Shin Splints

Sooner or later almost all runners experience pain in the calf or shin. There are several types of overuse injuries that may develop in this region as a result of the repeated pounding from running. Shin splints, stress fractures, and chronic compartment syndrome have a common mechanism of development. Understanding the circumstances that lead to these injuries is the key to preventing them.

The overall recurring theme that leads to overuse running injuries is excess training with inadequate recovery. Excess and inadequate are relative terms and must be judged against one’s usual training routine. The more that excess and inadequate deviate from the usual training routine the less time it takes for an overuse injury to develop. Keeping this theme in mind one can now examine the specifics for how shin splints develop.

A simplified view of the mechanics of running shows a foot-strike, then a loading/energy transfer phase, and finally a push off (“toe-off”) with the forefoot. Each foot-strike delivers a shockwave that travels up the leg. This energy must be absorbed by the musculoskeletal system. The harder the running surface the greater the shockwave. Soft grass, smooth dirt, asphalt, and concrete represent, in order of increasing “hardness”, the usual spectrum of commonly encountered running surfaces. Concrete is very hard on the body and training on this surface should be avoided.

Distance running shoes are specifically designed to provide padding and support for the biomechanics of endurance running. They help absorb shock and facilitate efficient energy (motion) transfer. Matching the type of running shoe to the athlete’s specific biomechanics, and proper shoe fit are important. Similarly, worn out shoes should be replaced early because of reduced shock absorbing capacity. Runners with high rigid arches tend to experience greater pounding shock, whereas those with flat feet tend to experience greater fatigue of the muscles that support the foot -- and push-off. Both tend to develop shin splints

The term shin splints refers to a painful condition that develops along the inside (medial edge) of the shin (tibia). The usual location is along the lower half of the tibia, anywhere from a few inches above the ankle to about half-way up the shin. The repeated running cycle of pounding and push off results in muscle fatigue, which may then lead to higher forces being applied to the fascia, the attachment of fascia to bone, and finally the bone itself. Respectively, this represents a spectrum from mild to severe. On the relatively more severe end of the scale the injury may progress from stress reaction within the bone to an actual stress fracture.

In the early stage of shin splints a runner will describe a pain that is present when the training run first begins, but then disappears as running continues. The pain will often return after exercise or the following morning. As the injury progresses the athlete will experience more time with the pain, and less time without it. There is frequently a tender zone along the medial edge of the tibia that one can map out by pressing with the fingertips as they “march up” along the bone. Eventually, if ignored and training continued, the pain may become quite sharp and may focus on a very small area of the bone. If this happens a stress fracture should be considered.

The treatment for shin splints is rest. Depending upon severity it is often necessary to completely stop running for a period of time. Generally this is done until day-to-day activities are pain free. When running is resumed – and this is where many injured runners make a mistake – it must be significantly different from the routine that lead to the injury. The concept of relative rest employs lengthening the interval between training as well as decreasing the volume and intensity of training. One can often substitute cross-training activities (e.g., bicycling) for running to help increase the interval between running days. There should be a graded and gradual increase in run training, keeping an eye out for the return of any shin splint symptoms.

Stretching and strengthening the calf muscles can help prevent the injury from returning. However the most important preventive strategy is not to repeat the mistakes that lead to the injury. Examine all the training variables – surface, shoes, training volume, intensity, workout type, hills, weather conditions, etc. Seek help from a qualified trainer or coach. This all takes time and effort, but it is well worth it. copyright 2003 © Mark Jenkins, MD