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November 4, 2013, 12:00AM PT in Exam Preparation Blog  |  0 Comments

Muscles That Move the Leg

As a fitness professional and an exam candidate, there is no way of getting around the fact that you need to know your anatomy! Understanding how the body moves and creates movement with the muscles is a huge part of the job. In earlier blogs, we looked at how to study anatomy. We then started breaking down each body part with our latest three blogs looking at the muscles that move the scapulae, the muscles that move the arm and the muscles of the core. Here, we will look at the muscles of the hip, knee and ankle joints.

Hip Joint

The hip joint is created between the femur (thigh bone) and the acetabulum of the pelvis. The primary function of the hip is to support the weight of the body in both static and dynamic postures. Similar to the shoulder joint, it is a ball and socket joint that has many actions.

Hip joint

Action of the Hip

What the Action Looks Like (Move Your Body!)

Primary Muscles

Hip Flexion

Lift your leg in front of your body

Hip Flexors – quadriceps (focus on rectus femoris) and Illiopsoas

Hip Extension

From a position of hip flexion, returning your leg to the anatomical position or lifting your leg behind you

Hip Extensors – hamstrings (focus on biceps femoris) and gluteus maximus

Hip Abduction

Lift your leg out to the side, or from a squatting position, knees falls out to the side

Hip Abductors - gluteus medius and minimus

Hip Adduction

From a position of hip abduction, lower your leg to the anatomical position, or from a squatting position, knees fall in to the midline

Hip Adductors (know them as a group called the hip adductors)

Internal Rotation of the Hip

Rotate your leg in toward your body or try turning your foot so that your toes face inward (“pigeon toed”)

Because of the anatomical configuration of the hip, there are no true primary internal rotators of the hip. Muscles that play a role in internal rotation when the hip is first flexed to 90 degrees are the tensor fasciae latae, anterior fibers of gluteus medius and minimus

External Rotation of the Hip

Rotate your leg out away from your body or try turning your foot so that your toes face outward (“duck footed”)

External hip rotators are known as a group. Focus on piriformis because of its role in sciatica.

Hip muscles

Hip muscles

Knee and Ankle Joints

The knee joint consists of the femur bone connecting with the tibia and fibula. The two main actions of the knee are flexion and extension. The ankle joint consists of the distal ends of the tibia and fibula and the tarsal bones of the foot. The main actions of the ankle are plantar flexion, dorsi flexion, inversion and eversion.

knee joint

Action of the Knee and Ankle

What the Action Looks Like (Move Your Body!)

Primary Muscles

Knee Flexion

Bend your knee

Knee flexors – hamstrings, focus on biceps femoris

Knee Extension

Straighten your knee

Knee extensors – quadriceps, focus on rectus femoris  

Ankle Plantarflexion

Point your toes (plant your foot) or when standing, lift your heels off the floor

Plantarflexors - know them as a group called the plantarflexors; focus on gastrocnemius and soleus

Ankle Dorsiflexion

Lift your toes up off the floor toward your shin

Dorsiflexors – know them as a group called the dorsiflexors; focus on anterior tibialis

Ankle Inversion

Pull the foot toward the midline (ankle rolled out)

Anterior tibialis

Ankle Eversion

Pull the foot away from the midline (ankle rolled in)

Personeus longus and peroneus brevis

Knee muscles

Ankle muscles

A helpful way to learn the muscles is to get up out of your chair and move and mimic the actions for the muscles you are learning that week. Look at the picture of the muscle, find it on your body, and picture how the muscle is contracting and what muscles are involved in the movement. Make the muscle contract and complete the different actions that muscle is involved in.

If you have any additional questions that were not answered here, please don’t hesitate to contact our Resource Center at 888-825-3636, Ext. 796, or resource@acefitness.org.

By Belinda Thompson


Belinda Thompson is a Study Assistant Representative for the American Council on Exercise. She is an ACE-certified Personal Trainer, Group Fitness Instructor and Health Coach, holds a bachelors degree in Exercise Science and moved to the USA from Australia in 2011. Belinda is an exercise fanatic who loves to take on new challenges, recently completing an Ironman triathlon just for the fun of it!

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