I take Emergen-C, but not as part of my training. I don't track my heart rate anymore, but I did when I first started training. Are you tracking your resting heart rate or your rate as you exercise?
The usual formulas for maximum heart rate (ie, 220 - age) can be pretty far off. There's a newer formula (that I don't remember, but I bet our exercise science student can) that is somewhat closer, but the only true measure is to have someone test you. Resting heart rate can be really interesting to track. You can watch it decrease as your fitness increases and see that you are over-training if it starts increasing.
Has anyone out there had his VO2 Max tested? I have never talked myself into parting with the money (that can be spent on things like Mickey bars and Dole Whips ).
Minnie Marathon 15K - 4 May, 2008
Tower of Terror 13K - 25 October, 2008
Goofy's Race and a Half Challenge Plus 5K - 9-11 January, 2009
Princess 1/5 Marathon and 5K - 7-8 March, 2009