Canada Curling Coaching -- Push Delivery

      I am pleased that Sweep and the author have taken it upon themselves to present a "How To" curl article. The CCA's 20 year old manual is full of errors and poor technique. Whether right or wrong this author gave it his best shot. While no one has attacked or disagreed on paper with my many, many web page hypotheses, I'm hopeful they will and in Sweep. How else can differing views be evaluated -- by discussion! This article/analysis is generated in response to an article in "SWEEP," Winter edition-Jan./Feb. "A new look at the no-backswing delivery," an excellent article, but points out several areas that I am not in full agreement. I'm usually much more critical but judge for yourself if the physics as I see it makes sense to you.
PUSH DELIVERY: Now that the no-back swing has been around for 20 years and people can differentiate between the two styles, let's call this delivery "what it is" rather than "what it is not." It is the PUSH DELIVERY.
    AND the push delivery is different for small people (under100lbs./45kgs.) and larger (bigger mass) people. While it is necessary for coaches to teach small people the total rearward slider leg and body motion to gain maximum forward thrust, it is too bad bigger people retain this technique throughout their lives and steadily curl worse and worse because they cannot "adjust" forward thrust with their larger size and never, never, get and retain draw weight. People over 100lbs./45kgs. must change to the 3 pullback scenarios discussed below after they learn the smooth hack rocking motion, IF they want to curl at upper club/pro level. I will show you the proper pullbacks for needed draw, tap, hack, true board, upper board/normal, and peel weight.
   The physics are precisely the same as in GOLF in which the "swing" is the same but you change the club to get more speed/distance/height.
If you are watching the 2000 Hearts, you will note many women use one body rock motion and Linda and Ray's hack foot leg drive system. You will also note these ladies have poor stats!! Watch for the men using one body rock motion in the 2000 Brier. For all but the peel, a large man can minimize the backward rocking motion but more men use their mass/"right club" to throw each weight when it is smaller people who NEED rearward motion the most to accelerate the rock.
    The essential requirement to learn in arriving at these several weights is the method in which you trigger the mind to "recall" the proper muscle messages learned in practice. This is done by learning three pullbacks instead of the one full body and leg rearward motion learned as a small person/child and usually carried forward as an adult.
    The secret to weight control is: Attain the different delivery slide speeds/velocities, while still in the hack, by using the same "speed" of forward motion/drop for each shot and only vary the mass behind the shot by how much you bodyrock back, move the slider leg back, and/or move the rock back while in the hack!!! Remember: Mass x acceleration =force = 1/2mVsgrd. If we keep the acceleration of body drop constant and vary how much mass we put behind the rock, we are able to vary the resultant velocity of slide.
    The object, then, is remove one more variable, acceleration in the hack and hack foot/leg push out, from the delivery sequence formula. For peel weight on normal club ice, unless you are very big and strong, you will need to accelerate all your mass forward faster as well which is contrary to what I just told you. In curling, this is the only area a larger person MAY have an edge over a smaller person IF they don't understand mass x acceleration, i.e., men vs. women.
    AS a big person, I have recently learned to use a fourth pullback position. On 14+sec. H-H ice, I pullback 6" and not all the way back to the toe. I find that I can throw guard, top 12', or T-line weight more consistently with the minimum body pullback meaning my body weight moves rearward ever so little and the rock and body pullback is merely an alignment to the brush exercise only. Remember in EVERY delivery, to hit the brush more consistently, the initial ROCK pushout from the pullback position with BODY FOLLOW is what starts you on the line to the brush. Initial rock pushout provides up to 50%+ of necessary delivery weight. For small people (children and small women), the initial rock pushout is imperative to increase rock velocity. This fact points up the advantage of the two hand delivery in increasing initial rock pushout speed.

Two handed push delivery in motion. Rock at release point 3-6 feet back of hogline. Left hand has let go and right hand is releasing after turn applied from the 12 O'clock handle position. Turn is applied at release along with any needed "finger boost." Note curler is relaxed while sliding on the right foot AND left knee. The curler will now slide within feet of rock stop. Also note the right arm solid against the leg and not wavering in the breeze as with the non-dominant left foot slide. The brush crutch IS NOT NEEDED as the curler is stable on 5 points of contact with the ice. Rock is under the nose on brush line of sight. Note: Most people lower the body at the release stage while reaching for the brush. This is "OK" if: Do not "body" push as you drop your shoulders down while reaching out, especially for draw weight as you will never, never get consistent draw weight.

