Saturday, January 26, 2019

A treatise for skiing at the highest levels.

           The Use of Muscles and Movements in top-level World Cup Skiers

The previous Post (one article below) in which I demonstrate the differences between world cup skiers prompted me to offer a more complete explanation as to what is happening in detail. The best racers have figured this out, the less efficient show more rotation and leaning, without the effective coiling shown by the best. 

Perfect preparation for a release, Hirscher with a coiled body holds his counteracting until the critical moment.

The energy that Helps with Release and Transition
There is an extraordinary reaction in athletic activities due to the response of a muscle to stretching. This reaction exists in all sports where a muscle is stretched beyond its resting length. In certain sports, such as golf and track and field, the reaction is known and exploited, while in skiing the influence of the muscle reaction has not been recognized.

Releasing the Tension in a Stretched Muscle
When a muscle is stretched beyond its resting length it creates tension within the muscle. When released from its stretch, just like a spring, the muscle will pull back to its original length, without an active effort to contract that muscle. You can use this recoil or release of tension on its own, to create some movement without active effort, or you can use it to augment your effort — after the moment of stretch, the muscle can contract more strongly than without the pre-stretch.

In the body, there are many opposing muscle sets in which one can be used to pre-stretch the other. Think, for example, of counterbalancing. If you contract the muscles on the right side of the torso, pulling the right ribs toward the right hip, then the left side of the torso will be stretched. In order to release the tension developed in the left side, one must only relax the right side. If you alternate the counterbalancing movements rhythmically from side to side, then each time that you relax one side, you get the spring effect on the other side of the torso that will start to pull you in the new, desired direction.

Hirscher holds his coiled body until he's ready for a transition.

Managing Actions and Reactions
Many people who participate in sports never get the sense of body movements that are a reaction; they only sense and perform active, premeditated efforts. In our counterbalancing example above, they might sense the effort to crunch one side then the other, without ever being aware of the “spring back” of the torso that results simply from relaxing or ceasing their efforts. There is a different sense of control between active efforts and reactions.

When you release stored energy, you may or may not be able to control the reaction that results once it starts. The key to success is proper preparation. Consider the release from a ski turn: if you are in balance over the skis and ready to tip the feet and counterbalance in the new direction, then an energetic release will create the desirable result of High-C angles. If you are leaning back with your arms and torso rotated, then the energy from release will likely cause you to rotate further and probably fall backwards. This completely undesirable reaction is due to poor preparation prior to release. With correct preparation, you can simply relax one or more parts of the body, let the stored energy take you, and know that you will achieve the desired result.

Efficiency of PMTS Technique
When I developed PMTS technique, I based it in mechanics and dynamics. My premise was that efficient movements that produce the desired results with the skis would create progress and results for all skiers. In the process of developing and teaching the technique, I have found that effective technique not only makes the skis do what you want for one turn, it also prepares the skis and the body to take advantage of the reactions of one turn for performing the next. These reactions include the energetic rebound of ski equipment and the release of stored energy in muscles under tension. Effective technique produces the desired results in one turn, the reactions that help with linking turns, and the preparedness to unleash these reactions without having to consciously control their outcome.

Diminished Performance from Incorrect Technique
If you are trying to push your body from one arc to the next, you will never experience skiing as it is intended. Skiers are often taught to push their bodies downhill toward an imaginary point, toward the center of the upcoming arc, or simply up and down the slope. This pushing effort, an extension of the new outside or stance leg, is intended to move the body from one side of the skis to the other, and to create body and edge angles. The deliberate extension requires effort, and it outweighs any rebound or release energy that might be available to assist with the turn transition. Indeed, the turn that results from an energetic extension often lacks the sort of rebound energy that I described above.

Your Previous Athletic Experiences May Not Be Helping
Sometimes, previous athletic experiences and movement familiarity may hold us back from experiencing low-effort, high-performance skiing. Virtually all sports and activities require a “push-off” type movement of the leg. This is what we term a concentric contraction of the quadriceps ( the thigh muscle on the front of the upper leg). In a concentric contraction, the muscle shortens as it is tensed. Starting in the schoolyard with running and jumping, we have trained our legs to extend with contraction of the quadriceps muscle. Continue into soccer, football, basketball (run, cut, and jump); track and field (more running and jumping); ice or inline skating (push off hard to skate faster). All these sports train us to push off the ground by extending the leg, the concentric contraction.

