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The effect of foot orthotic use on exercise related leg pain in cross country athletes
Physical Therapy in Sport 13 (2012) 214e218
Contents lists available at SciVerse ScienceDirect
Physical Therapy in Sport journal homepage: www.elsevier.com/ptsp
Original research
The effect of foot orthotic use on exercise related leg pain in cross country athletes Mark F. Reinking*, Ann M. Hayes, Tricia M. Austin Saint Louis University, Department of Physical Therapy and Athletic Training, Doisy College of Health Sciences, 3437 Caroline Street, Saint Louis, MO 63104, United States
a r t i c l e i n f o
a b s t r a c t
Article history: Received 3 September 2010 Received in revised form 12 September 2011 Accepted 31 October 2011
Objectives: The purposes of this research were to (1) investigate the effect of foot orthotic use on exercise related leg pain (ERLP) in cross-country (XC) athletes, and (2) determine if an association between foot type and foot orthotic use exists. Design: Prospective cohort design. Setting: High schools and colleges in a Midwestern metropolitan region. Participants: 213 high school and college XC athletes (107 male, 106 female). Materials/Methods: Participants were seen before the fall XC season for classification of foot type, visual orthotic inspection, and questionnaire completion regarding foot orthotic use and ERLP. Statistical analysis of relationships (chi-square) was conducted. Results: 37 of the 213 XC athletes (17.4%) used foot orthotics; 31 of the 37 athletes using foot orthotics (83.8%) reported a history of ERLP. Of these 31 athletes, 17 (54.8%) were using orthotics for ERLP and 15 reported a decrease in ERLP with orthotic use. Fourteen athletes were using orthotics for a reason other than ERLP and only 2 reported a decrease in ERLP with orthotic use. Athletes using orthotics included all three foot types (pronated, neutral, supinated) with no relationship between orthotic use and foot type. Conclusion: One-sixth of the XC athletes used foot orthotics and most using orthotics for ERLP reported a decrease in ERLP symptoms. The majority of athletes using orthotics for reasons other than ERLP reported no change in ERLP symptoms. There was no association between foot type and orthotic use. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Foot orthotics Exercise related leg pain Overuse injury Running
1. Introduction Exercise related leg pain (ERLP) is a regional pain syndrome in which pain is located between the knee and the ankle and occurs during exercise (Brukner, 2000; Reinking & Hayes, 2006). The pathologies manifesting as ERLP include medial tibial stress syndrome, chronic exertional compartment syndrome, stress fractures, tendinopathies (posterior tibialis, anterior tibialis, peroneals (fibularis), and Achilles), nerve entrapment syndromes, and vascular syndromes. Medial tibial stress syndrome and stress fractures, both overuse injuries, are common causes of ERLP (Ugalde & Batt, 2001), while nerve entrapments and vascular syndromes are quite rare (Bradshaw, 2000; McCrory, 2000; McCrory, Bell, & Bradshaw, 2002). Research on risk factors associated with ERLP has attempted to identify modifiable factors that can be addressed for prevention and treatment purposes. Foot type is considered a modifiable risk factor as the mechanical behavior of the foot can be changed using foot orthotics (MacLean, Davis, & Hamill, 2006; MacLean, Davis, &
* Corresponding author. Tel.: þ1 314 977 8505; fax: þ1 314 977 8513. E-mail address: [email protected] (M.F. Reinking). 1466-853X/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ptsp.2011.10.005
Hamill, 2008; Mundermann, Nigg, Neil Humble, & Stefanyshyn, 2003; Nawoczenski, Cook, & Saltzman, 1995). Some studies have shown an association between excessive foot pronation and ERLP (Bennett, Reinking, Pluemer, Pentel, Seaton, & Killian, 2001; Reinking, 2006; Sommer & Vallentyne, 1995; Willems, De Clercq, Delbaere, Vanderstraeten, De Cock, & Witvrouw, 2006; Williams, McClay, & Hamill, 2001; Yates & White, 2004), while two studies have reported an association between a supinated foot and lower extremity overuse injury (Burns, Keenan, & Redmond, 2005; Korpelainen, Orava, Karpakka, Siira, & Hulkko, 2001). However, other studies have reported no association between foot type and ERLP (Michelson, Durant, & McFarland, 2002; Reinking, Austin, & Hayes, 2007; Reinking & Hayes, 2006). Tiberio (1988) described the subtalar joint of the foot as the most frequent site of compensation for foot abnormalities. He postulated that compensatory changes in the amount, speed, or timing of subtalar joint motions impose abnormal stress on surrounding structures which can lead to tissue breakdown, resulting in overuse injury. The use of foot orthoses for the prevention or treatment of overuse injuries is commonly recommended by sports medicine health professionals. This is based on the hypothesis that foot orthotics attenuate the amount, speed, or timing of motions as described by Tiberio (1988). Limited evidence demonstrates the
M.F. Reinking et al. / Physical Therapy in Sport 13 (2012) 214e218
effect of foot orthotics on lower extremity kinematics and kinetics (MacLean et al., 2006, 2008; Mundermann et al., 2003). All three of these studies have demonstrated a decrease in rearfoot eversion motion with the use of foot orthotics. Two studies have reported runners’ perception of the effectiveness of orthotic use based on survey data. In the study by Gross, Davlin, and Evanski (1991), 75.5% of 347 long distance runners reported either full resolution of, or much improvement in lower extremity symptoms with the use of orthotics. In their sample population 7.2% had “shin splints” but the authors reported that results of orthotic treatment were independent of the diagnoses. Eickhoff, Hossain, and Slawski (2000) surveyed a sample of collegiate cross-country (XC) athletes at 14 National Collegiate Athletic Association (NCAA) Division II institutions. Of the 164 respondents, 14 of 16 athletes wearing prescribed foot orthotics reported a favorable effect with the use of foot orthotics. Loudon and Dolphino (2010) used a prospective cohort study design to study the effect of a combination of off-the-shelf orthotics and calf stretching on pain in a group of community runners with medial tibial stress syndrome (MTSS). While the authors found decreased MTSS pain in over half of the participants, the design of that study did not allow the researchers to assess the relative contribution of orthotics and stretching to the relief of MTSS pain. In a systematic review and meta-analysis of the use of foot orthotics in the prevention or treatment of overuse injuries, Collins, Bisset, McPoil, and Vicenzino (2007) examined the evidence for the use of foot orthotics for the treatment and prevention of overuse injury. They concluded that while support exists for the use of foot orthotics in preventing overuse injury in a military population, there is insufficient evidence to support the use of orthotics for treatment of overuse injury or for the application to populations other than the military. In another systematic review on the effectiveness of foot orthotics in the treatment and prevention of lower limb injuries (Hume, Hopkins, Rome, Maulder, Coyle, & Nigg, 2008), the authors concluded that “customized semi-rigid FOs [sic] have moderate to large beneficial effects in treating plantar fasciitis, moderate effects in preventing posterior tibial stress fractures, and small to moderate effects in treating or preventing patellofemoral pain syndrome.” A recent randomized controlled trial of the use of custom foot orthotics in the prevention of overuse lower limb injury in military trainees (Franklyn-Miller, Wilson, Bilzon, & McCrory, 2011) found the orthoses to be effective in preventing such injuries. Consequently, this research was conducted to (1) investigate the effect of foot orthotic use on exercise related leg pain (ERLP) in high school and college XC athletes, and (2) determine if an association between foot type and foot orthotic use exists. 2. Methods The data presented in this paper are taken from two larger prospective cohort investigations of high school and college XC athletes examining risk factors for the development of ERLP (Reinking et al., 2007; Reinking, Austin, & Hayes, 2010). These studies were approved by the University’s institutional review board. 2.1. Participants Study participants were 213 XC athletes (88 collegiate and 125 high school) from 6 different high schools and 5 colleges representing both public and private schools in a Midwestern metropolitan region in the United States of America. Before the XC season, the athletic director and XC coach from each institution were contacted regarding their willingness to allow the researchers to invite participation of their XC athletes. When a signed letter of cooperation was received from an institution, a recruitment meeting was
