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How is it possible skinny legs more powerful than muscular legs

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How is it possible skinny legs more powerful than muscular legs

11 Nov 2010 03:24

I was born with quite large muscular legs. Throughout school I could kick a ball further than most, squat more than most, etc.

Then I started bike racing. I've been racing and training for awhile now and something that I've noticed that I just can't understand is how it is possible that some of these 65kg riders with their puny skinny legs seem to timetrial faster and sometimes even sprint faster than guys like me with huge legs. It's not like I'm unfit and untrained.

Shouldn't more muscle kind of suggest that I should have more strength and perhaps power? I see the same thing in the pro ranks. How can such skinny legs generate so much power?
User avatar Indurain
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11 Nov 2010 03:34

Umm, power to weight ratio?
User avatar TexPat
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11 Nov 2010 03:37

Well you have to get to what causes the bike to actually move. Its pretty much like your car, the engine turns to spin the wheels the faster you spin the cranks on the bike the faster you go, if you have huge muscle mass it can help you but if you can't spin fast you won't go fast or faster than the other guy with the skinny legs. So if you have both the muscle mass and can spin fast, super!

Of course there are many other factors to consider, like endurance and amount of time you can spin fast till you can't any longer, and etc., but in a nutshell spin baby, spin!
User avatar ElChingon
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11 Nov 2010 03:44

Not just power to weight ratio - you have to look at the duration of the event as well. A large muscle will theoretically be able to output more in a single repetition than a smaller muscle if the mass being moved is the same. However, what about after 10 reps? How about 100 per minute - for 2 hours?
Then what if the mass is different (it basically has to be given the mass includes the muscle itself)?

What about efficiencies? Cadence, aerobic, anaerobic, upper body, etc.

Its really not much different to track and field - how many large legged 1500m+ runners are there?
User avatar Martin318is
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11 Nov 2010 03:53

And your position makes a significant difference.
User avatar TexPat
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11 Nov 2010 04:27

And whether you have skinny legs or big legs, if you don't have much in the way of fast twitch fibre's in your muscles, sprinting will never be your forte.
PCutter
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11 Nov 2010 05:34

Probably because for aerobic based exercise the actual size of the muscles has very little to do with it.

For the activities you described - kicking a football and squats are primarily determined by fast twitch muscle fibres and given that these actions are one that are more of a biomechanical nature, ie: exerting the maximal amount of force in the shortest period of time. This usually requires Big Muscles.

Endurance is more of a biochemical limiter. The ability to transport fuel/oxygen to the cells, the mitochondrial density, the ability to remove and process metabolites etc are the issues (amongst others). These are not determined by muscle size.

So you can be stick thin and have an excellent threshold. Conversely there are road sprinter types out there who still have an excellent threshold aerobic power - though they usually still have more weight and hence suffer when the road goes vertical.
Tapeworm
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11 Nov 2010 06:07

Indurain wrote:Shouldn't more muscle kind of suggest that I should have more strength and perhaps power?

Because strength and sustainable aerobic power are not related. Endurance cycling is not a strength sport, it's an aerobic sport.

Tapeworm outlined most of it. The limiters are aerobic metabolic in nature, not strength/force related.
User avatar Alex Simmons/RST
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11 Nov 2010 09:07

Okay, I see what your saying, but by way of example:
putting potential doping aside how is it possible that someone like Contador can match Cancellera in a timetrial. Especially given Cancellera's legs are twice the size of Contadors. Do they have similar strength? I don't see Contador spinning any faster. Could this suggest that Contador could one day win Paris-Roubaix if he wished?

Likewise, some of those sprinters seem very small, Cavandish 69kg's?? McEwen even smaller. How they generate so much power for such a small guy is beyond me. You'd think bigger riders like 'Thor' would kick their butts.
User avatar Indurain
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11 Nov 2010 09:33

Indurain wrote:Okay, I see what your saying, but by way of example:
putting potential doping aside how is it possible that someone like Contador can match Cancellera in a timetrial.


2009 Final TT had a 3km climb in it and Fabian suggested that there was a flotilla of vehicles in front providing shelter, 2010 flat TT and Alberto and Shleck were knocked for a six.
Especially given Cancellera's legs are twice the size of Contadors. Do they have similar strength? I don't see Contador spinning any faster. Could this suggest that Contador could one day win Paris-Roubaix if he wished?


Bigger muscle is a stronger muscle. But also means more weight to cart uphill and more frontal area to punch into the wind. And as mentioned above strength is not a factor once your event is longer than 10sec, the supply of energy to the muscle starts to decide the result from that duration onward.

Likewise, some of those sprinters seem very small, Cavandish 69kg's?? McEwen even smaller. How they generate so much power for such a small guy is beyond me. You'd think bigger riders like 'Thor' would kick their butts.


I'm surprised it doesn't get mentioned more but look at how aero Cav is compared to the others. Word from one of the former British Track Coaches is that Cav doesn't put out a huge amount of power but is very smart with what he has got.
User avatar CoachFergie
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11 Nov 2010 09:37

With the sprinters cavendish is short so his muscle of inch of height is similar if not more than for example bonnen
BrindSurch
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11 Nov 2010 20:55

many people have different muscle fibers some are full of fast twich fibre and some are slow twitch.
they can all be developed to some degree.
the size of the muscle is not important to the amount of the muscle that you are useing.
most good cyclists have fairly lean muscles.
brianf7
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12 Nov 2010 00:10

Quality posts from Alex Simmons and Coach Fergie again. Thanks guys, you're always informative.

