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Skidded turns vs carved turns

post #1 of 43
Thread Starter 
Compare two runs top to bottom made at the same vertical drop per minute speed. One run is made with skidded turns and the other is made with carved turns that finish going slightly uphill and are wider across the hill than the skidded turns.

How do the runs compare to each other in terms of calorie consumption and why?
post #2 of 43
calorie consumption? or effort?

Caloric consumption is dependent upon so many variables ... I'm not even going to try going there.

Effort? Skidded turns take more effort. (unless you *suck* at carving and fall alot)
post #3 of 43
Thread Starter 
Calorie consumption is used here for the purpose of measuring the efficiency of the turns. Higher calorie consumption = more energy expended.

Effort is a subjective measurement. I'm looking for something that could scientifically be measured, if need be.
post #4 of 43
rusty,

to measure calories you need to know a lot info
- weight
- resting heart rate
- heart rate while skiing
- duration at each HR interval
- total duration of exercise
- temperature outside

etc. etc.

kiersten
post #5 of 43
I dunno. Let me try the excercies while wearing my Heart rate monitor (it counts calories.) I know my wife Laure on average burns about 100 calories per run, but that includes some hiking. I think you'd have to do something like set a race course to compare apples to oranges.

I'm going to hypothesize that carving, while more efficient burns more calories, because of the higher speeds and resultant higher G loads that the body must support.

L
post #6 of 43
I would think the caloric count would be the same as the kenetic energy of the vertical rise in both cases. The additional calorie count would be in the realitive inefficiencies of the skiers involved.
post #7 of 43
Thread Starter 
Quote:
Originally Posted by klkaye
rusty,

to measure calories you need to know a lot info
- weight
- resting heart rate
- heart rate while skiing
- duration at each HR interval
- total duration of exercise
- temperature outside

etc. etc.

kiersten
Kiersten,

Same skier making both runs. All those factors should be the same, especially the total duration of the exercises (same vertical drop per minute speed over the same run).
post #8 of 43
Quote:
Originally Posted by therusty
Compare two runs top to bottom made at the same vertical drop per minute speed. One run is made with skidded turns and the other is made with carved turns that finish going slightly uphill and are wider across the hill than the skidded turns.

How do the runs compare to each other in terms of calorie consumption and why?
I guess that more calories would be consumed by skidding. I think you would be using more energy, using the leg muscles countering the motion of the skidding skis (downward). I'm no physicist though
post #9 of 43
Quote:
Originally Posted by Pierre
I would think the caloric count would be the same as the kenetic energy of the vertical rise in both cases. The additional calorie count would be in the realitive inefficiencies of the skiers involved.
I dunno. We should throw in a straight run in as a control effort!!
post #10 of 43
Am I sensing the emergence of new cutting edge ski technique/instruction marketing campaign? STEER AWAY THOSE EXTRA POUNDS!!
post #11 of 43
Carving.

Especially so, since the carve finish uphill.....
post #12 of 43

Pwls

could this be the birth of Primarily Weight Loss Skiing? Is the book forthcoming?
post #13 of 43
Thread Starter 
Yes, my next book is entitled: The Kool Aid Diet.

Big E - please elaborate.

Lonnie - a straight run would use the least energy, but it would violate the terms of the test (i.e. same vertical speed). Hmmm - unless we used a wind brake of some sort.

Skicrazed - my thoughts too, but a person more knowledgable than I disagrees so I seek the Bear's collective wisdom
post #14 of 43
Rusty... I hypo much earlier doing long fast carved turns....

This assumes not a heap of defensive steering but sort of gentle smearing type steered turns.... eg medium radius sort of stuff...
post #15 of 43
Cause the carved turn (up the hill) has placed the skiier out of the natural momentum of the fall line.

The skidding skier has never been out of the fall line?

More extension necessary to initiate return each time.

I think you are getting at the notion that the two "imperfect" techniques will balance out in terms of work/ergs/effort?
post #16 of 43
Thread Starter 
I'm actually trying to claim that skiers on shaped skis, as opposed to straight skis, get less tired because (s)carving your turns is more efficient than skidding your turns.
post #17 of 43
work = force x distance

since the carves finish slightly uphill, the vertical distance that the skier travels is greater - the skier does more work. But that's not all there is to it...

