Ulthera and People with Muscle Athrophy?

I'm not sure what laser can cause muscle atrophy, but in answer to your question, Ultherapy ultrasound skin tightening and lifting won't cause atrophy or enlargement of muscle.

What one typically experience with normal aging process is lipoatrophy and muscle laxity and not necessarily muscle atrophy. The best set of treatments to consider would be Ultherapy first to bring out tightening of the skin of the face and neck, reversal of muscle laxity followed by a series of Sculptra injection by a trained and experienced board-certified core aesthetic physician to less the appearance of lipoatrophy by replenishing much needed facial volume along upper half of the face. 

Ultherapy does not affect deep facial musculatore. It works on the skin and a thin muscle layer called SMAS which cuases skin tightening. Read the Ultherapy ebook provided on the link below. 

Ulthera shouldn't cause any muscle atrophy, since the focused ultrasound produces such a discrete injury at 0.5 mm and 0.9 mm in size.  The muscle layers are not targeted, so I find very little risk of this.  I hope this helps!

Ulthera works by stimulating fibroblasts produce collagen. There is no evidence that Ulthera will stimulate new muscle growth.