I am currently researching the effects of asymmetrical loading (with regard to leg length inequality/discrepancy).

I’d like to use the correct/up to date terminology when referring to the micro and macro biological factors of muscular tissue.

1) Trunk rotation activates lumbar paraspinal muscle contraction for balance correct (Knutson, 2005; Crawford et al., 2018).

2) Motor neuron changes alter neural firing: “repeated activation decreases excitability to synaptic input,” (Wan, et al., 2017) thus resulting in impaired muscle force and muscle fatigue.

3) Hypertonicity is increased muscle tone. “Hypertonicity is largely the result of supraspinal inhibition to the spinal cord” (Guccione, et al., pp275, 2011).

4) Muscle fatigue neural contributions: supraspinal/motor cortex excitory drive to motor neurons is lower (Wan, et al., 2017).

While considering the crossbridge and it’s process (the molecular globular myosin heads), drawing the adjacent actin filament into the A band of the sarcomere, I’d like to correlate the appearance of this in hypertonic of tissue.

Earlier studies have asserted that there would be too much overlap of myosin heads (Sahrmann, 2002) and I understand how this is possible. I also understand that there are many factors which affect the strength of the hypertonic muscle with regard to the cross-bridge activation (e.g. neural activation, calcium, ionic channels, ATP, etc.)

If some up to date information/literature, with hypertonicity and the strength of hypertonic tissue directly in mind, could be made available it would be appreciated!

(I’ve added a few direct references, though have read wider research on the direct topics).

1. Crawford, R., Gizzi, L., Dieterich, A., Mhuris, A.N., Falla, D., (2018) “Age-related changes in trunk muscle activity and spinal and lower limb kinematics during gait”. PLOS ONE 13(11). Available: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0206514

2. Guccione, A.A., Avers, D., Wong, R., (2011). Geriatric Physical Therapy, 3rd edn. USA: Elsevier.

3. Knutson, G., (2005). “Anatomic and functional leg-length inequality: A review and recommendation for clinical decision-making. Part II, the functional or unloaded leg-length asymmetry”. Australasian Chiropractic & Osteopathy 13(12). Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1198238/

4. Sahrmann, S. (2002). Diagnosis and Treatment of Movement Impairment Syndromes. Mosby, St. Louis, MO.

5. Wan, J-J., Qin, Z., Wang, P-Y., Sun, Y., Liu, X., (2017) “Muscle fatigue: general understanding and treatment”. Experimental & Molecular Medicine. 49(10). Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5668469/