I am a massage therapist who specializes in neuromuscular therapy. i have two clients that are also using hyperbaric oxygen therapy, is this ok?

No !!: The application of hyperbaric oxygen is limited, such as severe peripheral vascular disease and danger of gangrene or in carbon monoxide poisoning , I am not aware of any benefit musle related problems!

Quite ok: No problem of massage therapy in patient using hyperbaric oxygen.

Not sure: I am not sure what neuromuscular therapy is (massage therapy? Physical training? A form of rehab?). I imagine that your client is getting neuromuscular therapy, and getting hyperbaric oxygen therapy (hbot) for other reasons (i am not aware of any uses of hyperbaric oxygen for neuromuscular-type therapies). I think that this is probably ok, as hbot has few (if any) muscle side effects.