Relationships Between Arch Height Flexibility and Medial–Lateral Ground Reaction Forces in Rearfoot and Forefoot Strike Runners

in Journal of Applied Biomechanics
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  • 1 Harvard Medical School

Higher medial–lateral forces have been reported in individuals with stiffer foot arches. However, this was in a small sample of military personnel who ran with a rearfoot strike pattern. Therefore, our purpose was to investigate whether runners, both rearfoot and forefoot strikers, show different associations between medial–lateral forces and arch stiffness. A group of 118 runners (80 rearfoot strikers and 38 forefoot strikers) were recruited. Ground reaction force data were collected during running on an instrumented treadmill. Arch flexibility was assessed as the difference in arch height from sitting to standing positions, and participants were classified into stiff/flexible groups. Group comparisons were performed for the ratio of medial:vertical and lateral:vertical impulses. In rearfoot strikers, runners with stiff arches demonstrated significantly higher medial:vertical impulse ratios (P = .036). Forefoot strikers also demonstrated higher proportions of medial forces; however, the mean difference did not reach statistical significance (P = .084). No differences were detected in the proportion of lateral forces between arch flexibility groups. Consistent with previous findings in military personnel, our results indicate that recreational runners with stiffer arches have a higher proportion of medial forces. Therefore, increasing foot flexibility may increase the ability to attenuate medial forces.

The relationship between measures of foot arch function and musculoskeletal injuries in recreational runners and military personnel has been reported in several previous studies.16 Much of this work has focused on the height of the medial longitudinal arch, often characterized by the arch height index.1,36 However, flexibility of the foot arch has recently received more attention. One study showed that individuals with similar arch heights can display vastly different measures of arch flexibility.7 Furthermore, these differences can result in different gait mechanics and ground reaction force (GRF) loading patterns.8 Second, measures of arch flexibility have shown associations with musculoskeletal injury in runners. Specifically, stiffer arches have been associated with a higher risk of medial tibial stress syndrome.2

A recent study by Zifchock et al9 provided preliminary evidence for a mechanism by which stiffer arches may increase the risk for musculoskeletal injury. The authors reported that military personnel with stiffer arches had a higher distribution of their GRFs during running in the medial and lateral directions. They hypothesized that these higher mediolateral forces could lead to injury. However, there were 2 primary limitations to this study. First, it was conducted in a relatively small sample (group sizes = 11 stiff and 14 flexible arches) of military personnel. Second, only participants who ran with a rearfoot strike pattern were included. It has been demonstrated that runners with a forefoot strike pattern exhibit higher loading at the foot and ankle in comparison to those with a rearfoot strike.10,11 In addition, one study has demonstrated that the midfoot, specifically, is loaded to a higher degree during forefoot strike running.12 Seemingly, this would place a greater demand on the foot arch, resulting in different relationships between foot arch flexibility and medial–lateral GRFs compared with rearfoot strikers.

Therefore, the purpose of this study was to compare the relationship between foot arch flexibility and medial–lateral GRF distribution in a large sample of recreational runners that includes both rearfoot and forefoot strike runners. We hypothesized that, overall, runners with lower (stiffer) foot arch flexibility would demonstrate higher proportions of medial and lateral GRFs, comparative to the vertical component. Second, we hypothesized that these differences would be even greater in forefoot strikers, compared with rearfoot.

Methods

Experimental Design and Participants

An observational, cross-sectional design was used to assess the relationship between arch height flexibility (AHF) and the ratios of medial:vertical and lateral:vertical GRF impulses. In total, 118 healthy runners were included for the current study, including 80 rearfoot strikers and 38 forefoot strikers. Written informed consent was obtained prior to all testing, and all study procedures were approved by the local institutional review board. Participants were part of an ongoing study on the effects of footwear and foot strike patterns on gait mechanics. To be in this ongoing study, participants had to be injury- and pain-free for at least the previous 3 months and running at least 10 miles per week for the previous 6 months. For the current study, only participants who ran habitually in conventional, cushioned type footwear were included. Foot strike pattern was assessed during the normal course of testing. While participants ran on a treadmill, foot strike was captured in the sagittal plane using high-speed cameras (125 frames per second; Basler AG, Ahrensburg, Germany). Each participant’s foot strike pattern was classified visually, using previously reported methods.13

Procedures

The AHF was assessed in a manner consistent with previous studies.9,14,15 Briefly, arch height was measured as the height of the dorsal surface of the foot, at 50% of total foot length, using the arch height index measurement system.15 Arch height was measured while seated and standing, and AHF was calculated from the difference in measurements using the following, previously published formula14:

