Monday, March 2, 2015

Guiding Rocks Down the Ice

There was a time when in a clinic or high performance camp setting (and I say this with a good measure of embarrassment) if we ran out of time, which we did on occasion, brushing was the casualty. Well, that's no longer the case, in fact, I now make sure this is one of the first areas I/we cover, it's become that important to the overall performance of a team, playing at the highest level or a team wanting to achieve a goal in its curling facility, it's never achieved before, so recreational curlers, this is for you too!

I played a good deal of my competitive career with a broom, not a brush (let's not travel down memory lane) but suffice to say, there was no sport science to prove that anything we were doing was correct (i.e. causing maximum affect). It was "participant observation", in other words, we did what we thought was the most effective way to sweep a stone, be it for draw purposes or to hold the line on takeouts. What we believed to be true was what we did. The proof for us was on the ice!

Even though we now have more sport science in the area of brushing than over before (what an understatement that is) a team still has to brush in a manner it feels is best meeting its needs. Part of what I'm going to say here IS sport science and part is what I believe to be true and I will try my best to not confuse them.

There are now, for want of a better term, instrumented brushes available to imperically know precisely what's happening as a brusher brushes. My friend Dr. John Newhook in Halifax has been most helpful to me in understanding the intricacies of brushing from a science perspective. He has an instrumented brush in development that will do everything but tie your shoes. He's tried to explain how it all works but he doesn't have a very bright student I'm afraid when it comes to the details!

I've said this before. in my coaching/instructing career, I am now able to begin much of what I say with the words, "The sport science tell us ...!". I then let the athlete(s) make the final decision. Some will buy into the sport science immediately while others want to see it happen on the ice. So, what does the sport science say about brushing? Well, a number of things have been learned through some research that has  taken place in the last number of years. In capsule form they include:
  1. brushing IS effective (that was good news, eh)
  2. the science alone is not good enough, it takes excellent technique, clean & dry brush heads and a degree of brushing fitness as well
  3. there was no discernible difference between a hair brush and a synthetic brush
  4. maintain the angle of the brush head to the handle at 90 degrees
  5. brush at 45 degrees to the path of the rock
  6. when brushing for distance, brush the entire path of the rock
  7. when brushing a take out, brush the "inside" portion of the rock's path*
  8. to promote more curl as the rock ends its journey, brush the "outside" portion of the rock's path*
  9. the most important brushing for a down weight shot is at the end (last 10 sec.)
  10. power cleaning will add significant distance to the brushing of a down weight shot
  11. even the most fit brushers can only brush at maximum efficiency for about 10 sec.
  12. your "away" (push) stroke is more powerful than  your "return" (pull) stroke
  13. the most effective brushing for a takeout occurs early in the rock's journey
  14. downward pressure seems to be more important than stroke rate (but both are desirable
The next item of business is understanding why curling stones curl, and of late there are a few theories out there explaining this most interesting phenomenon. The one I'm going to put forward is the one that makes the most sense to me and if there's one you feel is better and differs with mine, well, that's what makes the world such an interesting place!

I wish I could add some animation at this point but failing that, I'm going to ask you to use your powers of imagery and visualization. So, here we go!

I want you to imagine that you're walking behind a curling stone that's making its way down the ice rotating in a clockwise fashion (I know, check the clock on the wall to re-acquaint yourself with clockwise as opposed to counterclockwise for those of you of the digital age). Can you see that stone rotating clockwise, making its way down the ice and at some point, beginning to move from left-to-right? Good! Now, why is that happening? Here's what I believe to be true.

The running surface on the left side of the stone as it rotates clockwise, is moving in the same direction as the stone is traveling down the ice. But, the running surface on the right side of the stone is moving back towards you, in the opposite direction of the path of the stone. That unequal directionality is for me, what causes the running surface (r/s) to slide over the pebble on the left side but grab the pebble on the right side causing that left-to-right movement. Don't forget, the running surface is relatively rough compared to the "shiny" portion of the stone and the roughness of the r/s in conjunction with the quality of the pebble (let's not go further down that road today) is what makes the stone curl with directionality of the curl dependent upon the rotation (left-to-right when a clockwise rotation is applied and right-to-left when a counterclockwise rotation is applied).

OK, let's see what the sport science tells us about enhancing the path a running stone takes. Let's start with a straight draw.

