Lifting Vs. Sliding The Feet in the Snatch & Clean
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- Опубликовано: 7 окт 2018
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There’s a concern among some lifters and coaches that lifting the feet in a snatch or clean is reducing the force in the pull, or is inefficient because the lifter is jumping.
A jump is an elevation of the center of mass above its resting level-in other words, the body as a whole moves up off the floor. However, lifting the feet in a snatch or clean isn’t jumping. The feet are elevated off the floor, but the body as a whole moves down. This is the exact opposite of jumping-it’s falling.
In a snatch or clean, the lifter actively pulls under the bar after reaching the top of the pull. To do this, the pressure against the floor initially needs to be removed to prevent resistance. Lifting the feet completely off the floor ensures zero resistance and allows maximal acceleration down.
It’s possible to have no pressure when keeping the feet on or very near the floor and sliding them into the receiving position, it’s just more difficult to do correctly. Neither is more effective if each is equally mastered, but athletes will typically perform better with one or the other naturally.
Lifting the feet on the way down in no way prevents complete force application in the pull because it’s occurring after the legs and hips are no longer applying force against the ground anyway. At this point, all force on the bar is coming from the active pull under with the arms, which preserves the bar’s existing upward momentum as it moves the lifter down.
The key is timing the lift of the feet properly, which is as the lifter is moving down, not before the lifter has completed elevating and accelerating the bar in the second pull. This timing is the same with significant foot elevation or sliding.
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"it's the opposite of jumping, it's falling."
You're the best, I love how you explain even the most obvious things in the calmest way. Always looking forward to another podcast episode with you and Ursula :D keep it up!
Thank you Greg. You content helps my lifting. It's great you take the time to put this stuff out. Cheers form Portland OR
The owner of the gym I go to is an ex cross-fitter and told me that when I snatch and lift my feet/stomp is bs, when really it helps me… Thanks for the vid so I can prove him wrong 😆
Always looking at this channel to become better as an athlete and coach. Thanks. Please keep it coming.
This is the video to look for if you want to transition from power clean to squat clean
Really enjoying these. Please continue! You are well appreciated.
Incredible breakdown. That’s amazing slo-mo action 👍
Awesome explanation. Thanks
Great Video! Great descriptors and explanation.
excellent description!!
Thanks you don’t hide tricks of this games ❤…I am reading your book
Thank you.
Great video, Greg.
Stellar
Adam Maligov leads the league in thumbnail titles
Greg, beard looks good. Not sure if me knees can handle much more hammering, so playing around with sliding by doing no jump-no hook.
I've been wondering about this. Does it apply to the split jerk as well?
Essentially yes
Say that again
1 minute 14 seconds....very close.
Your actual conclusions about this are wrong; you try to incoprorate physics but you only address the most surface level aspect of the physics, and for that reason get it wrong. Sliding your feet is definitively better than jumping. To understand why you need to consider the physics at play. Once you are airborne your center of mass, which includes the weight of the bar, has a fixed trajectory that will only be affected by gravity. This is the basic principal of conservation of momentum (which applies provided you don't have wings with which to use the air). Any movement of a mass will not affect the location of the center of gravity, relative to the earth, after being airborne for this reason. This means that for any mass that is moved downwards, a corresponding amount of mass will move upwards to conserve momentum. Any mass that is moved upwards will force a similar amount of mass to move downwards, again to conserve momentum. This means that by elevating your legs in order to slam them down you force your abdomen and the bar downwards, again to conserve momentum.
This may sound good if you're thinking about the center of mass being roughly inside your abdomen or chest, because it would mean that by elevating your legs you lower the position of your abdomen such that it's closer to the ground, which is what a lot of lifters want (an abdomen closer to the ground to catch the weight), but the thing is that because your center of mass includes the weight above your head, by elevating your legs you force your chest and the bar to path downwards. Thus, by elevating your legs to slam you actually decrease the upwards momentum of the bar so that you can increase the relative upward momentum of your legs. When it's all said and done this means that the bar will not travel as high for a given amount of effort when you move your legs upward.
