I am doing a corrective training program for a client who sits behind a desk using a computer for 8 hours per day and then commutes out of London on a train journey that can take up to 90minutes. How long does it take for the process of Adaptive Shortening to take place? On talking to another trainer they said that it takes as little as 10 minutes for this process to start. If this is true what is actually happening at cellular level in the muscle? I would be grateful if you could answer my question or write a future article on this subject or even direct me to a journal or book.
How long does it take for adaptive shortening to occur? Well, there are many factors that determine this such as prior injuries, how long the adaptation has been in place, etc. Basically, it will be different for every person.
The effects of posture are additive as time progresses. When posture is chronically at fault, every wrong move and individual joint strain tends to accumulate. Postural alignment depends on the resting length of the soft tissues, including muscle, that surround each joint. Abductors and adductors, or flexors and extensors, produce opposing forces and moments.
These changes can encompass not only the muscular but the fascial system as well. When bad postural habits are consistently utilized, persistent fascial dysfunction can lead to contractures in the fascial sheaths. The result of this "tug of war" determines a joint's habitual position or posture.
A posture is a kind of immobilization, and animal studies show how muscles' resting lengths and length-tension properties adapt or change when they remain at a fixed length for weeks or months. Over time this induces semi-permanent changes in posture, usually with the fascia on one side of the body being over-stretched, and the fascia on the opposite side is placed into a shortened, retracted state. A common example of this leads to the development and progression of the "hunchback" posture
that occurs once the upper body becomes displaced interiorly (1,2).
Over time, the fascia is redistributed, altering the joint position. A muscle that is chronically elongated adds sarcomeres. Over time, its resting length increases and its length-tension curve shifts rightward. A muscles that is chronically shortened loses sarcomeres. Over time, its resting length decreases and its length-tension curve shifts leftward (3,4). Fascial restrictions also place an enormous amount of compression force on affected joints. This situation results in muscle imbalance and altered joint mechanics. It can disrupt balance, and it can also produce a multitude of muscle and joint pain syndromes. These muscular and fascial changes are biomechanically inefficient since the body supports itself by passive muscle and connective tissue tension in order to minimize energy usage. Exercise restores fascial integrity, posture and bodily function. Connective tissue can be quickly regenerated. As the fascial framework shifts into a more correct position, spatial relations of the embedded nerves and vascular structures return towards their normal position. This offers an opportunity for improved local tissue nutrition and can benefit the functioning of the nervous system (1-4).
- Baker, J.H. & Matsumoto, D.E. (1988), Adaptation of skeletal muscle to immobilization in a shortened position. Muscle & Nerve, 11, 231-44.
- Lieber, R.L., & Friden, J. (2002). Spasticity causes a fundamental rearrangement of muscle-joint interaction. Muscle Nerve, 25, 265-70.
- Williams, P.E., Catanese, T., Lucey, E.G., & Goldspink, G. (1988). The importance of stretch and contractile activity in the prevention of connective tissue accumulation in muscle. Journal of Anatomy, 158, 109-14.
- Williams, P., Watt, P., Bicik, V., & Goldspink, G. (1986). Effect of stretch combined with electrical stimulation on the type of sarcomeres produced at the end of muscle fibers. Experimental Neurology, 93,500-509.