We planning on visiting AC in late March. My husband will be in training and is looking for someplace that has weights so he can maintain his workout. Is there a gym or do any of the resorts have a weight room on the island?

For upper body, I would start with Kayaking, then curl and bench press scuba tanks. That leads into the legs, which will get a great workout diving. Then, take a trip to Lamanai and do some step training. For aerobic benefit, learn to Punta and strengthen the abs by drinking too many wierd blue drinks.
There may be exercise equipment somewhere on the island (try to search the board, I think it's been posted before), but I think the island IS exercise equipment.
Hope you two have a great trip.