The Nature of Fatigue

Today's runs made me think about the fickle nature of fatigue and how the body reacts to stress in the short- and long-term. When I say fatigue, I mean the "breaking down" feeling you get after overloading your body for a few days that can persist for weeks. I guess the more technical term is overtraining. Every runner who has hit mileage or workouts a little too hard knows the feeling. Everything over the course of the day, even simple daily tasks, are harder and take more mental strength to get through. All the runner wants to do is lay around and not have to concentrate or undertake any sort of physical or mental task. Just walking up a flight of stairs or writing a new blog post can be a daunting prospect. I tend to get this more from just running mileage with no workouts. When I run workouts I ideally run my easy days easy enough that I feel pretty good on workout days, so the only time I feel run down is the day after a hard workout. When I started back up in this cycle I wasted no time getting to high mileage, so I felt terrible for about 2 weeks and then all of a sudden I came out of it and started feeling better, mentally and physically. I don't think medical science has yet determined the physiological causes of this kind of long-term fatigue, so it is an interesting thing to ponder.

Also interesting is the way the body handles the exact same stresses at different times. For instance, today I had one of the better training days of my life. I ran 15 miles at a good pace in the morning, then tonight came back and ran 5 more at a pace faster than maybe every other secondary run I've ever done. This capped off a 115 mile week, the highest I've done since at least the summer, and my first week of workouts. Yesterday I ran very easily but accumulated a lot of miles, and today I fully expected to feel at least a little bit fatigued from the last 1-3 weeks of work. But I felt great! It truly is a mystery why I felt so good today, after an accumulation of quite a bit of work for me, and bad some other days with much less crap in my legs. I am sure the easy day yesterday made some difference but I felt so much better today than yesterday that I can't believe it's attributable to only one factor. I can only hope that this kind of feeling continues, but given how little I know about the nature of my body's fatigue I'm sure that I'll wake up one morning, after being in a routine, and feel completely different than I did the day before. I'll probably feel worse, but that's part of what training is for - the mentally callousing aspect of training and being able to get through the bad patches as well as revel in the good patches, like today.