894 calories in an 18 mile ride - could that be correct?

Mad Monkey

Went for a ride on Sunday with my new Garmin Edge 305 - nice piece of kit, though I hope the battery life is extended by the fact that the backlight doesn't work - and did one of my usual training circuits: just under 18 miles, undulating roads though nothing too hilly, didn't hang about (for me, that is - I'm an old duffer who gets excited if I can average over 15mph), and the 305 says that I used 894 calories.

I don't know how calories used are worked out, but that seems a lot for only 18 miles.

Any thoughts?

milton50

So we're talking about 1:15 hrs of riding averaging 15mph?

Well there are so many factors involved in determining calories lost and I don't know what you have to input into a Garmin Edge but I would expect someone to burn around the 700 calories mark for the ride you described. So with all the variables possible it may not be that inaccurate.

Unless I'm completely wrong..........

andrewjoseph

I burn about 1000 calories an hour on the mtb, a bit less on the road bike.

I'm 47, not as fit as I want to be, nearly 80kg with a max hr of 190b/m riding around the welsh valleys.

Did you have a max heart rate figure to input for the unit or did you let the unit work out you hr based on age? As far as i know the 220 minus your age figure is not that accurate.

chuckcork

Time for comparative statistics. Start point, I'm 37 and weigh about 81kg.

Last Sun I did a ride of 160km/100 miles in 6 hours and according to my computer went through 4800 calories, which equates to 800 calories/hour or 48 calories/mile. That was including some (for me) long climbs, 2 of which were Cat 1. An 18 mile ride at that pace would therefore be 864 calories.

A week before on a 127km/78.9mile 4hr.33min ride I went through 3500 calories, which works out at 758 calories/hour or 44.4 calories/mile, so 18 miles = 798 calories. Thats at an average speed of 28 kph/17.4mph.

A less energetic rides like my trip home yesterday was more laid back, 496 calories in 22.6km/14 miles in 45.15 minutes, a burn rate of 660 calories/hour or 35.4 calories/mile, your 18 miles would therefore be a efficent 637 calories.

In the end though what you burn will be affected by your weight, your age, your level of fitness, the terrain you ride over, whether you had a headwind and so on. The more riding you do though the more efficient your body will get and the lower the figure will be.

fuzzynavel

I've been using the bikes at my gym recently to improve my power output.
I have been doing 1 hour rides....distance isn't important. It is set to a pre-programmed undulating course and set on the hardest effort level.
I am pushing an average of 304 watts over the hour but the machine says that I am using 1100-1200 calories for that ride. I am only pushing between 40 - 60 rpm and keeping my heart rate under 170 (approx 90%) of max for my age
The one thing that the Garmin can't take into account is the gearing on the bike....you could be pedalling like a demon on a loose granny gear or you could be doing 40-50 rpm on decent sized cog. Energy usage will be very different in both cases.
The garmin also won't take your weight or fitness level into account so it is a very loose approximation.

Kléber

Only an SRM type ergometer accuratlely measures watts and kilojoules/calories and that has a +/- 2% margin of error, so a sat nav and heart rate tool is going to be way off.

The measurements on heart rate monitors are indicative but not accurate at all, if it says 894, that's probably anything from 600 to 1000 calories by my estimate. Besides, is it calibrated to measure the 894 of effort in pedalling, or does it factor for the calories used for your normal metabolism?

Mad Monkey

Thanks All

I'm a complete newbie to thinking about cycling in fitness terms - obviously I know that cycling is good for you, but since I started cycling 3½ years ago I have just enjoyed cycling for the enjoyment of cycling, and in my own terms I cycle in a pretty determined way, though probably wimpish by comparison with many of you.

All you input into the 305 is age (53) and weight (67kg) so it certainly isn't going to be in any way personalised to my physiology.

