Stationary bike watts to calories burned

emmylootwo

I read that the formula to use is average watts * hours performed * 3.6. Is this fairly accurate?

So, for a 30 minute session with average watts of 40, that would mean I burned 72 calories. It sounds a bit low to me, but I realize that it is a non-weight bearing activity... on the treadmill the fact that I weigh 350 lbs is way more significant. (unfortunately couldn't do the treadmill today because of blisters)

What do you guys think? MFP suggests I burned 236 calories for very light effort.

Edit: Also sorry might have used wrong forum this time

Safari_Gal

Do you have a resistance knob on your bike? That makes a difference. I do spin 3-4 times a week - it does seem a bit low to me - but it depends on the effort or resistance. It can be very weight bearing if you have the knob turned up Maybe take a peek at what numbers you get if you plug in spin class light effort on MFP to compare.

erjones11

Mine measures watts and calories burned based on watts, weight age and time. I still don’t believe it.

sijomial

Yes it's a very accurate way of estimating and it's also net calories not gross. There are some slight variables but not that significant. It's far superior to HR or other methods of estimating.
It's a mathematical formula for converting power to energy but includes an estimated efficiency ratio. But that part isn't really a huge variable as cycling efficiency doesn't vary much between people (far smaller variable than exercise heart rate for example).
If you want to read more - http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/

@mg07030 - perceived effort or how it feels aren't a good guide to energy expenditure at all. 150w feels easy to me (all day pace), 250w feels easy to a really good cyclist etc. etc
@erjones11 - your weight is only relevant when standing cycling and your age is a total irrelevance.


BTW the reason that you are getting such a low burn is that you appear to creating a tiny, tiny amount of power - sorry!
Have you got an appropriate amount of resistance dialled in? You shouldn't just be twirling your legs.
Aim for a cadence between 80-100rpm but with pressure on your pedals.

erjones11

@sijomial my age sure feels relevant to me.

By the way my wattage meter is usually well above 100, at A resistance of 13 on my bike I am at bout 120 watts. That said my Apple iWatch also logs calories for the same session is usually at about 1/3 rds of what the bike's computer says. I assume the watch is based on heart rate. Which do you think is more accurate?

As for logging I put in the minutes in to MFP for stationary bike low effort at whatever time, then a manually reduce the calories by dividing them by two and plug that number for calories burned. I end up at about 160 cals for 45 minutes in my MFP log.

So for 45 minutes I get about 500 calories on bike, 180 on iWatch and log 160 cals burned in to MFP.

Guessing none of this is accurate but what's a guy to do?

Safari_Gal

sijomial wrote: »

Yes it's a very accurate way of estimating and it's also net calories not gross. There are some slight variables but not that significant. It's far superior to HR or other methods of estimating.
It's a mathematical formula for converting power to energy but includes an estimated efficiency ratio. But that part isn't really a huge variable as cycling efficiency doesn't vary much between people (far smaller variable than exercise heart rate for example).
If you want to read more - http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/

@mg07030 - perceived effort or how it feels aren't a good guide to energy expenditure at all. 150w feels easy to me (all day pace), 250w feels easy to a really good cyclist etc. etc
@erjones11 - your weight is only relevant when standing cycling and your age is a total irrelevance.


BTW the reason that you are getting such a low burn is that you appear to creating a tiny, tiny amount of power - sorry!
Have you got an appropriate amount of resistance dialled in? You shouldn't just be twirling your legs.
Aim for a cadence between 80-100rpm but with pressure on your pedals.

@sijomial Hi! Hmm- I reread what I wrote- i didn’t mean it to come off as perceived effort being a guide- i was talking about spinning being a weight bearing exercise and resistance goes up as you crank that dial.

sijomial

erjones11 wrote: »

@sijomial my age sure feels relevant to me.

By the way my wattage meter is usually well above 100, at A resistance of 13 on my bike I am at bout 120 watts. That said my Apple iWatch also logs calories for the same session is usually at about 1/3 rds of what the bike's computer says. I assume the watch is based on heart rate. Which do you think is more accurate?

As for logging I put in the minutes in to MFP for stationary bike low effort at whatever time, then a manually reduce the calories by dividing them by two and plug that number for calories burned. I end up at about 160 cals for 45 minutes in my MFP log.

So for 45 minutes I get about 500 calories on bike, 180 on iWatch and log 160 cals burned in to MFP.

Guessing none of this is accurate but what's a guy to do?

@erjones11

For calorie calculations from power age is completely irrelevant. Age has a factor in being able to produce the power you could say - but that's immensely varied.

If you have a power reading it is sensible to use it. It's the most accurate reading you will get outside of a sports science lab.

