Chaser, I spent the most Chaser, I spent the most part of my summer of last at the gym, well, 3 days out of the week for about 3 months. I didn't do a 1 rep max, but I'd estimate a good 200+ lbs. Nearing the end of summer/ fall, I began to run, and I enjoyed it very much. I was averaging about 20 mins. for the 5k also. Absolutely IT IS POSSIBLE, to add muscle mass, (proportionately of course) and still be able to run. I am going to hit the gym come spring time, and go even bigger and stronger than ever! However, I am going to add more focus, and intensity instead of just going because well, some magazine or book says I should. I am really going to litsen to my own body this time, while having a balance of good form to prevent injury (think Repetive Stress Injuries).