Koffee - It's great to hear from someone who clearly has an in-depth understanding of heart rate, aerobic and anaerobic threshold, etc. - since I have a few questions!
First, in the absence of laboratory testing, I've used a calculation that I'm not sure I saw referenced in this thread, that - based on how I "feel" at various heart rates - I think comes a lot closer than the 220 minus age. - It starts with 220 minus age, but then subtracts resting heart rate. You then apply the percentage you want to work at, and then add your resting heart rate to the product. At age 48,with a resting heart rate of 45, this formula gives me 140 for 75%, compared to 129 based on 220 minus age, or 153 for 85% as opposed to 146. - Does this make some sense?
Okay, that's my calculation question . . . Now, to the "practical applications" questions . . . Since this winter has been so bitterly cold and snowy/icy compared to last winter, I have spent a lot more time in the gym - spinning, treadmill and weights - and paying more attention to my heart rate monitor, and would love to understand a few of the things I am discovering. So, if you can help, would love your answers to the following:
1) When doing a spinning class interval ride, during a hard effort, my heart rate will hit between 155 and 160 for the 30 to 60 seconds that we are sprinting, or whatever . . . and by the end of the effort, I am either breathless, or my legs feel like they couldn't sustain the speed (or resistance, as the case my be) a second longer - or, more often than not, both! - And yet, when we do an endurance ride, I have found that my heart rate just gradually increases, and after 30 minutes or so, I'm feeling so good in the mid-140s that I increase my speed or resistance, and move easily to 155, and am able to sustain that rate for much longer - AND, it doesn't "feel" anywhere near as difficult as that same rate feels during an interval ride. - Is this typical? Why is this? And what should it mean for my training?
2) There are some days (usually after several days in a row of intense training, including strength work) when my legs get in the way - i.e., my legs just can't take the necessary resistance and/or speed to get my heart rate up over, say 65%. One of the spin instructors keeps trying to tell me it's lack of oxygen, but that makes no sense to me . . . since I'm not having any trouble breathing and my heart rate is staying relatively low - my legs are just sore or fatigued. Am I right in thinking that there are times when your muscles can not keep up with what your body is capable of aerobically?
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?
Thanks . . . I look forward to your answers.