Dorsal heightSeated(mm)Dorsal heightStanding(mm)40%BW(kN)
Prior to running, participants were fitted with standard laboratory shoes that matched their habitual footwear (Nike Air Pegasus). Participants were part of a larger study that necessitated the use of laboratory shoes to collect accurate foot kinematics. The GRF data were collected using an instrumented treadmill (AMTI, Watertown, MA) embedded with 2 force plates sampling at 1500 Hz. Participants were given a short warm-up (2–3 min) at a self-selected pace. The speed was then increased to 2.68 m/s, and GRF data were collected while the participant performed a modified Stroop test16 to limit their ability to focus on their running form. The test was displayed on a large screen directly in their natural line of gaze. Participants were given verbal instruction on the test prior to running and were informed that they were not being scored nor timed on it. Sixteen seconds of GRF data were collected for analysis (approximately 20 strides per leg).

Data Reduction

Participants were subclassified based on AHF into having “Stiff” or “Flexible” arches based on the previously published median cutoff.7 An AHF < 14.8 mm/kN was considered stiff, and an AHF ≥14.8 mm/kN was considered flexible. The GRF data were low-pass filtered using a 4th order Butterworth filter with a cutoff frequency of 50 Hz. Medial, lateral, and vertical impulses were calculated across all of stance and for each stride. Impulses were averaged across all available strides. The medial–lateral GRF distributions were calculated as a ratio of the medial:vertical and lateral:vertical impulses.9 The left leg was used for analysis, as preliminary analyses revealed that the distribution of participants falling into the stiff and flexible AHF categories was more even for the left side.

Data Analysis

All analyses were conducted with IBM SPSS Statistics (version 25; IBM Corp, Armonk, NY). Descriptive statistics were calculated for demographic and GRF variables within each foot strike pattern and AHF grouping. Normality was assessed using Shapiro–Wilk tests. Mean age was compared between groups using Mann–Whitney U tests, and the distribution of sex between groups was compared using chi-squared statistics. Mean differences in medial:vertical and lateral:vertical impulse ratios, between stiff and flexible arch groups, were assessed using independent t tests or Mann–Whitney U tests. These comparisons were performed separately for rearfoot and forefoot strikers. In forefoot strikers, the distribution of sexes was found to differ significantly between AHF groups. As such, mean comparisons were also performed with sex as a covariate for this group, using analysis of covariance. Cohen d was calculated to assess effect sizes and interpreted according to established guidelines.17 Finally, as the sample was one of convenience, post hoc power was calculated for all analyses, using G*Power (Franz Faul, version 3.1.9.2; Universität Düsseldorf, Düsseldorf, Germany). An alpha level of .05 was used for all analyses.

Results

Descriptive statistics for demographic characteristics by AHF group are presented in Table 1. In rearfoot strikers, 39 participants were classified as having stiff arches and 41 as flexible. In forefoot strikers, 15 were classified as having stiff arches and 23 as flexible. No significant differences in mean age were detected for either foot strike group (U = 155–791, P = .62–.91) or in the distribution of sexes for rearfoot strikers (X2 = 0.22, P = .64). For forefoot strikers, there was a significantly higher proportion of men with stiff arches compared with flexible (X2 = 4.80, P = .03).

Table 1

Descriptive Statistics for Demographics by Arch Flexibility and Foot Strike Pattern Groupings

GroupAge, yBody mass, kgHeight, mSex (%M/W)
All RFS (n = 80)33 (10)69.6 (11.5)1.72 (0.10)54/46
 Stiff AHF (n = 39)33 (10)71.9 (13.3)1.72 (0.10)56/44
 Flex AHF (n = 41)34 (11)66.2 (10.4)1.70 (0.11)51/49
All FFS (n = 38)31 (9)69.8 (13.2)1.73 (0.08)66/34
 Stiff AHF (n = 15)32 (9)77.3 (14.4)1.78 (0.06)83/17
 Flex AHF (n = 23)31 (9)64.9 (9.9)1.70 (0.08)52/48

Abbreviations: AHF, arch height flexibility; FFS, forefoot strikers; RFS, rearfoot strikers. Note: All data are presented as mean (SD).

Descriptive data for medial:vertical and lateral:vertical GRF impulse ratios, between AHF groups, are presented in Figure 1. For rearfoot strikers, results of mean comparisons showed significantly higher medial:vertical ratios in the stiff AHF group, with a small effect size (P = .04, d = 0.48). This was also true for the forefoot strike group, although the difference did not reach significance (P = .08, d = 0.56). However, the differences in medial:vertical ratios between the stiff and flexible arches of the forefoot strikers were similar to those of the rearfoot strikers (0.47% vs 0.60%). No difference in the lateral:vertical ratios for either foot strike pattern was noted (rearfoot strike: P = .13, d = 0.34; forefoot strike: P = .48, d = 0.08). In forefoot strikers, no changes were found in mean comparisons of medial or lateral GRF impulse ratios after adjusting for the effects of sex, based on the results of analysis of covariance.

