Im sure this question will have been asked on here before, but does anyone know how many calories per hour i might burn on a sort of medium intensity ride ?
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300 easily?
Hard to say without knowing your height, weight, speed and distance travelled.
Google!
Around 400 to 500 for the middle ground (my feeling is HRM's over-estimate, for marketing reasons). All sorts of complications and BS around on the subject though.
According to mates gps/phone/...
14 miles, 1.5 hours, 720ft gain (basically 7 miles up gradual hill, then down) (surface was dry, hard pack) 480.... makes me feel guilty about beer afterwards
for 100kg rider+bike, one vertical metre of climb is approx one calorie
* if it makes a difference bloke with gps was mid 30ish, ex semi pro footballe, runs 5k about 5 times a week........
(maybe an older, heavier me burned more .....)
14 miles for 480 cals squares nicely with the broad average of 35 calories per mile.
Working out the basic physics from height gain gives shocking low figures, even taking into account the c. 25% efficiency of the human body (which is still way better than a combustion engine).
No idea how efficency varies with fitness though, e.g. if a bunch of us on a club ride all cover the same distance in the same time (and leaving weight differences out of it), do the fitter people burn fewer calories ?.
Working out the basic physics from height gain gives shocking low figures, even taking into account the c. 25% efficiency of the human body
that's where my figure comes from
Wish I was wearing my hrt kit.
Did 72 miles at 80% effort and loads of hills and sprints.
Dunno about Kcal but I couldn't walk the next day lol.
Strap yourself in, this gets technical.
Stuff like hills, weight, fitness all get in the way of this so we need a measure which ignore these and that is power. Whether you are riding flat, hilly, mud or tarmac you probably output the same amount of power. You just go further on a flat road. So, for the sake of argument lets say you can hold 250watts for one hour (well done you!).
That's 250watts (or joules per second) for an hour which comes to 900KJoules. A calorie is just an old imperial measure of energy and it happens to be 4.184Joules so our 900K becomes 215,105cals. In food we really mean a kCal when we talk calories so for our hour we've got about 215kCals of work done.
BUT, the body isn't 100% efficient in converting food calories to produced energy and as far as I know it's about 25% efficiency. So at 250watts you're burning about 860kCals of nosh. More if you ride harder, less if you ride easy.
that's OK, except one has no idea what 250W feels like to do. Using my 1kCal/m figure, that means climbing 860m in an hour, which is hard going.
Looking at the GPS tracks for some recent big climbs looks like I can manage about 400 metres an hour...
To add to the numbers, it's reckoned a fit person can push out 200W until the need for sleep intervenes. At the high end, a TdF rider on a big climb (Marco Pantani) works out as something like 379W for 45 minutes-ish ([url= http://mitpress.mit.edu/catalog/item/default.asp?tid=10063&ttype=2 ]'Bicycling Science, 3rd ed'[/url]).
In calorie terms, the most the body can take in per hour is around 300; anyone who's done a long enough ride knows it's just not possible to eat enough to replace the calories burnt if you cycle at anything other than an easy pace (result=weight loss if you do it for days in a row) - it's a case of eating as much as your body can tolerate, and filling in the rest from reserves.
Sample scary number: Rob Dean - who I'd say knows enough to report a pretty accurate figure - reckons he burnt 13,000 calories in 20 hours yesterday (about 650/hour). Getting close to the physical limits of the human body.
makes me feel guilty about beer afterwards
...afterwards? forget calories and work on navigation!
my polar HRM typically gives me 600 cal/hr when working hard - live on edge of peak and 40minutes uphill is not unusual this compares pretty much to what Concept 2 rower at gym tells me for similar intensity
[waveswilly]7.5/mph average on hardpack is nearer to a recovery/slow fat burning workout pace for me, and i'm hitting 50 this year, not 30 and fit[puts smallorganaway]