# Is there a cap on how much I can burn?

## Replies

• Posts: 709 Member
INDOOR ride with 2x20' and 1x10' tempo if memory servers. January 23 test puts my FTP at 247 using the indoor trainer so the power meets the ride. And yes, I average 2mph faster outdoors with similar RPE. Also yes, VP is not the most accurate and likely will shift the actual FTP but it's a consistent deviation (KK acknowledges the fact in their equation). And I do maintain a consistent setup (tire pressure, dedicated bike, etc).

Percentage efficiency is inversely proportion to calories expended (higher the efficiency, less calories are needed, (KJ / % efficiency) * 4.184 = Calories). 20-25% is the general range with few exceptional measured in the 27% range. Most elite cyclist are in the 25% range. At 25%, it's a 13% drop in calories but I don't think I ever hit that level of efficiency even in my early twenties when I was racing collegiate Bs with a few forays in USCF Cat 4 some 26 years ago. 22% is just a comfortable margin without paying for the actual testing since I don't plan to race anymore (wasn't that good or had much luck in the first place). I don't always eat back all my exercise calories so the 107.6 difference is not that big of a deal and it already has a comfortable margin to other estimates.
• Posts: 9,532 Member
edited April 2015
kcjchang wrote: »
Based on weight of 170.2, the calculated calories for my March 3 indoor ride of 1:00:01 covering a distance of 18.7 miles are as follows:
* MFP - 926 (16-20 mph)
* MET - 973
* IpBike - 895 (derived from power output based on empirical relationship of speed to power for the Kurt Kinetic Road Machine @ 22% efficiency, 232 average watts).

Bikecalculator.com is giving ~630 calories, 184W output. This is assuming no grade changes. Your numbers are pretty much inline with what I get from Strava, and I know from careful logging that Strava's numbers are too high, at least for me.

I trust Bikecalculator.com more than I trust any other source, at this point.
• Posts: 1,404 Member
yeah walking and doing abs are not going to burn that many calories in 2.5 hrs. unless you are severely obese then maybe but I still dont think it would be that high. I can walk for 3-4 hrs when I go to the mall and dont even burn that many,even when I was 70 lbs overweight I still didnt burn that many. Also who can do abs for 40+ min? isnt that redundant?.

I agree. I'm thinking that there are much more efficient ways to exercise and have a nice calorie burn and still have time left over to have a life. And there's no way just walking and "abs" will generate that type of calorie burn.

I am a little jealous of all these people who can burn so many calories during their hour workouts or so, definetely don't get that type of burn when you're 5 ft 1 and 120. Figures, cause I have the appetite of a football player!
• Posts: 709 Member
Bikcalculator gives 19.4mph at 56.29min at 232 avg watts which is in line with the KK VP curve deviation verses outdoor speed. 746 is the estimate for calories expended (zero bike weight, clincher, bar top, & 77 deg F). You just make me feel much more comfortable with values I got from IpBike. Keep in mind I did not have 19.4mph blowing over my body to keep me cooled. It would be a lot more precise estimation if one can input efficiency.
• Posts: 1,895 Member
kcjchang wrote: »
This looks a lot like the numbers in MFP's database, at least for cycling (for example, 16-19MPH being 12 METs, which at my weight would be about 1000 kcal/hr and I can tell you that's way high.
Based on weight of 170.2, the calculated calories for my March 3 indoor ride of 1:00:01 covering a distance of 18.7 miles are as follows:
* MFP - 926 (16-20 mph)
* MET - 973
* IpBike - 895 (derived from power output based on empirical relationship of speed to power for the Kurt Kinetic Road Machine @ 22% efficiency, 232 average watts).

Disclaimer for 2011 Compendium categories in red are estimated MET values and 16-19mph is one of them. I'm pretty sure that had I been going at 19mph my calories based on power would be in line with MFP (and that's not that big of a deviation from MET calculations). I was getting much bigger discrepancies based on HR when I got back to cycling 10 months ago (on high side at lower speeds if memory serves). With lower speeds, MFP was also very generous.
Outdoors, 19mph wouldn't require anywhere near 232 watts, unless you were way heavier. I would take power numbers from a trainer "calibration curve" with a grain of salt, since things like tire type and pressure can have an impact. And using 22% efficiency is also likely to inflate kcal estimates unless you've had lab testing to determine that's accurate for you. A straight kj = kcal (25% efficiency) is more commonly used.

I am 145lbs and at 250 watts I am moving at about 23mph on my road bike, and about 25-26 on my tri bike. However on flat terrain it really depends on your CdA, more than your weight. On a flat road, your power is more about overcoming drag than your own body weight.