215
arranged for the investigators to describe the study objectives and methodology to the XC athletes and, in the case of the high school athletes, their parents/guardians. Because most of the high school XC athletes were younger than 18 years of age, both parental consent and athlete assent were necessary for their participation in the investigation. For the collegiate athletes, the inclusion criteria included being 18 years or older so no parental consent was required. For all athletes, the inclusion criteria included being rostered on a high school or college XC team and the ability to fully bear weight on the lower extremities to allow for foot assessment. 2.2. Initial questionnaire During August and early September, the investigators arranged an initial data collection visit at each of the institutions. All XC athletes with appropriate consent received instructions on completing an initial questionnaire. The initial questionnaire included items on ERLP history, whether the athlete was currently using orthotics and the effect of the orthotics on ERLP. To enhance the accuracy of ERLP history, study participants received a verbal review of the definition of ERLP and a visual demonstration of the location of ERLP. Additionally, participants were given pictures of the location of ERLP for reference during questionnaire completion and investigators were available for any questions during questionnaire completion. 2.3. Visual assessment of foot type Visual assessment of foot type was performed using the method described by Dahle, Mueller, Delitto, and Diamond (1991). One of the investigators (AMH) observed each foot in bilateral stance for three factors: calcaneal position (inverted, neutral, or everted), presence or absence of a medial talonavicular bulge, and height of the medial longitudinal arch. Based on the criteria established by Dahle et al. (1991), for a foot to be classified as either pronated or supinated, the foot was required to have all three criteria for that foot type. If three criteria were present e the calcaneus was everted more than 3 , a medial talonavicular bulge was present, and the height of the medial longitudinal arch was low, the foot was classified as pronated. Conversely, if the calcaneus was inverted more than 3 , a medial talonavicular bulge was not present, and the height of the medial longitudinal arch was high, the foot was classified as supinated. If the foot did not meet all three criteria for either foot type, it was classified as neutral. Dahle et al. (1991) reported a Kappa value of .724 for intertester reliability of this measure. In our study, one investigator (AMH) performed all the visual assessments of foot type. We used a blinded test-retest reliability study of 15 subjects in a single day and the investigator’s Kappa value was .75 for intratester reliability of this measure. No intertester reliability was calculated as only one investigator assessed foot type in this study. 2.4. Visual inspection of orthotics Athletes that reported using orthotics on the initial questionnaire were asked to remove the orthotics from their shoes for visual inspection by the investigators. The orthotics were classified as custom made, off the shelf, or modified off the shelf. Additionally, the orthotics were classified as rigid, semi-rigid, or soft. All orthotic inspection was completed by one investigator (AMH). 2.5. Usability study Prior to data collection with athletes, usability of the initial questionnaires for the high school and college studies was assessed using 5 competitive athletes not involved in the study. The athletes
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completed the questionnaire and provided the investigators with information on ease of questionnaire completion, question clarity, and question routing. Based on the athletes’ feedback, minor changes were made in the questionnaires. 2.6. Data analysis All statistical analyses were completed using SPSS for Windows Version 10.0.5 software (SPSS, Chicago, IL). Frequency distributions were calculated for ERLP history, visual assessment of foot type, and orthotic use. Relationships between categorical measures were calculated using Chi-square and Cramer’s V. 3. Results A total of 403 athletes including 279 high school athletes (187 female, 92 male) and 124 collegiate athletes (63 female, 61 male) were rostered on the XC teams invited to participate. Consent/ assent forms were obtained from 213 athletes (125 high school and 88 collegiate) to participate in the study. The 213 athletes included 106 females and 107 males with an age range of 14e24 years. ERLP history was reported by 163 of the 213 athletes (76.5%). At the time of the initial questionnaire completion, 37 of the 213 athletes (17.4%) were using foot orthotics. A higher percentage of collegiate athletes (23/88, 26.1%) were using orthotics as compared to the high school athletes (11/125, 11.2%). Of the 37 athletes using foot orthotics, 31 (83.8%) had a history of ERLP, and among those 31 athletes, 17 (54.8%) were using orthotics for ERLP. Based on the questionnaire responses, we know that the other 14 athletes were using orthotics but not for ERLP. We do not know the specific indications for the orthotic use by those athletes. The visual assessment of foot type revealed that most athletes in this study had neutral feet (159/213, 74.6%), with pronated feet the second most common type (44/213, 20.7%), and very few supinated feet in the sample (10/213, 4.7%). There were no differences in the percentages of athletes with pronated, neutral, and supinated feet between those with and without ERLP history (Table 1). Table 2 presents the distribution of foot type (pronated, neutral, and supinated) between those using and not using foot orthotics. A greater percentage of those athletes with a pronated foot type used foot orthotics compared to those athletes with a neutral or supinated foot type. Concerning the effectiveness of the orthotics for management of ERLP, 17 athletes (54.8%) reported a decrease in ERLP with orthotic use, and 14 athletes (45.2%) reported no change in ERLP with orthotic use. No athletes reported orthotic use worsened their ERLP. However, further exploration of these data reveals a significant relationship (c-square ¼ 16.95, p ¼ .000) between orthotic effectiveness and whether the athlete was using orthotics specifically for ERLP (Table 3). Of the 17 athletes using orthotics for ERLP, 15 reported that the orthotic use decreased their pain. Of the 14 athletes with a history of ERLP but using orthotics for another reason, only two reported a decrease in ERLP. We found no Table 1 Visual assessment and ERLP history. Right
Pronated Neutral Supinated
a
Foot type
Pronated Neutral Supinated a b
Righta
Leftb
Orthotic n ¼ 37
No orthotic n ¼ 176
Orthotic n ¼ 37
No orthotic n ¼ 176
13 (35.1%) 22 (59.5%) 2 (5.4%)
31 (17.6%) 137 (77.8%) 8 (4.6%)
13 (35.1%) 23 (62.2%) 1 (2.7%)
36 (20.4%) 132 (75%) 8 (4.6%)
c-square ¼ 5.98, p ¼ .05. c-square ¼ 3.80, p ¼ .15.
