A 3D-geometric model for the deformation of a transversally loaded muscle

Force reduction induced by unidirectional transversal muscle loading is independent of local pressure

“…Although the muscle reacts in principle like a longitudinally pre-stretched elastic body under transversal load (Siebert et al, 2012), the mechanisms underlying the longitudinal force decrease are likely very different. First, there seems to be no passive, elastic, three-dimensional structure that hampers the muscle in producing longitudinal force at different lengths.…”

“…Then, the decrease in longitudinal force would depend more on the transversal load than on the local transversal pressure. Determining these dependencies is important for further development and validation of simple, computationally inexpensive muscle models that can account for effects of two-or three-dimensional loading conditions of muscles (Siebert et al, 2012(Siebert et al, , 2014a.…”

Multidimensional models for predicting muscle structure and fascicle pennation

“…3D models allow changes in dimension of the muscle belly in all directions of length, width and depth. Previously, 3D modelling of isolated rat medial gastrocnemius undergoing isometric contractions have shown changes to the depth and width of the muscle belly (Siebert et al, 2012) and 3D fascicle and muscle deformations in the rabbit soleus for multiple contracting conditions (Böl et al, 2013). However, there are relatively little data available on the 3D changes in the dynamic structure of muscles in man that would allow detailed 3D models to be validated for human muscle contractions.…”

Intermuscular pressure between synergistic muscles correlates with muscle force

“…Furthermore, the process of contraction entails changes in the muscle shape, e.g. increase in muscle thickness (Röhrle et al, 2008;Siebert et al, 2012;Böl et al, 2013Böl et al, , 2015Wakeling et al, 2013). Because most muscles are tightly packed in muscle packages (compartments), these deformations may cause additional transverse forces ( perpendicular to the line of action) in between contracting muscles or between muscles and surrounding tissues, e.g.…”