Introduction
The Human Movement System (HMS) is a beautiful yet intricate system. In layman’s terms when the HMS is functioning optimally the body is said to be firing on all cylinders. When there is dysfunction in the HMS, body parts start to wear out and break down. But what exactly is the HMS? The HMS is the skeletal, nervous, and muscular systems working interdependently to produce optimal neuromuscular control. In order for optimal neuromuscular control to be achieved the body must start in an ideal posture state. When the body is properly aligned there are normal length-tension relationships, force couples and joint arthrokinematics. The muscle has an optimal length that allows it to produce the most tension. This is termed the length-tension relationship. When the optimal length-tension is disrupted there is dysfunction which can result in reciprocal inhibition. As noted the muscles function interdependently of each other. The agonist may produce the prime movement but it is also the work of the antagonist, synergists and stabilizers that allow the entire movement to happen. It is the synergy of all the muscles and their independent actions that provide for an unhindered force couple. If this force couple is disrupted it will result in synergistic dominance where the synergists and stabilizers will take over for the prime movers, hence, doing a task they were never designed to do and increasing the risk of injury. The joints also have an optimal range of motion. When these normal ranges of motion are disrupted joint arthrokinetic inhibition can occur affecting the muscles surrounding the joint. When the HMS is functioning optimally there is optimal sensorimotor integration, neuromuscular efficiency and tissue recovery. When the system is disrupted there is altered sensorimotor integration, neuromuscular efficiency and tissue fatigue and break down.
Often the first thing that presents itself is the symptom of a dysfunction in the HMS. As health professionals I want us to start looking past the symptom to identify and address the cause. This is very applicable from the client who has back pain to the soccer player with Iliotibial Band Syndrome (ITBS). What problems may arise from poor posture? If an athlete has a weak hamstring what are the parts of the HMS that may be altered? We must ask ourselves where in the kinetic chain is the problem occurring?
The Trickle Down Effect
The most common lateral, overuse injury in runners is ITBS (Falvey et al., 2010; Grau, Maiwald, Krauss, Axmann & Horstmann, 2008). The Iliotibial Band (ITB) is a thick fibrous tissue that runs from the Tensae Fasciae Latae (TFL) to the lateral femoral epicondyle. Patients and/or athletes will usually complain of a lateral knee pain. At first glance one may think that the problem is isolated to the lateral, distal part of the femur. But as was discovered earlier the HMS functions as an interdependent system. The laymen train of thought would be that ITBS must be caused by a tightITB. Therefore, stretch the ITB and this should solve the problem. The professional says let’s look at the whole kinetic chain. Devan, Pescatello, Faghri & Anderson (2004) studied 53 NCAA Division 1 female athletes and found that a tight ITB did not lead to ITBS but a decreased Hamstring to Quadriceps ratio (H:Q), as well as, genu recurvatum increased the athlete’s risk to overuse injuries at the knee. Another study linked ITBS to decreased hip adduction, less internal and more external rotation of the tibia and less eversion at the subtalar joint (Grau et al., 2008). Findings such as these mentioned above and understanding the dynamic relationship of the HMS can also help the athletic trainer and/or physical therapist when diagnosing and treating injuries. A study by (Falvey et al., 2010) on 20 human cadaver ITBs suggested that the treatment should be directed at lengthening the TFL and gluteus maximus rather than the ITB. Fredericson & Wolf (2005) mentioned another example of treating a part of the kinetic chain not necessarily near the presenting problem. They suggested that a tight gastrocnemius and soleus leads to decreased dorsiflexion leading to increased ankle pronation and knee flexion, hence, increasing the risk of ITBS.
Conclusion
For optimal function of the human body an interrelated muscular, nervous, and skeletal system termed the Human Movement System must be viewed in its entirety. As a health professional we should ask ourselves- What is the cause of the problem not just focus on the symptom or presenting problem.
References
Devan, M. R., Pescatello, L. S., Faghri, P. P., & Anderson, J. J. (2004). A prospective study of overuse knee injuries among female athletes with muscle imbalances and structural abnormalities. Journal Of Athletic Training, 39(3), 263-267.
Falvey, E. C., Clark, R. A., Franklyn-Miller, A. A., Bryant, A. L., Briggs, C. C., & McCrory, P. R. (2010). Iliotibial band syndrome: an examination of the evidence behind a number of treatment options. Scandinavian Journal Of Medicine & Science In Sports, 20(4), 580-587.
Fredericson, M., & Wolf, C. (2005). Iliotibial band syndrome in runners: innovations in treatment. Sports Medicine, 35(5), 451-459.
Grau, S., Maiwald, C., Krauss, I., Axmann, D., & Horstmann, T. (2008). The influence of matching populations on kinematic and kinetic variables in runners with iliotibial band syndrome. Research Quarterly For Exercise & Sport, 79(4), 450-457.
Written by PJ Musilli CSCS
