So I bought a heart rate monitor yesterday, RTFM last night, entered my height (72”), weight (207lbs), age (30), resting hart rate from this morning as soon as I woke (51 bpm), set the target zone to 70-80% (149 – 164) and went for a ride on a short local loop to test it out.

My speed averaged out at 14.8mph over the 1hr 3mins It took, at what I'd describe as a leisurely pace, no shortness of breath, very little leg burn, pretty much wanting to go a bit faster all the time but not being able to do so without getting beeped at for going over the target 164bpm. I did stray to 185 a couple of times when I couldn’t resist the few climbs on the route, but the watch says I stayed down within the target zone for 75% of the ride.

So how realistic is the 1380 kcal’s it says I’ve just burnt off? Surely that can’t be right? Seems way too high, and yet it also says I’ve burnt 0.4g of fat, and that seems a bit low?

How acurate are these things? and for anybody else that uses one, how do you use it to train, and build fitness?

I'll be honest, I only bought it because I was interested to know just how fast my hearts going when it feels like its going to explode at the top of a long climb, but now I read a little into it, I can see it may genuinely help me get fitter.

Calorie counters are notoriously inaccurate when calculated from HR data only.

turn off the cojoined/tandem setting

I think all the calorie counter apps are optamistic at best. I mean mine can't even tell when I've stopped for a pie, stupid thing.

turn off the cojoined/tandem setting

😆 Trust me I've looked for one!

Did you calculate your maximum heart rate too? Or just do the 220-age formula. That could have shot things out.

Although to be honest, manufacturers probably just make the numbers artificially high in these calculations, as it makes people happier with the products.

Joe

looks a bit high i might agree,

but you are 15stone and averaging 15mph (is this on the road?) and your HRM thinks you have done been at 900cal/hr. If i weighed that much and rode that fast, i'd be f***ed

are you reading Kcalories or KJoules?

i have a polar cs100 and for me it seems to work ok – giving as low as 250cal/hr pootling with youngest kid (much higher with older one)!
400cal/hr or so on recovery type rides trying to keep HR lowish
650cal/hr on hilly stuff working hard say 25% of time HR in serious training zone

sure its not reporting Kjoules? approx divided by 4 would give a sensible answer

Polar have a patent on the algorithm used to calculate calories consumed, theirs is pretty accurate IMO, most others aren't even close, my Garmin reckoned I did 4100 calories in 3.5 steady hours yesterday.

I have a Polar and although I cannot vouch for its accuracy it seems to reasonable to me. I use ot more as a way of estimating my work out and that allows me to compare sesisons I have done. The event I did on saturday saw a mix of running and biking over 4 hours and it reckoned I burned up 3700 odd calories. Max heart rate didn't go above 161 apparently. Numbers are generally a lot lower on the Polar than they are on the gym equipment I use. But, as I say, I'm not really using it for an absolute calorie burning counter.

I would say it is wrong by a few hundred. I used to use one at the gym and used to aim to hit 1000kcal or an hour which ever came first.

To hit 1000kcal I used to row 5k in sub 23mins run 5k in around 25mins then do 100 sit ups, leg raises and push ups.

So my heart rate monitor would say 1000kcal whereas adding the two machines totals up plus a bit added on for the floor work would get a figure similar to yours.

As said above it is inaccurate but if you always use that to measure your exercise it is still a valid method in my opinion. Hell unless your an Olympian stick with it.

1380 kcal seems a massive amount to burn for an hours ride and I don't think I burn anywhere near that amount.

My ride to work takes me just over an hour, then the same home, both rides done at a reasonably fast pace. So If I was burning calories the way you do I'd burn roughly 2800 a day just riding my bike. I don't think thats's the case.

I used to use one at the gym and used to aim to hit 1000kcal or an hour which ever came first.

Not unless you weigh 80 stone! That's just as inaccurate. You may manage 8-900 exercising flat out, but no way is the average person gonna do >1000hr

I've got an older Polar HRM, and that works out about 800-900 cals per hour for normal fairly high exertion mtb riding. A couple of recent outings with the wife and kids have seen reported burns between 150 and 300 cals / hours.

