The issue was twofold which has made solving it a bit harder.
Heat on my back was the major problem as when a spot on my spine got hot the nerve conduction was compromised. This week I solved this by running in a one piece bathing suit that doesn't have a back (I also wear shorts over it too.). Doing that seemed to make a difference, but I was still struggling some after about 1.3 miles.
That's when I went back and did some more research on endurance training. I discovered in an earlier post that I'd been happily running at 90% of my max which is great mountaineering training where you have to be able to work at or near the point where you are working anaerobically, but it you want to increase your endurance you have to go slower.
In "The Outdoor Athlete" by Courtenay and Doug Schurman (which you can get at http://bodyresults.com), they have a section on Endurance Training.
They define 4 levels of intensity
- Recovery below 65% Maximum Heart Rate (MHR)
- Distance Aerobic (low intensity) Session 65-75% MHR
- Tempo Aerobic (medium intensity) Session 75-85% MHR
- Anaerobic (high intensity) Session > 85% MHR
I'd been working out at 160 bpm so I choose 150 bpm (even before looking up the above) as a limit. That works out to be around 85% of my max heart rate. This is pretty high, but it's difficult for me to keep my working heart rate under that when I'm really exercising and it seemed worth trying as a starting point.
A note on Max heart rate. If you really want to know your max heart rate get on a treadmill with a heart rate monitor and run till you drop and note your heart rate as you're dropping. I am not joking. All of the formulas are just estimates. 220-your age is off (by 5 for me). Even the more accurate 209-.7(your age) is off as I get older. (I should probably insert the usual "Please consult with your Doctor before trying to establish your max heart rate" caveat.)
So after a light meal (1/2 a sandwich) and equipped with lemonade (though I usually have Gatorade), in my bathing suit and shorts with my ipod and heart rate monitor off the gym I went.
The gym wasn't crowded and was decently cool. There was a Lacrosse game going on in the closest field to me that I could watch and ponder if Lacrosse really did have rules as they claim.
I entered in my info to the treadmill and chose a starting speed of 5.0 mph which is the speed I'd been working at. My idea was every time my heart rate got to 150-151 bpm, I would decrease my speed by 0.1-0.2 mph, even past the point of what I considered ridiculous.
Very quickly I decreased my speed to 4.8 mph
Then sometime after that to 4.6 mph
At that speed I passed 1.0 mile and then 1.25 miles. No leg drag. Somewhere in there I dropped it down to 4.4 and then not long after that was around 4.0 mph, but I was still running and no leg drag (and I'm starting to marvel at this). 2 miles passed and I was still ok. (Whoa). Then my pulse started to climb and I dropped it into the 3.8 range which is a really fast walk for some people, but I was definitely jogging and getting a good benefit from it and was in the middle of being amazed that I was still going. I stopped paying as much attention to the details as I was so far past my goals but when I hit 2.85 I realized that I might be able to make 5K (3.25). Dropping my speed to 3.6 mph and even occasionally as low as 3.5 mph worked. I discovered this a little while back on a different run. Going really slow can be beneficial and a great confidence booster.
My foot started to get sore so I finally stopped at 55 minutes and 3.63 miles which is the furthest I've ever run in one session and I didn't stop to walk at all. All this from keeping my pulse right at or just under 150 bpm. I was never out of breath and at 160 bpm (90% MHR) I definitely get that way. As I got further into the run I had to pay more attention on my foot placement but I was not battling chronic leg drag.
So the lessons were. Do what works for you. Though definitely use outside advice as a guide, but do what works for your body. I had to mentally get past running so slow, but that was an excellent workout for me. I can speed up later as my endurance improves.
It's also kinda cool that I got past the 5k limit as then if I wanted to I could enter a 5k run though things change when you're the one controlling the speed (instead of the treadmill) and other people are whizzing by you and you can't help but want to speed up, but that's another challenge for another day. I'm going to celebrate this milestone. i think it's time to make chocolate chip cookies.