glucosamine and chondroitin

Question
I am an avid 47 year old runner.  I am currently training for my first 50K Ultramarathon in March.  I've been a runner now for 5 years and try to run ~30-50 miles per week.  I love to run marathons (4h marathoner) and also run many races 15K and longer.  I do most of my training on asphalt and many of the races are also on asphalt/concrete.  I also try to get off road at times and have also registered for an off road marathon and (another off road) 50K Ultra this coming summer.

My question is that I am concerned that at my age I probably should be worrying about the health of my knees considering the punishment I put them through.  I don't have any pain at this time other than the nag I've had from cartilage surgery in 1975.  It's pretty insignificant.  I've heard of the use of Glucosamine and Chondroitin suppliments to maintain joint health.  I believe I should be taking these supplements but not sure how much and what kind.  Would you be able to help in this area and what other supplements should I be taking at this time?

Thank you so much for your time.

Answer
eric
first your age is not a problem.Second to take care of your knee's and the rest of body you should develope a weight program to take care of the inbalance you develope over time.About your knee's.You need to strenthen your quads and hamstrings and focus your routime on the core strenth which consist of abs back extentions primarily.
There is know need to take those suplements since you do not have a problem at this time.weights...weights..weights.
Youe knee tracks like a train on a railroad track.When the knee does not track properly that is when you develope cartiledge problem.Biking is another great way to keep the knee tracking properly.Hope this helps you eric.Anything else get in touch.
The very best to you
John