From when I used to do mountaineering expeditions, we used to work on 6000+ calos / day energy budget – so circa 1000/hr prob not too high an over-estimate. Very weight sensitive though. The energy required to heft around a 15st bloke like me will be considereably more than needed for a sub 10st weight weenie.

I believe that the Garmin GPS HRMs give much higher calorie burns.

Make sure you get your max HR right. I had huge readings on my polar till I updated the max to 207 (which it is) and now it appears to be about right. An hours offroad hardish ride is 700-800 calories.

I don't really know how the Garmin ones work frankly!

My last MTB race was 2hrs 24, ave HR of 182, 4000ft of climbing, and 1634 calories burnt.

Road ride yesterday was 3 hrs 18, ave HR of 167, 4000ft climbing again (weirdly), and allegedly 4173 calories.

Seems dubious… I've never actually paid the figure any attention I must admit.

800 per hour seems the normal. I don't tend to use mine now really.

Thanks Chaps, I guessed it was pretty high. I wonder what a more realistic figure would be? Ive found an option to apply a corection factor to the callorie count to get a little more accurate.

SOOBalias, Its about 30% road to be fair, and the rest is fairly hardpack gravely bridelway, so pretty fast rolling stuff. I double checked and its deffinatly Kcals. I know 15St is heavy, but at 6ft, I dont look particually chunky. 8)

I know 15St is heavy, but at 6ft, I dont look particually chunky

And yet you're still right at the upper end of 'overweight' by BMI classification. Maybe the optimistic calorie counters are to blame for our obese population!

oooh hang on that says 1hr3mins not 1hr30 mins – ignore me.

I would calculate your maximum heart rate properly, by doing a stress test.

Mine is over 200, and I am roughly the same age as you, whereas this is obviously assuming it is 190ish. If that is wrong, then all your other calculations are wrong too.

I reckon on road, riding quite hard in a hilly area, I use about 600 calories/hour, just judging from the amount of extra food I need on commute days.

Joe

I'll burn between 900 to 1000 calories on a 1 hr 20 min fast ride (tech singletrack) the same result on both a Polar and Sigma HRM.

Can anyone recommend a good hrm? I take it Polar are the market leaders?

Sorry for the hijack.

Polar unless you want digital transmission in which case Sigma are OK.

my "back of the envelope" calculations are that flat out i can burn 700kcal per hour, and i've got around 1400kcal stored up, so if i go absolutely flat out as hard as i can with no breaks for 2 hours without eating i'll bonk.

Can anyone recommend a good hrm?

Polar.

Time to put that theory to the test Horatio!

Report back with pictures please, when you've wept your way home at 3mph.
😛 😈

and i've got around 1400kcal stored upand i've got around 1400kcal stored up

so how do you work that out?

According to my Polar I burnt 640 calories in a 45min spinning class, which is doing intervals and pretty high HR the whole time – that'd be 850 cal/hour.

1380 seems way too high.

Thanks for al your input! I think we've established that 1380 is way way out. There is no input for MaxHR, the device must estimate that from age, the only input that will correct the high reading is a calorie correction factor, the default is obviously 1, and by substituting it with 0.6, id be somewhere around 828 kcal's, which sounds nearer. But thats a huge correction to have to make. How much does your resting rate effect the callorie calc?

How can you possibly know how many calories you have 'stored up'?

For the geeks, one of the Polar patents is US 6605044 which explains how they work it out. It's a pretty simple equation which uses the heart rate and two constants, which are likely to be calculated from the weight and sex of the user. Hard to see how this can be really accurate.
Also, just because it's in the patent doesn't mean that's what they use.
You can get the patent here: http://www.pat2pdf.org

Polar gives much higher calories than Garmin for me. But when I convert .tcx files into Polar the training diary software re-works the calories out for me, so they're comparable. The key is to ignore the absolute numbers and use them to compare one session to another. They seem accurate enough in that context.

So in summary, don't use it to see how many pies you should have for tea.