February 2016

Plantar fasciitis: clinical concerns in cleated sports

Orthotic-Devices-for-the-Win

By Patricia Pande, MClScPT, CSCS, CPed

Sponsored by an educational grant from Medi USA.

Cleated sports are associated with a high incidence of lower extremity injuries. American football and soccer are particularly troublesome due to unique risk factors involving footwear design, loading patterns, and sport-specific biomechanics.

Plantar heel pain is one of the most common ailments in athletic populations, presenting as pain with the first step in the morning and the sensation of walking on needles. The plantar fascia may become inflamed from repetitive stress or undergo degenerative changes, commonly called fasciosis.

Loss of playing time related to plantar fasciitis in highly compensated football and soccer players has been widely reported by the media, but such injuries are not limited to elite athletes.1 Plantar heel pain is responsible for up to 10% of all visits to sports clinics.2 Although little research has focused specifically on plantar fasciitis in cleated sports, numerous evidence-based hypotheses can be made.

In a study of intercollegiate American football players who participated in the National Football League (NFL) Combine, 72% reported a history of foot and ankle injury.3 Although the study did not include plantar fasciitis, forefoot and midfoot injuries observed by the authors are likely due to the torsional bending and compression that results from pushing against 300 to 400 pounds of unyielding force in a lightweight shoe—a magnitude of loading that over time could also contribute to plantar fasciitis. The position of plantar flexion associated with playing football also engages the windlass mechanism of the plantar fascia and may put this tissue at risk for tearing.

Risk factors

There is a paucity of data on the cause of plantar fasciitis in cleated sports athletes, but findings related to a number of sport-specific risk factors lend themselves to extrapolation.

BMI. Van Leeuwen et al found a positive association between high body mass index (BMI) and plantar fasciitis,4 and in an earlier plantar fasciitis study BMI was the only variable that predicted disability.5 BMI has been correlated with plantar fascia thickness in symptomatic patients, but a causal relationship remains unclear.6 Higher BMI theoretically causes increased vertical force during heel contact, with a concomitant increase in tissue stress.7

In the NFL, the average BMI is 31.35 kg/m2, which meets the World Health Organization definition of obesity; nose tackles (40.20 kg/m2) and defensive tackles (38.22 kg/m2) have the highest averages.8 Although the muscularity of football players makes BMI a poor measure of fitness, the magnitude of body weight in football players means foot and ankle injuries are not surprising. Simply put, “football players are heavy people that run a lot.”8 Reduction of body weight, though often recommended for nonathletes with plantar fasciitis, may not be a solution in certain football players.

Plantar loads. Studies show runners with plantar fasciitis have higher plantar loads and loading rates than uninjured runners;9 this suggests the level of running required of many cleated sports athletes influences plantar fasciitis risk. Although the relationship between loading and plantar fasciitis in cleated sports is not established, the high plantar loads and peak pressures associated with pivoting, cutting, or jumping merit further study.

Wong et al found that soccer players had higher peak pressures under the medial heel and arch than runners because of the sideways and diagonal cuts required by the sport.10 Pivoting and cutting in football also requires push-off from the medial aspect of the foot.11 Extrapolating these findings to the cleated sports population as a whole supports the use of treatments that aim to reduce this medial pressure. However, the simultaneous need to avoid overloading the fifth ray (due to fifth-metatarsal fracture risk in cleated sports athletes)12 necessitates a delicate treatment interplay; this need to balance the foot may be optimized by a more minimalistic approach to orthoses in athletic shoes.

Reducing shear stress may be as important as reducing plantar loads for preventing injuries to the plantar aspect of the foot and may also increase healing rates. Shear stress during gait is associated with foot pain in patients with rheumatoid arthritis;13 however, few studies have studied shear in sports.14

2medi-istock29589300-copyCleats. Modern cleats are much more lightweight and flexible than in the past; a coach and trainer, for example, claim cleats are akin to ballet slippers with spikes.15 For many football players, the style and feel are the most important considerations when selecting cleats. In one study, 22% said they choose shoes based on weight, 21% on appearance, and 18% on safety.16

Although athletes often prefer a tight cleat that can confine the foot, research suggests an improvement in balance with cleats versus a barefoot condition due to greater ground contact area, which could intuitively help with heel pain.17 However, the limited volume in a cleated shoe—especially one that fits snugly—is an important consideration for orthotic management.