Another factor not mentioned here is fat.

Many of us carry more body fat than the pros and the presence of subcutaneous and interstitial fat makes the muscles look bigger than they really are. If we were able to get down to 6% body fat we might find our muscles aren't that big any more.

And then it's also "horses for courses".

Chris Hoy's legs output a peak of 2300W for the kilo which lasts less than 60 seconds.

Image



These two spindly legged guys output 400-500W for 45 minutes

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User avatar Polyarmour
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12 Nov 2010 00:45

@ Polyarmour. What, I don't rate a mention? :D

Also another comparison from the one you made in relation to Hoy/Schleck is that of a road sprinters, they need to be very aerobically fit as fatigue has a great impact on your ability to hit said peak power. No point having a 5s power of 1500watts if the windup to the line @ 400watts leaves you grovelling.

Because their goals are different it is rarely seen but the like of Boonen can time trial quite well.

I try to emphasise this point to roadies who declare themselves as a "sprinter" and hence don't need to have a pimping FTP. :rolleyes:
Tapeworm
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12 Nov 2010 02:32

Tapeworm wrote:@ Polyarmour. What, I don't rate a mention? :D

Also another comparison from the one you made in relation to Hoy/Schleck is that of a road sprinters, they need to be very aerobically fit as fatigue has a great impact on your ability to hit said peak power. No point having a 5s power of 1500watts if the windup to the line @ 400watts leaves you grovelling.

Because their goals are different it is rarely seen but the like of Boonen can time trial quite well.

I try to emphasise this point to roadies who declare themselves as a "sprinter" and hence don't need to have a pimping FTP. :rolleyes:


Actually I did mean to put your name in there too when I initially thought of posting and for some reason it slipped me as I was writing it. So thanks also.

Tom Boonen's legs. Not quite as big as Chris Hoy's but as you say more aerobic fitness to go the distance.

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User avatar Polyarmour
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12 Nov 2010 03:13

And just to further highlight the point of how the size makes little difference to the power:-

The Stick Man, Bradley Wiggins
Image

And Bert "I've Got THIGHS" Grabsch, who is not a sprinter
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Tapeworm
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12 Nov 2010 03:58

The legs are a reciprocating lever in the cycling machine, i.e. they must lift themselves up as well as push the pedals down. The heavier the legs, the more energy required to lift them up before each power stroke. As the cadence increases, the energy required to lift them goes up exponentially. For this reason riders with large/heavy legs need to expend more energy to drive the cranks than skinny legged riders. They can generate more energy, but it takes more energy than the skinny legs just to move them up and down and the faster you pedal, the more energy it takes until skinny guy's legs are at a point where they produce more net power than big guy's legs.

I believe that guys with heavier legs should resist the pop culture teachings of the 'high cadence for everybody' lobby. There is an optimum gear and cadence for your leg-power to weight ratio.

My advice; the bigger your legs, the bigger your gear.
Hangdog98
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12 Nov 2010 04:07

Some great points PolyArmour. I guess even Tom Boonen could have legs like Chris Hoy if he was training for 1min vs the aerobic distances. I've got no doubt my legs will lose some of their size as I lose weight and put in some more endurance miles, but will still be bigger than most. Pity it means very little.

What is defining however, is how skinny Bradley Wiggans legs are compared to what they use to be like. He has lost some of his timetrialling ability but perhaps not that much.

What does however strike me as a little odd is how some of these Pro's like Brad McGee, Stewy O'Grady can ride events like the TdF, etc and then suddenly ride successfully on the track for the Olympics. You'd think all that endurance training would slow them down a little. I know they're not in the sprints, but still.
User avatar Indurain
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12 Nov 2010 04:33

It is kind of complex, but i believe power/strength centers in the mind

short/skinny/tall/large - some people are smokin' fast


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User avatar tubularglue
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12 Nov 2010 05:07

Hangdog98 wrote:The legs are a reciprocating lever in the cycling machine, i.e. they must lift themselves up as well as push the pedals down. The heavier the legs, the more energy required to lift them up before each power stroke. As the cadence increases, the energy required to lift them goes up exponentially. For this reason riders with large/heavy legs need to expend more energy to drive the cranks than skinny legged riders. They can generate more energy, but it takes more energy than the skinny legs just to move them up and down and the faster you pedal, the more energy it takes until skinny guy's legs are at a point where they produce more net power than big guy's legs.




Incorrect. Given that cranks are fixed to each other (unless you are using powercranks or the like) the weight of the leg on one side balances the other leg. Almost the prefect counterweight*, ie: all the power driving the crank is driving the crank unless you are actively pushing on the upstroke (which usually does not happen). There is no "lifting" of the opposite leg.

Hangdog98 wrote:I believe that guys with heavier legs should resist the pop culture teachings of the 'high cadence for everybody' lobby. There is an optimum gear and cadence for your leg-power to weight ratio.


Yep, the best cadence is the only where you produce the most power. That varies person to person. Though nothing to do with leg size.

Hangdog98 wrote:My advice; the bigger your legs, the bigger your gear.


As above.


* Not the PERFECT counterweight as everyone is asymmetrical.
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