Phasic vs Tonic Muscles
Every muscle in the body can be categorized into phasic or tonic muscles. Look up Vladimir Janda’s research to see a full chart. Tonic muscles are the muscles that hold our bodies upright in space, hince they tend to be highly facilitated neurologically. Tonic muscles are typically highly type 1 muscle fibers because of their aerobic nature. Phasic muscles are typically the muscles that are underused. These are muscles that produce movement and do not add to posture. These muscles usually have a higher type 2 fiber content. Phasic and tonic muscles tend to be antagonist. Tonic muscles have a natural higher neurologic tone so phasic muscles are typically the first muscles isolated in a treatment process. Synergizing and integrating phasic and tonic muscles are the steps to creating an ideal motor pattern. Synergistic use around a joint gets broken down into stiffness vs torque. Stable joints typically produce more torque while mobile joints typically need more stiffness. As we enter concentric contraction, especially in a mobile joint, we need antagonistic eccentric load to create enough stiffness.