Thank you for your comment. I hadn't paid any attention to why sitting was bad for your health, I thought that my daily routine of exercise was sufficient to take care of this issue. Now that your comment has explained this really clearly - that it's the prolonged hours of the inactivity of the legs that's the issue, I will definitely make it a point to get up and move around more frequently. I can and have just sat at my desk for stretches as long as 4-5 hours just concentrating on code routinely. Your comment may have saved me from my work habits contributing to an early demise :-)