Alpine skiing requires different types of muscular contraction, including isometric — the muscle stays the same length while tensed, not straightening or bending the leg — and eccentric
— the muscle lengthens while contracted, causing the leg to bend more. Here are examples of each type of contraction. Imagine that you are holding a heavy box that you need to set down on the floor. Holding the box, slowly squat down toward the floor. This is the eccentric contraction of the quadriceps. When you are part way down to the floor in your squat, stop and hold that position for a moment or two — that’s isometric. Then, stand back up, still holding the box. That’s a concentric contraction.

Even though we are most familiar with the concentric contraction, and we train it most often, having strength, balance, and control in isometric and eccentric contractions of the quadriceps will be more important in skiing. The hamstrings will contract to maintain fore/aft balance while the quads are controlling the extension or the flexing of the leg. What does this imply about cross training for alpine skiing? Well, vertical jumps and leg extensions are not the most important movements to practice.

If we list movements of the legs in order of their importance in skiing, tipping the feet would be first, followed by flexing or bending the legs. Taking it further we’d go to retracting the legs — an active effort to shorten or bend them, not just a passive relaxation — which is used in quick, short turns in bumps, steeps, and slalom racing. This points to the fact that pulling the feet and legs toward the body is more important in skiing than pushing the body away from the feet.

What Efficient Leg Movements do the Skis
If you tip your skis onto the new edges in the upper part of the arc, before the skis turn or travel downhill, and establish solid balance with counterbalancing and continued tipping, you are starting the new arc correctly. The skis’ sidecut will engage in the snow, with the result being an arc that curves into the fall line. Increase the edge angle by flexing (bending) the inside leg and tipping more while staying in balance and riding the skis through the arc. Extend the outside leg enough the stay in contact with the snow and to prepare for the loads through the middle and bottom of the arc. These movements create a great turn. As the arc of the skis brings you back across the hill, relax the outside leg (don’t contract the thigh muscle as hard). When you reduce your resistance to the loads at the bottom of the arc, the outside leg will bend and your body will start to travel downhill, across the skis, and into the new turn arc without any need to push.

The motion of the body out of the old arc, into the new arc, is a reaction to relaxing the old stance leg. It’s a result of the proper preparation throughout the arc. With it comes a certain sense of uncoiling and unfolding from the angles of the old turn. It’s often an unsettling sensation for skiers who haven’t felt it before. Most skiers and instructors never feel this uncoiling because they prepare for and perform their “release” by extending the new outside leg, pushing themselves out of the old turn. This pushing movement completely ignores the stored energy in the arc of the turn; if there was stored energy in their skis and body from the previous arc, it is dissipated without contributing to the start of the new turn.

If you ski with correct technique, starting the release by relaxing the legs and allowing the legs to bend, you release the stored tension in the muscles and the rebound of the ski. The energy that you stored in your body and skis through the arc is made available to help with the turn transition. Bending the ski through the turn arc — which is produced by using the leg movements described above — is necessary for creating rebound. Not only will bending the ski tighten the turn arc and assist with speed control, it has the desirable effect of making energy available at the release.

Creating Tension in the Muscles
Muscles are stretched, creating stored tension, through several efforts of PMTS technique. Counterbalancing stretches one side of the torso while the other side is contracted. Counteracting twists the torso, stretching many muscles. Deep flexing of the inside leg stretches the hamstring and gluteus muscles. Most of the muscles subjected to stretching, and thus the stretch response, are on the free-foot side of the body.

If you are skiing with PMTS technique, then you are either performing this stretching already, or you are on the verge of it. Remember that to produce the stretching response, the muscle has to be stretched beyond its relaxed length. So, your range of motion needs to be sufficient to stretch the muscles. If you are counterbalancing, you can’t just tighten the muscles while the torso remains in line with the legs; you have to tilt the torso enough to stretch the muscles on the free-foot side of the torso. You have to make an angle between your torso and your legs.

