I went to the YMCA after work yesterday to ask about what they had that would be useful for my needs. The guy at the front desk was clueless, but he eventually brought down a personal trainer and she was more knowledgeable. At one point, she sized me up and said that I had a small build and thin bones, so finally connected the dots that I might have an osteo problem like I told her, regardless of my age and sex.
We talked about different classes I could take and the different weight exercises or machines I might use. Most of that I knew from my reading, but I wanted to hear what a trainer had to say. It was also for me to think about whether joining there or another gym would make sense. I'm not a gym person, so I would rather not go to one if not needed. Dolly seemed distressed when I told her I went there. Apparently, she thought I was going to join there as well as take the karate class, which means I wouldn't be home much in the evenings.
After she mentioned the cardio-kick-boxing class, I asked that involved punch bags, though I knew it didn't. That was a lead in to a question about whether a punching bag would be useful for bone building. She agreed, but with her usual caveat that it depends on the level of osteoporosis, so the bones are not stressed too much too early.
I don't if for sure if there is anything I can do to bone building, or is all this just going to maintenance of what bone I have left. It could be overkill for what it will actually accomplish.