The front of the lower leg is susceptible to stress fractures and other painful conditions. In runners, the most frequent cause of lower-leg pain is medial tibial stress syndrome, commonly called shin splints. This condition and other potential causes of lower leg pain are described below.
Medial tibial stress syndrome (shin splints)
Diffuse pain and tenderness at the inside or front of the tibia (shin bone) may be caused by medial tibial stress syndrome, commonly known as shin splints. As its medical name implies, this condition occurs when the lower leg is not well conditioned and experiences repeated and chronic strain, such as at the start of a new training program.
Many experts believe shin splints are caused by inflammation or other minor damage to the calf muscles, tendon or tibia. While the exact root of pain may not be clear, the treatment is: resting and periodic icing should relieve the symptoms.
Tibia stress fracture
Tibia stress fractures are the most common type of stress fractures associated with running. Among runners, women with a lower than average body-mass index are at the highest risk for a tibia stress fracture.1
A tibia stress fracture is a crack in the tibia, or shinbone. It develops gradually and usually causes deep pain on the inside of the shin. This pain is most noticeable while standing, walking, or running, and the area of skin over the suspected fracture may be tender and painful. Left untreated, this pain will get worse over time.
Some stress fractures are difficult to see on standard X-ray. A doctor who suspects a stress fracture may order an MRI or bone scan to confirm the diagnosis; however, this step is not always necessary before beginning non-surgical treatment. Recovery typically takes 4 to 6 weeks.
Pulled calf muscle (gastrocnemius muscle)
The gastrocnemius muscle is the largest muscle in the calf, and it is prone to strains and tears in runners.2 These strains and tears may occur from ramping up a running routine without adequate training or from sudden motions such as jumping, pushing off or making a quick turn.
Small tears in the gastrocnemius muscle's fibers can cause mild aching. The muscle may need a week or two for recovery. During this time the calf may feel stiff and sore but the person will still be able to walk and may do light jogging (though it may be a little uncomfortable).
A severe muscle tear, defined by a full rupture of the muscle, will be quite painful and cause bruising and swelling. A person with a severe muscle strain may not be able to walk normally and may require months to recover. In rare cases, surgery may be recommended.
Chronic compartment syndrome (Anterior compartment syndrome)
Less common than shin splints, a pulled muscle or a stress fracture, chronic compartment syndrome can also cause painful symptoms in the lower leg.
The lower leg has four "compartments" that each contains muscles, nerves and blood vessels, and is wrapped in a thin membrane of relatively inelastic tissue called fascia. Running and other repetitive exercises can create extra pressure within a compartment. If this pressure becomes too great, it can limit the blood flow to the compartment's muscles and nerves, resulting in local numbness and difficulty moving. The person may also notice the affected muscles bulging under the skin.
Chronic compartment syndrome is most common at the front compartment of the calf (called the anterior compartment) and can be confused with shin splints. This syndrome can also occur elsewhere on the leg, in other extremities, and in the buttocks. Symptoms usually stop when the person stops exercising.
Chronic compartment syndrome is different than acute compartment syndrome, which is often preceded by a traumatic injury and requires immediate medical attention.
Any calf injury should be treated and monitored so it does not lead to a secondary injury. For example, a strained calf muscle, while not considered a serious injury, can eventually lead to Achilles tendonitis.