Figure 1
Figure 1

—Mean impulse ratios by arch flexibility grouping and foot strike pattern. Error bars represent 95% confidence intervals. FFS indicates forefoot strikers; RFS, rearfoot strikers. *Statistical significance at P < .05.

Citation: Journal of Applied Biomechanics 37, 2; 10.1123/jab.2020-0205

Results of post hoc power analyses for mean differences in medial:vertical ratios revealed relatively low statistical power (β = 0.38) to detect the moderate effect size in the forefoot striking group. In addition, power was low for the analyses of lateral:vertical ratios in both foot strike groups (β = 0.06–0.32). However, the observed effect sizes were also negligibly small for these comparisons.

Discussion

The purpose of the current study was to reexamine the relationship between arch flexibility and the distribution of medial–lateral forces during running. Building on a previous study,9 we examined these relationships in a larger cohort of recreational runners, as well as specific to rearfoot and forefoot strike patterns. We hypothesized that runners with stiffer arches would demonstrate higher ratios of medial:vertical and lateral:vertical GRF impulses. In addition, we hypothesized that these differences would be even greater in the forefoot strikers compared with rearfoot.

Overall, we found similar mean medial:vertical GRF impulse ratios as reported by Zifchock et al,9 with medial forces constituting approximately 2% to 2.5% of the vertical. However, we also observed much lower lateral:vertical ratios; approximately 0.8% to 1% compared with 3% to 4% reported previously. The most apparent explanation for this discrepancy is the difference in speeds where participants were required to run between studies. Zifchock et al9 required their participants to run at 3.13 m/s, whereas our standard speed was 2.68 m/s. A study by Nilsson et al18 reported a decreased vertical impulse and no change in total medial–lateral impulse, with increasing speed. Furthermore, this was true of increases in speed similar to the differences in standard speeds used by our study and that of Zifchock. However, they do not report separate medial and lateral impulses. This makes it difficult to confirm whether this would result in similar medial:vertical impulse ratios, but higher lateral:vertical.

In partial support of our first hypothesis, our results demonstrated a significantly higher distribution of medial GRFs in rearfoot strike runners with stiffer arches. This also partially confirms previous findings by Zifchock et al9 in a smaller sample of military personnel, replicating their results in a larger cohort, and consisting of recreational runners. A more flexible arch may offer a wider base of support through running stance, thereby limiting movement in the frontal plane. Given the cross-sectional nature of both the Zifchock and current study, there is also the possibility that the relationship is in the opposite direction. Runners in the stiff AHF group may have developed stiffer arches in response to higher medial and lateral GRFs, in order to better stabilize the base of support. A prospective design would be needed to determine whether the stiffness was a cause or effect of the higher medial:vertical impulses we found. Ideally, this would be a study where novice runners are followed longitudinally to determine if the foot arch adapts to an individual’s distribution of medial and lateral GRFs, or if the relationship remains constant.

In contrast to our hypotheses, and previous findings, we did not observe a higher distribution of lateral GRFs in the rearfoot strike runners with stiff arches. While statistical power was low for this comparison, this was partially due to the low effect size for the mean difference. In addition, the observed mean effect was actually in the opposite direction than Zifchock reported, with lateral:vertical impulse ratios slightly higher in the flexible arch group. This difference in findings may be due, in part, to the differences in running speeds and populations between studies.

Also, in contrast to our hypotheses, we did not find significant differences in the distribution of medial–lateral GRFs between AHF groups in forefoot strikers. We expected that there would be even larger differences in medial:vertical and lateral:vertical impulse ratios than those reported by Zifchock, given the higher demand placed on the foot arch by forefoot strikers.12 Forefoot strikers with stiff arches did display higher medial:vertical impulse ratios and with a larger effect size compared with rearfoot strikers. In addition, the statistical power for this comparison was low, partially due to the high variability in the forefoot strike group. Consequently, it may be that an increased sample size would show the differences to be both statistically significant and clinically relevant. This is the first study to make these comparisons in forefoot strikers. Therefore, while it appears that forefoot strikers do show a similar relationship between AHF and distribution of medial GRFs, further research is needed to confirm this.

