Water running, while terribly boring, will get you VERY fit. I was doing 2 to 21/2 hour water runs and besides the flexibility and mobility I gained in the knee, it got me fit. If you want it bad enough, I think you should be fine.
Gary, did you actually “run” in the water (i.e. you’re feet made contact with the pool bottom or were you in deep water and doing running motions without contact?
Hey, thanks for the question, and sorry I wasn’t specific. It was DEEP water running where I could not touch the bottom. I used a vest to help float, and actually tethered myself to the starting blocks or lane line hooks. By angling my body I could use differing muscle groups. I know a number of runners who have done that and have been amazed at the fitness gains. It sure helped me both before and after surgery. In fact, a friend who was national class runner did it for 3 months after having 2 femur stress fractures and when starting running again PR’ed a 5k within 3 weeks.