Fulcrum, Lever, Who?

Part II

This is another section from my book, “Fulcrum-Lever-Sport: A Handbook of BioMechanics for Improved Performance and Injury Prevention” aimed at explaining what the heck MRoss is talking about when he starts blabbing about Fulcrums and Levers.

Humans are comprised of four main levers: our two arms and our two legs. These levers attach to the torso by four main fulcrums: two fulcrums of the low back/pelvis (lumbopelvic) area, and two fulcrums of the shoulder (scapulothoracic) area.

When we compare the biomechanical system of the human body with the mechanical system of a seesaw, it’s clear that both systems use a variety of fulcrums and levers. In the human body, the scapulothoracic and lumbopelvic segments act as the main fulcrums, while the arms and legs act as the main levers. Similar to the basic mechanics of a seesaw, the amount of torque on the fulcrums is multiplied over the length of the levers. Whether we’re pushing, pulling, squatting, lunging, walking, or running, the amount of torque on the lumbopelvic and scapulothoracic fulcrums is roughly equal to the mass/weight multiplied by the length of the levers.

One difference between the biomechanical and mechanical systems is that, in the human body, there isn’t one specific hinge point at each of the fulcrums. Instead, a group of muscles surround the hinge joint. In the biomechanical system, this can be referred to as the fulcrum muscles. 

Another difference is that in the biomechanical system, the human body doesn’t automatically respond with catastrophic failure when a fulcrum is overloaded with torque. Instead, the body uses reactive muscle guarding. Reactive muscle guarding occurs because the human body has built in mechanisms that attempt to react, lockdown, and guard, and thus compensates for the overloaded areas in an attempt to prevent injury.

This is beneficial, as it helps us retain the ability to move and function, even when our system is out of balance. Reactionary and artificial guarding serves to bring the fulcrums to a level where they can handle the overload for a short period of time. However, this is only a temporary fix. The system is attempting to artificially stabilize something that’s unstable and improve the imbalance that exists between the fulcrums and levers.

When the body responds this way, we feel the reactive muscle guarding as tightness in our lower back, pelvis, and shoulders. Most experts will report that the way to fix this problem is to stretch out these muscles, and it’s not just clinicians that say this is the solution—it’s yoga instructors, CrossFit® instructors, and everybody in between that tells you that you need to stretch. However, this feeling is not a diagnosis. When an area feels tight, we may not know why it feels this way. It could be due to overload, imbalance, injury, or a problem with the range of motion.

In the case of overload and imbalance, if we try to loosen up our muscles, we’re undermining and working against the protective mechanism that’s stabilizing our overloaded fulcrum. While we may feel temporary relief, we’re engaging in a chronic tug-of-war with our own compensation mechanisms. Stretching and loosening the muscles may manage the symptoms momentarily, but it’s merely putting a Band-Aid on the problem, rather than resolving it.

Fighting with our body’s natural processes will only keep us in a chronic state of artificial compensation. That is, until the mechanism fatigues and is no longer capable of maintaining this artificial state. This is when catastrophic failure is possible. We’ve chronically pushed this imbalance to where our body can no longer compensate, and we’re pulling the rug out from underneath our already overloaded system.

Think back to Rule #1, which states that the fulcrum needs to be strong enough to withstand more than the amount of torque that’s produced by the levers. If we decrease the fulcrum’s ability to handle torque in this artificial, guarded state, we are further increasing the imbalance between the fulcrums and levers. This increases the risk of eventual injury and/or catastrophic failure.

In this scenario, the best thing to do is to work on increasing the stability, strength, and durability of the fulcrum muscles. The goal of an optimal biomechanical system is to have as much healthy function as possible. While we could decrease the load and torque on the fulcrum, this would also decrease our function and allow us to do less. Conversely, if we are able to increase the strength, stability, and durability of the fulcrum muscles, we will then increase and improve our overall function. We can fulcrum more, fulcrum longer, and fulcrum harder.

Rule #2 states that any sort of looseness, laxity, or instability in the mechanical system fulcrum will lead to catastrophic failure. In the biomechanical system, literature shows that the hallmark sign of instability of a joint complex is localized reactive muscle guarding of the muscles around the joint. This is similar to reactive muscle guarding discussed in Rule #1, when the fulcrums become overloaded by the levers. Reactive muscle guarding occurs when there’s overloading of the fulcrums, or in this case, if there’s instability in and around a fulcrum.

Rule #3 states that if we were to build the perfect biomechanical machine, we would begin with the fulcrum to establish stability. Rules #3 and #3a start with creating functional durability and strength of the fulcrum from a stability standpoint, rather than a mobility standpoint.

The challenge with building stability and durability is that when we embark on an endurance activity, we want to start training with mobility because there’s a desire to get moving towards our goal. If a person wants to run a marathon, their first thought is that they need to start running, because that’s the function that they’ll be doing. But, if we think back to Rule #3 and #3a, this would be putting the cart before the horse. Training this way is putting the levering phase before the fulcrum phase. What we need to do is take a step back and think about stability first.

On the first day of training for an event, our fulcrums and levers are already at established levels and are hopefully in balance. If we start by training our levers, this will create an imbalanced ratio. The lever arms will become more capable and more functional than the fulcrums. If the levers are stronger than the fulcrums, this imbalance can lead to injury, dysfunction, and ineffective performance. In an ideal model, it’s pertinent to engage the fulcrums to a certain level where they’ll be ready, durable, and stable. This will establish and maintain the optimal fulcrum-to-lever ratio.

If the fulcrum is more stable and more durable than the lever, no injury occurs. Increased stability decreases the risk of injury—if it doesn’t move, it doesn’t get injured. When your lever arms are producing more torque than your fulcrums can withstand, injury occurs. This happens when you’re unstable or out of balance. The system doesn’t perform as well because the fulcrum wasn’t designed to carry the load that you’re putting onto it. At some point, it will get overloaded and it will fail. This is a common cause of injury.

As always, if you have any questions. please feel free to email me at ross@drtri.com

-MRoss