Clearly one would only brush a stone that is designed to remain in play if the weight of the stone is such that it will not arrive at its destination. In curling parlance, it's "light"! Instinctively a brusher, sensing and/or timing the stone as light will begin to brush as hard as possible but if you go back to the sport science points above, you'll see that the best way to brush a draw is to power clean to about the far hog line and then "hurry hard". I know. I know. That jump-all-over-the-lightly-delivered-stone is a hard instinct to break but trust the sport science or better still, do you own on ice experimentation and you'll see that the sport science is on to something. This "power-clean-then-go-hard" idea is even more important if the down weight shot is a come around a guard type shot. And, the brushers will brush completely across the r/s (but as you'll soon see, that might be the only time that the brushers will do so).

Before I go on, let's talk about the length of the brush stroke. With the angle of the brush head at 90 degrees to the handle of the brush and the angle of the brush stroke at 45 degrees to the path of the stone, most brushers' brush stoke is much, much to long. Turn a stone over and you'll see that the diameter of the r/s is about the distance between the thumb and little finger of an adult hand. If you brush according to the previous sentence the brush stroke, to be most effective should be small, very small. I'm watching draw #3 of the Brier as I compose this and I see many brushers, very good brushers, who could be even better if they only shortened their brush stroke.

With that out of the way, let's talk brushing takeouts. If late brushing is most effective when brushing a down weight shot, exactly the opposite is true for the brushing of a takeout because brushing a take out is not for weight but for line. Simply said, the sooner the brushing takes place on a takeout, the more effective it will be but, there's a caveat with this. If the brushers, thinking that the stone has been delivered "tight", jump all over it, that might be just enough to miss the shot so brushers beware!
But let's assume that your venerable skip calls you "on" to "hold the line", then brushing the inner half of the stone's path is what you want to do (it's that "grab" side referred to above) and the brusher on that "grab" side should be closer to the stone so his/her push stroke (see #14) is closer to the stone. The challenge on brushing takeouts comes with the lead brush (the brusher further away from the stone). He/she must reach across the stone's path to get to the inside half. That's why I encourage video recording of brushing to ensure that both brushers are on the the inside (grab) side.

Before I continue, I want to make a point about brushing in general and this is for any team member who's charged with the responsibility of calling the brushing. If the brushers are already brushing a takeout and you're not absolutely, 100% certain that they must stop brushing, you will make far fewer errors if you keep them brushing! Experience tells me that when brushers stop and that stone hits that first patch of unbrushed ice, we know what happens. It moves, and often does so quite noticeably. Then, in reaction, you call the brushers back on and by the time the message is delivered, received, and acted upon, oops, too late! Yuk!!!!

Let's move to brushing draws of the come around variety. This is where my note about brushing a generic draw re-enters the picture but the difference's are around two important points. One is "break point". On championship calibre ice such as the ice upon which the players are playing here in Calgary this week at the Brier, down weight stones don't travel on a uniform trajectory. They move relatively straight and then "break". On most curling facility ice, stones tend to move in a uniform curved path. If you're playing on Brier/Scotties type ice, you need to know the location of the break point and it may be somewhat different from path-to-path. You might miss a come around because you brushed "through the break point".

OK, with that aside, let's get back to that stone that's moving nicely down the ice with you and your brushing partner sensing the weight is about right. As the stone begins to curl toward the edge of the stationary stone (i.e. guard), you and your brushing partner should be positioned relative to the stone as though you were brushing a take out (see the paragraph above re. which brusher brushes closer to the stone for take outs) because you need to get around the stationary stone (perhaps when you complete this posting you might wish to refer to an earlier one entitled "Code Red Or Code Blue" [1/19/15]). But, when the running stone successfully passes by that stationary stone, you and your brushing partner should switch positions AND sides of the stone. I call it the "double switch" because now you want to promote the curl, not hold  the line, as you do with take outs. You will want to leave that "grab" side unbrushed and you want the closer brusher's push stroke to be closer to the stone which now is the brusher on the "high" side of the stone's path.

Experience has demonstrated that the best way to execute this "double switch" is for the inside brusher to lift his/her brush and allow the stone to catch up to the outside brusher. During this brief time period that initial inside brusher can reach across the stone's path to become the outside brusher (a lot of inside's and outside's here I know).

If you couple this relatively new sport science with the other three elements described initially in this  post, you really can "guide stones down the ice"! Let me know how it goes and don't hesitate to ask questions or seek clarification. I suggest you print this posting and take it onto the ice and give this a try (don't forget to visually record your brushing)!

* For those who might feel that I'm promoting the breaking of a brushing rule, the World Curling Federation rule actually encourages brushing the running stone such that at times the brusher(s) may wish to brush only a portion of its path. It's  Rule #7 a) The sweeping motion is in a side-to-side direction (it need not cover the entire width of the stone)...

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