I think this strategy is appropriate for people who have a wider catch stance than their pull stance where a lot of expansion in the hips needs to take place, but if you can catch in a relatively similar stance to your pull stance, you can conserve the upward momentum of the bar path, as well as apply force into the bar as soon as your feet are settled. You can see a classic example of this in your video at 0:50, where the blue on the left loses bar momentum where as Tian Tao's bar rapidly accelerates even after reaching his head, whereas the blue lifter has all but lost his momentum, (because the blue lifter had to move probably 45 kilos of mass upwards which correspondingly means 45 kilos from the rest of his center of mass is moving downwards. Downwards momentum of the bar is obviously very bad. You can see the negative effect of that when you look at the blue lifter's catch; he catches the bar and is in an identical position as Tian Tao, but because the bar's momentum is pathing downwards more rapidly his catch position fluctuates rapidly as his butt almost stops moving when it hits the floor. Compare this with Tian Tao, who slides his feet, and has almost no downward bar movement relative to Blue and is able to catch the weight while only moving an inch or two from the time he is fully locked out to the time he stops the bars momentum completely. Now obviously the weight differences in this video might make you think otherwise, but checkout this video of Tian Tao snatching 180 kilos. From the moment he is in the catch position, to the moment he starts squatting, the bar moves down maybe a single inch. Why? Because he conserved the upward momentum of the bar and entered the catch position before the bar started accelerating downwards, unlike Blue in this video who clearly accelerated the bar downwards before entering catch position and as a result had a catch that lasted probably as much as six inches of flexion. ruclips.net/video/NkJcVNwbWYg/видео.html
Another way to illustrate this principal is to look at a traditional vertical jump test. Often times athletes who are professional will have a very large amount of windmill motion with their hands which essentially levitates their body. This is an example of the opposite case happening, where because their hands path downwards after striking the markers the center of mass is moved downwards, but to conserve momentum the rest of their mass, relative to earth, moves upwards. This is why if you look at their feet they levitate once they begin to move their arms downwards. ruclips.net/video/lgkCxnSHV7w/видео.html
My physics is most certainly rusty, but I do believe this checks out. Every action has an equal and opposite reaction, so if that action isn't acting upon the ground, then it has to act on the total mass.
I was questioning this concept that the two styles are equal before I read this post, but this is logical I believe. For the legs to come up this brings the other mass down, and makes it difficult to be smooth, which is generally efficient.
More simply, and please correct me if I'm wrong, the goal is to lift the bar and get under it to receive and catch it, any extra leg movement is wasted energy, no?
Regardless of whether my logic of physics here is confused, it's certainly a complex and interesting thing to think about.
so I'm thankful for the well done video to stimulate such interest
@@smolboyi Yeah I think it's one of those things that if people keep doing for hundreds of years eventually there will just be one accepted way to do it professionally. I'm not sure it requires too much more effort since the body is in free fall when they elevate their legs, but another thing that's negative about it is they lose time under tension by keeping their feet away from the platform. Force is just equal to a momentum divided by the time it takes to create or stop that momentum. In the case of a lifter here, during the catch, the force placed on the legs is greater if the bar momentum is larger, and or if the time needed to stop the momentum of the bar is shorter. In terms of the physics, by elevating your legs like this you decrease the upward momentum of the bar, and indirectly increase its downward momentum during the catch, and you simultaneously decrease the time used to stop the momentum of the bar path. Force = momentum / time, and since the time is shorter because their feet are airborne longer, the force experienced is much higher. High force in snatch is often when we see snatches bottom out, because it provides more time for the momentum to be stopped and thus decreases the force placed on the body at a given time. It's like why cars are made of plastic now days; the crumple zone decreases the force placed on the bodies inside the cars by lengthening the duration of the crash.
So good vid, but why on earth put the captions directly over the lifters body so we can't see the physics going on? lmao kinda stupid..
Sorry when your feet lift off the floor you've technically jumped
Overanalysis 101