Marathon runners in Seattle are taking every initiative to prepare for Saturday's Rock 'n' Roll Marathon. In addition to their extensive training and healthy eating regimes racers might want to consider something that could have an even bigger impact -- their footwear.

In a trend inspired by a popular research article and a best-selling book, many runners are choosing to run without shoes or in near-barefoot shoes under the belief that traditional shoes might lead to more injuries than barefoot styles. Unfortunately, many are making the switch based more on the fad's popularity than on solid science. In fact, no scientific studies show that traditional running shoes directly cause injury or that barefoot running reduces injuries.

Just as there is no easy, workout-free diet that will help you lose 30 pounds in 30 days, there is no shoe that will guarantee pain-free running. Countless factors play a role in the development of injuries in runners, including training program and history, cardiovascular fitness, musculoskeletal strength and nutrition.

The case for barefoot running is often made on anecdotal evidence -- "It worked for me, so it must work for everyone!" But there are no studies showing that barefoot running leads to a decrease in injuries. A review conducted by Cory Hofmann at the Cybex Research Institute found that studies show only that barefoot running encourages changes in biomechanical variables, as the body adapts to soften the impact of running on hard surfaces. These changes could potentially contribute to changes in athletic performance or injury rates. Potentially.

While studies show that running with a barefoot style is different, for example promoting a forefoot or midfoot strike instead of a rearfoot or heel strike commonly promoted by traditional running shoes, they don't actually prove such a style guarantees fewer or less-severe injuries. Enter the marketers, who claim that near-barefoot shoes encourage a more "natural" running style, restoring modern runners to a prehistoric age when hunters ran long distances in bare feet.

The Endurance Running Hypothesis suggests that early man survived despite of not being able to run faster than animals because we could run longer. Problems arise when that theory is used to promote barefoot running today. For starters, early humans were likely lighter than modern day humans. And, they ran on soft grassy Savanna, not concrete and asphalt, likely at significantly slower paces over longer periods of time than most modern runners.

In reality, the potential for changes in athletic performance or injury rates don't guarantee positive changes. For example, an increased activation of the plantar flexors, as has been found in barefoot running, could lead to greater fatigue, Achilles tendinitis, or instability in the arches. On the flip side, gradually increased activation of the plantar flexors could help the muscles strengthen over time, helping to stabilize the Achilles tendon and longitudinal arch. The bottom line: the science is unclear. Additionally, the changes in running style promoted by the barefoot approach can be made in traditional shoes with attention to form.

While barefoot running is not inherently bad, it isn't inherently good, either. It will take a runner's body time to adapt to the new style. Introducing a new set of drastically different mechanical demands to an unprepared body could potentially be very harmful. Starting any new training program or running style should be done carefully, with a slow buildup of mileage and intensity to help the body adapt to the different demands of the new style.

Discerning runners would be wise to disregard the marketing lingo and instead focus on their own biomechanics, experiences and preferences. Examining the causes of an injury is an extremely complex task, dependent on many factors. The truth is, every body is different, and there is no single "best" way to run, just as there is no "best" fad diet for weight loss. What works for one runner might not work for you.

Regardless of running style, any training program should be started with caution. There is no silver bullet -- or silver shoe -- for becoming a successful long distance runner. It takes a commitment to working and training both hard and smart.

Dr. Paul Juris is the executive director of the Cybex Research Institute.