Residual force enhancement decreases when scaling from the single muscle fiber to joint level in humans.

ABSTRACT:

Background

Residual force enhancement (rFE), defined as increased isometric force following active lengthening compared to a fixed-end isometric contraction at the same muscle length and level of activation, is present across all scales of muscle. While rFE is always present at the cellular level, often rFE "non-responders" are observed during joint-level voluntary contractions.

Methods

We compared rFE between the joint level and single fiber level (vastus lateralis biopsies) in 16 young males. In vivo voluntary knee-extensor rFE was measured by comparing steady-state isometric torque between a stretch-hold (maximal activation at 150°, stretch to 70°, hold) and a fixed-end isometric contraction, with ultrasonographic recording of vastus lateralis fascicle length (FL). Fixed-

SUBMITTER: Hinks A 

PROVIDER: S-EPMC11863329 | biostudies-literature | 2024 Oct

REPOSITORIES: biostudies-literature