Thanks, LBTC. It's possible that my muscles are particularly compromised because I am getting over being really sick with bronchitis and a sinus infection. Thank God for the miracle of drugs. I probably shouldn't be outside exercising in the cold, so today i went on my trainer and did a core dvd. My immune system is really twitchy; no particular disease, but I am very sensitive to big jumps in exercise intensity, mostly when it's something other than cycling. So, I am dealing with the aches and trying to baby myself a bit, at least until I am done with my meds. I know the illness is getting better though, since my HR was back to normal when I was on my bike today and it is always higher when I am getting sick or sick; like a radar system!