Lots of things we do are catabolic, but I would just say that long distance steady state running is definitely not conducive to building mass. I do know, however, that I am forced to do some running and I don't feel like it's cost me much mass.
Current PRs at 242, raw w/ wraps- 525, 355, 605, 1485
Roboro tui, perimo vester adversarius
(Build yourself, destroy your enemy)