Specific conditions
Overused Muscle
One cause is overused muscle, either an acute injury or DOMS (delayed-onset muscle soreness). The muscle pain is caused by any activity that involves running, jumping, and sometimes even swimming. An individual not accustomed to running may experience pain in the shin muscles the next day even after a single, short bout of intense running. There may even be immediate discomfort in the muscles from a build-up of lactic acid.
Inflammation of Connective Tissue
Shin pain may also be the result of inflammation of connective tissue such as periosteum (periostitis). The pain may be caused by a stress fracture in the bone or some other problem like osteosarcoma. Pain in the lower leg may also be referred from a distant area of the body, such as pressure on the sciatic nerve (sciatica) near the foot joint.
Chronic Compartment Syndrome
A problem which can mimic anterior shin splints is chronic compartment syndrome (CCS). This is a serious problem which can lead to significant loss of function in the lower leg. CCS occurs when swelling within the indistensible anterior compartment of the leg reduces blood flow. This relative lack of blood, ischemia, can cause more swelling and generate a positive feedback loop. In severe cases the result can be acute compartment syndrome (ACS) which requires emergency surgery to prevent ischemic muscle necrosis, muscle death due to lack of blood.
Diagnosis
Think of CCS when pain worsens steadily during exercise rather than improving as the ligaments and muscles warm. Tingling in the foot is a particular red flag; it indicates compression of the nerve.
If a bone problem is suspected to be causing inflammation of connective tissue, a bone scan can be useful in confirming the diagnosis.
Causes
The purpose of the muscles of the anterior shin (tibialis anterior) is to dorsiflex the foot (raise the toe). It may not be obvious why a muscle which raises the toe can be stressed or injured by running, given that it is not responsible for propulsion. The reason is that unskilled runners overstride, and land heavily on the heel with each footstrike. When this happens, the forefoot rapidly slaps down to the ground. Effectively, the foot, which is dorsiflexed prior to making contact with the ground, is forcefully extended. This forceful extension of the toe causes a corresponding rapid stretch in the attached muscles. A reflex in the muscles responds, causing a powerful contraction. It is this eccentric contraction which leads to muscle soreness and possible injury to the muscle, tendon or connective tissue.
In a similar way, improper pronation of the foot during the footstrike can also cause pain in the muscles which oppose pronation, on the inside or outside of the shin. In proper pronation the foot strikes the ground on the outside of the heel and then rolls toward the inside of the foot approximately 5%. The ideal degree of pronation varies slightly with the individual. It is determined by factors such as the height of the arch (a higher arch has more clearance for pronation than a low arch) and the flexibility of the arch. In over pronation, the foot rolls in too far. The result is that the foot pushes off almost entirely from the big toe, causing excessive strain on the big toe and the outside of the shin. In contrast, under pronation occurs when the foot does not roll enough. This causes the entire weight of the foot strike to concentrate on too small an area on the outside of the foot, which places a corresponding strain on the shin.
It is also commonly believed that a contributing cause of shin muscle pain in some cases is the relative weakness of the muscles on the anterior of the lower leg compared to those in the calf. In this case, exercises that preferentially strengthen the anterior muscles may help alleviate or avoid shin splints. The shin pain is attributed to a forced extension of the muscle, in this case by the opposing calf muscles which "overpower" the shin.
Bikers who have to use their feet to change gears or apply brakes can suffer from shin splints after long rides.
Treatment and prognosis
CCS
If you suspect CCS seek medical attention before continuing to train. If you suspect ACS, seek medical attention immediately night or day.
Acute treatment
The immediate treatment for shin splints is rest. Running and other strenuous lower limb activities like soccer and other sports which include flexing the muscle, should be avoided until the pain subsides and is no longer elicited by activity. In conjunction with rest, anti-inflammatory treatments such as icing and drugs such as NSAIDs may be suggested by a doctor or trainer, though there is some controversy over their effectiveness. Some people will use acupuncture to treat shin splints though there has not been any conclusive or comprehensive study in the effects of acupuncture on shin splints.
http://en.wikipedia.org/wiki/Shin_splints
Huh, nothing about microfractures there. I'm pretty sure that's what my doc mentioned. Hmm.