significant relationship between the type of orthotic (custom or offthe-shelf), but it is an interesting observation that both of the athletes using orthotics for ERLP who reported no change in symptoms with orthotics use were using off-the-shelf devices. The results of the orthotic inspections are provided in Figs.1 and 2. As is evident, the most common orthotic type in the collegiate athletes was a custom made orthosis whereas the most common device in the high school athlete was an off-the-shelf device. Concerning the rigidity of the device, the semi-rigid orthotic was the most common orthotic used by the collegiate athletes and the soft device was the most common orthotic used by the high school athletes. 4. Discussion Our purposes for this research included investigating the effect of foot orthotic use on exercise related leg pain (ERLP) in crosscountry (XC) athletes, and determining if an association between foot type and foot orthotic use exists. We found that about onesixth of our participants reported foot orthotic use during running with a greater percentage of collegiate runners (26.1%) as compared to high school runners (11.2%). We also found that most collegiate runners were using custom foot orthotics, and most high school runners were using off-the-shelf devices. Consistent with the findings of Gross et al. (1991) and Eickhoff et al. (2000), most of the XC athletes (88.2%) who were wearing orthotics for ERLP reported a decrease in symptoms with orthotic use. There was no difference in whether they were using custom or off-the-shelf orthotics. One curious finding is that the 14 athletes who had a history of ERLP but were wearing orthotics for a reason other than ERLP generally reported that the orthotics had no effect on their ERLP. This raises the question of the placebo effect of an orthotic based on the athlete’s understanding of why the orthotic was prescribed. While no published studies that examined the potential placebo effect of foot orthotic use were found, one study has investigated this effect in ankle taping. Sawkins, Refshauge, Kilbreath, and Raymond (2007) reported that athletes with ankle instability perceived that both real and placebo ankle taping was effective in increasing ankle stability. These researchers proposed that this finding was a result of the athletes’ belief of the effectiveness of taping. In a randomized control trial, Landorf, Keenan, and Herbert (2006) examined the effect of orthotics (sham,
Table 3 Effectiveness of foot orthotic use on ERLP.
b
Left
ERLP Hx n ¼ 163
No ERLP Hx n ¼ 50
ERLP Hx n ¼ 163
No ERLP Hx n ¼ 50
35 (21.5%) 118 (72.4%) 10 (6.1%)
9 (18%) 41 (82%) 0 (0%)
38 (23.3%) 117 (71.8%) 8 (4.9%)
11 (22%) 38 (76%) 1 (2%)
ERLP ¼ exercise related leg pain, Hx ¼ history. a c-square ¼ 3.76, p ¼ .15. b c-square ¼ .88, p ¼ .64.
Table 2 Visual assessment and orthotic use.
Orthotic effect on ERLP Increased ERLP Using foot orthotics for ERLP Using foot orthotics for reason other than ERLP
No change
Decreased ERLP
0
2
15
0
12
2
ERLP ¼ exercise related leg pain, c-square ¼ 16.95, p ¼ .000.
M.F. Reinking et al. / Physical Therapy in Sport 13 (2012) 214e218
Fig. 1. Orthotic type school Level.
prefabricated, and custom) on pain and function in patients with chronic plantar fasciitis. While they found that the prefabricated and custom orthotics decreased pain and increased function, the sham orthotic group also showed a decrease in pain and increase in function. This finding and the results of our study raise the possibility that a person’s perception of the effectiveness of foot orthotic use may be influenced by their understanding of the clinical
217
condition for which the orthotic was prescribed, and the expectation that the orthotic would be effective for that condition. This possibility certainly requires further study as it suggests that a person’s perception may be a contributor to the effectiveness of orthotic devices. Based on a visual examination of athletes’ feet and classification into one of three foot types e pronated, neutral, and supinated e we did not find a relationship between foot type and the use of orthotics (Table 2). Of the 31 athletes with a history of ERLP and using orthotics, approximately two-thirds had a neutral foot type with the preponderance of the remaining third having a pronated foot type. Overall, a greater percentage of those athletes with a pronated foot type used foot orthotics compared to those athletes with a neutral or supinated foot type (Table 2). In a recent critical appraisal of the meta-analysis by Collins et al. (2007), Richter, Austin, and Reinking (2011) raised the question of application of research findings in evidence-based practice. The authors pointed out that interpretation of relative risk (RR) and associated confidence intervals requires consideration of the risks and benefits of a particular intervention. In their meta-analysis on the use of foot orthotics for the prevention of overuse injuries, Collins et al. (2007) a priori established a clinically beneficial effect in favor of foot orthoses as a RR > 1.5. Based on four randomized controlled trials on the prevention of overuse injuries using orthotics, they reported a RR of 1.49 with the 95% CI ranging from 1.07 to 2.08. Richter et al. (2011) suggested that given 1) the upper limit of their confidence interval indicated a beneficial effect of orthotics on overuse injuries, 2) the low risks (few adverse events) associated with the intervention, and 3) the low cost of off-theshelf orthotics, foot orthotics should be considered as a possible intervention for lower extremity overuse conditions. The data from the current study would support their recommendation as there were no reports of foot orthotics worsening ERLP and there was no difference between custom and off-the-shelf orthotic devices in the perceived effect on ERLP. Limitations of this study may affect the applicability of this research. First, this study relied on self-report of ERLP in high school and collegiate runners. We did not perform any diagnostic testing of those who reported ERLP. Second, our study design did not provide detail regarding the chronology of ERLP history. Consequently, establishing cause and effect from the history data is not possible. Third, this study was limited to 11 institutions in 1 large Midwestern metropolitan area and may not be generalizable across all colleges and universities. 5. Conclusion Approximately one-sixth of the 213 high school and collegiate XC athletes in this study used foot orthotics with one-half of those using orthotics for ERLP. A preponderance of those athletes using orthotics for ERLP reported a decrease in ERLP symptoms with orthotic use, but the majority of athletes using orthotics for reasons other than ERLP reported no change in ERLP symptoms. We found no association between foot type (pronated, neutral, supinated) and ERLP but a larger percentage of athletes with pronated feet used orthotics as compared to those athletes with neutral or supinated feet. We believe that orthotic use should be considered in the treatment of ERLP given the relatively low cost of devices and the low risk of adverse events. However, further research is required in understanding the possible mechanisms resulting in decreased pain, including the possibility of athletes’ beliefs in the effectiveness of the devices.
