I’m not sure what a recovery board is but…Another idea which may be practical for your setting (assuming an arm ergometer is not) is to set up a chair with a light band behind it and have her march very quickly in the chair while either punching forward with the band behind or upward with the band below the chair. This WILL increase her heart rate if done quickly and usually doesn’t cause knee pain.
Aquatic exercise is excellent for all clients. I just put a college football prospect through a series of water workouts and he was amazed at the effort it took. And his 40 time is down .2 seconds. Though not all due to the aquatic work.
And my deep water class is loaded with mobility challenges. All are getting rave reviews from their doctors.
Go Aquatic!! Join the Movement!!