Does weight affect one's ability to handle the heat?

Weight is NOT the only variable. I had the largest BMI on all my teams. I was always the best in the hottest races.

Would dropping 10 lbs have helped you, most likely, 10 -20 seconds. Would it have got you back to near your PRs, NO WAY.

I always thought that working in the sun for 8 hours between morning and evening runs was why I raced well in the heat.

Like a previous poster stated weight is not the only reason you may have run slower. If you current weight is not your ideal race weight then that def had some impact. Another thing to consider is that running in warm weather often times means you will run slower per mile compared to colder temps. I am from and train in warm weather. Try and think of other things leading up to the race that could have impacted performance as well. Hydration,proper eating, and your fitness. As we saw with the mens and women's steeple at USATF championships you can still run good times in warm weather.(lots of PRs) Running with less weight, assuming its healthy, will result in faster running times hot or cold. I don't know about you but I ate horribly in college which was why my weight was higher than it should have been.

I would actually expect the outside conditions to matter more as a person's surface area to volume ratio went up. That would actually mean the smaller and skinnier a person is the more sensitive they would be to hotter temperatures. But that's just thinking about it, not based on any particular experience.

Guy O'Leighken wrote:

I would actually expect the outside conditions to matter more as a person's surface area to volume ratio went up. That would actually mean the smaller and skinnier a person is the more sensitive they would be to hotter temperatures. But that's just thinking about it, not based on any particular experience.

This is why the Bushmen of the Kalahari are built like Sumo wrestlers.

A quick Google would teach you that size affects your ability to dissipate - and thus handle - the heat, not necessarily just weight. Body surface area. The 5'11 part of your physique is what will limit you in handling the heat.

Guy O'Leighken wrote:

I would actually expect the outside conditions to matter more as a person's surface area to volume ratio went up. That would actually mean the smaller and skinnier a person is the more sensitive they would be to hotter temperatures. But that's just thinking about it, not based on any particular experience.

The biggest source of heat is internal, so the surface area matters more for rates of evaporative heat loss. All things being equal, heavier athletes will tend to have more heat production per unit volume compared to their surface area for cooling. It's hard to figure out which matters more and it obviously depends on how heavy you are. If you're carrying around 30 extra pounds, that will make a big difference. 5 pounds probably will not.

I was thinking of it the same way: basically all heat generation is internal and an increasing function of your volume. But the question isn't really who dissipates the generated heat better, it's who has the most similar net heat gain under two conditions: 1. good evaporative cooling over the available surface area, and 2. worse evaporative cooling over the available surface area. I don't know if it makes any sense, but I guess I was picturing people with high volume to surface area, being less dependent on evaporative cooling even in optimal conditions, and therefore more immune to temperature increase.

dingle wrote:

The biggest source of heat is internal, so the surface area matters more for rates of evaporative heat loss. All things being equal, heavier athletes will tend to have more heat production per unit volume compared to their surface area for cooling. It's hard to figure out which matters more and it obviously depends on how heavy you are. If you're carrying around 30 extra pounds, that will make a big difference. 5 pounds probably will not.

... If you think of most + heat as internal and most - heat as evaporative then it does just seem like the more surface area you have the more you're affected by increased temperature.

dingle wrote:

The biggest source of heat is internal, so the surface area matters more for rates of evaporative heat loss. All things being equal, heavier athletes will tend to have more heat production per unit volume compared to their surface area for cooling. It's hard to figure out which matters more and it obviously depends on how heavy you are. If you're carrying around 30 extra pounds, that will make a big difference. 5 pounds probably will not.

I'm not sure I get this. I think you're assuming that per surface area heat loss is constant as temperature goes up, but that isn't so. At low temps there is little sweating so the heat loss per unit area is low, but as temps go up there is more sweating and, generally, lower atmospheric vapor pressure, so the amount of sweat that can be evaporated can go up.

People with more surface area have more scope to regulate their body temperature at the high temp end, but it doesn't mean they lose a constant amount of heat per unit surface area.

I have no effing idea what I'm talking about. Shall I continue? I'm just imagining heat loss through conduction, like in Newton's law of cooling. As the difference in temperatures (skin vs air) goes down, the rate of heat loss per square inch goes down. Whatever fraction it goes down per square inch, multiply that by total surface area and you get the reduction in total rate of heat loss.

Everyone has enough skin to keep from overheating over 3000m.

What not everyone has is the blood volume required to dissipate the heat and still run fast. Blood is diverted from the muscles to the skin for the task. Training in hot weather should raise blood volume.

A lot of heat is lost through the head and hands. Try soaking your head in water before racing.

Thanks for the feedback everyone. And it definitely wasnt just the heat, I haven't been training that great since school ended, so im definitely somewhat out of shape and I cant find any hurdles near my house so my barriers were trash. And yeah I dont eat very well, especially at school. Ive been trying to work on that, down ~12 pounds since the start of spring track. Could probably stand to lose another 5-10 though.