The short anser is that I think that the two skiers will be expending very similar amounts of energy from initiation to fall-line, but the carver will be expending way more from fall-line through completion and neutral up to initiation.

Why? Since the turns are carved, there is no skidding. Since there is no skidding, there is a greater amount of decelerating forces needed to deflect the skiers body from continuing it's path downhill and into the traverse.

Why more? Because In the skidded case, the forces decelerating the skier are spread over the entire turn, in the carved case, they are concentrated at the bottom of the arc -- they require more energy to resist. Which means more muscle involvement by larger muscle groups, and more calories burnt.
post #18 of 43
I just know I need to be feed faster when we carve more....
post #19 of 43
Quote:
Originally Posted by therusty
I'm actually trying to claim that skiers on shaped skis, as opposed to straight skis, get less tired because (s)carving your turns is more efficient than skidding your turns.
I think that most folks feel that way regardless of ski, because when they are (s)carving, they don't really finish their turns in the same way as they to when they are skidding.

The (s)carver is usually much faster, and so spends much less time on the run. That means the time the muscles are under tension is lower -- a key difference, especially if you consider that the skidding skier could be out there a few minutes longer....

Also, the (s)carvers don't usually finish their turns in the way your example suggests.
post #20 of 43
were you to use calorie conumption as a guage for skier turn-efficiency, then i'd have to assume you'd say that most racers are really inefficient skiers. further, turns made strcictly by carving, with no skidding, are useful only in freeskiing.
in a course, some skidding needs to occur, as the gates dictate the line, the skier's preference doesn't.
post #21 of 43
is the hypothesis based on turns of approximately the same shape ('course, don't how to maintain descent rates doing that, as pure carved turns should be faster than round skidded turns)?

Are we presupposing a push the tails or shovels skid, or a "side slip" turn that is round with the skis flattened?

Seems like so many variables as to be darn near impossible to effectively test the hypothesis.
post #22 of 43

Foul !!!

And the ref tosses the flag high into the air.

Your initial proposal never mentioned skis that you can hardly find anymore.

And yes when I am tired and lazy .... I just scarve my azzz off. Way less effort on my 156 SL's ....
post #23 of 43
Thread Starter 
Yuki,

I have a pair of straight skis in my closet saved just for this experiment! Worst investment I ever made. The comparison I'm trying to make here will be relevant to skiers who quit the sport before shaped skis and are now consider coming back.

Lenny,
The presumption is that since the vertical rate of descent needs to be the same and a carved turn is faster than a skidded turn, that the carved turn needs to travel a greater distance. Although it's possible to do this without going uphill at turn finish, I've explicitly added the uphill criteria to make the turns relatively similar in width and under the belief that uphill turns provide "free energy" braking that a skidded turn will not get. (note to those who will complain unfair - will you concede that a skidded turn finished uphill would get less of this effect than a carved turn would?)

Does the uphill component of the turn reduce the energy consumption required to control speed? Are their other differences that contribute energy savings for the carved turns?

Sorry for all the obtuseness, but I'm trying to not put words under peoples fingers.

BigE - physicsman would be proud!
The distance for the carved turn would be more than a skidded turn, but F=ma too.
post #24 of 43
My own opinion is that it's WAY less effort to skid turns down a groomed run than it is to make fully carved high C-type carved turns.

I engage far more muscles when initiating and maintaining a carve than when simply skidding down a run.

Just my $.02.
post #25 of 43
It would depend on how you are carving your turns. If you are banking and keeping your legs fairly straight and being skeletally stacked, you can get down while spending very little energy. If on the other hand, you are trying to get the most out of every turn abosrbing, extending, pressuring the skis to the limit, then keeping that pressure there while using leg motion to keep the pressure adjusted, you can spend a lot of calories.

Scarving will require an energy level somewhere in between. You will have to spend more energy just because of the unsteadyness of the load as the ski skims over roughness.

It depends. That's my answer and I'm sticking to it.
post #26 of 43
It seems likely that skidded runs use less calories ... but not always. At one end of the scale you have simply falling down and sliding down the hill: pretty much zero calories. Working your way up from the flying Wedge O' Death thru the snowboarder's classic run-long sideslip to ineffectual skidded turns up to hard-edge set skids one would seem to use progressively more calories. It would all how much you're using your body during the run: picture the body in action independent of the fact you're on skis.

