As a Strength and Conditioning Coach/Personal Trainer I have to often scrutinize popular exercise trends and systems. I care for my clients. I follow the mantra:

Rule Number 1– do no harm to your client
Rule Number 2– achieve strength and fitness goals
Rule Number 3– do not sacrifice Rule number 1 for Rule Number 2
(From the CFSC certification course)

This gives me pause with Heart Rate Training. First is the idea that achieving a certain heart rate translates to performance goals. My heart rate goes up on roller coasters. I don’t like the treadmill…can I just ride roller coasters? Of course I’m being facetious, but my point is that heart rate isn’t a direct exercise performance response, it is a sympathetic nervous system (fight or flight) response.

I’ve had clients sweat and climb heart rate on balance and simple core exercises. These often are not the best exercise choices I’ve realized because it counters the goals of mastery of movement and loading. So basically heart rate can also climb during a training session when there is any pain, discomfort or any “threatening” or scary exercises in a program.
Do burpees get your heart rate up more than any other exercise? May it partially be because you are falling on the ground every rep?

Even if we chose to use heart rate as our work/exertion indicator what formula do we use?
The gold standard in the fitness industry has been the Karvonen Formula (the popular 220-age=max heart heart). Well, this gold standard formula is inaccurate.

Seventy percent of the population is 10-12 beats per minute off of the Heart Rate Max formula of 220-age. That means if you have a class of ten people watching heart rates, only three of them will be in their accurate “zone.” Even scarier, thirty percent of the population is 20-24 beats per minute in deviation from the 220-age formula. So the majority of the population is either under-training or over-training.

Safe? Could be scary to push an incorrect heart rate goal on somebody
Effective? Not accurate for majority of population
Compromise safety for unknown effectiveness?
I’ll pass

*Disclaimer
I’m a Certified Exercise Physiologist that has performed multiple stress/ VO2 max tests. I’ve found actual Max and submax heart rates and have used them as targets in programming. I was never able to predict the numbers off of a formula