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Barefoot Running: An Exciting New Training Dimension to Consider for Certain Clients
Christopher Pauls and Len Kravitz, Ph.D.

With the release of Born to Run: A Secret Tribe of Superathletes, and the Greatest Race the World Has Never Seen, Christopher McDougall's book about the Tarahumara Indians of Copper Canyon in Mexico, interest in barefoot running has soared. The author became interested in barefoot running as a means to increase both foot strength and to improve running mechanics in order to become more competitive in ultra-marathons (50 kilometer and 50 mile distances). This awareness has prompted many exercise professionals to introduce some barefoot training sessions with clients. In this column a review of running popularity, injuries, injury prevention strategies and barefoot training program ideas are presented.

Running Motivation and Popularity
For many people, running provides a feeling of wellbeing. As tired and fatigued one may feel before a run, there is a satisfying energetic surge after the run. As well, many people experience feelings of euphoria and stress relief after a good run. A great number of enthusiasts participate in running for disease prevention and body weight management. According to the National Sporting Goods Association, 35.9 million people (>7 years of age) participated in running and jogging in 2008, which is an 18% increase from 2007.

Running Injuries
Despite its increasing popularity, the incidence of running injuries still remains high. Lun et al. (2004) tracked musculoskeletal injuries of 87 recreational runners (44 men and 43 women, age >18 yrs) for six months. Subjects were running more than 20 km/week (~12.5 miles/week) and had no current injury at the start of the study. The incidence (number of new cases) of injury was 79%, which was the same for both sexes. In a review of 172 relevant articles on running injuries, van Gent and colleagues (2007) summarize that the majority of running injuries are at the knee (7%-50%), followed by the lower leg (9.0% to 32.2%), the foot (5.7%-39.3%), and the upper leg (3.4%-38.1%). Macera (1992) observed that the biggest predictor of running injuries is running distance. van Mechelen (1992) supports this evidence stating that 50-57% of injuries are due to overuse, the constant repetition of the cyclic impact from running. Cavanagh and Lafortune (1980) add that the impact force of running is up to 3 times the runner's body weight. From his review, Macera recommends less than 32 kilometers (18.5 miles) of running per week to lower injury risk.

Pronation, the turning of the foot at the ankle in which the inside arch flattens to absorb force, has also been identified as a key factor related to running injuries (Hart and Smith, 2009). Cavanagh and Lafortune (1980) explain that the internal forces at the foot strike in running place the foot into pronation. As the body shifts over the foot, the foot motion changes to supination (slight outward rolling of foot), which increases the rigidity of the foot during this push-off phase. Runners who over pronate may have more ailments that affect the foot, ankle, knees, and hips.

Running Injury Prevention
Orthotics, cushioning footwear and shock absorbing running surfaces (such as treadmills with flex or suspension decks) are common interventions used help reduce lower extremity injury risk from running. Properly fitted orthotics have convincingly been shown effective for reducing lower extremity pain and injuries (Mundermann, et al., 2003). Hart and Smith (2009) note that the research is conflicting whether footwear cushioning meaningfully dampens impact forces. In fact, subjects tend to adapt their foot loading technique during running when wearing hard and/or soft shoe midsoles, often neutralizing the effect of the shoe cushion. Suspension or flex deck treadmills are promoted to allow exercisers to run at relatively higher intensities with less-than-usual lower body discomfort. Lanford et al. (2003) compared a 'soft belt' treadmill to a traditional 'hard belt' treadmill with 27 active-duty soldiers (13 female,14 male) who had lower extremity musculoskeletal injuries. The subjects walked and ran at gradually increasing speeds until they experienced either the beginning of pain or an increase in pain from usual levels. The soft belt treadmill allowed subjects to exercise at 15% higher pain threshold speed, compared to the hard belt treadmill. However, it is not certain if the impact forces speeds were significantly different (impact forces usually tend to increase as a function of running speed), as these were not measured. Thus, a practical safety measure for exercise professionals is to caution their students and clients from too high of running speeds on soft belt treadmills as their perception may not truly reflect the impact forces they are experiencing.

Enter Barefoot Training
It is not the intent of this column to debate the mechanical parameter differences in barefoot running versus running shoes (referred to as 'shod' running). Indeed, one of the goals of exercise professionals (in helping clients attain their individual goals) is to introduce various exercise stimuli that may enhance performance, motivate clients, develop a component of fitness, or help to minimize injuries. It is with this spirit that barefoot training may present an exciting new dimension for personal trainers to consider with some clients.