One complication: a carver can store energy in the ski and use it to move his legs for him, thus saving caloric expenditure. Therefore, there may be a set of skidded runs using more energy than a carved run. Those runs would be "almost carving" runs that failed to re-use the stored energy in the ski.

On the other hand, the original problem defined the run time to be the same. Since the carving skier has to go farther, he also has to go faster, with K.E = 1/2mv**2. Because he's going so fast he's got a big F=ma task ahead of him in order to change direction...and probably a lot more work=F*d, too. On the other hand, the skidding skier of controlling his velocity by dumping off energy using friction.

A possible flaw in this problem setup is that the carving skier probably has to do a lot of extra work in order to keep from beating the skidder downhill. He's definitely going to go faster because he's not dumping energy to friction. He's forced to stretch out his run so that the times work out even. He has to use his body to resist G-forces due to his speed and the fact he isn't using friction.

So exactly what is the point, here, since the problem may not be that realistic.
post #27 of 43
Hi Rusty -

I think the comparison could go either way.

Probably the absolute least energy-intensive way to descend a smooth, well-packed slope at a constant downhill velocity is to stand almost perfectly still and fast sideslip the entire thing, staying in a narrow corridor, and making no changes in the direction your skis are pointed.

If the surface is sufficiently smooth, the only thing the skier has to do is make barely perceptable fore-aft and edging adjustments. Since his muscles are barely changing length when skiing this way, and since the only force the muscles have to overcome is only 1 G, the skier will use only slightly more metabolic energy for this sort of sideslipped descent than he would if he had simply stood absolutely still for the same length of time. By the time the skier gets to the bottom, he might be a nervous wreck because of concern about catching an edge, but at least he won't be winded.

Because this skier is doing little more work than he would if standing still, this endless sideslipping technique will almost certainly use less metabolic energy than skiing the run with even well executed carved turns.

Even if the skier throws in a few old-style up-unweight and pivot changes in the direction the skis are pointed (I don't want to call this a turn...), this method of descent is still very low energy.

At the other extreme, if you crank up the tempo, and ski the hill using old-school, rapidly-repeated, tail-swishing skidded "turns" with lots of up-unweighting (but maintaining the same average downhill velocity, and other constraints), you can use arbitrarily large amounts of metabolic energy.

If you are not burning calories sufficiently fast at 1 "turn" per second, make two turns per second like the crazed jackrabbit skiers many of us used to be in the 1970's when descending a steep slope. When the hill is skied this way, from a metabolic point of view, the skier might as well be doing fast twisting jumping jacks for the entire duration of the run. This technique will almost certainly use more metabolic energy than skiing the run with even poorly executed carved turns.

Anyway, it's not the clear-cut, definitive answer that you probably would have preferred, but that's my $0.02 on the subject.

Tom / PM


PS - I see that someone else jumped in with very similar comments. That'll teach me to go off and answer emails after starting a reply to a post.
post #28 of 43
As Physicsman said, there are many different types of skidded turns, and many different radii of carved turns (sl vs gs, etc). I'd say that in general, carving well requires much more energy than skidding around on groomers. At the end of a 35 or 40 second slalom run, I'm breathing heavily and my quads are burning - if I just skidded on down, or even carved casually down the same trail, I wouldn't exert myself nearly as much as intense slalom-type carving. To quote a novice racer from last weekend "I don't see why you'd need to be strong to be a ski racer"... she's clearly not carving yet
post #29 of 43
Bsather,
W=F*d, but use a frame of reference fixed with the skier and and d=the distance from CM to ski. Whatever skier gets the most W uses the most callories.
post #30 of 43
Thread Starter 
Quote:
Originally Posted by bsather
So exactly what is the point, here, since the problem may not be that realistic.
I'm trying to justify a claim that skiing on shape skis is less tiring than skiing on straight skis. I've already got personal testimony that this is the case. But Robin Leach would like to know WHYYYYYY.

I can feel the difference on a one turn to a stop basis when I finish the carved turn by going uphill, but that's cheating because I'm transferring kinetic energy into altitude. My starting theory was that going uphill is free speed control energy (negative acceleration force of gravity), but I realize there are other factors involved. The variety of input on this topic has been enlightening.
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