A running revelation?

Last week was a tough running week for me.  The distances keep increasing (only 7 weeks until the Mogathon!), and last week I was to run 5K, 8K and 13K.  After my 12K run last Sunday my knee was feeling tweaky.  I wondered if it was maybe my shoes wearing out.  I bought them last summer and though I didn't use them a lot over the winter, I hear that a person should replace your shoes about every 6 months.  I think that is especially true if you are running, as it places a lot of extra strain on shoes, and your body.  I went and picked up some new shoes this week and after skipping my first run of the week to allow my knee to rest, I went to the gym on Thursday to test out the new shoes on a treadmill (in case I had to return them because they weren't comfortable).  I did 5k on the treadmill, and the shoes felt fine and so did my knee. 

After a fairly busy weekend involving going to see Riverdance and a Mother's Day bbq lunch at our house I was struggling to find the motivation to go run my 13K yesterday.  After a nice hour long nap in the afternoon, I finally sucked it up and drove myself down to the river.  The running felt good, and I decided to try a walk/run schedule of 10 minutes of running followed by a one minute walk.  I did very well with that until I reached somewhere between 8 and 10k.  That is about the time that my legs started to feel heavy and I noticed my knee feeling a bit tweaky again.  I took a few more walking breaks and actually stopped to stretch out my hamstrings and adductors a little.  I managed to run 13k in 92 minutes! 

On the way home I started thinking about my run, and my tweaky knee.  I had a thought that maybe the problem is fatigue in my muscles.  After running the 8-10k or 60-70 minutes I think that possibly my muscles are running out of stored energy and possibly fatigue in the muscles makes me lose my form which leads to a tweaky knee.  I felt like that was quite a revelation.  I don't know if it is true, but I think next week on my long run I am going to take along a gel energy pack, or possibly Gatorade instead of water.  Just something to get some quick sugar energy to my muscles so I can complete the longer distance runs without hurting myself.