The PUSH delivery is most easily learned by sliding on the dominate already "trained" right foot for right handed pushers. Left foot for left handed pushers. The delivery arm is solidly against the slider leg.
DOMINANT FOOT SLIDE:
     The non-dominant foot slide is a carry over of the lesser efficient (on today's keen ice) "lift" delivery in which it was necessary to get the right leg out of the way of the rock or suffer a hit with a 42lb. rock and to counterbalance the rock weight with the left leg. It is recognized that on "river" ice in the "old days" it was necessary to lift and fling the rock to make the house. I have found rocks that vary from 41lbs. to 43 lbs. --at the same club.
   THIS HACK IS DESIGNED WRONG!!!
Nov., 2000 update study. Note the wrong design of this hack and the too high positioning in the ice.
Why is the hack designed wrong and what does it do to the curler? It is designed like a "starting" block instead of a friction "rocking" pad which resists forward motion in the delivery. You should not push off with the hack foot. This causes body rotation. "Leg thrust" comes from the slider leg and body acceleration and not the hack leg! The mass of the sliding leg and forward body thrust is where you get controlled forward rock and body speed. Remember the body speed should be identical to the rock speed at release.
First, note the VERY high positioning of the hack above the ice level-2inches.
Second, note the very high angle tip forward.
Note the way the curler must bend the hack foot and lower leg ahead making it a "strain" to leg muscles to rock backward to develop the mass x acceleration force to throw hit speed. The hack is so far tipped forward, it is impossible to ROCK the body easily on the hack foot . For the PUSH delivery,this one basic fault significantly translates into the difficult to attain accurate hit speed scenario for small people, under 120lbs..
What does this forward leg angle do to the curler? The curler has difficulty rocking the entire body backwards while holding the foot on/in the hack. IF the hack pad was 1/4 -1/2 inch above the ice and nearly flat, it would be very easy to rock backwards to attain body speed in the push delivery. The pictured design severely handicaps small people and children since it is difficult to rock backwards while maintaining the foot in the hack.
Also, for those curlers using the dominant foot slide, right foot for right handers, the cross board attaching the two hacks is sticking up in the way of the sliding foot.

Again relating to the above picture:
The two handed push delivery pictured with the right foot dominant slide foot:
The curler is in the maximum rearward thrust position before the rock initial pushout and subsequent follow through with body and slider leg coming in behind rock for maximum takeout weight. The total weight of the rock and slider foot is not carried on the hack foot as is the case with the lift delivery. In the push delivery the weight shift is backward with SOME but not all weight on rear foot. The delivery is a "rocking chair" motion with a steady weight shift transition backward to gain maximum rearward mass ready for the forward acceleration for heavy takeouts/peel. It is easy to see why this hack resists the ability to rock backwards with a smooth motion back-forward. Children with small body mass need to learn this rocking chair action to throw hack/board weight. Children should NEVER be encouraged to throw more than true board weight (true board -- rock just stops at bumpers) as it will ruin their delivery technique (cause arm boost) while straining/damaging the body. The lift delivery should NEVER be taught to anyone. There is a reason the Workman's Compensation Board requires no one to lift more than 40lbs.!!!
    In the "lift" delivery it is absolutely necessary to slide on the non-dominant foot as the weight of the body and rock is carried on the hack foot when the rock and left slider leg are moved back in preparation for the forward thrust.
    It is not necessary to slide on the non-dominant foot (left foot for right handers) in the push delivery and is even counter productive in efficiency, muscle strain and ease of learning. The dominant right foot for rightees is always the "step out" foot on a line to an imaginary target. The dominant foot and eye coordination to hit a target line is already learned at an early age from walking and other sports. In basketball, you lift forward the right leg for a right handed lay-up shot.