HR is extremely varied across individuals - I've seen 50% difference between two experienced and fit cyclists producing the same power / burning the same calories. For steady state work HR can give consistent estimates for an individual (but consistently accurate or consistently inaccurate), for intervals it's pretty useless.

Effort is completely subjective and hopeless for calories. I've just done an exhausting hour of intervals at 130 and 250watts but the average burn rate is dragged down by my 130w recovery (Zone 2) periods. I could burn far more calories in the same time doing an easy feeling steady state workout. The most I can sustain for an hour is 213watts and that's maximal effort for me but for someone like Chris Froome he's cruising easily with minimal effort. But both of us at 213w would be burning at the same net calorie rate (but he could do it all day long!).

sijomial

mg07030 wrote: »

sijomial wrote: »

Yes it's a very accurate way of estimating and it's also net calories not gross. There are some slight variables but not that significant. It's far superior to HR or other methods of estimating.
It's a mathematical formula for converting power to energy but includes an estimated efficiency ratio. But that part isn't really a huge variable as cycling efficiency doesn't vary much between people (far smaller variable than exercise heart rate for example).
If you want to read more - http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/

@mg07030 - perceived effort or how it feels aren't a good guide to energy expenditure at all. 150w feels easy to me (all day pace), 250w feels easy to a really good cyclist etc. etc
@erjones11 - your weight is only relevant when standing cycling and your age is a total irrelevance.


BTW the reason that you are getting such a low burn is that you appear to creating a tiny, tiny amount of power - sorry!
Have you got an appropriate amount of resistance dialled in? You shouldn't just be twirling your legs.
Aim for a cadence between 80-100rpm but with pressure on your pedals.

@sijomial Hi! Hmm- I reread what I wrote- i didn’t mean it to come off as perceived effort being a guide- i was talking about spinning being a weight bearing exercise and resistance goes up as you crank that dial.

@mg07030
Spinning is only weight bearing exercise for the standing cycling portions of the workout. While you are seated it's not weight bearing whatever resistance level you use.
Standing does spoil the power to calorie sums though as standing cycling is far less efficient a movement. Power to calories would then be an underestimate.

emmylootwo

@sijomial Thank you!

Also, damn why was my power so low? You're right, I must not have had much resistance on the pedals because I was peddling at a pretty good pace the entire time! (I think 90 rpm) Will try upping the resistance today and see what I can do.

aokoye

erjones11 wrote: »

@sijomial my age sure feels relevant to me.

By the way my wattage meter is usually well above 100, at A resistance of 13 on my bike I am at bout 120 watts. That said my Apple iWatch also logs calories for the same session is usually at about 1/3 rds of what the bike's computer says. I assume the watch is based on heart rate. Which do you think is more accurate?

As for logging I put in the minutes in to MFP for stationary bike low effort at whatever time, then a manually reduce the calories by dividing them by two and plug that number for calories burned. I end up at about 160 cals for 45 minutes in my MFP log.

So for 45 minutes I get about 500 calories on bike, 180 on iWatch and log 160 cals burned in to MFP.

Guessing none of this is accurate but what's a guy to do?

Your age might feel relevant, but it (as well as your weight) really isn't with regards to calculating calories burned on a bike. As long as the power meter on your exercise bike is calibrated (there should be instructions in the manual - or I'd hope that would be the case), that's going to be the most accurate method of figuring out how many calories you burned.

sijomial

emmylootwo wrote: »

Thank you!

Also, damn why was my power so low? You're right, I must not have had much resistance on the pedals because I was peddling at a pretty good pace the entire time! (I think 90 rpm) Will try upping the resistance today and see what I can do.

Nice cadence, much better than mine when I started.

That's the benefit and also the frustration with training under the unblinking and unfeeling eye of a power meter.
"I smashed it today!" - and then the power meter says oh no you didn't.

Keep it up and you will improve quickly as you build your base fitness.

collectingblues

emmylootwo wrote: »

@sijomial Thank you!

Also, damn why was my power so low? You're right, I must not have had much resistance on the pedals because I was peddling at a pretty good pace the entire time! (I think 90 rpm) Will try upping the resistance today and see what I can do.

The resistance will help. I was so surprised when I *thought* I was doing really well in spin class, and was keeping cadence, but then my stats weren't as good as everyone else's. And then during another class, the instructor made a comment about how upping the resistance adds power, and I was all "OH. THAT EXPLAINS EVERYTHING."

emmylootwo

FOUND THE PROBLEM! Haha oh whew. More than doubled my wattage by increasing the resistance! Thanks so much guys!

lorrpb

Interesting thread, especially since I plan to do my first spin class this week!