If you play doubles tennis on clay courts, its pretty easy on the knees. My grandpa is able to play after knee replacement, and I was only allowed to play on clay for 3 months when I was returning from surgery. Its more pressure than, say, swimming, but its also way more fun than just going back and forth across a pool. Just make sure its clay, not hard courts which are basically cement. Good luck!

Similar to swimming, but has he considered Water Polo? It has a lot of the team and competition and game aspects of soccer without the impact to the knees because of the water.

I've got a couple Trikkes. They are 3-wheeled cambering vehicles. Very easy on the knees. I'm one of the younger riders I know. If you've ever seen any late night infomercials on the golf channel, that would be what I ride.

I got into it a few years ago. Lots of fun to ride distances, you can alter the way you ride to work different parts of the body harder. I enjoy the challenge of hills, personally. I love my Trikkes.

www.trikke.com is the main site

www.bloodpowered.com is a great resource site but currently down for the week as they make upgrades. There is also discussion there on other HPVs.

So I realized my reply was incomplete. As for competitiveness- I like to race cyclists. They never know I'm racing them unless it's my dad, but really it's a competitive thing for me to try to keep up with the cyclists. It's how I push myself.

The downfall is that it's bodyweight only. I sometimes ride so that it's like I'm doing single leg squats. More often than not though, I just like to leave the lifting for the gym and entertain myself while "racing" the cyclists and get a good workout by practicing my hill climbing.

Way more comfortable than a bicycle, but that's just my two cents.

I used to run about 3-4 miles 3-4 times per week. I had a knee injury a couple of years ago from which I recovered (soft tissue only). But we have knee problems and arthritis in our family, so I have been looking for other exercises that do not stress the knee, similar to your husband.

In terms of work-outs, I now do a combination of kettlebells, floor exercises (i.e. push-ups), and Burpees, and some yoga. I now have the best muscle tone of the past 10+ years.

I don't have much time for competitive sports these days, but I always enjoyed volleyball, which is more jumping and sprinting and doesn't bother my knees. In the past I have done rock climbing, and that is not hard on the knees much at all in my experience.

My top suggestion would be swimming. If he wants to work on his upper body? He can use a pull-buoy, my favourite of all time is the one made by Tyr. Work on the lower body? Kickboards. And swimming is fun. He can be inside, outside, flip around and float when he's done with his set. If he really starts getting into it there are Master teams he could join to be competitive again. Also yoga and pilates. Good luck!