A physiotherapist can give you this piece of good advice: if you can walk, walk; if can't walk, stand; if can't stand, sit! I would add: do zhan zhuang chi-kung at the same time. The objective is try our best to prolong the onset of each stage, and hopefully we can still be able to walk (with a cane) until our very last day.
How about those old people who are already on wheel-chairs? Worse yet, how about the situation when they suffer from Alzheimer disease at the same time? What can a healer do to help these old folks?
For the last few years, I have the good opportunity to help some old people to improve their health conditions (both physically and mentally), in particular, help them to generate chi to increase their mobility and general well-being.
It is a challenging but sometimes frustrating experience, in particular the most severe cases. What can a healer do? Your "client" is totally passive!
One thing that we chi-kung healer can do is to do sole-massage for them. The best way of doing it is like stimulating a pain-reaction. It is like redirecting the energy generated from the client's muscles contraction (stimulated through sole-massage). And redirecting it in such as way that chi-energy of the client is "driven back" to his hip joints where he has to dissipate this energy through activating primarily his pelvic floor muscles and secondarily his diaphragm.
If you're a seasoned chi-kung practitioner, try it on an old client when you got the chance. It will be very beneficial on your client and will improve your understanding of chi as well as your healing ability.