While not the primary aim of the study, we assessed arch stiffness by strike pattern and by sex. A greater proportion of forefoot strikers (15 vs 23) exhibited flexible arches compared with rearfoot strikers, who were equally distributed across stiff and flexible arches. Forefoot strikers tend to land with greater ankle inversion at foot strike and exhibit greater eversion excursion.19 This additional range of motion with every running step may lead to greater flexibility of the feet. There was also a greater proportion of females with flexible arches in the forefoot strike group. This is consistent with the other reports of increased arch flexibility in females compared with males.14

There are several limitations to the current study. Given the cross-sectional design of the study, we cannot determine the directionality of the relationship between AHF and the distribution of medial–lateral GRFs. In addition, the interpretation of our data is limited by the analysis of AHF as a dichotomous variable. Essentially, we cannot say whether the relationship between AHF and medial:vertical impulse ratios is linear, only that individuals with the lowest AHF (<14.8 mm/kN) demonstrate a higher proportion of medial forces. Still, our results do provide preliminary evidence as to the nature of these relationships, for future investigation. Second, post hoc analyses revealed low statistical power for several of the comparisons. Our sample was one of convenience, and as such, we did not recruit participants based on their AHF grouping to meet sample size requirements. It is worth noting that the sample sizes, even for forefoot strikers, were larger than those included in the previous study by Zifchock. Therefore, we believe that our results still hold value, as the largest study to examine these relationships in recreational runners and specific to foot strike pattern.

Conclusion

The current study adds to previous work, demonstrating that recreational runners with stiff arches generally exhibit a higher proportion of GRFs in the medial direction. These findings provide specific guidance for the treatment and prevention of injuries that may result from higher medial forces during running. Our findings indicate that runners with stiffer arches may benefit from programs aimed at improving longitudinal arch flexibility. This study also provides guidance for future research. Future studies should focus on confirming our findings in forefoot strikers, as well as exploring the potential causal relationship between medial and lateral GRFs and injury.

Acknowledgment

The authors have no conflicts of interest to disclose.

References

  • 1.

    Nakhaee Z, Rahimi A, Abaee M, Rezasoltani A, Kalantari KK. The relationship between the height of the medial longitudinal arch (MLA) and the ankle and knee injuries in professional runners. Foot. 2008;18(2):8490. doi:10.1016/j.foot.2008.01.004

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2.

    Kudo S, Hatanaka Y. Forefoot flexibility and medial tibial stress syndrome. J Orthop Surg. 2015;23(3):357360. doi:10.1177/230949901502300321

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Williams DS 3rd, McClay IS, Hamill J. Arch structure and injury patterns in runners. Clin Biomech. 2001;16(4):341347. doi:10.1016/S0268-0033(01)00005-5

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Kaufman KR, Brodine SK, Shaffer RA, Johnson CW, Cullison TR. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med. 1999;27(5):585593. PubMed ID: 10496574 doi:10.1177/03635465990270050701

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Cowan DN, Jones BH, Robinson JR. Foot morphologic characteristics and risk of exercise-related injury. Arch Fam Med. 1993;2(7):773777. PubMed ID: 7906597 doi:10.1001/archfami.2.7.773

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6.

    Beard JH. Physical rejection for military service; some problems of reconstruction. Sci Monthly. 1919;9(1):514.

  • 7.

    Zifchock RA, Theriot C, Hillstrom HJ, Song J, Neary M. The relationship between arch height and arch flexibility: a proposed arch flexibility classification system for the description of multidimensional foot structure. J Am Podiatr Med Assoc. 2017;107(2):119123. PubMed ID: 28198638 doi:10.7547/15-051

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8.

    Williams DB III, Tierney RN, Butler RJ. Increased medial longitudinal arch mobility, lower extremity kinematics, and ground reaction forces in high-arched runners. J Athl Train. 2014;49(3):290296. PubMed ID: 24840580 doi:10.4085/1062-6050-49.3.05

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Zifchock R, Parker R, Wan W, Neary M, Song J, Hillstrom H. The relationship between foot arch flexibility and medial-lateral ground reaction force distribution. Gait Posture. 2019;69:4649. PubMed ID: 30660951 doi:10.1016/j.gaitpost.2019.01.012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10.

    Kleindienst FI, Campe S, Graf ES, Michel KJ, Witte K. Differences between fore-and rearfoot strike running patterns based on kinetics and kinematics. In: ISBS-Conference Proceedings Archive, Vol 1; 2007:252255.

    • Search Google Scholar
    • Export Citation
  • 11.

    Stearne SM, Alderson JA, Green BA, Donnelly CJ, Rubenson J. Joint kinetics in rearfoot versus forefoot running: implications of switching technique. Med Sci Sports Exerc. 2014;46(8):15781587. PubMed ID: 24500531 doi:10.1249/MSS.0000000000000254

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Kelly LA, Farris DJ, Lichtwark GA, Cresswell AG. The influence of foot-strike technique on the neuromechanical function of the foot. Med Sci Sports Exerc. 2018;50(1):98108. PubMed ID: 28902682 doi:10.1249/MSS.0000000000001420

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13.

    de Almeida MO, Saragiotto BT, Yamato TP, Lopes AD. Is the rearfoot pattern the most frequently foot strike pattern among recreational shod distance runners? