BASIC-02 · Kinesiology and Biomechanics: Levers, Muscle Physiology, Contraction Types, and Arthrokinematics

Kinesiology and Biomechanics: Levers, Muscle Physiology, Contraction Types, and Arthrokinematics. Part of the Foundational Sciences series of the Reflex PM&R Board Review podcast. Audio correction: In the audio: a chronically shortened spastic muscle is weak because its sarcomeres are jammed up with excessive overlap (too short) — Correct: The mechanism is the opposite: chronic spasticity makes the muscle lose sarcomeres in series, so the remaining sarcomeres are stretched BEYOND their optimal length onto the DESCENDING limb of the length-tension curve, with REDUCED actin-myosin overlap (in-vivo measurements in spastic/CP muscle confirm this). The written chapter is correct. The full companion chapter and a linked board-style Q-bank set for this topic are at https://www.reflexpmr.com/read/BASIC-02.