Developing a Barefoot Training Program for Clients
Hart and Smith (2009) propose that a barefoot training program doesn't start with barefoot running. They suggest the training program should begin with doing different activities of daily life without shoes. Activities to initially consider include gardening, walking to the mailbox, and barefoot walking around the house. Next, the authors suggest doing some movement activities on an even grass surface or indoor surface. Perhaps do some walking, jogging, calisthenics and games (e.g. volleyball or frisbee) at a park or grass field. As with any training program, Hart and Smith recommend a progressive overload approach. They suggest doing barefoot training in multiple short sessions (e.g., 10 minutes at then beginning with another 10 minutes at the end of the workout) within a regular workout or two to three 10-minute bouts throughout the day. Gradually increase the time and/or combine the shorter sessions into one session. For the first two weeks, Hart and Smith suggest keeping the total barefoot training time per session no more than 30 minutes. For variety, attempt to expose the client to indoor and outdoor (grass or sand) movement activities. Gradually transition to harder surface (such as a side walk) walking and activities, but be very award of rocks, glass and harmful surface disturbances (e.g., holes, rough spots). Hart and Smith note that cold environments can be a deterrent to barefoot training. Perhaps the use of a fitness facility, indoor spot, mall or school gymnasium (where the temperature is more reasonable) would be much more manageable. The authors propose that injured runners should not begin doing any barefoot training until the symptoms of their injury have subsided. Several shoe companies are now promoting new shoes that purportedly simulate barefoot training. Some clients may prefer this approach. Importantly, keep consistent with the barefoot training as data shows there is a weakening of the lower extremities with cessation of the training (Hart and Smith). Lastly, Warbuton (2001) suggests that barefoot running is contraindicated for people with diabetes because of diabetes peripheral neuropathy, which may lead to a loss of protective sensations in the feet.

Final Thoughts
Increasing the amount of time your clients run, walk and exercise barefoot may be surprisingly beneficial. The implementation of barefoot training to an exercise program is quite simple and natural. Perhaps it is best to finish with this thought from Christopher McDougall's book cover. “The secret to happiness is right at your feet, and that you, indeed all of us, were born to run”.

Side Bar 1. Five Benefits of Adding Barefoot Training to an Exercise Program
Some of the proposed benefits of adding barefoot training to an exercise program include:
1) Barefoot training increases running efficiency. Divert and colleagues (2008) demonstrated that barefoot training allows for mechanical (bodily) modifications that increase running economy. This increase in running economy allows the exerciser to do more work with less metabolic demand of the body.
2) Barefoot running is less fatiguing. Divert et al. (2008) also showed that barefoot running leads to lower energy consumption, and thus delays the onset of fatigue from running.
3) Barefoot training increases sensory input. It is hypothesized that with barefoot training the exercisers will more accurately perceive the actual impact forces of the activity, potentially reducing the injury risk (Vormittag, Calongie, and Briner, 2009) white increasing proprioception (knowledge of the position, location, orientation and movement of the body and the ability to react accordingly) (Warburton, 2001).
4) Barefoot training may be protective from injury. Vormittag, Calongie, and Briner (2009) note that several barefoot sports, such as martial arts, beach volleyball, diving, boardsports (e.g., surfing, windsurfing, kitesurfing, and bodyboarding) have low risk to lower extremity injury. Gymnastics is the exception due to higher risk of ankle injuries with doing a dismount at the end of a routine.
5) Barefoot training may increase lower leg strength. Hart and Smith (2009) propose that one of the overlooked benefits of barefoot training is the increase in foot and ankle musculoskeletal power and strength.
Side Bar 2: Implications for Barefoot Training with the Elderly?
Falls are one of the leading preventable risk factors for injury among the elderly. Robbins, Waked, and McClaran (1995) observed that plantar (under surface of the foot) tactile sensitivity and foot position awareness are key factors that contribute to falls in the elderly. They found that as age increased, sensitivity to potential hazards decreased. Furthermore, their research suggests that as shoes increase in softness, sensitivity to hazards decreased. The authors recommend the use of thin, hard-soled shoes for the elderly while participating in activities. However, research is presently needed to determine if, in fact, participating in activities while barefoot may actually lead to increased stability in the elderly.

Christopher Pauls BA is a masters candidate in community health education at the University of New Mexico, Albuquerque. He earned his bachelors degree at UNM and taught high school for ten years; currently, he works with incarcerated men teaching health and reading. His research interests include human performance and exercise for general health and success. Christopher is an avid ultra marathon runner.

Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, Albuquerque, where he won the Outstanding Teacher of the Year award. Len was recently honored as the 2009 Canadian Fitness Professional Specialty Presenter of the Year and chosen as the American Council on Exercise 2006 Fitness Educator of the Year. He also received the prestigious Can-Fit-Pro Lifetime Achievement Award.

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