Oh My Aching Legs...Shin Splints
Shin splints are the most common overuse injury among runners. Either you, or someone you run with, have likely suffered from this painful malady. Like most running injuries, shin splints are largely preventable. However, if not prevented, they can derail your training program and put your dream race in jeopardy.
Shins splints are an inflammatory condition of tibia (shin bone). The result is pain in the front or inside of the lower leg that usually gets worse with prolonged running. It may not hurt much in the first couple of miles, but will often evolve into a dull ache or throbbing pain as you run. It may be sore and tender for days following long runs. In most cases, it is tender when you press along the front or inside of the shin over the middle one third of the leg (halfway between the knee and ankle).
This is an injury that is caused by unaccustomed and excessive exertional forces to the legs...otherwise known as overtraining. The term “overtraining” confuses many people. I will often have patients who say they don't think they are overtraining, but suffer from classic overtraining injuries. Most often, it is a novice runner who is increasing mileage rapidly in preparation for a race. They seem to think that they can't be "overtrained" because they just started training. In this case it is not the total miles, but the sudden increase in stress from a rapid increase in either intensity or distance, that creates the stress known as overtraining. The stress overcomes the body's ability to compensate and injury results.
Let’s say a new runner suddenly goes from running 2 miles a day, 5 days a week (10 miles per week), to running 3 miles a day, 5 days a week (15 miles per week). This would be a 50% increase in weekly mileage. If this novice runner has not yet prepared the musculoskeletal system with the requisite level of base fitness to deal with the stress of running, even though it is only 1 mile added each day, such an increase may cause an overuse injury. Additionally, most novice runners start improving both speed and endurance at the same time. The simultaneous increase in speed and distance can produce a dramatic increase in stress to the bones, muscles, ligaments, and supporting connective tissues.
The other scenario occurs with the seasoned runner. Although the experienced runner may have an extraordinary level of base fitness, it is still easy to develop overuse injuries. These folks are more likely to add speedwork sessions, intervals, or hill training that can be enormously stressful to the legs. There is also the temptation to "go longer" on a given run if the sun is shining and you happen to feel particularly spry that day. The other time is when you delude yourself by remembering that after your last extra-long run you felt great, even if it was months ago.
In addition to the simple case of "overdoing it," there are other circumstances that can predispose any runner to shin splints. Running on hard surfaces such as concrete, running down-hill, and running only on one shoulder at the side of the road have all been related to shin splints. In addition, excessively worn running shoes, or running shoes that are the wrong type for your particular foot type and running style can also contribute to shin splints. The right running shoes in good condition can support the foot/legs and decrease the stress that can lead to shin splints.
Other biomechanical risk factors for shin splints include flat feet, high arches, and having one leg longer than the other (limb length discrepancy). Although these problems are inherent in a runner's make-up, they can be corrected. Wearing the proper shoes is most important. If that is not enough, a podiatrist can evaluate you to see if you need custom orthotics to correct the condition. In my practice, most people actually do not need custom orthotics, but are just using the wrong shoes, or making errors in their training program.
To prevent shin splints, increase your mileage gradually; 10% increases in weekly mileage are an old standard and generally safe. Otherwise follow a training program such as CTC's Marathon or Half Marathon Training Program. Wear your orthotics (if you have them to correct for flat feet, high arches, or a limb length discrepancy), but make sure they are in the right shoes. Replace the shoes when the outsole becomes worn, or when the midsole starts to collapse causing wrinkles in the back of the heel of the shoe. Avoid prolonged training on concrete. Run on the crown of the road, or alternate sides of the road. If you do hill training, start with running up, but walking down. Don't do intervals or any kind of speedwork without the guidance of an expert (the local traithlon clubs and running clubs have a whole bunch of friendly ones who will likely guide you at the scheduled CTC sessions).
Above all, stick to your training program, put in the miles (but respect the rest days) and you, and your shins, will be ready for the big race.
Christopher Segler, DPM, AACFAS
Award Winning Foot & Ankle Surgeon
Doc On The Run San Francisco Bay Area Podiatry Sports Medicine House Calls
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