Heart Rate or power meter?
When monitoring training, I’ve heard more and more people talking about heart rate monitors (HRM) being obsolete because of the almost ubiquitous use of power meters in cycling these days.
A popular podcast I was listening to was talking about how HRM is not reliable as heart rate (HR) is too easily altered by different things like, heat, fatigue, caffeine, dehydration, etc. Their contention was the all powerful power meter is reliable and consistent…therefore much better?!?
I think if you know how to use your tools, you can get the best out of all of them. There is also a 3rd element to add into the mix…you need to be honest with yourself about your session RPE (rate of perceived exertion). These 3 together form a powerful monitoring system that can keep you on track.
but does that make power better?
I think power meters are an amazing tool. I bought one as soon as I could afford one and I wouldn’t be without it. I never stopped using heart rate though. I think the relationship between the two is fascinating and far more enlightening than using only one or the other. Joe Friel has written some really interesting work about cardiac drift and the ‘de-coupling’ of heart rate from power.
The ability to maintain the relationship between HR and power on an aerobic ride is part becoming aerobically fit. The longer you can hold at your aerobic threshold without decoupling, the more aerobically fit you are.
Clearly, this relationship cannot be seen if you are not using both power and HR. It’s also a good way to monitor progress, as you become more aerobically fit you will see this in the length of time you can ride before decoupling occurs.
so which to use for monitoring training?
The power meter gives you a measure of the workload in the session.Then the heart rate is telling you what the workload is doing to your body. You may think you are on an easy Z1 (3 Zone Model) ride based on your power…but if your heart rate is solidly in Z2…you aren’t going to get the adaptation you are aiming at.
You don’t need to be testing yourself every single ride, that would be an occasional thing. So which to use? For me, each ride priorities one and keeps an eye on the other as a check and balance. For example, zone 1 rides use HR as the priority and I keep an eye on the power to compare my fitness over time. However, when it’s intervals day or race day, the power meter gets priority and I just keep an eye on my HR.
Monitoring training during and interval session, for example 4×8 minute intervals, I will target the highest average power I can manage with all intervals being equal in average power. The heart rate will gradually drift up over the intervals and will peak in the final interval. If it starts going beyond what I know is good for me I use HR to know when to back off. This means I can avoid going too deep and affecting future training sessions.
NO race is won off the back of ‘one epic session’. So keeping control and hitting your marks in repeated sessions with consistency is what gets the gains.