There are many ways to build strength and stay flexbile. Have you wondered what poses* might be most effective for rowers?
And when the workout is done, whether on water or land, consider some targeted stretches to loosen up the muscles rowing targets (hint: almost all of them):
Example: Revolved seated staff stretches your lower back, outer hips, and IT band
* As always, consult with a medical professional about your exercise plans, needs, and concerns.