In actual fact it is easier to lose muscle than we realize. Now this is the extreme end of the scale but........If you immobilise a body part IE splint, cast or sling and it recieves no direct stimulation for 24-48 hours muscle catabolism takes place (breakdown). It takes place at an alarming rate also. But in answer to your question, you will not make any gains doing what you mentioned but you probably would not lose any appreciable amount of muscle.