I have good experience with running, but mostly at the 12kph speed mark. I do at least 8km a day, but it's mostly tempo work on a treadmill.
I recently bought a new treadmill to put in a lot more speed to my runs, to try and get a time of 18 or less for my 5k. I want to improve my time by gaining speed for a long time (like elite athletes) without losing endurance.
However, as soon as I stepped up to 16kph for 2km or so, I began having pain the next day. To the point where I find it difficult to walk for a couple of days. The pain is in the Calf to Heel region, and it seems to be the achilles tendon.
Is this going to go away? I have the stamina and endurance to do it, but I fear my legs are going to give in.
I have just done 3k at speed, after having rested 2 days, and the pain seems to be coming back. Help.