Heart Rates Indoors v Outdoors

bradman

I train by heart rate and, although I can achieve and maintain desired heart rates outdoors, particularly on hills, I find it much more difficult to achieve/maintain those rates indoors on my turbo.
As my intention in the better weather is to use the turbo for higher level efforts, this is a little frustrating!
Presumably this is purely a mental issue and I need to apply myself better.
Is this a common problem? How can I achieve desired levels indoors? I already use music as an aid.

Alex_Simmons/RST

Well it is common for power to be different on an indoor turbo than outdoors. That is possibly why your HR is not responding but hard to say. Too many variables to say what causes HR to do what it does.

If you don't use a power meter, then you would be better off using another measure of ride intensity on a trainer - such as wheel speed. Many trainers have a predictable speed v power relationship (but many don't!). Or good ol' RPE and feel.

You mentioned using indoor trainer and HR to guide shorter more intense efforts. Since HR has a significant response time lag to actual effort and the effect known as "cardiac drift" occurs, then it is not a good guide to pacing shorter efforts. I've posted before but examples of HR v power on indoor trainer show two things:

For longer efforts HR will gradually drift higher over time, even at the same level of effort (power): This effort showing 2 x 20-min efforts at near TT pace will give you some idea of what I mean (power yellow, HR red):


Even longer efforts show this drift. Here is a one hour tempo effort:


But the impact on shorter more intense efforts is more pronounced, such as these 4-min VO2 Max efforts:


The reasons for indoor/outdoor power differences are well documented, primarily to do with:
- many trainers not reproducing road feel very well (low inertia),
- environmental conditions, esp cooling not equivalent to outdoors (you need a bloody big fan for cooling)
- frequency of use/adaptation to trainer (the more you use it the closer your indoor/outdoor power will be), and
- motivation can be harder to muster indoors for some