by Ashley Border
Discussion of Motion
Plantar Flexion (PF) is a movement at the talocrural joint. PF can be described as bringing the sole of the foot towards the ground in a seated position or lifting the body up on the toes in a standing position. PF at the ankle, however, is usually performed in a combination of three movements at the ankle (the talocrural and subtalar joints) that produce one fluid motion. The combined motions are PF, inversion (INV), and adduction (ADD). The combination movement is often referred to as "supination."
This motion can be instructed to the patient by simply saying, “Point your toes to the ground.”
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- Primary Muscles: gastrocnemius and soleus muscles (both insert into the Achilles Tendon)
- Secondary Muscles: tibialis posterior, flexor digitorum longus, and flexor hallucis longus (these muscles contribute to ankle INV and ADD)
- Peripheral Innervation: tibial nerve
- Spinal Root: contributions from the spinal roots from L4-S3.
Mobilizing – Increasing Range of Motion (ROM)
PF range of motion (ROM) can be increased by stretching the primary muscles that control the opposing motion, dorsiflexion. These muscles are tibialis anterior, fibularis longus, and fibularis brevis (also referred to as peroneus longus and brevis). Below are three stretches that can increase PF ROM:
- Each stretch should be held for 30 seconds x 2 sets, and should be performed 1-2 times per day, or according to prescribed physical therapy home exercise program.
- The expected sensation when performing these stretches is a slight muscle tensioning from the knee down to the top of the foot, in the front of the shin, and the outside of the lower leg.
Indications for Stretching
- Overuse Injury: Shin Splints, or Tibial Stress Injuries, can be prevented or treated with stretching of all ankle ROMs in addition to physical therapy.1
- Limited PF ROM: Normal PF ROM is 0o-50o.2 Stretching is appropriate in addition to a physical therapy routine when PF is limited due to tight anterior tibialis, fibularis longus, or fibularis brevis muscles. Additionally, decreased joint mobility in the talocrural joint secondary to surgery or injury to ankle complex can limit PF ROM; this can be treated with Posterior-to-Anterior talocrural joint mobilizations.
Posterior-to-Anterior Talocrural Joint Mobilization:
Strengthening
- Begin in standing position with feet shoulder width apart. If needed, stabilize body with a chair using as little reliance on the hands for balance as possible.
- Lift body weight onto balls of feet, lower heels back onto the floor, and repeat.
- The exercise can be made harder by shifting body weight onto a single leg and performing heel raises.
- Exercise can be performed with 10 repetitions in sets of 3, 1-2 times per day, or as prescribed by your physical therapist.
- Begin by standing on a stair (or a 6" inch stool). Body can be stabilized with a railing, as needed.
- Lift body weight onto toes, shift body weight to one leg, and slowly lower body down until the heel is below the lip of the step. Repeat.
- This exercise can be made harder by holding a weight while performing the exercise.
- Exercise can be performed with 10 repetitions in sets of 3, 1-2 times per day, or as prescribed by your physical therapist.
- Begin by sitting on a bed with legs straight and the foot off the edge of the bed.
- Wrap the elastic resistance band around the ball of the foot and point toes towards the floor. Slowly return the foot back to neutral, and repeat.
- This exercise can be made harder by increasing the resistance level of the elastic band.
- Exercise can be performed with 10 repetitions in sets of 3, 1-2 times per day, or as prescribed by your physical therapist.
Potential Clinical Syndromes or Etiologies
The above series of stretches and strengthening exercises may be used for general increase in PF mobility and strength, but may also be implemented in a variety of clinical syndromes, such as:
- Gait Deivations4
- PF concentric weakness leads to decreased push off during ambulation
- PF eccentric weakness leads to decreased stability during stance phase of ambulation
- S1 Radiculopathy5
- compression of S1 nerve root is apparent in S1 dermatome
- S1 dermatome is tested with a manual muscle test (MMT) of plantar flexion muscles
- treatment would be focused at the S1 spinal nerve root compression in the back
- Tibial Neuropathy6
- the tibial nerve supplies the PF muscles
- injury to the tibial nerve can cause PF muscle weakness
- Ankle Sprain7
- at appropriate stage of healing, rehabilitation for an ankle sprain includes ROM stretching exercises and strengthening
- strengthening exercises for PF stability can help prevent ankle sprains
- Achilles Tendon Injury8
- at the appropriate healing stage of an achilles tendon injury, eccentric exercises can help with control and strength of the PF muscles
- Shin Splints9
- prevention and treatment includes both strengthening exercises of PF muscles and stretching of dorsiflexion muscles
Resources for Further Information
For more information on the pathophysiology supporting the need for stretching and strengthening damaged muscle and soft tissue during the healing phase, please explore these lecture notes:
