I came accross this 2016 research: “Direct effects of physical training on markers of bone metabolism and serum sclerostin concentrations in older adults with low bone mass” The link is https://www.springermedizin.de/direct-effects-of-physical-training-on-markers-of-bone-metabolis/10244156
Table 1 lists accurately some exercises performed during one session. The conclusion is that “in participants with low bone mass, resistance exercise influenced the serum concentrations of CTX, a marker of bone resorption, but walking did not.”
I think I will try these excercises excluding the physioball too risky for me.