I missed my chance for a run in the morning yesterday so I was stuck between going to the gym and waiting it out and running in the cooler evening temps. Of course I picked the wrong day to wait things out because the temperature was going to be in the 80's with 100% humidity (hooray afternoon thunderstorms!). But, run I must, so I geared up. I was planning on doing 6 out and back and about half way. I tried to go at a reasonable pace to avoid overheating, nevertheless, my legs were fine but I was huffing and puffing. I took a short walk break and decided to keep that up for the rest of the run which, while certainly not very fast, was tolerable and somewhat enjoyable despite the dripping sweat.
Clearly I'm not the first guy to think of talking a walk break during a run, but the man most associated with that strategy has to be Jeff Galloway. His Run-Walk-Run method is one of the cornerstones of the numerous books he has written (Book on Running) and the countless people he has coached. He owns a couple of running stores in Atlanta, GA where he continues to coach and organize races. His name runs parallel in running history with Amby Burfoot and Bill Rodgers (college teammates) as well as Frank Shorter (co-founder of the Florida Track Club).
Anyway, the basic idea of run-walk is to set up a ratio of running to walking and stick to it, even it you feel strong. This gives you rest time that you can bank to retain strength for later in a race. I was using a 3:1 yesterday and it felt great. Steve Runner has begun dabbling in run-walk and Episode 237 of Phedippidations features him running a 10K road race at nearly 8 minutes under his goal time (acutal time 0:57, desired goal 1:08).
Many people do this for much longer races and are able to dramatically extend their endurance. Paradoxically, like Steve, they are able to complete the race faster by walking than by trying to run the entire thing. For me, it is a great solution to the stifling heat of summers in Florida.