After years and years of ‘just riding’ im now trying to follow a trining plan using HR zones. I did the 30 min FTHR test 4 weeks ago and got an average of 151 for the last 20 mins. i repeated the test today and got a result of 170. I was on rollers indoors and running in the same gear with the same cadence. This seems like a massive jump – does FTHR vary this much? The only changes are a new HR monitor, less ‘racy’ rear tyre and doing the test in the morning as opposed to the afternoon. I’m confused and am not sure which value to use to set my zones – any advice much appreciated, thanks

Heart rate is variable dependant on alot of things how ever

FTP tests are as much about learning the test as they are about your ability.

If you get the pacing wrong you can get misleadingly low numbers due to blowing up.

Unless your 60 years old or incredibly unfit it’s likely that 170 is closer to your actual

The only changes are a new HR monitor

That might be a large contributory factor. Have you moved from a wrist / watch monitor to a chest strap version?

That might explain your improvement.

The chest strap version would be more accurate in any event, so go with that value.

Unless your 60 years old or incredibly unfit it’s likely that 170 is closer to your actual

I agree. I’m 66 and FTHR is (apparently) 155. This was the result of only one attempt (on road) and I am aware it can take several goes to get the pacing right and avoid hazards like an artic reversing into the local garden centre. I think it seems reasonable though given my heart’s stubbornness to go above 163. I am intending to test again over the winter, this time indoors and also try a ramp test for comparison.

Thanks for the replies. I replaced a very old garmin hr chest monitor with a new garmin version last week. The old one started spiking wildly about two weeks ago and a battery replacement made no difference. Im 54 and am fairly confident that my max hr is 184 and resting is about 52. The 184 number has been fairly repeatable and comes from riding a long uphill with a really technical rooty last section which i have only cleared a few times and im really gasping at the end of it. It just seems confusing that with the same cadence and gear ratio that there should be such a large jump in hr, perhaps i should have waited more than 20 mins for my porridge and tea to have been digested!

I get my FTHR from races. 150 is not yours. If you have a closed circuit near you, ride that for an hour as fast as you feel comfortable.

Or ride up a big hill hard, take your max HR from that and then add a scaling factor of about 0.9.

Indoor rollers will not get you to your FTHR. Resistance is too low.

I get my FTHR from races.

Same here, no way I could maintain the same effort outside of an event or on rollers. In an XC race, within the first 30 secs you can either taste vomit or blood, and you pretty much maintain that effort for 90 mins.

Some people just have slow heart rates, some fast. Yours gets slower as you age but it’s relative to your own past rates not anyone else’s. So you could still be younger and slower than someone else.

Some people just have slow heart rates, some fast. Yours gets slower as you age but it’s relative to your own past rates not anyone else’s. So you could still be younger and slower than someone else.

What’s that got to do with the fact he has two wildly different numbers and doesn’t know which to trust….

He knows his max is 184 outdoors.

It’s highly unlikely his father is going to be 151.
Further compounded that in a later test it was 170.

It would be wiser to remind him that indoor and outdoor heart rate max/zones and. Power zones can be different due to heat build up and other such influence.

Indoor rollers will not get you to your FTHR. Resistance is too low.

Disagree. I regularly test on rollers (and a direct drive Wahoo, for comparison). Plenty enough resistance with a 52t ring. Can happily(!) hit 300w+ intervals.

Thanks all, lots of good advice. I’m using a 52/15 ratio and cadence of around 95 so I don’t think I’m at the top of the rollers limit but I will try to find a suitable place outside to redo the test. I wanted to use the rollers because the test would be repeatable regardless of weather. If I use 184×0.9 as suggested, I get 166 which isn’t that far off 170 so 170 looks more sensible than 151. My old hr sensor started spiking 5 days after the 151 test so perhaps it was on the way out when I did that test. I did originally think that 170 was too close to 184 to be realistic but I was shattered after 30 minutes

Disagree. I regularly test on rollers

Me too, but I wouldn’t do an FTP test on my 3” Kreitlers. I use my KICKR or race stats for serious intervals.

Your FTHR is 165-170. It won’t be a constant anyway. But set your zones based on 170 and you won’t be far off. If a workout then seems too easy, you’re having a good day. Too hard? You might be tired or ill.

Are you riding fixed on the rollers? They are repeatable, but check your tyre pressure is consistent as it’s the main source of resistance. (That isn’t the reason for your difference though)

Thanks TiRed, my rollers are elite arion parabolic – basic non resistance 3 roller design that you just balance your bike on and im obsessive about keeping the same tyre pressure, gear ratio and cadence so hopefully, my only variables are fitness and health. I don’t want to start spending on smart trainers and am hoping i can get away with my cheap rollers

https://cricklesorg.wordpress.com/ is free, link it to your Strava account and it will give you your estimated Lactate Threshold Heart Rate from 20min+ efforts, plus your heart zones.

A quick update. I repeated the FTP/HR test today and got exactly the same HR as last time, 170, and my power was up 5W. So I’m putting the low first result down to a faulty HR test. This is the 3rd time I’ve done the test and although the pacing gets easier it really is ridiculously hard work! I’m following a Joe Friel fast after 50 plan and I find the training plan a lot easier than the testing!

Great stuff. Your my age and following a similar training plan. 170 is about right and yes it’s always hard! That’s why I look for mine in races, where I don’t have to think about it! Enjoy those rollers.

Out of interest are you measuring at the end of the test or the average? I find my HR lags behind by about 12minutes if im pacing myself correctly (e.g. whatever my last test was plus a few percent).

I’m measuring the last 20 mins of the 30 min test as per the british cycling test protocol for both power and Hr. The one big negative to the rollers is I’m so knackered after 30 mins that I have to stop myself keeling over and falling off the rollers!

Thanks for the replies. I replaced a very old garmin hr chest monitor with a new garmin version last week. The old one started spiking wildly about two weeks ago and a battery replacement made no difference. Im 54 and am fairly confident that my max hr is 184 and resting is about 52.

My old Garmin strap started to behave quite erratically after years of reliable use. Changed the battery but still kept dropping out, defaulting to around 73bpm, and seemingly just making figures up. I’d be inclined to believe your strap was at fault.

My max and resting are similar to yours and I’d run around 170, give or take, depending on levels of fatigue, etc.

Have done quite a few tests now and am repeatably getting around 170 HR for FTHR so thanks for all the advice. I bought a 4iiii left hand crank power meter and am curious about repeatability. I’m on rollers with tyre pressures checked, same gear, same cadence but power can vary by upto about 15 from one day to the next. Usually very consistent, but every once in a while I will have a day with low numbers. I calibrate each test and ambient temps are stable. Battery life is about 50%. Any ideas why this may be happening

15W variance from slightly differing levels of fatigue from day to day?

If I’m in the same gear and maintaining the same cadence I would have thought my power would be the same from one day to the next. If I was fatigued I assumed it would be my HR that would be the only variable that would change