My last two runs I ran on an outdoor track in the early evening... it's hot and humid, but not unbearable at that time of day-- low 80s maybe.

But both of my last two runs I've been so TIRED. Yesterday, I had to really force myself to keep going on my usual 30 minute program, when usually I'm very comfortable for that distance.

Am wondering how much the heat is a factor-- especially in someone with a higher BMI.... is my body just working that much harder to keep me cool, which is making me tired, or was it just a coincidence.

Heat is a MAJOR factor. Do not try to hold the same pace as you would hold in cooler weather. 80 degrees will increase effort about 20% at the same pace over 55 degrees.

Oh, heat affects me immensely I slow right down to a crawl and I'm really slow to start out with ... Usually in the summer I just bike unless it's on the coolish side, then in the Fall I almost have to start at square one ... Oh, well, c'est la vie for me ...

But, just make sure you are well hydrated before, during and after your run, just keep plugging away all the while keeping in mind if you are slower than usual, it's just the heat

And realize that even if you are slower the effort is the same. You will still make fitness gains at this slower pace and then when it cools off you will feel like a speedster.

Also it takes about 3 weeks of consistent running in heat and then you WILL start to adapt. Being in the PNW I never ever get that opportunity. I think 56 and sunny is downright hot - especially since 90% of my running is at 5 am. Then we get our 1 week of 100 degree weather and I am comatose.

I feel your pain, uber - last night was a cool night for my run at only 86. I swear I can feel dried up salt on my face when I finally cool down. I'm a lot slower on runs in the heat, too.

I bought a Nathan's fuel belt with water bottles, 2 of the 10 oz. I'm thinking about getting two extra clips for more, or possibly moving to a four bottle belt. It it killing me without enough water.

I'm so glad you posted this Uber, perfect timing.
We're going away tomorrow til Sunday and I've got my running gear ready to take with us. Where we're going is supposed to be nice and flat so thought it would be a perfect chance to run somewhere different.
However the weather here at the moment and for the rest of the week is hot for us UK'ers. Don't get me wrong, I love the warm weather and hope it lasts, but I was wondering if it will just be too much effort to run in the heat.
I think I will make sure to run early in the morning if possible, and if it feels really hard then I'll know the heat could be part of the reason.

Oh, thanks, everybody! I feel so much better now! I guess I am doing okay then because I'm actually keeping my pace on target and HR is on target but I'm just KILLING MYSELF not to walk for a while.

That's SO funny you posted this uber, I was just whining about this yesterday!

Lately my runs have been cut short because of the heat. I've been paranoid that I lost all my endurance from a little break, but I think it's just the heat getting to me. I'm going to start running earlier in the morning. 7 AM if I can, and run with my camelbak.

Perhaps try running earlier, or whenever it's coolest out. And running with a camelbak with ice cold water helps a LOT... you can pick one up for pretty cheap at Walmart, Target, or Costco.

I'll try the camelbak-- that's a great idea! I ran indoors tonight and I felt terrific, so I guess it was the heat!

I had the same issue on Sunday. I think I was a little dehydrated, and I about died after 1.5 mi. I had to quit way early and I actually just laid down on the floor in the den for 10 min once I got back. It was awful. But today, in similar conditions, I did 5K in a new PR for me! I do miss running when it's 50 outside