Training & Nutrition - 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.

I'm glad you posted this topic as I am trying to find information on it at the moment. I rode my indoor fluid trainer last night for the first time this year. I had the same issues. My avg. hrate was 139, usually in the upper 150's outside. I felt like I was exerting the same effort and was soaked with sweat even with a fan. I felt the effort was equal from what I could tell. It is so hard to tell because I want to keep up my intensity and be at the same level of fitness come spring. I'm going to ride harder tonight and see if I can even maintain the 150s on the trainer because that will explain that it is just harder.

You do not get the same feedback working indoors as outside. There is no increase in wind or ground speed. Without these, you are probably less motivated (even if you don't realize it) to push yourself to maintain higher exertion levels. Also, indoors you tend to get hotter and sweat more, giving you a false indication that you are working harder than you are.

Sell the rollers, buy some base layer clothes and go outside to play.

The main difference stems from the environmental factors that you have to contend with outside, and the lack of environmental factors you have to contend with indoors. Outside, you have wind, which is in my opinion the major contributor of the increased HR. Also, there is the friction force from the ground (depending on the type of terrain you're riding on - concrete, blacktop, cobblestones, etc). And the sun plays a role too - by making your body work slightly harder because of the heating effect it has (since it's kind of a hot star :p ).

Indoors, you're in a much more controlled environment, so you don't have as many things to contend with so to speak. Your rollers or trainer have very very smooth (typically) drums for your tire to roll on, so you'll experience much less resistance to that friction force. Then the lack of wind, while it won't have a cooling effect like it does outside, doesn't make you work any harder.

Interesting theory, and I'm sure it's true for the most part. Like when you get into that zone hammering on a flat or just get excited to be outside. It's completely possible, but I would say that the majority of the variance in your HR comes from the lack of environmental variables you have when riding indoors. Good topic!

I'm glad you posted this topic as I am trying to find information on it at the moment. I rode my indoor fluid trainer last night for the first time this year. I had the same issues. My avg. hrate was 139, usually in the upper 150's outside. I felt like I was exerting the same effort and was soaked with sweat even with a fan. I felt the effort was equal from what I could tell. It is so hard to tell because I want to keep up my intensity and be at the same level of fitness come spring. I'm going to ride harder tonight and see if I can even maintain the 150s on the trainer because that will explain that it is just harder.

That's good that you noticed that. Another thing to note is that time spent on the trainer is "worth more" than time spent outside. If you do, for example, 1 hour on the trainer at a pretty good effort, it's equivalent to about 1.5 hours outdoors...as long as it's not TOO much of a change from the outside as far as wind, etc goes. On the trainer, you're working at the intensity for that entire duration of the workout, while outside you have uphills and downhills where your power output will fluctuate, and then you have the stop signs and street lights to contend with and stop at (where your power drops to zero for that time being). But indoors, you're putting out 'x' watts of power for the whoooooolllllle time, and it doesn't leave much room for slacking off or looking for that next stop sign to take a breather :D

Funny, I hit my record heart rate on the trainer this week during my second, 4 minute out-of-the-saddle "climb".

Raise your cadence and resistance and then see how you do. ;)