Interpreting (and using) Heart Rate Test Results on the Bike
I got a voicemail from a really confused athlete the other day about her heart rate zones. This is my initial response, but I'd love your input too!!!! Thanks Team!
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Compared to a previous test, her HR was lower. Yet she went faster and further than before…so she assumed that she must be fitter = more work at a lower "rate" of effort….right? Fast forward to her training and it's clear that the lower HR has translated to lower overall zones…and now she is riding "steady" but her "new HR" says she's in Zone 5.
Truth is, we have to go back to the assumptions made at the point of the test. Completely avoiding the fact that the first test itself might have been an aberration or outlier…a lower HR in a test with better results isn't about being more efficient…remember, your heart isn't driving your legs, your muscles are. Your heart rate is an expression, just one expression, of the work your body is doing.
There are a ton of things between your legs and your heart that will affect your overall heart rate, including but not limited to: fatigue, hydration levels, time of day of the test, temperature, sun exposure, wind, food choice, stress levels, etc.
In the 21st century, cycling power is king if only because we get real time data to work with. Heart rate data is very fuzzy; using it to target specific zones is a real challenge. Your week one zone two ride might be 18 mph average, but the same ride the following week in similar conditions yields 16 mph average. Same heart rate, different results…it's not that you just lost massive fitness, it's that with only Heart Rate on the table you can't truly be consistent with the work your body is doing.
The Veteran HR Athlete
As a Heart Rate athlete then, you have no choice but to become fluent in both Perceived Exertion (how hard any given effort "feels") and an honest user of your speedometer (as in, don't just look at it when you are riding down hill).
Over the course of a month, you will have four long Saturday rides and four slightly harder Sunday rides. Each ride is a step towards internal calibration and micro-goal setting. For example, here on this stretch of road I usually see 22mph; on this hill my speed drops to 6mph as I force my way over it. This is what I expect of my self for my level of fitness right now, and with that in mind, I look over at my Heart Rate monitor to see what all this work is getting me.
To be clear, I do the work I expect…and then confirm. Test, and verify. If you have a powermeter you can drive your workouts with it, but you can't do the same with Heart Rate. That would be like having a gas consumption meter on your dashboard of your car, and basing how fast you drive off of what you are burning…it's a useful metric AFTER you drive to Aunt Bernie's. Maybe next time you will take off the roof rack or inflate your tires to improve MPG…but it doesn't tell you if you are doing the speed limit or if you will cover the next 50 miles in an hour to be in time for the annual fruitcake unveiling.
So What To Do?
In Training -- Use your HR zones as a guide, but not the be all end all. Calibrate your bike performance as you do the run, and soon you'll be building fitness and getting to know your body better.
In Racing -- You need to be very careful in monitoring your effort across your day given (A) the natural lag between the work you are doing and the HR that shows on the display and (B) the natural drift of HR that happens across a day. Both can be "honed" during your race simulation workout, where, as a Heart Rate athlete, you should strive to simulate the expected temperature / conditions of your event. Powermeter athletes are exempt from this type of intense focus, but should still be paying attention to HR as a secondary value.
Comments
30 April test = LTHR = 161. Max HR = 176. (distance 14.41 miles/average 21.6 mph) – faded in the last 5 mins, lungs ok, nothing left in legs
3 April test = LTHR = 162. Max HR = 174. (distance 13.92 miles/average 20.9 mph) – good test, coming off bike free week/holiday, accidentally had more resistance on trainer than previous tests
25 Feb test = LTHR = 164. Max HR = 179. (distance 14.17 miles/average 21.2 mph) – poor test, used previous test figures for training
6 Jan test = LTHR = 176. Max HR = 185. (distance 14.13 miles/average 21.1 mph) – went out too fast, spiked HR in middle of the test
I would not have expected my HR to change all that much or that I would be riding faster at a lower HR now than in January. Technically that’s what happened but it’s happened because I did a really bad first test – rode the first half at 26mph and spiked my HR which stayed high for the rest of the test whilst I massively slowed down.
Of course my training is easier with the lower zones but it feels more realistic. With the short OS intervals of 8 mins I could manage the higher HR zones but there’s no way, unless I massively spiked my HR first that, I could have done last week’s 10', 15' , 20' (4') intervals in the original zones.
Patrick,
Thanks for the explanation, it is much clearer now! I knew HR could be fickle based on outside factors, so I will definitely use RPE and HR as a back up.
Jennifer
Yup makes sense, I worked out about a month into the OS that I needed to change how I did my intervals and I have been doing them based on pace since then. I don’t think this is explained clearly anywhere (if it is I missed it). I changed my approach because I read what the pace people were doing for their power intervals and realised that I would dig myself into a huge hole if I followed the training plan to the letter (which some HR athletes do). E.g. my average HR for a 40 min test is 162 (my HR start of test was about 130, end of test 176). Riding the whole test at 168 would have meant another 10 mins at the start of test at 22mph to get into the zone and then some backing off at the end to stay in the zone. This would make for a very long and hard test.
I think displaying the HR zones on the training plan page reinforces the idea that HR athletes should be basing their training on HR zones (lots of plans do this so it’s not a daft assumption). Is there any reason (other than no easily available calculator) why the bike zones aren’t done by pace for HR athletes? Apologies if this has been raised before.
I am going to assume, perhaps very naively, that based on people's power data you could wok out a rule of thumb which says if you zone 5 target pace is XX on your test course then your zone 1 target pace should be approx XX on your test course.
If I had this data I could ride at my zone 1 and 2 paces and get a really good feel for what my RPE should be at those paces and see what my HR is doing. At the moment, every ride feels like a huge experiment and I am having trouble dialling in my RPE/working out what my IM pace should be. So far I’ve gone too hard and way too easy (I think).
I can totally see the downside of telling people to race their IM bike leg at a specific pace but I can also see a few advantages to using it as a guide. When I start the bike leg my HR is probably going to be 150+ which is mostly due to excitement, getting through transition, etc. I suspect I will also feel great because I will be well rested, if I know that on a flat road/no wind XX is way over my IM pacing guideline I can quickly dial things back – or push things a bit and say no, this is too slow/way too easy.
Hope you take this as constructive feedback rather than criticism! Things are ticking along ok with my training.