However, the purchase of a new bike (Sunday September titanium bike with Ultegra SL kit and handbuilt wheels etc in place of a Halfords Carrera Vanquish) made me think in terms of a more structured approach to cycling, so I get "fit" in a more organised way, rather than "cycling must make me fitter", as I have done sofar, so I have been looking at various articles on heart rate zones etc.

The 305 estimated my MHR at 185, which is about 13 higher than many age calculators come up with, so I will certainly aim to do a stress test to measure my own MHR more accurately.

I have never visited the Training forum before tonight, and reading some of the other threads has been really interesting - think I'm going to get hooked on training properly!

judokev

Hi there Mad Monkey,

A good idea if you get some time is google heart rate or calories there will be loads of information to look at with some cycling specific info as well as others.

good luck
judo kev

fuzzynavel

Mad Monkey wrote:

Thanks All


I have never visited the Training forum before tonight, and reading some of the other threads has been really interesting - think I'm going to get hooked on training properly!

I have become hooked too over the last 8 weeks. and have lost a stone in weight by just upping the exercise frequency and intensity....was 17stone and 5`11" now approx 16 stone....looking to lose at least another 3 stone to improve my hill climbs!

Someone on the beginners forum pointed me towards the following cycling training site..There is so much information to take in and it is all useful.

http://www.cptips.com/toc.htm#table

hope this helps.

nmcgann

I only have a comparison between my Polar S720i and a real measure via a Powertap. If anything the Polar very slightly under-reads which I found quite surprising.

I output between 500kcal/h (slow-ish club rides) and 900kcal/h (25 mile TT) measured on my Powertap. (the ptap actually reads kjoules, but the typical energy conversion efficiency in the human body means there is an approximate kj=kcal equivalence)

A fairly intense hour on the turbo (2x20 or similar) is about 800kcal.

Neil

The good doctor

Mad Monkey,

I posted a reply in know how was it ? Anyway I have used this site which says given your 67kg weight you would have burned 744 calories riding the 18 miles. Don't know what others may think but seems more accurate if you're interested.

http://www.coolrunning.com/engine/4/4_1/94.shtml

John

Mad Monkey

Thanks all - loads of info around and I have melted my printer last night printing out stuff to read and compare - not all say the same thing, which is why I printed it out.

It has been a real transformation in my attitude to cycling - important never to lose cycling just for the joy of being out on the bike, but I feel "renewed" just by planning to structure my cycling with a purpose. The pointers I've got from this post really help too.

Much appreciated.

DaveyL

nmcgann wrote:

I only have a comparison between my Polar S720i and a real measure via a Powertap. If anything the Polar very slightly under-reads which I found quite surprising.

I output between 500kcal/h (slow-ish club rides) and 900kcal/h (25 mile TT) measured on my Powertap. (the ptap actually reads kjoules, but the typical energy conversion efficiency in the human body means there is an approximate kj=kcal equivalence)

A fairly intense hour on the turbo (2x20 or similar) is about 800kcal.

Neil

Isn't that a bit of an assumpton? Is there any info out there on how good that assumption is? Surely it can't be 25% for all people all of the time?

freshtrax

I have a Garmin 305 and a polar HRM, the garmin will consistantly estimates calorie consumption at about 35% to 40% higher than the the polar. If the Garmin was correct I couldn't possibly still weigh 85 kilos. The polar estimates between 600-800 calories per hour, with a maximum 1000 in a really full on spiinning class. The garmin estimates between 1100 and 1200 per hour up to 800 just for a 26 minute 10 mile TT. Talking to various people it appears the polar is much closer to reality.

nmcgann

DaveyL wrote:

nmcgann wrote:

I only have a comparison between my Polar S720i and a real measure via a Powertap. If anything the Polar very slightly under-reads which I found quite surprising.

I output between 500kcal/h (slow-ish club rides) and 900kcal/h (25 mile TT) measured on my Powertap. (the ptap actually reads kjoules, but the typical energy conversion efficiency in the human body means there is an approximate kj=kcal equivalence)

A fairly intense hour on the turbo (2x20 or similar) is about 800kcal.