HACK vs. Track Style Starting Blocks:
    The hack has always been used as a friction counterbalance (in the lift delivery) to the forward thrust of both the leg and rock. Never was it necessary to get a "leg drive" from the hack. The hack provided the friction only resistance force to the forward acceleration of sliding leg and rock. As a matter of fact, if you also "pushed off" with the hack foot, you would never learn draw weight or hit the broom consistently as it causes a body rotation and "confuses" the sliding leg in its attempt to come out on a line behind the rock with the target brush.
Starting Blocks and pool edge:
    Contrast now starting blocks and a pool edge in which BOTH feet are anchored and a literal pushoff will benefit the athlete in a more rapid acceleration. Stored kinetic energy in the form of tensioned muscles will be released through the blocks/pool edge for a more rapid acceleration. At the pool edge, the swimmer tries to maintain a high arch push off to allow the body weight to increase velocity in its fall to the water (mass x acceleration, (G),=force=1/2MVsqrd.. The toes dig in to the pool edge for more lateral thrust and resultant increase in launch velocity. The speed swimmer must avoid jumping up too much from a crouched bent knee position on the starting pool edge, but must launch at a low angle to increase velocity. A higher arch is less efficient in that there is a trade off to attain fall velocity with flat longitudinal velocity. A high launch means the swimmer will penetrate the water too deeply instead of making a surface flop slowing recovery. The swimmer pre-sets the arms in the back for rapid acceleration forward at the starting gun. The more mass that can be "thrown" ahead, the more acceleration the swimmer will have at the start. The arms are full extended for the first thrust upon hitting the water.
    The sprinter also uses stored muscle energy which is released as the runner comes up and out of the blocks. The upward thrust increases "effective" body weight which increases friction to the track for faster acceleration. Both legs drive out from blocks.
In curling; however, one leg (slider leg) drives out from a hack and IT IS NOT THE HACK leg! It is the sliding leg and body thrust forward and down from the back-up and rock pullback position that gives maximum ACCURATE thrust. It is possible to use hack leg thrust (many people do) BUT it causes non-uniform weight control and misalignment in the drive to the brush target line of site. You want to "DRAG" that hack foot out of the hack as it is your RUDDER and extends the body line along the line of site line to the brush. Again, the hack foot/leg is the counter thrust force leg on a foot fulcrum and carries the equal and opposite forces generated from the slider foot and body drop acceleration forward thrust force only (and not extra boost)!!!
    It Is Not A Track Style Starting Block leg muscle thrust platform.
If you do not believe me: I can throw "t-line" weight without the use of a hack. This is possible because on keen ice it only takes 50lbs. of energy to propel the rock and I have enough friction on a gripper to counterbalance the body drop forward acceleration force. On keen ice (pictured), 14sec. H-H, I (my weight is 220lbs.), pullback only 6'' (fourth push position) as any more backmass will result in a too heavy/fast a rock. In the picture I am ready to start forward after only pulling back 6" from the aim position. This is the only way to control draw weight on super keen ice and that is by varying the mass behind the delivery.
    When going from 12sec. H-H ice to 14+sec. H-H ice, I use the no-pullback (-6")as my way of reducing thrust. On 12sec. H-H ice, I must use the normal rock back to the toe and body "pullback" to get enough thrust to make the t-line as I am pushing at "board" weight to get the t-line.
    On super keen ice, for most take-outs up to 9seconds, I need only the pullback to the toe with no rearward movement of the slider leg. For 7-9sec, H-H takeouts (second picture), I must bring the slider leg and body fully back to provide the mass x acceleration needed to fire the rock faster WITHOUT using arm boost.
    On keen ice, I have NOT ever seen a case where faster than 9secs. H-H is necessary even with the removal of 3 rocks (on average, it takes 1 second of speed per rock for removal out the back 12' for rocks in the house). Hitting accuracy is more important than non-used/non-needed excess hitting energy. What happens to even the pros. (witness last weeks cash spiels-2 pros. with 38% hit percentage) because they "ARM BOOSTED" instead of using slider leg drive to get the body and rock (as one) acceleration to make an accurate hit. Throwing MACHO hard is what costs the pros. and club curlers most misses! (I've been there and "damn" still do it). Any off the object rock center strike by a fast takeout shooter will usually result in the shooter not "sticking around" and how many games have been lost for that reason?
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