I've just started a HIIT training routine and after two workouts my arms (triceps & biceps) grew 1/4 inch. I went to the gym this morning and after I got home 12 hours later measured my arms and they'd shrunk by 1/8th of an inch.
I know that muscles grow when I rest and sleep. But will the gain return in the morning? And is the shrinkage a sign of possible over training? I haven't trained to failure in any of my muscle groups in the last week.