Biomechanics can be complicated.

But to make a real difference most people just need to remember three basic principles.

I call these the Easy 123 of Muscles.

  • Muscles can get shorter and pull.

    Muscles are attached to bones.

    They can get shorter and pull on the bone.

    This can hold the bone in position against the force of gravity (posture).

    Or it can change the angle of the joint and cause movement.

  • Muscles can stop pulling and get longer.

    To allow the bones to return to their starting positions the muscle must release:

    • stop pulling

    • go back to its original (longer) length.

  • Muscles are controlled by the brain.

    Signals going out from the brain and other parts of the nervous system tell the muscle when to contract or release.

    Signals also come into the brain with information about what is happening. This monitoring process is called proprioception.

A triangle makes a nice memory aid.

Interested in understanding what can go wrong?

Click here

  • Muscles can get shorter and pull

    Muscles are attached to bones.

    They can get shorter and pull on the bone.

    This can hold the bone in position against the force of gravity (posture).

    Or it can change the angle of the joint and cause movement.

    We call this contraction.

  • Muscles can stop pulling and get longer

    To allow the bones to return to their starting positions the muscle must

    stop pulling

    and

    go back to its original (longer) length.

    We can this release.

  • Muscles are controlled by the brain

    The change between contraction and release happens in response to instructions from the brain and the rest of the nervous system.

    Repeating a particular posture or movement can lead to it becoming an ingrained habit.

    I call this programming.

    It is also important for the brain to monitor what is happening throughout the body so that the instructions it sends are appropriate.

    We call this proprioception.

Easy 123 of Muscles

I like to write these three principles on the corners of a triangle as a memory aid.

Different types of exercises help at different corners of the triangle.

Exercises for strengthening help the muscle in the pulling phase.

Exercises for loosening help the muscle in the release phase.

Exercises for proprioception and programming help the control of the muscle by the brain.