Muscle Anatomy & Physiology for Personal Trainers


Personal Trainers need to have a sound understanding of muscle anatomy and physiology. Since muscles are the main organs of the body we affect it is crucial we understand how they respond and adapt to training. If a client asks you the name of the four quadriceps can you tell them? If you have to communicate with a physiotherapist or a doctor for a client will you be able to speak to them in medically accurate terms? Many anatomy courses and text books often go into excessive detail about concepts that personal trainers do not need to understand, this can often be daunting or lead to discouragement. Muscles 101 was designed for personal trainers to learn the most important concepts for applied personal training.

How can I train my upper pecs from my lower pecs?

A basic understanding of muscle origin and insertion can help you understand how to train specific muscle groups. Notice how the clavicular head attaches to the upper region. If you want to train the upper pecs perform incline chest press, or cable pulls with an upward motion. This line of pull will train the upper pecs - conversely a downward motion, or decline press will train the lower pecs (though research has show flat press to train the lower head just as well). Consider how your pecs are also sore after pull ups. The pecs contribute to shoulder extension (an action in the pull up).

Major Muscles of the Lower Body

The following list consists of the larger muscle groups primarily responsible for the gross movement for the lower body - more in demo and full course

Actions at the hip joint:

  • Flexion
  • External rotation
  • Anterior Pelvic Tilt
  • Actions at the hip joint:

  • Flexion
  • Abduction
  • Internal rotation
  • Actions:

    Flexion, abduction, and external rotation of the hip. Flexion of the knee

    Actions at the hip joint:

  • Extension
  • External rotation
  • The quadriceps are made up of 4 individual muscles (The Vastus Group - 3 in total, and the Rectus Femoris)


    Extension of the knee & flexion of the hip (rectus femoris only).

    *it may be important to note that the rectus femoris acts as a hip flexor while the vastus medialis, vastus lateralis, and vastus intermedius only extend the knee.

    The hamstrings are made up of 3 individual muscles (Semitendinosus, Semimembranosus, and Bicep Femoris)


    Flexion the knee & extension of the hip (bicep femoris only).

    *it may be important to note that the bicep femoris assists to extend the hip as well as contribute to knee flexion

    The calves are made up of 2 individual muscles (Gastrocnemius & Soleus)


    Plantar flexion of the ankle and flexion of the knee (gastrocnemius only)

    *it may be important to note that the gastrocnemius flexes the knee while both muscles contribute to plantar flexion at the ankle

    Joint Movement Terminology
    Personal trainers must know proper joint movement terminology, especially when talking with other health care professional because the terms accurately describe the direction of movement at specific joints. For example, a client with a herniated disc must avoid forward hip flexion as well as posterior pelvic tilt. 

    This page is included in Muscles 101 since muscles and joint actions go hand in hand.

    There are 3 axes of rotation in the body, each is associated with a different plane of motion. These planes of motion are a part of basic fitness theory for personal trainers or first year anatomy. Axis of rotation are a part of mechanics, or more specifically, biomechanics. These concepts can often be quite difficult for new personal trainers. Depending on which exam and certification you are taking this concept may not be super crucial to fully comprehend. What is important to know are the specific joint movements and could you demonstrate each if necessary.

    Sagittal Plane Movement
    sagittal axis
    Movements in the sagittal plane correlate with the medio-lateral axis. Movements include:

  • Flexion & Extension
  • Hyperextension
  • Anterior & Posterior pelvic tilt
  • Plantar flexion & Dorsi flexion

  • walking

    Last modified: Wednesday, 27 February 2019, 7:00 PM