Originally Posted by
Grotug
Well that was interesting; first 25+ miles of my ride yesterday I was feeling fantastic; was struggling to keep it into zone 2 and not go harder. Was averaging about 170 watts and about 125BPM; then, inexplicably, pedaling became difficult to generate more than 100 watts. It may have been because I didn't eat enough; or maybe my legs can only do 170 watts consistently for an hour and a half before hitting fatigue. Nevertheless, I forced myself to push harder and maintain at least low end of zone 2. I also missed a turn and added 10 miles to my ride; which meant I got back pretty late (was getting dark). I recovered somewhat on the last leg of my ride, and my heart rate was higher per watts produced than it was during the first third of the ride (I've noticed this happen when I'm fatigued).
This morning my resting HR was about 45.5 (once it settled down it was very stable between 45 and 46). Last 30 seconds standing HR was about 58 BPM.
170w @ 125 HR is normal for you? Your drop-off probably had nothing to do with eating. Say you're JRA and you come to a little steep hill. You come up and hit it, your HR rises nicely, by the top you're breathing hard and your HR is still coming up like it always does. Fine. But suppose you do that and you just aren't feeling it. You look down and see your HR is not coming up normally even though you're breathing hard. That's not good. In the latter example you're overcooked and need at least one rest or easy day, maybe two. HR vs. power is a very important thing to watch. They should operate in tandem, though HR will always lag power by some normal amount of time, and you should know what normal looks like. I would think you've been riding long enough to know that.
It's also possible that you've been riding on the edge of glycogen depletion. If your power was still low toward the end and HR was going up, that's not a good sign. Enough more of that and you'll feel really tired and 16 mph will be your max speed. Usually hormonal exhaustion (overcooked) means HR drops off and it gets difficult to raise anything much over Z1 no matter how hard you push on the pedals. HR is sort of low-normal but there's no power, that's usually low glycogen. You can test that by drinking a half bottle of sports drink or taking a gel or shot blok. If things get way better in the next 15', low glycogen. If not, overcooked. If I'm in good condition, fueled, and ready to ride at the start, I can still raise sprint power and LTHR after 200 miles.