Fig. 2. Orthotic rigidity school Level.
Conflict of interest None declared.
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M.F. Reinking et al. / Physical Therapy in Sport 13 (2012) 214e218
Ethical approval This research was approved by the Saint Louis University Institutional Research Board (IRB #13861 & 14475). All subjects gave informed consent/assent to the work, parental/guardian consent was obtained when needed. Funding None declared. References Bennett, J. E., Reinking, M. F., Pluemer, B., Pentel, A., Seaton, M., & Killian, C. (2001). Factors contributing to the development of medial tibial stress syndrome in high school runners. Journal of Orthopaedic and Sports Physical Therapy, 31(9), 504e510. Bradshaw, C. (2000). Exercise-related lower leg pain: vascular. Medicine and Science in Sports and Exercise, 32(3 Suppl), S34eS36. Brukner, P. (2000). Exercise-related lower leg pain: an overview. Medicine and Science in Sports and Exercise, 32(3 Suppl), S1eS3. Burns, J., Keenan, A. M., & Redmond, A. (2005). Foot type and overuse injury in triathletes. Journal of the American Podiatric Medical Association, 95(3), 235e241. Collins, N., Bisset, L., McPoil, T., & Vicenzino, B. (2007). Foot orthoses in lower limb overuse conditions: a systematic review and meta-analysis. Foot and Ankle International, 28(3), 396e412. Dahle, L. K., Mueller, M. J., Delitto, A., & Diamond, J. E. (1991). Visual assessment of foot type and relationship of foot type to lower extremity injury. Journal of Orthopaedic and Sports Physical Therapy, 14(2), 70e74. Eickhoff, C. A., Hossain, S. A., & Slawski, D. P. (2000). Effect of prescribed foot orthoses on medial tibial stress syndrome in collegiate cross-country runners. Clinical Kinesiology, 54(4), 76e80. Franklyn-Miller, A., Wilson, C., Bilzon, J., & McCrory, P. (2011). Foot orthoses in the prevention of injury in initial military training: a randomized controlled trial. American Journal of Sports Medicine, 39(1), 30e37. Gross, M. L., Davlin, L. B., & Evanski, P. M. (1991). Effectiveness of orthotic shoe inserts in the long-distance runner. American Journal of Sports Medicine, 19(4), 409e412. Hume, P., Hopkins, W., Rome, K., Maulder, P., Coyle, G., & Nigg, B. (2008). Effectiveness of foot orthoses for treatment and prevention of lower limb injuries: a review. Sports Medicine, 38(9), 759e779. Korpelainen, R., Orava, S., Karpakka, J., Siira, P., & Hulkko, A. (2001). Risk factors for recurrent stress fractures in athletes. American Journal of Sports Medicine, 29(3), 304e310. Landorf, K. B., Keenan, A. M., & Herbert, R. D. (2006). Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Archives of Internal Medicine, 166(12), 1305e1310. Loudon, J. K., & Dolphino, M. R. (2010). Use of foot orthoses and calf stretching for individuals with medial tibial stress syndrome. Foot & Ankle Specialist, 3(1), 15e20.
MacLean, C. L., Davis, I. M., & Hamill, J. (2006). Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners. Clinical Biomechanics (Bristol, Avon), 21(6), 623e630. MacLean, C. L., Davis, I. S., & Hamill, J. (2008). Short- and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clinical Journal of Sport Medicine, 18(4), 338e343. McCrory, P. (2000). Exercise-related leg pain: neurological perspective. Medicine and Science in Sports and Exercise, 32(3 Suppl), S11eS14. McCrory, P., Bell, S., & Bradshaw, C. (2002). Nerve entrapments of the lower leg, ankle and foot in sport. Sports Medicine, 32(6), 371e391. Michelson, J. D., Durant, D. M., & McFarland, E. (2002). The injury risk associated with pes planus in athletes. Foot and Ankle International, 23(7), 629e633. Mundermann, A., Nigg, B. M., Neil Humble, R., & Stefanyshyn, D. J. (2003). Foot orthotics affect lower extremity kinematics and kinetics during running. Clinical Biomechanics, 18(3), 254e262. Nawoczenski, D. A., Cook, T. M., & Saltzman, C. L. (1995). The effect of foot orthotics on three-dimensional kinematics of the leg and rearfoot during running. Journal of Orthopaedic and Sports Physical Therapy, 21(6), 317e327. Reinking, M. F. (2006). Exercise-related leg pain in female collegiate athletes: the influence of intrinsic and extrinsic factors. American Journal of Sports Medicine, 34. Reinking, M. F., Austin, T. M., & Hayes, A. M. (2007). Exercise-related leg pain in collegiate cross-country athletes: extrinsic and intrinsic risk factors. Journal of Orthopaedic and Sports Physical Therapy, 37(11), 670e678. Reinking, M. F., Austin, T. M., & Hayes, A. M. (2010). Risk factors for self-reported exercise-related leg pain in high school cross-country athletes. Journal of Athletic Training, 45(1), 51e57. Reinking, M. F., & Hayes, A. M. (2006). Intrinsic factors associated with exerciserelated leg pain in collegiate cross-country runners. Clinical Journal of Sport Medicine, 16(1), 10e14. Richter, R. R., Austin, T. M., & Reinking, M. F. (2011). Foot orthoses in lower limb overuse conditions: a systematic review and meta-analysisecritical appraisal and commentary. Journal of Athletic Training, 46(1), 103e106. Sawkins, K., Refshauge, K., Kilbreath, S., & Raymond, J. (2007). The placebo effect of ankle taping in ankle instability. Medicine and Science in Sports and Exercise, 39(5), 781e787. Sommer, H. M., & Vallentyne, S. W. (1995). Effect of foot posture on the incidence of medial tibial stress syndrome. Medicine and Science in Sports and Exercise, 27(6), 800e804. Tiberio, D. (1988). Pathomechanics of structural foot deformities. Physical Therapy, 68(12), 1840e1849. Ugalde, V., & Batt, M. E. (2001). Shin splints: current theories and treatment. Critical Reviews in Physical and Rehabilitation Medicine, 13(3), 217e253. Willems, T. M., De Clercq, D., Delbaere, K., Vanderstraeten, G., De Cock, A., & Witvrouw, E. (2006). A prospective study of gait related risk factors for exerciserelated lower leg pain. Gait & Posture, 23(1), 91e98. Williams, D. S., 3rd, McClay, I. S., & Hamill, J. (2001). Arch structure and injury patterns in runners. Clinical Biomechanics, 16(4), 341e347. Yates, B., & White, S. (2004). The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. American Journal of Sports Medicine, 32(3), 772e780.
