"The 33"-Road Bike Racing - Training with a HRM, note sure what to make of recent ITT stats

Ok, so when I first got my HRM, the first thing I did was what Friel suggests. A good warmup, then a 30 minute time trial like effort on my trainer at home and record my heart rate for the last 20 minutes of it. I did that back in the fall and my average heart rate came out to 168. My max was 183. I then based all of my training zones off of that and begun my winter training.

Fast forward to 3 weeks ago. I do an indoor TT. Did a nice warmup like before, get ready to start, have my HRM start recording and go. 23 minutes and 29 seconds later, I finished and come up with an average heart rate of 184 and 193 for a max. I think its just a fluke and I don't adjust my training zones

Fast forward to yesterday. I do another indoor TT. 22 minutes of suffering like before and my average heart rate now comes out to 187 with a max of 195.

Is it time to adjust my training zones? Also, does anyone have any clue as to why this would have happened?

people tend to overheat during indoor rides, causing their hr to elevate.

Is your fitness level significantly different from when you started. It's certainly possible to improve your threshold heart rate by training. As for the max, is there any possibility that you're trying harder? I mean, the overheating thing is a possibility, but that's a pretty big delta.

And yes, adjust your training zones.

So wouldn't my heart rate have elevated just the same when I did my intial TT test, at home on the trainer? I had a fan and just about the same ambient temp for both.

people tend to overheat during indoor rides, causing their hr to elevate.

Uh, no, this is not the correct answer. Did you miss the part where the first test was also indoors?

The right answer is probably that the OP op much more motivated for the TT, which was a race, and he found that he was capable of a harder effort than he was motivated to do on the home trainer. Should you adjust your training zones? I don't know the answer to this, but 168-184 or 187 is a HUGE difference.

It's also possible that there were other factors in play that cause HR drift, but to be in the same ballpark twice seems like compelling evidence that your LTHR is well above 168.

the 184-187 sounds much more normal for a TT. you probably learned how to push your self over the past 6 weeks. thus you are now getting good data. where as before you probably weren't going 100%.

Oh, another thing to consider - your average HR for an all-out ~20 minute effort WILL be higher than your LTHR. How much higher? I dunno, but 168 is still certainly too low to be your actual LTHR. Unfortunately, it's pretty hard to compare the distance of an indoor TT to real distances, but that time suggests something in the 8-10 mile range, which Friel suggests would give an average HR of 105% of LTHR when done as a race. That might be in the ballpark, but you would be better off doing that outside, I think.

The right answer is probably that the OP op much more motivated for the TT, which was a race, and he found that he was capable of a harder effort than he was motivated to do on the home trainer.


Agreed. Its going to be a heck of a lot harder to push yourself to what you're really capable by yourself, than it is with the motiviation of competition. Particularly if you're new to training, and haven't done a lot of racing.

The training bible addresses the fitness test vs race issue.

You use 100% of the last 20min for a test. The system has you adjust the numbers if they are obtained in a race. For a short TT he claims you ride at 108% of LTHR, and for Long TT 105%. If you multiply your short TT Ave HR by 0.925 you get 170bpm which agrees pretty well with your earlier test.

One other thing to consider is that good training, in addition to any physiological adaptations, allows you to make yourself suffer more than you would have when you were untrained.

Enthalpic has the right answer. Race effort is above LT. LT isn't some magic number at which all systems shut down. Its just the point where lactate builds up faster than you can clear it. In other words, it hurts. In a race, you're willing to hurt more than at home on a trainer.