heart rate discrepancy outdoors/turbo trainer

[Sturgis]

Hi all,
Am new to this forum, but have lurked for a while. Didn't want to hijack the thread 'heart rate- where should it be' so started this as a new topic.

After many years of running I got back on my bike about a month ago (running related injuries mounting up). I am a 55 year old female.
I ride a mountain bike in hilly terrain, nothing too technical, and on days I can’t ride use my turbo trainer. I try and simulate my outdoor rides by constantly changing the resistance on the turbo trainer, but I cut out the downhills to use my time as efficiently as possible.

I use a heart rate monitor as feedback that I am working hard enough. Here is what I found:
When I ride outdoors, my heart rate on steep hills goes to 170bpm, which on the ensuing downhill drops very quickly to around 115. Riding at 170bpm naturally feels very hard and I breathe heavily, but it doesn’t feel like I have to stop (the highest heart rate I have ever measured was running intervals at 176bpm which is spot on using the Sally Edwards calculation from the other thread).
When I ride on the turbo trainer, when simulating a hill, I can just nudge 160bpm before I simply run out of puff. The resistance feels similar to riding hills outdoors and I stay seated so as to simulate mountain bike riding on gravelly surface.

Am curious as to why my heart rate goes up quite easily when I am outdoors but not on the turbo trainer? Has anybody else found the same thing?
Cheers,
Sturgis

PS: I should mention that I have a 2nd degree AV block Wenkebach (also called “Athlete’s heart”) which is benign, but causes my resting heart rate to be very low (down to 37 -38 overnight). All symptoms usually disappear during exercise. I am particularly interested to hear from other riders with this condition.

[sogood]

Well known observation and has nothing to do with your AV block. A common suggestion for indoor "performance" is to find an industrial floor fan and have it face you when on the indoor trainer. Your body needs to efficiently release the heat generated to reach its peak. At least this is known to be the major root cause.

[Sturgis]

Thanks, sogood, it's good to know that it is a common thing. Not sure about the industrial fan, may have to settle for lower heart rates on the turbo trainer, as long as I know I am working hard.
Could possibly also have to do with the fact that on the turbo trainer I never let my heart rate drop below ~145 and then try and ramp it up from there. When I am outdoors there is a much larger range of bpm because of the hills, so often ramp up from ~115bpm.

[sogood]

On hills, you have no choice but to keep riding or do the embarrassing dismount. On a trainer, there's so much less mental pressure.

[Ross]

I believe too that when running you generally see a higher HR than when cycling.

I've never heard of AV block Wenkebach before but my resting HR is 46 bpm which is actually 4 under the official limit for donating blood. Last time I went to donate blood the attendant rang the hospital and I got the all clear in the end for me to donate after explaining I was a cyclist and an "elite athlete" ( her words not mine! ).

Your "true" max HR would most likely be a bit higher than 176 bpm. At your true max HR you should be close to falling off the bike.

[clackers]

Sweat pours off me when on a trainer, Sturgis - much more testing than the real thing! If you go to Bunnings you can buy a huge cheap fan that sits low on the floor.

I must say, that even trying to liven things up with DVDs where you lift or reduce your effort to match the camera going around a route in America, I struggle to retain interest!

[Sturgis]

Yup, turbo trainer is very boring, maybe its the lack of excitement that keeps the heart rate down, I'll go with that.

[Alex Simmons/RST]

Yup, turbo trainer is very boring, maybe its the lack of excitement that keeps the heart rate down, I'll go with that.

A lack of adequate cooling and very low inertia trainers tend to suppress our ability to generate power, and so it's little surprise that HR is lower for some people when they train indoors.

There are several ways to make indoor trainer more interesting / less boring, but it does help to have specific goals in mind.

[Sturgis]

Thanks everybody for your comments.
Have started using Spinervals DVDs and am now reaching a heart rate of 168 (even without a fan). It sure helps having Coach Troy yell at you.