Neil

Isn't that a bit of an assumpton? Is there any info out there on how good that assumption is? Surely it can't be 25% for all people all of the time?

That's why I said approximate. It supposedly varies between 20-25% for "most trained cyclists" according to Coggan&Hunter, but the 1:1 relationship is still reckoned to be a workable assumption.

I presume there are some exercise phsysiology experts out there that could provide more data?

Neil

DaveyL

If it varies between 20-25% I'd say that a powermeter is probably just as vague as a Polar HRM when working out calories burnt then....

[Puts big stirring spoon back in the drawer...]

Seriously though. Say your powermeter says you have done 2000 kJ of work. That equates to 478 kcal. At 20% efficiency, it means you actually burned 2390 kcal. At 25% efficiency you burned 1912 kcal. Am I right?

Alex_Simmons/RST

DaveyL wrote:

If it varies between 20-25% I'd say that a powermeter is probably just as vague as a Polar HRM when working out calories burnt then....

[Puts big stirring spoon back in the drawer...]

Seriously though. Say your powermeter says you have done 2000 kJ of work. That equates to 478 kcal. At 20% efficiency, it means you actually burned 2390 kcal. At 25% efficiency you burned 1912 kcal. Am I right?

Yes but an individual's efficiency doesn't vary much (it is more correlated with a rider's muscle fibre type distribution). So for any individual, a PM will still give you very clear indication of energy requirements from one ride to another. The same can't be said of calculations relying on HR or speed.

The only way to really know total calorie usage is by gas exchange measurement in a lab.

DaveyL

So I guess the only way to measure efficiency woud be to get hooked up to a gas analyser while rding a stationary bike with a calibrated power measurement system?

Alex, how much info is out there about efficiency? Does it vary at all, e.g. with level of fatigue/how rested one is, or even the intensity you are rding at? This seems like quite an interesting topic.

Alex_Simmons/RST

DaveyL wrote:

So I guess the only way to measure efficiency woud be to get hooked up to a gas analyser while rding a stationary bike with a calibrated power measurement system?

Basically, yes.

DaveyL wrote:

Alex, how much info is out there about efficiency? Does it vary at all, e.g. with level of fatigue/how rested one is, or even the intensity you are rding at? This seems like quite an interesting topic.

I'm probably not the best person to ask (I'm not an exercise physiologist) but studies of efficiency while cycling have been around for at least 50 years. Cycling has been well covered in this respect since cycling ergometers are a great way to controllably measure training intensity in a lab and have been used in exercise studies for a long time. e.g Astrand reported on the (lack of) effect of crank length on mechanical efficiency in 1953.

I certainly haven't read them all as I have relied on the summation of such information from those eminent people whom I respect greatly for their far deeper understanding of all the issues.

Some sample studies include the following and I'm sure you can at least view the summaries via PubMed. Even still, one does need to ensure the conclusions drawn are supported by the data presented. IIRC, the study by Lucia et al was called into question by others listed here and the Luttrell study has certainly been discussed ad nauseum on other forums.

BANGSBO, J., P. KRUSTRUP, J. GONZALEZ-ALONSO, and B. SALTIN.
ATP production and efficiency of human skeletal muscle during intense exercise: effect of previous exercise. Am. J. Physiol. Endocrinol. Metab. 280:E956–E964, 2001.

COYLE, E. F., L. S. SIDOSSIS, J. F. HOROWITZ, and J. D. BELTZ.
Cycling efficiency is related to the percentage of Type I muscle fibers. Med. Sci. Sports Exerc. 24:782–788, 1992.

GAESSER, G. A., and G. A. BROOKS.
Muscular efficiency during steady-rate exercise: effects of speed and work rate. J. Appl. Physiol. 38:1132–1138, 1975.

HOROWITZ, J. F., L. S. SIDOSSIS, and E. F. COYLE.
High efficiency of type I fibers improves performance. Int. J. Sports Med. 15:152–157, 1994.

