Fulcrum-Lever-Sport : Part 1 - The Basics

Basic Mechanics

Structural Engineers, Architects, and Builders/Contractors all know that in any mechanical system the most vital piece of a functional machine is the “Fulcrum”.  The Fulcrum needs to support it’s own weight plus the weight of the entire system (including the “Levers”), and in many cases, repeated repetitions of loading weight upon the Fulcrum.

In simple terms, the Fulcrum is the point at which the Lever of a machine moves or ‘articulates’ around a specific point. Think of a child’s teeter-totter.  The point in the middle where the teeter-totter is supported would be the Fulcrum. In this example, the Fulcrum needs to be sturdy enough so the teeter-totter doesn’t collapse under the weight of the two people on the ends of the arms.  Any slack, give, or weakness at the Fulcrum point and the system is compromised and thus creates the potential for failure of the entire system.

This is why the Fulcrum is built first and foremost to a degree where it can support the weight of the lever and load on the ends, plus a huge stable margin of error to avoid failure of the system at any cost.  Hence, the Fulcrum is built to be the most stable part of the entire system.  Once the Fulcrum is built and sturdy enough, then and only then, are the lever arm(s) attached to it, and then a force (children on the ends of the teeter-totter) can be applied to the lever arm(s).

When building the fulcrum and lever system, the architect/engineer can determine how much weight is being applied to the Fulcrum point based upon the dimensions of the entire system.  This ensures that the fulcrum is not overloaded with the lever arms or with whatever weight (child) is going to be placed on the ends.  This weight on the Fulcrum point is referred to as the “torque” on the Fulcrum.  And in physics terms, torque equals (roughly) the length of the lever arm multiplied by the weight on the end.  For example, if one end of the teeter-totter is 3 meters long, and the child on the end weighs 30 kilograms, the resultant torque on the Fulcrum is 3m x 30kg, or 90 units of force.  An interesting point is that the same weight child would exert much more torque on the Fulcrum with only making the arm of the teeter-totter 1 meter longer (4 x 30 or 120 units).  We can see how a small change in the length of the Lever arm results in much more torque on the Fulcrum.

At this point, you may be asking yourself, “What does this have to do with my CrossFit training?”  Simply put, this basic concept of physics and construction is perhaps the single most important part of ANY training program, whether it be strength or endurance focused.  It also is the single most overlooked concept in the majority of training that is available, and the most common source of injury and performance limitation. In this next section, I will explain why.

Basic Biomechanics

In very simple terms, Biomechanics is the study of human movement in mechanical language.  We talk about movements of the arms, legs, and body in terms that we derive from non-human mechanical systems.  Concepts like torque, force, Fulcrum, mass, Newton-meters, and levers also apply to the human body when discussing movement and movement patterns.  More importantly, these concepts and terms are extremely important when looking at injuries and injury prevention.

If we take a very simplistic view of the human body we can see that we are simply four levers (2 arms and 2 legs) attached to a central Fulcrum.  A bit more specifically, we are four levers attached to a group of structures that form a “Functional Fulcrum Group” (FFG).  Unlike a non-human mechanical system, we do not simply have one Fulcrum point that the levers attach to, but rather a series of bones, joints, muscles, and ligaments that work together to create the FFG.  When we create force at the end of one of our levers, we stabilize our FFG and create movement.  A very simple example would be the movement created by levering our leg against the ground, otherwise known as walking.  We our hold our FFG (Fulcrum) stable and press against the earth (Force) with our leg (Lever) and walk.  In the average human during the gait cycle, there is between 3 to 7 times our body weight transmitted to our FFG depending upon whether we are walking, jogging, or running. 

So for a 180 lb person, this is between 540 and 1260 units of force (at least) being applied with each step.  That is a lot of force!   Not to mention, this is with a single step.  The durability of the FFG needs to be tremendous to withstand this repeated force being applied over the length of a workout.  This brings up perhaps the most important aspect of the FFG, durability.  Strength is important, but durability is even more important, especially when it comes to training.  The ability to withstand this force once or twice is good, but we are looking at roughly 1,500 to 2,000 steps in as little as a mile.  We can see that if the durability of the FFG is not optimal, then a lack of performance ability (the most extreme lack of performance would be not finishing) can occur.  And, a lack of performance ability can easily result in injury.  If I am not running well, it is easier for me to become injured.

From here, I will discuss where a split in methodology of training occurs.

But first, we must briefly delineate the difference between the “F” and the “C” word.

Fulcrum vs. Core

When we look at the majority of “core” training exercises they are primarily focused on training the abs and obliques.  This is akin to preventing injury of your triceps by training your biceps.  While strong biceps are needed for optimal function of the upper arm and may contribute to decreased injury of the upper arm as a whole, the injury rate of a specific muscle (triceps) is only achieved through direct training of that specific muscle (triceps).  The justification is often heard that training the abs and obliques will help to tighten the midsection and stabilize the back as a whole.  Not only is this NOT supported in research; it is not supported by biomechanics. 

This is where the distinction between “Core” and “Fulcrum”, or Functional Fulcrum Group (FFG), is very important.  In the human animal, the primary movement of the lower half of the body is forward and the primary FFG muscles that support this movement are the low back, glutes (butt), and hamstrings.  These muscles work primarily to stabilize the trunk while the legs propel us in a forward motion.  Our favorite motion, the squat, is also a primarily ‘forward’ type motion.  It is dependent on the FFG muscles stabilizing the torso, while we lever with the legs into an upright position.  Training any other muscle than the low back, glutes, and hamstrings is not effectively training the FFG.  Even more important is stability and durability of the FFG.  The majority of “Core” training to prevent injury, specifically to the back, is often accompanied by flexibility training and incorrectly justified by the phrase, “A flexible spine is a healthy spine”.  This has not resulted in lower occurrences of injury rates and is NOT supported in research. Any excess flexibility of the FFG will increase the risk of injury and decrease performance.  A flexible FFG is not a healthy FFG.  It will ultimately fail under any sort of repetitive load.  In fact, the research has shown in numerous cases that increased flexibility is not optimal when levering against the FFG especially in runners who use their levers over extended distances.

This change in semantics or paradigm shift from core to fulcrum (FFG), whichever you want to call it, is a subtle but huge differentiation that must be adhered to if optimal training is your goal.  Addressing the strength and flexibility of the “core” will result in less than optimal movement performance as well as increased risk of injury.  While focusing on fulcrum (FFG) training will improve functional durability of the system.

Next: Fulcrum-Lever-Sport : Part 2 - Back Extensions