HR on Trainer/Rollers vs. Outside
It's cold out there (yeah, I know I can still ride outside, but the cold takes all of the fun out of it for me and gear gets expensive), so I'm stuck inside either in my room on the rollers or in the gym on an old-school exercise bike. Today I was doing intervals on the exercise bike, and my HR never got above 180 (I'm 21, so my max is about 200). I was going hard and more out of breath than I typically get on even a steep hill outside. I was just outside yesterday and hit 190 on a hill without realizing it and had to slow down to not ruin my base training.
So on the dead time between sprints I was going at a pretty normal pace, and my HR was only around the 140 range. When I'm outside just cruising at a normal rate my HR is almost always above 150. I've been doing mostly rollers lately to get the feel of them, and I can go at what seems to be a normal (hard to judge) pace and my HR is only around 120.
I've come up with a theory, and I'm wondering what you think. Most of us probably know that lots of emotions- anger, fear, anxiety, happiness, etc. are often associated with sympathetic nervous system (SNS) activity. The SNS response leads to a whole host of things, most notably in this case an increased HR. I'm proposing that actually being out there on the bike arouses the SNS, leading to an increase in HR that may account for the lower HRs on the trainer. After all, it felt like I was working harder than normal on the exercise bike, but my HR was still lower than with a seemingly lower effort outside.
Just think of all the things that could arouse you: new places, new sounds, the thrill of going fast, the challenge of an upcoming hill or even an anxiety that you won't make it up the hill, the wind in your face, the sun on your back, barking dogs, angered motorists, the satisfaction of completing a goal or the anger/disappointment of failing to complete a goal.
Just as a note, I'm not overtrained, so that's not an issue.