Many runners find themselves asking, “Why do my calves hurt when I run?” Calf pain during or after running can be frustrating, and it’s not always a simple issue with the muscles. Possible causes include muscle tears, lower limb stress fractures, nerve trapping, and blood vessel narrowing. This blog outlines the most common and less common causes of calf pain while running, as well as how to diagnose it.   

Common Causes of Calf Pain While Running 

Gastrocnemius or Soleus Muscle Strain

A sudden sharp pain in the calf during push-off, sprinting, or hill running often indicates a partial tear of the calf muscles. There may be bruising, swelling, and difficulty walking or running. However, a tear of the soleus muscle can present with a gradual increase in pain, making the diagnosis of a soleus tear more challenging. 

Achilles Tendonitis 

Pain at the lower end of the calf near the heel may be caused by Achilles tendon swelling. This condition often presents as morning stiffness and pain in the lower calf, particularly when running. 

Shin Splints

Shin splints are caused by swelling at the muscle attachment to the shin bone. While this condition typically causes shin pain, some runners experience aching that extends into the lower calf. The pain is usually diffuse, worsens with impact, and improves with rest and modification of activity.

Tibial Stress Fracture

A stress fracture of the tibia or fibula can cause localised pain that worsens with loading. Runners with poor bone health, low energy availability, or vitamin D deficiency are at higher risk. 

Chronic Exertional Compartment Syndrome (CECS)

If you experience tight, cramping calf pain after a predictable running distance that eases with rest, CECS may be the cause. It involves increased pressure in the muscle compartments during exercise. This condition leads to muscle pain as you continue to run. Generally, the pain settles after 5-10 minutes of rest. 

Less Common Causes of Calf Pain while Running

Popliteal Artery Entrapment Syndrome (PAES) 

This rare condition involves compression of the popliteal artery behind the knee, leading to cramping calf pain during exertion. The pain disappears immediately with rest but recurs with exercise.

Peripheral Arterial Disease

Older runners or those with heart risk factors may experience intermittent calf cramping due to reduced arterial blood flow. This condition is triggered by walking or running and is relieved almost immediately by rest. 

Spinal Canal Stenosis 

Narrowing of the lumbar spinal canal can compress nerves that supply the legs. This condition causes burning or aching pain in the calves during walking or running. Typically, pain improves with rest, sitting or bending forward.

Muscle disease causing calf pain while running.

Rarely, bilateral calf pain may result from inflammatory or metabolic muscle disease. These muscle conditions may be associated with weakness, fatigue, or elevated creatine kinase on blood testing. A common cause found in younger people is McArdle’s disease. 

Deep Vein Thrombosis (DVT)

Though uncommon, DVT must be considered in any runner with unexplained swelling, warmth, and calf tenderness, particularly after travel or surgery. It requires urgent investigation with a Doppler ultrasound.

AVM Leg

Even less common are arteriovenous malformations of the calf that present with calf pain while running. Treatments conists of sclerosant injections or surgery. 

Assessment and Investigations to Determine ‘Why My Calves Hurt When I Run?’

To determine the cause of calf pain while running, a clinical assessment is essential. Important clues include when the pain begins, whether it’s sharp or cramping, if it improves with rest, and whether any swelling, weakness, or numbness is present. Your doctor should conduct a thorough examination, assessing the calf, lower leg blood supply, nerve function, and low back mobility, to help diagnose the cause. 

Investigations can help with a diagnosis and may include:

  • Ultrasound or MRI for muscle injury, tendinopathy, stress fractures or artery entrapment

  • MRI of the lumbar spine for suspected spinal canal stenosis

  • Doppler ultrasound or angiography for vascular causes

  • Ankle-brachial index for artery disease or blood vessel entrapment 

  • Blood tests (CK, autoimmune screen) for suspected muscle disease

  • Compartment pressure testing for chronic compartment syndrome. 

Final Word from Sportdoctordoctor on Calf Pain while Running 

If you’re wondering, “Why do my calves hurt when I run?” the answer may range from a simple overuse injury to more serious vascular or nerve-related conditions. Calf pain from running should not be ignored if it is persistent, severe, or doesn’t improve with rest and rehab. You should speak with a sports medicine professional for a thorough evaluation. 

Related conditions: