Long distance running is about the heart, lungs and legs. I have been running interval sprints to strengthen my heart and lungs. I have been increasing my slow long distance training runs to improve my legs.
I have been slowly increasing the length of my long runs. The goal is to increase my stamina, or the ability of my legs to run at a pace near my lactate threshold. The theory is that the more I run at this pace, the more my leg muscles adapt to more efficiently utilize oxygen.
To put it another way, I already can sprint at a fast pace. But I can only sustain that fast pace for a certain amount of time. The long runs cause changes in my muscles which will allow them to sustain my fast pace for longer periods of time until I reach my genetic maximum. The hope is that my genetic maximum is at least 40 minutes!
So today I dragged myself out of bed and ran 10 miles (16.4) for the first time. 5K seemed like a long run a mere 2 months ago. Now even 10K seems short. My legs felt fresh until I hit the 12K mark at which point they turned to concrete. According to the running book I borrowed, this "dead legs" feeling is exactly what I am aiming for. The stress of running with "dead legs" causes certain biochemical signals in the muscle cells, and these signals instruct the muscles to recover in such a way as to improve their efficiency.
At least that is the theory. In any case, I am happy to report that my weekly mileage is up to more than 35k per week. I run 10K on Monday with the goal of a 1K sprint at the end, 5K interval sprints on Wednesday and Thursday, 5K easy running on Friday and Saturday is my 10 mile long run.
Now I have to do the most important part of my training...sleep.
I ran 10 miles on Saturday and got a nice surprise when I uploaded the run to the Nike+ website. Apparently I have run 250 km since getting my nike+, so they gave me this really cool certificate. 