Adaptability of the load sharing between the longissimus and components of the multifidus muscle during isometric trunk extension in healthy individuals.

Purpose: Redundancy of the musculoskeletal system implies multiple strategies are theoretically available to coordinate back extensor muscles. This study investigated whether coordination between back muscles during a tightly constrained isometric trunk extension task varies within and between individuals, and whether this changes following brief exposure to activation feedback of a muscle.

Methods: Nine healthy participants performed three blocks of two repetitions of ramped isometric trunk extension in side-lying against resistance from 0-30% of maximum voluntary contraction over 30 s (force feedback).

Exploration of shear wave elastography measures of the iliotibial band during different tasks in pain-free runners.

Objectives: To determine whether shear wave velocity (SWV) of the iliotibial band (ITB): i) increases with active and passive static tasks, and a dynamic task, ii) differs between ITB regions, iii) changes after exposure to running. Additionally, it aimed to determine the between-day reliability.

Design: Case series & test-retest.

Shear modulus of multifidus and longissimus muscles measured using shear wave elastography correlates with muscle activity, but depends on image quality.

Shear wave elastography (SWE) estimates shear modulus in muscle. This is interpreted as an index of muscle stiffness, but depends on muscle characteristics. This study evaluated relationship between shear modulus and myoelectric activity of lumbar multifidus and longissimus muscles to assess its validity.