Grog,
I am sure more experienced runners will have better answers. For me, I usually run at night. I run the same route and when I run in the evenings I keep everything nice and even. When my routine must deviate, due to life, and I must run in the morning, I notice everything is slightly off kilter. Could be something to do with body temp, HR, and balance during various parts of the day?
Jennifer
“Live as if you were to die tomorrow. Learn as if you were to live forever.”
-Mahatma Gandhi
"We are what we repeatedly do. Excellence, therefore, is not an act but a habit."
-Aristotle