Contents lists available at SciVerse ScienceDirect
Physical Therapy in Sport journal homepage: www.elsevier.com/ptsp
Original research
The effect of foot orthotic use on exercise related leg pain in cross country athletes Mark F. Reinking*, Ann M. Hayes, Tricia M. Austin Saint Louis University, Department of Physical Therapy and Athletic Training, Doisy College of Health Sciences, 3437 Caroline Street, Saint Louis, MO 63104, United States
a r t i c l e i n f o
a b s t r a c t
Article history: Received 3 September 2010 Received in revised form 12 September 2011 Accepted 31 October 2011
Objectives: The purposes of this research were to (1) investigate the effect of foot orthotic use on exercise related leg pain (ERLP) in cross-country (XC) athletes, and (2) determine if an association between foot type and foot orthotic use exists. Design: Prospective cohort design. Setting: High schools and colleges in a Midwestern metropolitan region. Participants: 213 high school and college XC athletes (107 male, 106 female). Materials/Methods: Participants were seen before the fall XC season for classification of foot type, visual orthotic inspection, and questionnaire completion regarding foot orthotic use and ERLP. Statistical analysis of relationships (chi-square) was conducted. Results: 37 of the 213 XC athletes (17.4%) used foot orthotics; 31 of the 37 athletes using foot orthotics (83.8%) reported a history of ERLP. Of these 31 athletes, 17 (54.8%) were using orthotics for ERLP and 15 reported a decrease in ERLP with orthotic use. Fourteen athletes were using orthotics for a reason other than ERLP and only 2 reported a decrease in ERLP with orthotic use. Athletes using orthotics included all three foot types (pronated, neutral, supinated) with no relationship between orthotic use and foot type. Conclusion: One-sixth of the XC athletes used foot orthotics and most using orthotics for ERLP reported a decrease in ERLP symptoms. The majority of athletes using orthotics for reasons other than ERLP reported no change in ERLP symptoms. There was no association between foot type and orthotic use. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Foot orthotics Exercise related leg pain Overuse injury Running
1. Introduction Exercise related leg pain (ERLP) is a regional pain syndrome in which pain is located between the knee and the ankle and occurs during exercise (Brukner, 2000; Reinking & Hayes, 2006). The pathologies manifesting as ERLP include medial tibial stress syndrome, chronic exertional compartment syndrome, stress fractures, tendinopathies (posterior tibialis, anterior tibialis, peroneals (fibularis), and Achilles), nerve entrapment syndromes, and vascular syndromes. Medial tibial stress syndrome and stress fractures, both overuse injuries, are common causes of ERLP (Ugalde & Batt, 2001), while nerve entrapments and vascular syndromes are quite rare (Bradshaw, 2000; McCrory, 2000; McCrory, Bell, & Bradshaw, 2002). Research on risk factors associated with ERLP has attempted to identify modifiable factors that can be addressed for prevention and treatment purposes. Foot type is considered a modifiable risk factor as the mechanical behavior of the foot can be changed using foot orthotics (MacLean, Davis, & Hamill, 2006; MacLean, Davis, &
* Corresponding author. Tel.: þ1 314 977 8505; fax: þ1 314 977 8513. E-mail address: [email protected] (M.F. Reinking). 1466-853X/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.ptsp.2011.10.005
Hamill, 2008; Mundermann, Nigg, Neil Humble, & Stefanyshyn, 2003; Nawoczenski, Cook, & Saltzman, 1995). Some studies have shown an association between excessive foot pronation and ERLP (Bennett, Reinking, Pluemer, Pentel, Seaton, & Killian, 2001; Reinking, 2006; Sommer & Vallentyne, 1995; Willems, De Clercq, Delbaere, Vanderstraeten, De Cock, & Witvrouw, 2006; Williams, McClay, & Hamill, 2001; Yates & White, 2004), while two studies have reported an association between a supinated foot and lower extremity overuse injury (Burns, Keenan, & Redmond, 2005; Korpelainen, Orava, Karpakka, Siira, & Hulkko, 2001). However, other studies have reported no association between foot type and ERLP (Michelson, Durant, & McFarland, 2002; Reinking, Austin, & Hayes, 2007; Reinking & Hayes, 2006). Tiberio (1988) described the subtalar joint of the foot as the most frequent site of compensation for foot abnormalities. He postulated that compensatory changes in the amount, speed, or timing of subtalar joint motions impose abnormal stress on surrounding structures which can lead to tissue breakdown, resulting in overuse injury. The use of foot orthoses for the prevention or treatment of overuse injuries is commonly recommended by sports medicine health professionals. This is based on the hypothesis that foot orthotics attenuate the amount, speed, or timing of motions as described by Tiberio (1988). Limited evidence demonstrates the
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effect of foot orthotics on lower extremity kinematics and kinetics (MacLean et al., 2006, 2008; Mundermann et al., 2003). All three of these studies have demonstrated a decrease in rearfoot eversion motion with the use of foot orthotics. Two studies have reported runners’ perception of the effectiveness of orthotic use based on survey data. In the study by Gross, Davlin, and Evanski (1991), 75.5% of 347 long distance runners reported either full resolution of, or much improvement in lower extremity symptoms with the use of orthotics. In their sample population 7.2% had “shin splints” but the authors reported that results of orthotic treatment were independent of the diagnoses. Eickhoff, Hossain, and Slawski (2000) surveyed a sample of collegiate cross-country (XC) athletes at 14 National Collegiate Athletic Association (NCAA) Division II institutions. Of the 164 respondents, 14 of 16 athletes wearing prescribed foot orthotics reported a favorable effect with the use of foot orthotics. Loudon and Dolphino (2010) used a prospective cohort study design to study the effect of a combination of off-the-shelf orthotics and calf stretching on pain in a group of community runners with medial tibial stress syndrome (MTSS). While the authors found decreased MTSS pain in over half of the participants, the design of that study did not allow the researchers to assess the relative contribution of orthotics and stretching to the relief of MTSS pain. In a systematic review and meta-analysis of the use of foot orthotics in the prevention or treatment of overuse injuries, Collins, Bisset, McPoil, and Vicenzino (2007) examined the evidence for the use of foot orthotics for the treatment and prevention of overuse injury. They concluded that while support exists for the use of foot orthotics in preventing overuse injury in a military population, there is insufficient evidence to support the use of orthotics for treatment of overuse injury or for the application to populations other than the military. In another systematic review on the effectiveness of foot orthotics in the treatment and prevention of lower limb injuries (Hume, Hopkins, Rome, Maulder, Coyle, & Nigg, 2008), the authors concluded that “customized semi-rigid FOs [sic] have moderate to large beneficial effects in treating plantar fasciitis, moderate effects in preventing posterior tibial stress fractures, and small to moderate effects in treating or preventing patellofemoral pain syndrome.” A recent randomized controlled trial of the use of custom foot orthotics in the prevention of overuse lower limb injury in military trainees (Franklyn-Miller, Wilson, Bilzon, & McCrory, 2011) found the orthoses to be effective in preventing such injuries. Consequently, this research was conducted to (1) investigate the effect of foot orthotic use on exercise related leg pain (ERLP) in high school and college XC athletes, and (2) determine if an association between foot type and foot orthotic use exists. 2. Methods The data presented in this paper are taken from two larger prospective cohort investigations of high school and college XC athletes examining risk factors for the development of ERLP (Reinking et al., 2007; Reinking, Austin, & Hayes, 2010). These studies were approved by the University’s institutional review board. 2.1. Participants Study participants were 213 XC athletes (88 collegiate and 125 high school) from 6 different high schools and 5 colleges representing both public and private schools in a Midwestern metropolitan region in the United States of America. Before the XC season, the athletic director and XC coach from each institution were contacted regarding their willingness to allow the researchers to invite participation of their XC athletes. When a signed letter of cooperation was received from an institution, a recruitment meeting was
