Originally Posted by Viking55803

Your response was right on I think. Since that one ride I have been able to correlate my heart rate with my muscle fatigue. In fact, my legs seem to be limiting me more than my heart rate. I have been too focused on heart rate I think. Lately I've been letting my legs drive my heart rate instead of the other way around - if that makes sense. There are a lot of external and internal issues that drive heart rate - muscular exertion being only one. Stress, lack of sleep or rest, ambient temp etc. all have their effect.

In any case, the sensations in the legs are what I am paying more attention to with heart rate in a supporting role. Just last evening I set a personal record on a local 10K time trial course I've been doing regularly for the past 3 seasons. I destroyed my previous PR which was done on a road bike with aero bars while now I am riding a heavier gravel bike with 40mm tires. I think I was 2 minutes faster than my previous PR last night.

The other thing I've been doing as I prepare for my first "competitive" event - a 50 mile gravel race in October - was based on a post in the 50+ forum about 4X8 minute intervals. I've made sure I have a couple of days rest after an interval session which usually takes place in the middle of a 40 mile ride. I've been avoiding intervals but I'll tell you they seem to act like steroids and the results are evident after only a couple of weeks. My feeling, however, is that they need to be used wisely.