Originally Posted by
RISKDR1
my theory is that your working muscles generate the oxygen demand and your heart responds to that. Some days our muscles may be fatigued and do not generate the the oxygen demand and your heart will not respond by going as high. It probably indicates that you need more recovery in your working muscles. Also, the aerobic system is more than just the heart. It is the lungs, the blood, the arteries, veins, capillaries and the blood itself including your red blood cell count. People who are on beta blockers eventually develop those other elements to compensate for the lower heart rate. You can increase the stroke volume through targeted training. Increase RBC count, capillary beds, etc. If your perceived effort is high but your power output is low our muscles are not fresh.
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.