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arranged for the investigators to describe the study objectives and methodology to the XC athletes and, in the case of the high school athletes, their parents/guardians. Because most of the high school XC athletes were younger than 18 years of age, both parental consent and athlete assent were necessary for their participation in the investigation. For the collegiate athletes, the inclusion criteria included being 18 years or older so no parental consent was required. For all athletes, the inclusion criteria included being rostered on a high school or college XC team and the ability to fully bear weight on the lower extremities to allow for foot assessment. 2.2. Initial questionnaire During August and early September, the investigators arranged an initial data collection visit at each of the institutions. All XC athletes with appropriate consent received instructions on completing an initial questionnaire. The initial questionnaire included items on ERLP history, whether the athlete was currently using orthotics and the effect of the orthotics on ERLP. To enhance the accuracy of ERLP history, study participants received a verbal review of the definition of ERLP and a visual demonstration of the location of ERLP. Additionally, participants were given pictures of the location of ERLP for reference during questionnaire completion and investigators were available for any questions during questionnaire completion. 2.3. Visual assessment of foot type Visual assessment of foot type was performed using the method described by Dahle, Mueller, Delitto, and Diamond (1991). One of the investigators (AMH) observed each foot in bilateral stance for three factors: calcaneal position (inverted, neutral, or everted), presence or absence of a medial talonavicular bulge, and height of the medial longitudinal arch. Based on the criteria established by Dahle et al. (1991), for a foot to be classified as either pronated or supinated, the foot was required to have all three criteria for that foot type. If three criteria were present e the calcaneus was everted more than 3 , a medial talonavicular bulge was present, and the height of the medial longitudinal arch was low, the foot was classified as pronated. Conversely, if the calcaneus was inverted more than 3 , a medial talonavicular bulge was not present, and the height of the medial longitudinal arch was high, the foot was classified as supinated. If the foot did not meet all three criteria for either foot type, it was classified as neutral. Dahle et al. (1991) reported a Kappa value of .724 for intertester reliability of this measure. In our study, one investigator (AMH) performed all the visual assessments of foot type. We used a blinded test-retest reliability study of 15 subjects in a single day and the investigator’s Kappa value was .75 for intratester reliability of this measure. No intertester reliability was calculated as only one investigator assessed foot type in this study. 2.4. Visual inspection of orthotics Athletes that reported using orthotics on the initial questionnaire were asked to remove the orthotics from their shoes for visual inspection by the investigators. The orthotics were classified as custom made, off the shelf, or modified off the shelf. Additionally, the orthotics were classified as rigid, semi-rigid, or soft. All orthotic inspection was completed by one investigator (AMH). 2.5. Usability study Prior to data collection with athletes, usability of the initial questionnaires for the high school and college studies was assessed using 5 competitive athletes not involved in the study. The athletes
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completed the questionnaire and provided the investigators with information on ease of questionnaire completion, question clarity, and question routing. Based on the athletes’ feedback, minor changes were made in the questionnaires. 2.6. Data analysis All statistical analyses were completed using SPSS for Windows Version 10.0.5 software (SPSS, Chicago, IL). Frequency distributions were calculated for ERLP history, visual assessment of foot type, and orthotic use. Relationships between categorical measures were calculated using Chi-square and Cramer’s V. 3. Results A total of 403 athletes including 279 high school athletes (187 female, 92 male) and 124 collegiate athletes (63 female, 61 male) were rostered on the XC teams invited to participate. Consent/ assent forms were obtained from 213 athletes (125 high school and 88 collegiate) to participate in the study. The 213 athletes included 106 females and 107 males with an age range of 14e24 years. ERLP history was reported by 163 of the 213 athletes (76.5%). At the time of the initial questionnaire completion, 37 of the 213 athletes (17.4%) were using foot orthotics. A higher percentage of collegiate athletes (23/88, 26.1%) were using orthotics as compared to the high school athletes (11/125, 11.2%). Of the 37 athletes using foot orthotics, 31 (83.8%) had a history of ERLP, and among those 31 athletes, 17 (54.8%) were using orthotics for ERLP. Based on the questionnaire responses, we know that the other 14 athletes were using orthotics but not for ERLP. We do not know the specific indications for the orthotic use by those athletes. The visual assessment of foot type revealed that most athletes in this study had neutral feet (159/213, 74.6%), with pronated feet the second most common type (44/213, 20.7%), and very few supinated feet in the sample (10/213, 4.7%). There were no differences in the percentages of athletes with pronated, neutral, and supinated feet between those with and without ERLP history (Table 1). Table 2 presents the distribution of foot type (pronated, neutral, and supinated) between those using and not using foot orthotics. A greater percentage of those athletes with a pronated foot type used foot orthotics compared to those athletes with a neutral or supinated foot type. Concerning the effectiveness of the orthotics for management of ERLP, 17 athletes (54.8%) reported a decrease in ERLP with orthotic use, and 14 athletes (45.2%) reported no change in ERLP with orthotic use. No athletes reported orthotic use worsened their ERLP. However, further exploration of these data reveals a significant relationship (c-square ¼ 16.95, p ¼ .000) between orthotic effectiveness and whether the athlete was using orthotics specifically for ERLP (Table 3). Of the 17 athletes using orthotics for ERLP, 15 reported that the orthotic use decreased their pain. Of the 14 athletes with a history of ERLP but using orthotics for another reason, only two reported a decrease in ERLP. We found no Table 1 Visual assessment and ERLP history. Right
Pronated Neutral Supinated
a
Foot type
Pronated Neutral Supinated a b
Righta
Leftb
Orthotic n ¼ 37
No orthotic n ¼ 176
Orthotic n ¼ 37
No orthotic n ¼ 176
13 (35.1%) 22 (59.5%) 2 (5.4%)
31 (17.6%) 137 (77.8%) 8 (4.6%)
13 (35.1%) 23 (62.2%) 1 (2.7%)
36 (20.4%) 132 (75%) 8 (4.6%)
c-square ¼ 5.98, p ¼ .05. c-square ¼ 3.80, p ¼ .15.
