10 or 100 other things:

- you can generate higher forces with stronger muscles

- you can sustain energy production for longer duration

So, weight loss, all other things being equal, will make you faster.

But training makes all other things not equal, and will make you faster at the same weight, for short term, mid-term, and long-term reasons.

bruinboy wrote:

...less mass that you have to push down the track...there is less of you that is going to require blood to be shunted to...

The third, and most overlooked, reason for increased performance at lower weight is that the body can better cool itself with less mass (fat or muscle) covering the surface.

More weight increases energy cost. An old, unscientific formula by Tom Osler is every pound of excess weight will slow you down by 2 seconds per mile. Solinsky claimed to have dropped 8-10 pounds since 13:12 was his PR. Pretty close.

10*2*3miles??

=60 seconds

When did he have a minute pr??

Fat is also an extremely vascular tissue. Therefore, the less fat you have, the less vessels that you have that need blood support in that area, to keep pressure high, and the less work your heart will have to do to get blood where it really needs to be.

But sometimes to much weight loss can be negative. I thought my running would improve if I leaned up a little bit more (2-4lbs) but it just left me low on energy and lethargic. When I put the weight back on I was back to my old self.

Older and Wider wrote:

bruinboy wrote:

...less mass that you have to push down the track...there is less of you that is going to require blood to be shunted to...

The third, and most overlooked, reason for increased performance at lower weight is that the body can better cool itself with less mass (fat or muscle) covering the surface.

Just something off the beaten path resveratrol CRON sirtuin and super mitochondria

When a male runner is racing fit their body fat percent drops below 5 percent which triggers starvation mode(see above) which makes for super mitochondria which makes for a super performance.

wellnow wrote:

Laws of physics. Although there is no formula for predicting improvement from weight loss, because you have to learn a longer stride to get the benefits.

So a 3% loss of fat should give you a 3% improvement in pace in a long run (where wind resistance is negligable)but that improvement will only happen if your stride length/rate improves 3% with the same endurance ability.

?????

No.

Yes, the improvement in pace isn't immediately pro rata to weight loss, but it can be, in time, with practice.

Wellnow,No one asked for a formula, or speaks of pro-rata changes -- just the source of improvement. Adapting to a new stride is independent of weight loss.I wouldn't expect a linear relation between between % loss of fat, and % improvement in pace.

wellnow wrote:

Laws of physics. Although there is no formula for predicting improvement from weight loss, because you have to learn a longer stride to get the benefits.

So a 3% loss of fat should give you a 3% improvement in pace in a long run (where wind resistance is negligable)but that improvement will only happen if your stride length/rate improves 3% with the same endurance ability.

Well plenty runners here do ask for a formula.

Anyways, you completely wrong when you say: "Adapting to a new stride is independent of weight loss."

That's just plain daft. Fat runners who run a lot have short strides. Thin runners who run a lot have long strides.

The point I was making is that as you lose the weight you have to learn a longer stride. What's so hard to grasp about that fact.