Working out calories used

[XTCRider]

They must all be wrong then. cos I have had 3 makes of HRM in the last couple of years (cos they keep packing in). Different info required on each one and all 3 have had my cals about 100kcal per mile off road on my MTB , lower on the road bike and about half that on my spinner bike

 

[barq]

I wish I knew the underlying formula used by some of these HRMs. I had a Cateye cycle computer that estimated the calories, but the figures it came up with were just mad. For example when going fast downhill it would add loads of calories, but going uphill slowly would hardly register. They seemed to have made the assumption that climbing and descending would cancel out, but I don't think it works like that because the relationship between calories and speed isn't linear.

I think to work it out properly you are going to need a powermeter which is going to be expensive. But if you want a decent estimate then the best formulae I've found are here:

http://austinimage.com/bp/velocity/velocity.html
http://www.kreuzotter.de/english/espeed.htm (I like this one)

 

[simon_adams_uk]

Using some quickly researched figures for the Tour de France*

Stage distance = 120miles
Stage time = 6 hours
Stage calories burnt = 6000 KCal

That means for a supremely fit athlete his calorie expenditure will be:
50 KCal per mile (6000/120)
1000 KCal per hour (6000/6)

At any one time I'd be happy to be putting out half the power (or energy) that a TdF rider would so that means 25KCal per mile or 500 KCal per hour.

Taking them at face value, readings of 1000KCal/hr from a HRM implies you should be racing professionally!

S

* Approximate numbers for a mountain stage - not meant to be the last word in accuracy...

 

[TVC]

General rule for an 'average' bloke is 50cal/mile +1cal for every metre of climbing, though this falls to pieces if you get to freewheel down the other side.

As others have said above, invest in a heart rate monitor, there are some decent ones in the £30-50 price band if you want something by a known name.

 

[8-wheeler]

On gym cycle machines I usually do about 600kcals/hr. Anything much higher and I start to die. It's not as intense most other machines like the treadmill or crosstrainer, I think mainly because there's relatively little upper body workout.

When I cycle on the road, I don't go as hard as in the gym.. I think 500kcals/hr is a reasonable estimation for moderate pace city cycling.

 

[jimboalee]

It also depends on your age , sex and weight

Does it ??

 

[jimboalee]

Calories burnt is dependent on HR as well. Cant just work it out from speed alone. Sex, Age, Weight, HR and Av Speed are all entered into my HRM which uses this to give me calories. I burn about 100Kcal per mile, but I am over 3 stone overweight, therefore I burn more calories than a skinny bloke.

Thats with an avg HR of around 140-150bpm, Avg Speed about 13-14mph on my MTB

Is it ???

 

[jimboalee]

Here are some names to Google.

Sir Isaac Newton
James Joule
James Watt
Daniel Bernoulli
Paul Siple

 

[Shaun]

I've always use this simple formula:

1 hour of cycling = 1 mars bar's worth of calories.

There's no science behind it of course, but it feels right to me.

Cheers,
Shaun

 

[Chrisc]

I've always use this simple formula:

1 hour of cycling = 1 mars bar's worth of calories.

There's no science behind it of course, but it feels right to me.

Cheers,
Shaun

My take is similar, 1 hour = a pint of best B)

 

[redddraggon]

You need a powermeter.

1 Watt = 1 joule per second

Therefore if you average 200W for an hour:

200 x 3600 = 720,000 joules or 720 KJ

720 KJ = 172KCal

EDIT: It seems rather low

 

[redddraggon]

^^ obviously that doesn't include base metabolic rate

OK, my calculation doesn't include efficiency either, which is probably the discrepancy.

 

[willhub]

Calories burnt is dependent on HR as well. Cant just work it out from speed alone. Sex, Age, Weight, HR and Av Speed are all entered into my HRM which uses this to give me calories. I burn about 100Kcal per mile, but I am over 3 stone overweight, therefore I burn more calories than a skinny bloke.

Thats with an avg HR of around 140-150bpm, Avg Speed about 13-14mph on my MTB

You ain't burning 1000 calories every 10 miles

 

[MacB]

If you're only trying to get an idea of what you can eat to lose weight then the 50 calories a mile is a reasonable estimate. Speed is unimportant it's how hard you're working, obviously your speed and stamina will alter as you get fitter/lighter.

When I was commuting 40 miles a day I reckon I burned about 1800-2000 calories extra a day, certainly this was borne out by my intake versus my weight loss. This was true at the start when I struggled to break 10mph average and at the end when I was at 16mph average. My rough guess is I was running at about 75% of power. Anything less than 75% and I believe the calories burned would drop dramatically. When I've done the longer social rides, at low speeds, I've not felt any need to eat anything extra at all.

The only thing I would add is that it should be distances of 10 miles upwards for weight loss assistance. I don't bother counting any rides shorter than this now. I can't imagine anyone doing training/exercise rides of sub 10 miles anyway. But I do feel I get better weight loss from a 40-50 mile at 75% than from a 20 miles at 90%.

 

[psmiffy]

Calorie consumption is highly individal and varies form person to person - however

The figures quote above seem rather high but I am comparing them to what I worked out for myself - a rather portly middle aged geezer - using a variety of web based calorie calculators I worked out a daily calorie consumption rate based on their concensus and then used the HR monitor to come up with the additional calories for excercise specific consumption.

Seems to work I put on a bit of weight during the bad weather over christmas - using my calculated figures and a bit of an activity log and assessing what I was eating my weight has stabilised and is going the right way now

Gym machines definetly overestimate calories consumption by up to 40 -50% - most machines I use show me working at 10Mets when I am doing a fairly moderate session - easy breathing -no particular fatigue - lowish heart rate - Met = normal base rate - so something like 15Kcal/minute (I rate my calorie consumption for that sort of session at 7kcal/min) - 900kcal/hour - good encouragement for the ignorant - but counterproductive if you have the extra cake because you have earned it