This is a chapter 2 summary of the book “Movement” by Gray Cook. Funky Muscles There are anatomically two basic types of muscles; shunt and spurt. Shunt muscles compress and produce structural integrity because the distal attachment is far from the moving joint. Spurt muscles produce movement because the distal attachment is close to the axis of rotation. While these two muscle types are present, they can vary depending on the function performed. For example, if we perform a movement in the closed chain, the spurt and shunt roles become reversed. Focusing on a single muscle group causes us to lack understanding of the supporting matrix behind superficial muscle action. Muscle function depends on body position and joint in action. We can see this point illustrated in Lombard’s paradox, which involves the coactivation of hamstrings and quadriceps when performing a sit to stand. These muscles are antagonistic to one another at their respective joints, yet movement is produced. The resultant effect is the quads and hamstrings becoming global stabilizers. Muscle activity is task specific, therefore Gray purports four types of muscles: 1) Global Stabilizers: Multi-joint muscles contracting to produce stability and static proprioceptive feedback. 2) Global Movers: Multi-joint muscles that produce movement and dynamic proprioceptive feedback. 3) Local Stabilizers: Deep segmental muscles (1-3 segments) that produce stability and static proprioceptive feedback. 4) Local Movers: Single joint muscle that produce movement and dynamic proprioception. These different muscle types require different training modalities. The example given is stabilizer muscles. These muscles cannot
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