HR on Trainer vs. Street

I have found the two to be very consistent over multiple tests. One thing to watch out for is that you are "fresh" for the LT test. You don't want to have blown it out the day (or even two) days prior to the test so your body has had a chance to recover. My day-to-day "perceived" threshhold has quite a bit of variability depending on: how I slept, what I ate, if I was dehydrated, etc... Perhaps you should attempt another LT to add another data point before you draw any conclusions. Also, as noted above, watch the enviro conditions to make sure you're not in a sauna or even too cold.

My Power Tap works just fine on the trainer.  The beauty of training with power is that power is power no matter where you are riding.  250 watt ride on the trainer is the same as a 250 watt ride on the road even though HR may vary between the two (wind, heat, etc).

The main factor has to do with cooling; unless you have lots of air movement inside you are less able to cool yourself which leads to a lower HR.

For athletes that train both indoors and outdoors, it is often advisable to do a test for both rather than using the same numbers for both trainer and road riding.

Shane

  I suspect you're right but that rationale seems counter intuitive, doesn't it? The fact that you are less able to cool yourself makes you warmer and that puts more stress on the heart, not less? Just curious. In hot weather, for example, people with coronary issues are more lucky to have a heart attack when exercising because of the added heart stress. 

Thanks for the updates, when I ride the trainer I typically have a fan on and I lower the temp on the A/C (or heater) to help keep me cool.  But since I haven't monitored my HR on the trainer I can't tell if there was a difference.  Either way thanks for the info!