Exercise induced leg pain has many causes, including exertional compartment syndrome, popliteal artery entrapment syndrome, medial tibial stress syndrome and stress fracture. I will focus on these particular causes and give recommendations on how to treat each one.
Exertional compartment syndrome usually presents as a sharp, excruciating pain and tightness after a period of exertion and can become a medical emergency if not treated promptly. As the muscle is filled with blood during exercise, the muscle mass expands increasing pressure within the compartment. This, in turn, causes reduced blood flow to the muscle which leads to oxygen deprivation and extreme pain. This can eventually cause irreversible tissue loss.
Diagnosis of exertional compartment syndrome can be achieved by using a catheter to measure compartment pressures. This is usually done before and immediately following exercise to compare both pressure readings. Pressures of > 30 mm Hg 1 minute after exercise or > 20 mm Hg 5 minutes after exercises are considered diagnostic. Treatment usually consists of reduced activity or surgical decompression of the compartment by way of fasciotomy.
Popliteal artery entrapment is less common than exertional compartment syndrome and is usually due to abnormal position of the popliteal artery which is compressed by the surrounding structures. This can lead to an irreversible lesion of the artery such as thickening, anyeurism or thrombosis. Symptoms include calf pain, swelling, rest pain and cramping.
Diagnosis of this condition is usually done by CT scan, arteriogram or duplex ultrasonography. Treatment usually consist of surgical decompression, or in advanced cases, bypass with a saphenous vein graft or other appropriate material.
Medial tibial stress syndrome (shin splints) and tibial stress fractures are both due to biomechanical and structural conditions of the foot. These include outward tilting of the heel, rolling down and in of the arch (overpronation) among other structural deformities. Both conditions typically occur in athletes participating in high impact sports such as running, basketball and tennis. Shin splints are usually painful along the inside border of the shin (tibia) close to the ankle, while stress fractures are usually tender at a specific spot on the shin.
Diagnosis for both is usually by x-ray, CT (high powered x-ray) or bone scan. MRI is used to tell the two conditions apart. In both cases, treatment consists of active rest for up to 12 weeks. Ice, compression and anti inflammatory medications also help to reduce symptoms. Once the pain is gone and it is important to correct the foot function to re-establish normal biomechanics to prevent recurrence of the pain; otherwise, symptoms will return.
Although these are the most common causes of exercise induced leg pain, there are many others. While the vast majority of leg pain usually resolves with rest, ice, elevation and compression, when this fails it is important to consult a podiatrist with sports medicine experience to accurately diagnose and treat the source of the leg pain. Otherwise, consequences can be devastating and have a disastrous effect on training and put goals out of reach.