Looking at this ever growing sedentary positioning in regards to the Human Movement System, I believe that the foundation begins with the understanding of Neuromuscular Efficiency. That is, our body operates on the ability to create the right amount of force, on the right joint, at the right time. Simply stating, our bodies do not want to work harder than they are required to. This Neuromuscular Efficiency that is controlled by our Central Nervous System(CNS) recruits the appropriate muscles to provide the proper amount of force at the necessary joints to create the desired movement.
Throughout life, our body adapts to movements that we perform in normal daily living (motor learning), and our CNS becomes conditioned to activate certain muscle patterns to create this desired movement. Ideal alignment is crucial throughout each movable joint and if any joint is out of alignment, the CNS will draw upon additional means of muscle movement and correction to create this desired configuration of movement (Sahrmann, 2002). These pre-programmed patterns of movement are constantly modified to react appropriately to external forces such as gravity, ground reaction forces, momentum, and external loads or force around a joint (torque) (Neumann, 2010). As life progresses, we are introduced to dysfunctions of the human movement system through injuries, muscular imbalances, and faulty posture and mechanics. These possible misalignment’s are the beginning stages of micro trauma to the joints and supporting structures (Sahrmann 2002). When this occurs, as stated by the National Academy of Sports Medicine (NASM), relative flexibility through the kinetic chain, our body will always take the path of least resistance (Clark 2011). When are bodies are subjected to injuries that affect any of our optimal neuromuscular control such as arthrokinetics(movement around a joint location), our bodies will begin to exhibit dysfunctional movement patterns such as reciprocal inhibition, synergistic dominance(when smaller muscles take on the role of larger muscles) or altered arthrokinimatics. These muscle dysfunctions can result from arthrokinetic inhibitions, relative flexibility, and pattern overloads (Clark and Lucett 2011)
A common neuromuscular dysfunction is what was stated above, referred to as reciprocal inhibition; where an overactive or tightened agonist muscle(the largest muscle creating force) can create a decrease neural drive to its antagonist muscle(the largest muscle that is opposite of the agonist). Simply stating, if a primary mover is over active or tightened from over use or lack of extensibility training, that muscles’ direct antagonist will not receive the direct stimulus from the CNS and will call upon a synergistic muscle of that antagonist to help perform the desired motion. This reciprocal inhibition leads to synergistic dominance. When this occurs, it creates arthrokinetic inhibition, which in turns will eventually lead to joint or muscle injury as an unbalanced force will be created on a joint and possibly an adjoining joint. As an example, it is common that one might have weakened or underdeveloped gluteus maximus muscles which are responsible for the extension of the hip (the push off in running). The smaller, synergistic muscles that help with this are the hamstrings found in the back of the legs. When the glutes are underactive and not supporting hip extension, the hamstring muscles must help “pick up the slack” and can eventually “lock up” in what’s known as a “charlie horse” which many of us have experienced while running.
Sahrmann 2002, clearly states that “a restricted joint motion is considered the consequence rather than the cause of movement faults.” This treatment approach takes a much broader view than treating or rehabilitating the joint action that is causing musculoskeletal pain (MSP). This optimal neuromuscular functioning of the human movement system shows the vast importance on the fitness professional to create and design exercise movements that work through multiple planes of motion and do not just focus on the isolated movement of a joint. Length-tension relationships and force-couple relationships demonstrate how a single muscle can alter the kinetic chain of muscular patterns and affect multiple joints in the HMS.
For more information or to read other articles, visit www.darrenstrohces.com
Clark, Micheal, and Scott Lucett. NASM Essentials of Corrective Exercise Training. Philadelphia, PA: Lippincott Williams & Wilkins, 2010. Pr
Sahrmann, S. (2002). Diagnosis and Treatment of Movement Impairment Syndromes. St. Louis, MO: Mosby, Inc.