Contrary to popular belief, shoes with cleats that improve their grip on grass surfaces are likely to be associated with less stability than flat-soled shoes.18 Certain shoes and orthoses designed to affect balance may provide some protection from sprains and strains of soft tissue,19 and further study is required for implementation in these sports.

Because kinematics and kinetics during walking in individuals with plantar fasciitis differ from those of healthy volunteers,20 shoes and inserts designed to address these issues may be beneficial in cleated sports athletes with plantar fasciitis. Several studies on rotational stiffness of football shoes found more rearfoot eversion with a flexible shoe than a stiffer shoe.21 Additionally, carbon fiber inserts may shift pressure laterally.14

A personal communication between this author and a former professional football player shed some light on the problem of plantar fasciitis and footwear. Gerald Edwards, an American College of Sports Medicine-certified fitness trainer for high-level athletes in Los Angeles, believes that cleats—particularly those that screw in and are worn during game play—have an impact on foot pain. He suggested the rubber soles of molded cleats (worn primarily for practice) provide far more comfort than the hard plastic sole of screw-ins.22

Edwards suggested that plantar fasciitis in football players is the result of continual pounding against cleats without proper time for myofascial work. In fact, Edwards believes, because of their regimented practice and training schedule, most football players do not focus on their foot health until they either have plantar fasciitis or torn fascia. As such, he recommends that trainers adopt preventive measures to stem the incidence of plantar injury at every level of the sport.

Biomechanics. The first ray is an important consideration for football and soccer players. Its role in the windlass mechanism is most effective when the first metatarsal, sesamoid apparatus, and hallux are aligned with the plantar fascia or aponeurosis.23 Acceleration from a dead stop or rapidly changing direction—common maneuvers in many cleated sports—requires immense force at push off, which could impact the windlass mechanism at a higher speed, particularly if an athlete has not had proper time for warm up.

Warm up. In soccer, starting players are typically on the field for long periods and muscles remain in a lengthened position. Substitute players in soccer and football, however, are often sidelined for long periods, sometimes in extreme cold, allowing the body to cool and muscles to tighten. Proper warm-up before and during activity has been associated with improved performance24 and decreased injury rates,25,24 though injury prevention studies have not included large numbers of plantar fasciitis cases.

Rosenbaum and Hennig have suggested decreased electro­myographic activity and enhanced force development of the Achilles tendon after running on a treadmill for a 10-minute warm up could be a factor in injury prevention.26 Given that Achilles tension affects strain on the plantar fascia through anatomical and myofascial connections,27 warm ups may help mitigate the stress on this structure.

Treatment and prevention

The plantar fasciitis treatment paradigm of rest, cessation of activity, or both is often not feasible for high-level athletes. Furthermore, other strategies to reduce load on the foot, such as decreased stride length or change in walking or running pace,28,29 could hamper performance.

Plantar fascia corticosteroid injections may have a negative effect on the health and performance of cleated sports athletes, as suggested by an account of rupture after two injections given to enable the athlete to continue playing.30 Rupture rates increase with higher body mass and additional injections.31,32 As such, the risk of rupture (or rerupture) must be weighed against the pressure to return to sports.

Treatment must focus on other ways to mitigate the deleterious forces on the foot and ankle, including:

  1. Orthoses that reduce impact loading33 as well as loads associated with high BMI and sport-specific movements;
  2. Modifications to shoes or inserts that reduce plantar load (eg, cleats with deformable nubs);34
  3. Orthoses that can be adjusted to address the different demands imposed by different playing positions (eg, backward vs forward running, predominantly playing on one side of the field) and symmetry issues related to limb dominance; and
  4. Low volume inserts that fit comfortably and allow for biomechanical corrections within the constraints of a tight shoe without hindering performance.15

Plantar fasciitis in cleated sports will continue to gain prominence in the news as it affects more highly visible athletes. As healthcare practitioners, we need to help not just high-level athletes but also those who play recreationally for health benefits. Our level of knowledge and biomechanics must meet this challenge.

Patricia Pande, MClScPT, CSCS, CPed, is a physical therapist, pedorthist, strength and conditioning specialist based in Durham, NC. She is the founder of FootCentric, an online continuing education company dedicated to comprehensive, multidisciplinary foot treatment.

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