Calories burned spinning - HR vs power - YMMV
jjpptt2
Posts: 5,650 Member
I routinely see people insisting that HR is a terrible metric for gauging calories burned cycling/spinning, and that power is a far better measure. Conceptually it makes sense as there are (or so it seems) far fewer variables that can/will affect power than can/will affect HR. But in reality, that doesn't mean that HR is necessarily evil and power is necessarily gold, as some might have you believe.
Most of my miles and hours are on a real bike outside, where I don't have access to power data. But today I ended up on a spin bike at work (I work at a gym) that measures power. Just for *kitten* and giggles, I checked cals burned at the end of the ride...
lolololollllolololollololololol...
The data from the bike:
time: 54 minutes
average RPM: 88
average watts: 215
cals burned: (are you sitting down?) 833
The data from my garmin (wrist HR):
time: 53 minutes
cals burned: 431
MFP's estimates along with garmin's HR calculations have always been accurate enough to be useful for me, based on my logging, tracking, etc. So this isn't a "help, how to I measure cals burned" post. It's more of an "as with everything we discuss here, your mileage may vary" post. Sanity checking your numbers is never a bad thing.
Most of my miles and hours are on a real bike outside, where I don't have access to power data. But today I ended up on a spin bike at work (I work at a gym) that measures power. Just for *kitten* and giggles, I checked cals burned at the end of the ride...
lolololollllolololollololololol...
The data from the bike:
time: 54 minutes
average RPM: 88
average watts: 215
cals burned: (are you sitting down?) 833
The data from my garmin (wrist HR):
time: 53 minutes
cals burned: 431
MFP's estimates along with garmin's HR calculations have always been accurate enough to be useful for me, based on my logging, tracking, etc. So this isn't a "help, how to I measure cals burned" post. It's more of an "as with everything we discuss here, your mileage may vary" post. Sanity checking your numbers is never a bad thing.
1
Replies
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For about the same amount of time, you get twice as many calories from one method is another. That's pretty substantial in my book.1
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A lot of spin bikes are taking pretty silly shortcuts in their wattage, so it'd depend on how reliable the bike's power really is.3
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Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
3 -
My experience is that unless you know exactly how the “watts” were measured, you can’t really do a comparison. Whether it’s because of less wind resistance or what, my experience is that spin bike wattage numbers are significantly inflated.1
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fuzzylop72 wrote: »A lot of spin bikes are taking pretty silly shortcuts in their wattage, so it'd depend on how reliable the bike's power really is.
Yeah, based on the number, I half wonder if it's calculating watts based on rpms and resistance rather than actually measuring power.0 -
Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
Why don't you think the HR number is reasonable?0 -
My experience was pretty much the opposite. When I installed a power meter on my bike it cut the calorie estimate almost in half (using the same Garmin 920XT HRM etc)1
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Unless the spin bike power calibration is way off it's not inconceivable to be burning 700-800 calories in an hour. It may be a bit high but 431 sounds way low. For a 180 pound person, an hour brisk walk can burn close to 400 and the spin bike is way more intense than that.0
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Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
Why don't you think the HR number is reasonable?
The 215 avg watt number is reasonable - a hard workout but possible.
So the formula for watts to calories is 697.
So the bike was a tad high - the HRM though was rather low.
While the Garmin used FirstBeat does have a potential for better accuracy according to their study - it still relies on an estimate of VO2max - and that is based on older models user selecting some numbers regarding workout time/frequency weekly - or the device supplying that info and adjusting based on past history.
Plus the Lifetime athlete setting has a bearing if still used.1 -
Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
Why don't you think the HR number is reasonable?
The 215 avg watt number is reasonable - a hard workout but possible.
So the formula for watts to calories is 697.
So the bike was a tad high - the HRM though was rather low.
While the Garmin used FirstBeat does have a potential for better accuracy according to their study - it still relies on an estimate of VO2max - and that is based on older models user selecting some numbers regarding workout time/frequency weekly - or the device supplying that info and adjusting based on past history.
Plus the Lifetime athlete setting has a bearing if still used.