Next, in order to derive a benefit from pre-stretching the muscle, you have to release the stretch and contract those muscles right away after stretching — you cannot wait, or the benefit is lost. What does this mean in skiing? You cannot hesitate at release and still benefit from the pre-stretch. At transition, if you flatten your skis and then pause, gathering the confidence to tip further, then you’ve lost that additional impetus, that boost. Overcoming the hesitation, though it may feel like you are giving up control, will require less effort and will put you in the new arc sooner and faster.

When you relax to release from a turn with pre-stretch, at first you might not know what the outcome will be. We can tell you that the result is great, that you’ll go exactly where you want to go, but you’ll develop trust and confidence sooner if you begin on more gradual terrain.

Pre-Stretch in Counterbalancing
To build the correct tension in the free-side muscles using PMTS technique, after the release, tip, engage, keep flexing the inside leg and extending the outside leg. The energy that you build through the arc, both in the bent ski and the stretched muscles, can be “stored” until the time of release, or it can be slowly dissipated through too-early bending of the stance leg, or a late or too-slow release. When you maintain the stored energy until release and then flex to release, your body will start to move across the skis in a beautiful way. If you tip the feet toward the new edges at the same time, you can easily tip all the way to the new edges. This should be performed in a relaxed manner, not rushing or panicking.

As the feet are tipping from the old to the new edges, the upper body is tilting from the old to the new direction. This is where pre-stretching helps. At release, as the legs are relaxed, so should be the muscles in the stance side of the torso that were responsible for counterbalancing in the old turn. This releases the stretch in the muscles of the free side, making them momentarily “stronger” as they begin the counterbalancing effort for the new set of edges. You can counterbalance sooner and harder with the benefit of pre-stretch, readying you to balance on the new, High-C edges.

The combined results of ski rebound and counterbalancing pre-stretch make for a quicker than usual transition to the new edges. Though this might give you the sense that the hips are leading downhill through the transition, don’t actually push the hips. Once you are on edge, stay balanced and the ski will carve into the High-C part of the new arc. As long as you do not twist or turn the feet, you’ll be fine and you’ll be in control. Keep flexing and tipping to tighten the turn arc.

Pre-Stretch in Counteracting
If you have developed proper and sufficient counteracting movements through the arc of the turn, then the pre-stretch of the opposite set of counteracting muscles will give you a stronger turn transition. This is especially helpful on steep terrain and icy snow.

Once tipping angles are established and the skis are gripping on edge, counteracting movements align the skeleton so that the whole body can support the load of resisting momentum through the arc. Counteracting movements coil the upper body, down to the hips and lower back, relative to the lower body. If you counteract hard enough to stretch the opposing set of muscles, then the relaxation at release will unwrap you quickly from the old angles, and give you a head start into the angles and counteracting movements of the new turn. This works in tandem with the counterbalancing movements of the previous section. The result is a quicker transition, and an earlier arrival at balance on and engagement of the new edges.

Few show this perfect preparation.

Hirscher uncoiling, relaxing releasing his stance leg from holding to retraction.
Relax for Better Performance
As I pointed out earlier, we are accustomed to using and feeling strong extension of the legs in many sports and activities. When we bring this familiar activity into skiing, though pushing the body away from the feet may feel strong and forceful, extension at the wrong time diminishes the performance of the skis, makes you lose balance, and overall is simply a waste of effort and energy.

When you balance with the skis, rather than pushing away from them, you give the skis a chance to bend and store energy; you get better grip and a tighter radius in the current turn, and an easier transition to the next. Combine this with counterbalancing and counteracting movements that are strong enough to pre-stretch their opposing muscles, and you’ll get quicker and easier turn transitions that you ever thought, simply by relaxing. You’ll have a new elegance and effectiveness in your skiing, with an economy of effort. that’s a great goal for the coming season.

Written By Harald Harb, President, Harb Ski Systems and PMTS Trainer. Volume 7, Number 1

October 10, 2006, edited, updated January 2019.

No comments: