It is not new for me to say that yoga done seated in a chair or on a mat on the floor, can help build strength and balance.
Of course I recommend yoga practice. And also be aware; be careful and be smart.
I recommend the following article:
Bracing for the Falls of an Aging Nation
By KATIE HAFNER NOV. 2, 2014
Please read this important article.
And consider the following study too!
Yoga for Prevention of Fall
by Kathleen K Kelley*
Associate Professor of Physical Therapy, Quinnipiac University, USA