Gotcha, thanks
Considering I was at an RPE of about 6 for most of the ride, I'm not sure I believe the average power number, either.
ETA -
Just looked up the bike online...
I couldn't find any real detailed specs on it, but it does claim "direct power measurement" which sounds pretty nice. Maybe I'm a stronger rider than I thought... ?0 -
HR can be a good way to estimate calories but it can also be a really bad way due to individual differences in exercise HR and outside influences or inappropriate exercise modality.
I was doing a group Wattbike session and three of us were all producing the same power so pretty much identical calorie burn rate. The chap on my left was at 180bpm, I was at 150bpm and the guy on my right was at 120bpm.
We were all fit cyclists - start adding in people from the general population and the variation will be even bigger.
Your watts to calories conversion isn't right, even if the watts measured are accurate (should be close enough) you need to know what the bike is doing with the power data. My Wattbike uses a ridiculous algorithm which gives badly inflated numbers (vanity calories!), Garmin uses the standard formula for net cals, some spin bikes I've used clearly try to estimate gross calories as the over-read is time related and not intensity related.
If your spin bike asks for your gender, age and weight I would suspect it's estimating gross calories (gender and age are irrelevant for converting watts to calories).
I tweaked my HRM settings and got it to match a power meter really well, at least for steady state rides, intervals are another story though, seen a difference of 100 cals for 30 minute sessions both with same average power.
HR can also be badly affected by heat, stimulants, stress etc....
I hit my highest ever outdoor cycling HR last month. Not on a heroic climb at maximum output but on flat ground at moderate pace - heat exhaustion and dehydration.
Would add the caveat the accuracy is nice but reasonable estimates are good enough2 -
Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
Why don't you think the HR number is reasonable?
The 215 avg watt number is reasonable - a hard workout but possible.
So the formula for watts to calories is 697.
So the bike was a tad high - the HRM though was rather low.
While the Garmin used FirstBeat does have a potential for better accuracy according to their study - it still relies on an estimate of VO2max - and that is based on older models user selecting some numbers regarding workout time/frequency weekly - or the device supplying that info and adjusting based on past history.
Plus the Lifetime athlete setting has a bearing if still used.
Gotcha, thanks
Considering I was at an RPE of about 6 for most of the ride, I'm not sure I believe the average power number, either.
ETA -
Just looked up the bike online...
I couldn't find any real detailed specs on it, but it does claim "direct power measurement" which sounds pretty nice. Maybe I'm a stronger rider than I thought... ?
Was that 215 avg the result of Spin class type workout, interval in nature?
Or just sat there and pounded out a steady workout?
I personally would find the former easier to hit a high avg, because I recover fast. The steady-state feels much harder to me.
So could be. Or could be a bad reading.
Can you tell how it does the resistance - a felt pad on wheel - not likely used as part of wattage measurement then.0 -
Those calories from watts doesn't sound right. Of course, neither does by HR. Mine have been within 100 cal last few rides as long as I didn't do any lifting first to get inflated HR.
I'll let you have fun with it.
http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/
energy (kcal) = avg power (W) X duration (hours) X 3.6
Why don't you think the HR number is reasonable?
The 215 avg watt number is reasonable - a hard workout but possible.
So the formula for watts to calories is 697.
So the bike was a tad high - the HRM though was rather low.
While the Garmin used FirstBeat does have a potential for better accuracy according to their study - it still relies on an estimate of VO2max - and that is based on older models user selecting some numbers regarding workout time/frequency weekly - or the device supplying that info and adjusting based on past history.
Plus the Lifetime athlete setting has a bearing if still used.
Gotcha, thanks
Considering I was at an RPE of about 6 for most of the ride, I'm not sure I believe the average power number, either.
ETA -
Just looked up the bike online...
I couldn't find any real detailed specs on it, but it does claim "direct power measurement" which sounds pretty nice. Maybe I'm a stronger rider than I thought... ?
Was that 215 avg the result of Spin class type workout, interval in nature?
Or just sat there and pounded out a steady workout?
I personally would find the former easier to hit a high avg, because I recover fast. The steady-state feels much harder to me.
