I was out for a couple months and started training again. No base, and could not run 2 miles. This was last week, once I started our coach only had us do intervals. 5x1k @5k pace, 4x1.2k @ 5k pace,fartleks etc... Lately I feel my fitness coming back as I can keep up in wokouts, but I have a problem. Lactic Acid builds at the start of workouts. Like today, I was going 3:28-3:45 on 5x1000m on 5 min rest but lactic acid builds up so fast. It is actually manageable at the end of the workout than it is at the start(for whatever reason, it seems to dissapear at the end of workouts actually.) When will this feeling stop, if it ever will? My heat and lungs are fine, but my legs hold me back.