This is a chapter 2 summary of the book “Movement” by Gray Cook.
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 be trained with concentric/eccentric modalities for this will not change the real issue – timing and recruitment. Authentic stability is about effortless timing and the ability to go from soft to hard without a blink.
Joints, Ligaments, Fascia, and Breathing
Here Gray discusses how decreased muscle function affects the joints.
Muscles decrease function → joints are stressed→ microtrauma/wear→ Stiff joints give poor feedback→ Muscular demand increases→ Muscle imbalance, inhibition, and guarding occurs.
Both joints and ligaments interact with the nervous system to give us joint position sense, direction, and movement speed. This feedback affects how muscles react.
Fascia also plays a crucial role by redirecting stress and providing dynamic structure. The fascia is what links all the muscles together and facilitates muscle synergy to the nervous system.
Breathing is what connects the entire movement matrix, yet it is often the most neglected area for testing. A good breath can relax the system in the presence of stress and dysfunction. Breathing also has the ability to stimulate the parasympathetic nervous system and increase heart rate variability (HRV). Breathing dysfunction very much parallels movement dysfunction. If one cannot maintain a quality breath at end-range, then the movement is not authentic.
The Neuromuscular Network
One goal of the sensorimotor system is uprightness. This quality depends on three components:
1) Vestibular – head position
2) Proprioceptive – Body segments
3) Visual – Body relative to environment
These three areas account for constantly changing posture, as we must adjust to an ever-changing environment. The hands and feet in particular also play a huge role in how we interact with our environment.
When we talk about movement and injury, it is important to understand that pain experiences can alter motor control at multiple joints away from the injured sight. This is a highly individual and unpredictable process, and the lack of pain does not equate with normal movement or no risk factors.
While there are many different discussed points in the above section, the reason for this is that everything is very much interconnected. Highlighting one system neglects the others and does not paint an accurate picture.
There are three types of movement dysfunction:
1) Developmental – movement opportunities become denied.
2) Traumatic – Compensations stress other body regions. Baggage follows injuries.
Oftentimes developmental and traumatic dysfunction are very difficult to change. On the other hand, acquired dysfunction can readily be changed. There are two types of acquired dysfunction.
1) Unnatural activity repeated on natural movement base (throwers, unilateral sports, habitual postures).
2) Natural activity repeated on an unnatural movement base (fundamental limitations and asymmetries).
Changing acquired dysfunction does not necessarily mean moving more. Moving more does not equal moving well. We need to target particular dysfunction.