Skip to main content
Fig. 7 | Journal of NeuroEngineering and Rehabilitation

Fig. 7

From: Skeletal muscle mechanics, energetics and plasticity

Fig. 7

The relationship between pennation angle and muscle fiber length is not fixed for a given muscle, but varies according to contractile force. Three isotonic contractions (a) show a pattern of rotation of fibers that is proportional to force. Lower-force contractions involve more fiber rotation (b). It is hypothesized that the component of fiber force (Ff) oriented orthogonal (Fo) to the muscle force (Fm) tends to compress the muscle and reduce fiber rotation (c). At lower forces, a low Fo allows for more fiber rotation to higher angles of pennation. Fiber length and pennation angle measurements were obtained via implanted radiopaque markers and biplanar fluoroscopy [128]

Back to article page