However. After swimming I tend to limp. I am a bit fragile. If I swim again the next day my joints stiffen up. Not as much as they did before I began swimming, but I notice it, particularly when I get up the next morning.
If I take a day off swimming, or two, my knees feel better and I can do more without pain.
So. I need to swim to gain this benefit but I only get the benefit when I am having a rest day. Generally speaking. When I was in Las Vegas I did not swim at all all week. I did very well with my knees that whole time.