It's weird. When I jog at any sub-maximal speed, after a mile or so (often even less) my entire lower legs get very tender and hurt. My calves get sore all the way from just under my knee to my achilles tendon, and my ankles seem to get a little bit inflamed.
But if I do any kind of faster workout, as long as the repeats are kept to 400m or less with standing recovery (slow jogging recovery brings the above painful sensation), I don't seem to have any problems at all.
Curious about this phenomenon, I tried controlling the terrain I ran on and the shoes I wore. Running on the same terrain with the same shoes, the above trend still persists. Traditionally I don't stretch or do much warming up other than 2x400m jogging (only way I can warm up without hurting) and a few strides and drills.
I want to train for the sprints (not competitively, just for fun), but I am worried that even though speedwork doesn't hurt, there is some underlying imbalance or problem that will get me injured down the road if I don't sort it out.
I am currently a college freshman. I had this problem towards the end of high school as well, and it eventually got me to quit running after modest PRs of 2:06 and 4:50 in the 800/1600 on about 45 miles per week.
Should I just go ahead and start training again? I miss feeling like a runner, and speed work is better than no work.