What is the calf muscle and what does it do?
The calf muscles work to lift the heel off the floor and propel you forwards when walking
and running. There are two muscles that both attach to the Achilles tendon and into the
heel bone at one end. The deeper soleus muscle is also attached below the knee, and the
more superficial gastrocnemius is attached above the knee. Therefore, the gastrocnemius
will work more when the knee is straight and the soleus when the knee is bent. In this article we will explore what causes calf pain running
Types of calf pain From Running
The most common cause of calf pain is when the calf muscles are overloaded and the
demand is greater than the capacity of the muscle. When running the calf
muscles may not be strong enough for the intensity or duration of the run. The calf muscle will start
to feel progressively more tight and painful. As this progresses, this can trigger a cramp, a
strain or a tear.
Injuries can occur in the main belly of the muscle, in the junction between the muscles
and the tendon, or in the tendon itself. As well as feeling where the pain is, there are
common patterns that are seen when a muscle or tendon is injured.
Calf Muscle Vs Achilles Tendon Injuries
Tendon injuries can give pain at the start or end of the activity. They often feel a bit better after they have warmed up and before it has worked too much. Sometimes these will
cause delayed pain, which might be felt after being sat still for a while after exercise or even the next day.
Muscles tend to be more consistently painful when the muscle is used and worsens directly
the longer it is used for and the greater the intensity of work. It will then gradually get
better with rest.
Differentiating between the two calf muscles can be difficult but usually, pain that is specific
to the soleus is more pronounced when a heel raise is done with a bent knee and the
gastrocnemius when the knee is straight. The soleus can also give a more vague pain as it is
deeper and often the individual might find it hard to pinpoint the area of pain.
Calf Pain Running: Muscle Injury Grading
Determining the extent of the injury is important in order to direct the most appropriate
rehabilitation for recovery. Swelling and especially bruising, can take several days to appear
after the injury so is a poor indicator of injury in the acute phase. The history of the onset of
the pain, whether sudden or gradual, the intensity of the pain, and how the muscle can
function are all helpful indicators to diagnose the severity of the injury.
Muscle and tendon injuries are graded 0-4, based on the British Athletics muscle injury classification. 0 being a strain and 4 being a rupture or
complete separation of the two end of the muscle or tendon. A letter is now attached to the
grading which will indicate the location of the injury with (A) referring to an extension from
the fascia, (B) muscle or muscle tendon junction and (C) tendon involvement.
0 = Muscle strain, soreness after exercise, no sign on MRI.
1 = Small muscle tears, & <10% cross-sectional area, pain but no loss of strength, haematoma
seen on MRI.
2 = Moderate muscle tears, 10-50% cross-sectional area, pain with loss of strength, high
signal changes on MRI.
3 = Extensive muscle tears, >50% cross-sectional area, pain with loss of strength and
function, high signal changes on MRI.
4 = Complete muscle tears, 100% cross-sectional area, palpable gap, defect seen on MRI.
Why do my calves hurt when running?
Your calves might hurt when running as you may have an injury such as a strain or tear that
we have mentioned above. However, there are many other reasons why you might
experience pain when running that are less common.
Other causes that are less common include compartment syndrome. This is the result of restricted blood flow
to the calf muscle known as claudication, restriction of blood to the nerves of the leg known
as neurological claudication, or blood clots, also referred to as deep vein thrombosis (DVT).
Compartment syndrome is a condition where fluid can build up under a band of tissue that
is unable to stretch well. The skin will usually look pale, and the individual will feel pins and
needles, or numbness on the skin as well as pain. Often the muscle will be affected and may
not feel as strong or it might not be able to function at all.
A DVT is usually felt as extreme tightness and pain in the calf that worsens as intensity and
duration of the activity increases. There is usually a change in colour of the calf making it
look red or dark on the skin and it will be swollen. This is most common when an individual
has been completely inactive for a long period, such as a long haul flight or following
Other causes include issues with blood clotting, smoking, being overweight, severe
dehydration, varicose veins, taking contraceptive pill or HRT, cancer or heart failure.
Should I run with calf pain?
It is not helpful for recovery of a calf injury if the demand on the recovering tissue is too
high. Therefore the severity of the injury will guide what is good to do in terms
In a less severe injury in a strong individual it may be okay to have calf pain running, slowly on a flat
level ground but not to run fast or up hill. For someone less well conditioned or with a more
severe injury they may be better not running.
In some cases it is best to completely rest the muscle and you might be advised to used crutches for a period of time.
A good rule to follow is to not run if you don’t know what exactly is hurt or why. Without
knowing this you won’t know if you are doing more harm or not. It is best to see you
physiotherapist, doctor or physician to have this assessed and ensure that you follow the
best treatment to recover.
Online Physiotherapy with James McCormack
This is not medical advice and we recommend a consultation with a medical professional such as James McCormack to achieve a diagnosis. He offers Online Physiotherapy Appointments for £45.
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