3) Finally, before I do weights, I spend 10 to 15 minutes on the treadmill and get my heart rate up to about 65% to 75%, just to warm up. But, during the actual weight lifting, my rate generally stays below 50% - sometimes WAY below. - Is this typical for weight training? (I am generally doing 3 sets of 15 to 20 reps, and the weight I use brings me to near failure at the end of the 3rd set.) Does this mean I am not burning any fat when doing weights? Does it matter? I mean, am I still building muscle?
as has been already said, HR when weight lifting depends on which muscles are invloved as well as how many reps and how much break you do...
"during the actual weight lifting, my rate generally stays below 50% - sometimes WAY below. - Is this typical for weight training? (I am generally doing 3 sets of 15 to 20 reps, and the weight I use brings me to near failure at the end of the 3rd set.) "
well, i haven't worn my HR monitor while weight training in a while, but mine is _definitely_ higher than 50% --- i used to wear my HR monitor and use 105 as my "recovery" HR to start another set. i think when i do bench (10 set) my HR is about 135 or so and for lunges in the 145 range (my max is 194, LT 165)
"Does this mean I am not burning any fat when doing weights?"
with weight training you probably will burn very little fat while training, BUT b/c you caloric requirements will go up for weeks to follow first to rebuild the muscle, then to maintain the enlarged muscle mass, you will probably end up burning fat (simply because your body will burn more calories for weeks afterwards)