significant relationship between the type of orthotic (custom or offthe-shelf), but it is an interesting observation that both of the athletes using orthotics for ERLP who reported no change in symptoms with orthotics use were using off-the-shelf devices. The results of the orthotic inspections are provided in Figs.1 and 2. As is evident, the most common orthotic type in the collegiate athletes was a custom made orthosis whereas the most common device in the high school athlete was an off-the-shelf device. Concerning the rigidity of the device, the semi-rigid orthotic was the most common orthotic used by the collegiate athletes and the soft device was the most common orthotic used by the high school athletes. 4. Discussion Our purposes for this research included investigating the effect of foot orthotic use on exercise related leg pain (ERLP) in crosscountry (XC) athletes, and determining if an association between foot type and foot orthotic use exists. We found that about onesixth of our participants reported foot orthotic use during running with a greater percentage of collegiate runners (26.1%) as compared to high school runners (11.2%). We also found that most collegiate runners were using custom foot orthotics, and most high school runners were using off-the-shelf devices. Consistent with the findings of Gross et al. (1991) and Eickhoff et al. (2000), most of the XC athletes (88.2%) who were wearing orthotics for ERLP reported a decrease in symptoms with orthotic use. There was no difference in whether they were using custom or off-the-shelf orthotics. One curious finding is that the 14 athletes who had a history of ERLP but were wearing orthotics for a reason other than ERLP generally reported that the orthotics had no effect on their ERLP. This raises the question of the placebo effect of an orthotic based on the athlete’s understanding of why the orthotic was prescribed. While no published studies that examined the potential placebo effect of foot orthotic use were found, one study has investigated this effect in ankle taping. Sawkins, Refshauge, Kilbreath, and Raymond (2007) reported that athletes with ankle instability perceived that both real and placebo ankle taping was effective in increasing ankle stability. These researchers proposed that this finding was a result of the athletes’ belief of the effectiveness of taping. In a randomized control trial, Landorf, Keenan, and Herbert (2006) examined the effect of orthotics (sham,
Table 3 Effectiveness of foot orthotic use on ERLP.
b
Left
ERLP Hx n ¼ 163
No ERLP Hx n ¼ 50
ERLP Hx n ¼ 163
No ERLP Hx n ¼ 50
35 (21.5%) 118 (72.4%) 10 (6.1%)
9 (18%) 41 (82%) 0 (0%)
38 (23.3%) 117 (71.8%) 8 (4.9%)
11 (22%) 38 (76%) 1 (2%)
ERLP ¼ exercise related leg pain, Hx ¼ history. a c-square ¼ 3.76, p ¼ .15. b c-square ¼ .88, p ¼ .64.
Table 2 Visual assessment and orthotic use.
Orthotic effect on ERLP Increased ERLP Using foot orthotics for ERLP Using foot orthotics for reason other than ERLP
No change
Decreased ERLP
0
2
15
0
12
2
ERLP ¼ exercise related leg pain, c-square ¼ 16.95, p ¼ .000.
M.F. Reinking et al. / Physical Therapy in Sport 13 (2012) 214e218
Fig. 1. Orthotic type school Level.
prefabricated, and custom) on pain and function in patients with chronic plantar fasciitis. While they found that the prefabricated and custom orthotics decreased pain and increased function, the sham orthotic group also showed a decrease in pain and increase in function. This finding and the results of our study raise the possibility that a person’s perception of the effectiveness of foot orthotic use may be influenced by their understanding of the clinical
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condition for which the orthotic was prescribed, and the expectation that the orthotic would be effective for that condition. This possibility certainly requires further study as it suggests that a person’s perception may be a contributor to the effectiveness of orthotic devices. Based on a visual examination of athletes’ feet and classification into one of three foot types e pronated, neutral, and supinated e we did not find a relationship between foot type and the use of orthotics (Table 2). Of the 31 athletes with a history of ERLP and using orthotics, approximately two-thirds had a neutral foot type with the preponderance of the remaining third having a pronated foot type. Overall, a greater percentage of those athletes with a pronated foot type used foot orthotics compared to those athletes with a neutral or supinated foot type (Table 2). In a recent critical appraisal of the meta-analysis by Collins et al. (2007), Richter, Austin, and Reinking (2011) raised the question of application of research findings in evidence-based practice. The authors pointed out that interpretation of relative risk (RR) and associated confidence intervals requires consideration of the risks and benefits of a particular intervention. In their meta-analysis on the use of foot orthotics for the prevention of overuse injuries, Collins et al. (2007) a priori established a clinically beneficial effect in favor of foot orthoses as a RR > 1.5. Based on four randomized controlled trials on the prevention of overuse injuries using orthotics, they reported a RR of 1.49 with the 95% CI ranging from 1.07 to 2.08. Richter et al. (2011) suggested that given 1) the upper limit of their confidence interval indicated a beneficial effect of orthotics on overuse injuries, 2) the low risks (few adverse events) associated with the intervention, and 3) the low cost of off-theshelf orthotics, foot orthotics should be considered as a possible intervention for lower extremity overuse conditions. The data from the current study would support their recommendation as there were no reports of foot orthotics worsening ERLP and there was no difference between custom and off-the-shelf orthotic devices in the perceived effect on ERLP. Limitations of this study may affect the applicability of this research. First, this study relied on self-report of ERLP in high school and collegiate runners. We did not perform any diagnostic testing of those who reported ERLP. Second, our study design did not provide detail regarding the chronology of ERLP history. Consequently, establishing cause and effect from the history data is not possible. Third, this study was limited to 11 institutions in 1 large Midwestern metropolitan area and may not be generalizable across all colleges and universities. 5. Conclusion Approximately one-sixth of the 213 high school and collegiate XC athletes in this study used foot orthotics with one-half of those using orthotics for ERLP. A preponderance of those athletes using orthotics for ERLP reported a decrease in ERLP symptoms with orthotic use, but the majority of athletes using orthotics for reasons other than ERLP reported no change in ERLP symptoms. We found no association between foot type (pronated, neutral, supinated) and ERLP but a larger percentage of athletes with pronated feet used orthotics as compared to those athletes with neutral or supinated feet. We believe that orthotic use should be considered in the treatment of ERLP given the relatively low cost of devices and the low risk of adverse events. However, further research is required in understanding the possible mechanisms resulting in decreased pain, including the possibility of athletes’ beliefs in the effectiveness of the devices.
