Heart Rate for Distance Rides

[alanfw]

I bought a GPS/HR computer a couple of weeks ago and am figuring out my heart rate/training zones. Starting to train on heart rate rather than speed, and so far I like it a lot. My question relates to how to approach long rides (100km+). I can generally hold 140-145bpm for extended periods (hours). However, I have noticed that after an intense interval I can travel faster/feel fresher on the same heart rate than before the interval. So this has led me to wonder: on a long ride is it better to sit on a steady heart rate or is it better to throw in a few bursts (taking HR up to 80-90% max) every now and then? On my weekend 110km ride where I tried to keep an even HR, I found my speed reducing and exhaustion starting to set in towards the end of the ride. Had me thinking that maybe I would have felt better with a few more short bursts. (If it helps, I'm 50, with max HR close to 180-185)
Cheers
Alan W

[nickobec]

No, because it is your own body tricking you.

When you do high intensity activity, your body releases endorphins (part of the old fight or flight response) so you feel good afterwards.

What actually happens is your body is less efficient at high intensity and uses more energy in a shorter space of time. So it uses lots of glycogen which is stored in the muscles rather than fat which mainly used for energy at lower intensity. And there is less glycogen than fats, so you quickly burn through your limited supplies.

So a short interval 100km into a 110km ride, should refresh and revitalised you and get you home happier.

A short interval every 10km in a 110km ride, is going to find your exhausted and "bonking" early. As the intervals are going to burn up all the glycogen, and then when it comes to "normal" pace your body would like to use a little glycogen and as supplies are limited, your become tired, exhausted and "bonk".

You could train your body to do the short intervals every xxx mins/kms in a ride, so you get the extra endorphin rush, but it is not the most efficient way to ride.

ps I can't give advice on training by HR as I am on beta blockers, so my heart rate at a given intensity varies depending on time since I took my PDDs (performance decreasing drugs) and how much riding I have done that day. I can ride the same hill at the same intensity using a power meter and have a HR between 105 and 145 at the crest.

edited to make more sense and to add:

if that was you first 110km ride, you are expected to feel tired during and at the end of it. Even if it was not, slightly more challenging terrain or weather conditions, can really sap your strength during a ride.

[alanfw]

Thanks for your reply Nickobec. It makes a lot of sense! BTW, I've done a few solo 100ks, and one hilly 150km solo where I almost collapsed, but last weekend was my first with an HRM! I'm training for the transition from "C" to "B" grade in my club, and also for an 8 day 1600km Smiddy charity ride in Sept, so I'm hoping to improve speed over the intermediate distance as well as make myself more comfortable in the saddle for the long haul, so any advice is really appreciated.