LUCIA, A., J. HOYOS, M. PEREZ, A. SANTALLA, and J. L. CHICHARRO.
Inverse relationship between VO2max and economy/efficiency in world-class cyclists. Med. Sci. Sports Exerc. 34:2079 –2084, 2002.

MOSELEY, L., J. ACHTEN, and A. E. JEUKENDRUP.
No differences in gross efficiency between subjects with varying aerobic capacities. Med. Sci. Sport Exerc. 33:S87, 2001.

NICKLEBERRY, B. L., Jr., and G. A. BROOKS.
No effect of cycling experience on leg cycle ergometer efficiency. Med. Sci. Sports Exerc. 28:1396–1401, 1996.

BERRY, M. J., J. A. STORSTEEN, and C. M. WOODARD.
Effects of body mass on exercise efficiency and V˙ O2 during steady-state cycling. Med. Sci. Sports Exerc. 25:1031–1037, 1993.

Hopker JG, Coleman DA, Wiles JD.
Differences in efficiency between trained and recreational cyclists.
Appl Physiol Nutr Metab. 2007 Dec;32(6):1036-42.

Ostler LM, Betts JA, Gore CJ.
Gross cycling efficiency is not altered with and without toe-clips.
J Sports Sci. 2008 Jan 1;26(1):47-55.

Cannon DT, Kolkhorst FW, Cipriani DJ.
Effect of pedaling technique on muscle activity and cycling efficiency.
Eur J Appl Physiol. 2007 Apr;99(6):659-64. Epub 2007 Jan 17.

Mogensen M, Bagger M, Pedersen PK, Fernström M, Sahlin K.
Cycling efficiency in humans is related to low UCP3 content and to type I fibres but not to mitochondrial efficiency.
J Physiol. 2006 Mar 15;571(Pt 3):669-81. Epub 2006 Jan 19.

Moysi JS, Garcia-Romero JC, Alvero-Cruz JR, Vicente-Rodriguez G, Ara I, Dorado C, Calbet JA.
Effects of eccentric exercise on cycling efficiency.
Can J Appl Physiol. 2005 Jun;30(3):259-75.

Luttrell MD, Potteiger JA.
Effects of short-term training using powercranks on cardiovascular fitness and cycling efficiency.
J Strength Cond Res. 2003 Nov;17(4):785-91.

Hodges AN, Lynn BM, Bula JE, Donaldson MG, Dagenais MO, McKenzie DC.
Effects of pseudoephedrine on maximal cycling power and submaximal cycling efficiency.
Med Sci Sports Exerc. 2003 Aug;35(8):1316-9.

Martin R, Hautier C, Bedu M.
Abstract
Effect of age and pedalling rate on cycling efficiency and internal power in humans.
Eur J Appl Physiol. 2002 Jan;86(3):245-50.

Gore CJ, Hahn AG, Aughey RJ, Martin DT, Ashenden MJ, Clark SA, Garnham AP, Roberts AD, Slater GJ, McKenna MJ.
Live high:train low increases muscle buffer capacity and submaximal cycling efficiency.
Acta Physiol Scand. 2001 Nov;173(3):275-86.

Moseley L, Jeukendrup AE.
The reliability of cycling efficiency.
Med Sci Sports Exerc. 2001 Apr;33(4):621-7.

Passfield L, Doust JH.
Changes in cycling efficiency and performance after endurance exercise.
Med Sci Sports Exerc. 2000 Nov;32(11):1935-41.

Green HJ, Roy B, Grant S, Hughson R, Burnett M, Otto C, Pipe A, McKenzie D, Johnson M.
Increases in submaximal cycling efficiency mediated by altitude acclimatization.
J Appl Physiol. 2000 Sep;89(3):1189-97.

Chavarren J, Calbet JA.
Cycling efficiency and pedalling frequency in road cyclists.
Eur J Appl Physiol Occup Physiol. 1999 Nov-Dec;80(6):555-63.

DaveyL

Thanks Alex. That's a big reading list