So could be. Or could be a bad reading.
Can you tell how it does the resistance - a felt pad on wheel - not likely used as part of wattage measurement then.
lol... It was a "I just got back from vacation and need to burn off some toxins" workout. I just spun at a "comfortable difficulty" while I watched TV on my phone. No intervals, and it wasn't even a particularly taxing spin.0 -
HR can be a good way to estimate calories but it can also be a really bad way due to individual differences in exercise HR and outside influences or inappropriate exercise modality.
I was doing a group Wattbike session and three of us were all producing the same power so pretty much identical calorie burn rate. The chap on my left was at 180bpm, I was at 150bpm and the guy on my right was at 120bpm.
We were all fit cyclists - start adding in people from the general population and the variation will be even bigger.
Your watts to calories conversion isn't right, even if the watts measured are accurate (should be close enough) you need to know what the bike is doing with the power data. My Wattbike uses a ridiculous algorithm which gives badly inflated numbers (vanity calories!), Garmin uses the standard formula for net cals, some spin bikes I've used clearly try to estimate gross calories as the over-read is time related and not intensity related.
If your spin bike asks for your gender, age and weight I would suspect it's estimating gross calories (gender and age are irrelevant for converting watts to calories).
I tweaked my HRM settings and got it to match a power meter really well, at least for steady state rides, intervals are another story though, seen a difference of 100 cals for 30 minute sessions both with same average power.
HR can also be badly affected by heat, stimulants, stress etc....
I hit my highest ever outdoor cycling HR last month. Not on a heroic climb at maximum output but on flat ground at moderate pace - heat exhaustion and dehydration.
Would add the caveat the accuracy is nice but reasonable estimates are good enough
Completely agree. I quit caring about absolute accuracy a long time ago. Heck, even reasonable is a stretch for me at times because I just don't care all that much about exercise cals. Sometimes it makes for interesting conversation/thought though.1 -
HR can be a good way to estimate calories but it can also be a really bad way due to individual differences in exercise HR and outside influences or inappropriate exercise modality.
I was doing a group Wattbike session and three of us were all producing the same power so pretty much identical calorie burn rate. The chap on my left was at 180bpm, I was at 150bpm and the guy on my right was at 120bpm.
We were all fit cyclists - start adding in people from the general population and the variation will be even bigger.
Your watts to calories conversion isn't right, even if the watts measured are accurate (should be close enough) you need to know what the bike is doing with the power data. My Wattbike uses a ridiculous algorithm which gives badly inflated numbers (vanity calories!), Garmin uses the standard formula for net cals, some spin bikes I've used clearly try to estimate gross calories as the over-read is time related and not intensity related.
If your spin bike asks for your gender, age and weight I would suspect it's estimating gross calories (gender and age are irrelevant for converting watts to calories).
I tweaked my HRM settings and got it to match a power meter really well, at least for steady state rides, intervals are another story though, seen a difference of 100 cals for 30 minute sessions both with same average power.
HR can also be badly affected by heat, stimulants, stress etc....
I hit my highest ever outdoor cycling HR last month. Not on a heroic climb at maximum output but on flat ground at moderate pace - heat exhaustion and dehydration.
Would add the caveat the accuracy is nice but reasonable estimates are good enough
Completely agree. I quit caring about absolute accuracy a long time ago. Heck, even reasonable is a stretch for me at times because I just don't care all that much about exercise cals. Sometimes it makes for interesting conversation/thought though.
A lot of what I've investigated or discovered was just out of curiosity. I simply like to understand tools and training.
In the "real world" I don't even log my food and for the vast majority of my cycling I just use Strava estimates - but I have verified for me at least they are reasonable. Indoors with a power meter I use my Garmin numbers.
I did a long but moderate pace four hour ride today and my guestimate based on experimenting/messing about with power meters and HRMs for that speed/intensity is 500cals/hour.
Strava estimated 2050.0 -
215w & RPE of 6 for about an hour puts your FTP around 310w. If you weight around 79 kg, 3.9w/kg, that puts you at top of amateur ranks. Pretty good.1
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