Injury Prevention for Ice Hockey – Part II: Understanding the Governing “Rules”
We just finished discussing collisions as the primary cause of injury in hockey and looking to biomechanics or movement strategies as tools for prevention. Unfortunately these tools are commonly overlooked. I alluded to force distribution as a primary goal and would like to discuss why this is important. Then we will explore how to use it for injury prevention and why we are focusing on the “central cylinder.”
WHY FORCE DISTRIBUTION:
Think of your body as a team with all of the muscles, ligaments, bones, and tendons contributing in specific ways. Just like on the field, or in this case- on the ice, all of the team members need to do their part to be successful. The same is true in our bodies. Force distribution essentially makes sure every team-member knows their role and does their part.
Let’s compare two instances when the body takes an impact:
- Poor Force Distribution: The body takes an impact and (let’s say) 1 or 2 muscles or body structures do all of the work. The rest of the “team” of structures never get a chance to play. The 1-2 structures absorbing all of the force not only have a harder time at successfully completing the goal, but they fatigue and wear out much faster. This puts those structures under more strain and at more risk of injury.
- Proper Force Distribution: The body takes an impact and (let’s say) 10 or 15 muscles and body structures divide all of the work. Each teammate contributes where they should and every team member is part of the strategy. There may still be “key players” that take on more work than others, but there is a strategy to how much and when these players are required. Every player has a chance at recovery/rest and no single player is carrying the team; therefore risk of injury is reduced.
WHY START AT THE CYLINDER?
This area has large muscles which work in “chains” to transfer movement, forces and energy from the upper body to the lower body and vice versa. These chains, when properly functioning, allow the maximum support and “team” function throughout the entire body (not just the trunk).
In addition, this region forms our “foundation” or base of support for all movement. In order to move our arms or legs, keep our balance, or absorb forces, we must first create stability at the center.
WHAT IS THE CYLINDER:
This definition changes depending on what resource you reference or what application you are using. For my purposes, I would like to focus on the very center: the bottom of the ribcage to the bottom of the pelvis. The adjacent areas are equally important, however, for brevity and simplicity sake, I believe this region is a great place to begin.
Picture a cylinder. It has a “roof,” “floor” and circular walls. In our body, there is a cylinder containing:
- Roof: Respiratory diaphragm. This parachute shaped muscle is located toward the mid to bottom of the ribcage, depending on what phase of breathing you are in. When you breath in, it contracts, pulling down toward the abdomen and ending approximately at the bottom of the ribcage. It has two halves- a left and a right hemisphere. It is thin, but has connections onto many of the bony structures in the chest cavity.
- Floor: Pelvic Floor, also known as the Pelvic diaphragm. This parachute shaped structure is made up of several muscles and connecting fascia. It has several functions, one of which is to support the pelvic and abdominal contents when they are put under pressure- ie when the respiratory diaphragm pushes down the contents of the abdomen. This is exaggerated in activities such as lifting heavy weights or items, but it happens to various degrees even at rest.
- Walls: Abdominal muscular. There are several muscle layers and many muscles which make up this complex. It wraps all the way around from bellybutton to spine on both sides of the body and extends from the ribs above to the pelvis below. (Other body structures are also included here, but are not discusse
d so we can focus on the more “active” structures.)
HOW THE CYLINDER WORKS…
The basic premise is that as one portion of the cylinder is contracted, the other structures resist the load causing an increase in pressure within the cylinder. Picture a piston moving inside of a cylinder; as the piston presses down, the walls and floor remain solid. This causes an increase in pressure within the cylinder. See the diagram below to see the cylinder in action in our body.
Here is an example as it applies to Hockey: When the body collides, let’s say with another player, the muscles surrounding the abdomen quickly contract. No matter where in the body impact occurs, these muscles contract to provide stability to the body. Meanwhile, the roof and floor stay intact and resist this change in force. The resulting increase in pressure inside the abdomen is known as Intra-abdominal Pressure or IAP. IAP provides several things:
- It provides extra stability for the spine, the rib cage, the pelvis and more through increased pressure (think how rigid a ball is when full of air versus when partially deflated).
- It takes a local force that occurred in one specific place and spreads it out into a larger area (this is like pushing on your ball with a needle versus your flat hand at equal pressure- which is more likely to do damage?)
- It allows more body structures to absorb the incoming force. Initially the impact was sustained, let’s say at the shoulder. Now the forces can be absorbed not only by the shoulder, but also the abdominal muscles, the cylinder structures, IAP, and more.
COMMON FAULTS IN THE CYLINDER…
There are many things that can go wrong with coordination in this area. Coordination of muscle activity, strength, and endurance of each player’s cylinder muscles are very important. If an imbalance is present, the entire function will be weakened. One very common error which is also easy to identify, is in the simple starting position of the cylinder.
In order to work properly, the roof, floor and walls must all be lined up and stacked. This means the pelvis and the rib cage should be stacked on top of each other and parallel. If this position is altered, the pressure inside the cylinder becomes
focused on one area instead of dispersed. Again, picture a cylinder, this time one that has been bent somewhere in the middle. As the – the piston compresses, the force inside the container is focused on one wall and not evenly distributed; if not build to handle the different loads, the cylinder may be at risk of breaking.
Here are some common postures which compromise the neutral position (keep in mind our hockey players are not standing still, but moving….but the basic concept and position is still required!)
Now that we more fully understand why the cylinder is important and what we are looking at, let’s start talking about what we can do for injury prevention for ice hockey. Stay tuned for Part III as we dive into some great home care tools and techniques to improve your cylinder. In Part IV we will look at some case studies and discuss some of the ways these concepts apply in action!