38 deg F (3 deg C) is the best temperature for running

12 years ago, when I started doing races that were more than 20 minutes long, I joined a running group to help me get through long runs and to school me on distance racing. 

I did Saturday morning long runs with the A group of Marathoners that had 7-8 guys that were competitive age group marathonists.  Some of these guys had done 25+ marathons.  One of the biggest take always from participating with this group were all the golden nuggets of information shared on our Saturday morning long runs. 

I did my first Marathon in 83 deg F (28 deg C) and 83% humidity.  I felt I did very poorly in the race since I was 45 minutes over my goal time.  The seasoned runners had different opinions on how well I did.  They said the heat and the humidity were probably a lot bigger factors than I realized and that the ideal temperature for a Marathon was about 40 deg F.  I thought they were crazy.  I didn't like running outside in shorts in temperatures under 50 degrees and didn't think that it would be an ideal day if I couldn't run in shorts.  I thought that 60 deg F. would be a more ideal day than 40 degs F.  Fast forward to this morning's run.  Today it was 38 deg F when I did my morning run with very little wind (I like how those numbers are flipped backwards from the 83 degs. F on the day of my first Marathon).  I am starting to agree that 40 deg F is about perfect for a Marathon.  I flew through 12-1/2 miles this morning at a pace that was about 20 sec/mi faster than what I had on my training plan (the pace ended up being about my race pace for the run leg of a 70.3 triathlon).  I was trying to slow down for half the run and the other half of the run I just made sure I was staying relaxed and not straining and went with what felt like an easy and comfortable pace.  So...these run days at 40 deg F are really nice.  I hit race paces without even breaking a sweat.