Fig. 2. Orthotic rigidity school Level.
Conflict of interest None declared.
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Ethical approval This research was approved by the Saint Louis University Institutional Research Board (IRB #13861 & 14475). All subjects gave informed consent/assent to the work, parental/guardian consent was obtained when needed. Funding None declared. References Bennett, J. E., Reinking, M. F., Pluemer, B., Pentel, A., Seaton, M., & Killian, C. (2001). Factors contributing to the development of medial tibial stress syndrome in high school runners. Journal of Orthopaedic and Sports Physical Therapy, 31(9), 504e510. Bradshaw, C. (2000). Exercise-related lower leg pain: vascular. Medicine and Science in Sports and Exercise, 32(3 Suppl), S34eS36. Brukner, P. (2000). Exercise-related lower leg pain: an overview. Medicine and Science in Sports and Exercise, 32(3 Suppl), S1eS3. Burns, J., Keenan, A. M., & Redmond, A. (2005). Foot type and overuse injury in triathletes. Journal of the American Podiatric Medical Association, 95(3), 235e241. Collins, N., Bisset, L., McPoil, T., & Vicenzino, B. (2007). Foot orthoses in lower limb overuse conditions: a systematic review and meta-analysis. Foot and Ankle International, 28(3), 396e412. Dahle, L. K., Mueller, M. J., Delitto, A., & Diamond, J. E. (1991). Visual assessment of foot type and relationship of foot type to lower extremity injury. Journal of Orthopaedic and Sports Physical Therapy, 14(2), 70e74. Eickhoff, C. A., Hossain, S. A., & Slawski, D. P. (2000). Effect of prescribed foot orthoses on medial tibial stress syndrome in collegiate cross-country runners. Clinical Kinesiology, 54(4), 76e80. Franklyn-Miller, A., Wilson, C., Bilzon, J., & McCrory, P. (2011). Foot orthoses in the prevention of injury in initial military training: a randomized controlled trial. American Journal of Sports Medicine, 39(1), 30e37. Gross, M. L., Davlin, L. B., & Evanski, P. M. (1991). Effectiveness of orthotic shoe inserts in the long-distance runner. American Journal of Sports Medicine, 19(4), 409e412. Hume, P., Hopkins, W., Rome, K., Maulder, P., Coyle, G., & Nigg, B. (2008). Effectiveness of foot orthoses for treatment and prevention of lower limb injuries: a review. Sports Medicine, 38(9), 759e779. Korpelainen, R., Orava, S., Karpakka, J., Siira, P., & Hulkko, A. (2001). Risk factors for recurrent stress fractures in athletes. American Journal of Sports Medicine, 29(3), 304e310. Landorf, K. B., Keenan, A. M., & Herbert, R. D. (2006). Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Archives of Internal Medicine, 166(12), 1305e1310. Loudon, J. K., & Dolphino, M. R. (2010). Use of foot orthoses and calf stretching for individuals with medial tibial stress syndrome. Foot & Ankle Specialist, 3(1), 15e20.
MacLean, C. L., Davis, I. M., & Hamill, J. (2006). Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners. Clinical Biomechanics (Bristol, Avon), 21(6), 623e630. MacLean, C. L., Davis, I. S., & Hamill, J. (2008). Short- and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clinical Journal of Sport Medicine, 18(4), 338e343. McCrory, P. (2000). Exercise-related leg pain: neurological perspective. Medicine and Science in Sports and Exercise, 32(3 Suppl), S11eS14. McCrory, P., Bell, S., & Bradshaw, C. (2002). Nerve entrapments of the lower leg, ankle and foot in sport. Sports Medicine, 32(6), 371e391. Michelson, J. D., Durant, D. M., & McFarland, E. (2002). The injury risk associated with pes planus in athletes. Foot and Ankle International, 23(7), 629e633. Mundermann, A., Nigg, B. M., Neil Humble, R., & Stefanyshyn, D. J. (2003). Foot orthotics affect lower extremity kinematics and kinetics during running. Clinical Biomechanics, 18(3), 254e262. Nawoczenski, D. A., Cook, T. M., & Saltzman, C. L. (1995). The effect of foot orthotics on three-dimensional kinematics of the leg and rearfoot during running. Journal of Orthopaedic and Sports Physical Therapy, 21(6), 317e327. Reinking, M. F. (2006). Exercise-related leg pain in female collegiate athletes: the influence of intrinsic and extrinsic factors. American Journal of Sports Medicine, 34. Reinking, M. F., Austin, T. M., & Hayes, A. M. (2007). Exercise-related leg pain in collegiate cross-country athletes: extrinsic and intrinsic risk factors. Journal of Orthopaedic and Sports Physical Therapy, 37(11), 670e678. Reinking, M. F., Austin, T. M., & Hayes, A. M. (2010). Risk factors for self-reported exercise-related leg pain in high school cross-country athletes. Journal of Athletic Training, 45(1), 51e57. Reinking, M. F., & Hayes, A. M. (2006). Intrinsic factors associated with exerciserelated leg pain in collegiate cross-country runners. Clinical Journal of Sport Medicine, 16(1), 10e14. Richter, R. R., Austin, T. M., & Reinking, M. F. (2011). Foot orthoses in lower limb overuse conditions: a systematic review and meta-analysisecritical appraisal and commentary. Journal of Athletic Training, 46(1), 103e106. Sawkins, K., Refshauge, K., Kilbreath, S., & Raymond, J. (2007). The placebo effect of ankle taping in ankle instability. Medicine and Science in Sports and Exercise, 39(5), 781e787. Sommer, H. M., & Vallentyne, S. W. (1995). Effect of foot posture on the incidence of medial tibial stress syndrome. Medicine and Science in Sports and Exercise, 27(6), 800e804. Tiberio, D. (1988). Pathomechanics of structural foot deformities. Physical Therapy, 68(12), 1840e1849. Ugalde, V., & Batt, M. E. (2001). Shin splints: current theories and treatment. Critical Reviews in Physical and Rehabilitation Medicine, 13(3), 217e253. Willems, T. M., De Clercq, D., Delbaere, K., Vanderstraeten, G., De Cock, A., & Witvrouw, E. (2006). A prospective study of gait related risk factors for exerciserelated lower leg pain. Gait & Posture, 23(1), 91e98. Williams, D. S., 3rd, McClay, I. S., & Hamill, J. (2001). Arch structure and injury patterns in runners. Clinical Biomechanics, 16(4), 341e347. Yates, B., & White, S. (2004). The incidence and risk factors in the development of medial tibial stress syndrome among naval recruits. American Journal of Sports Medicine, 32(3), 772e780.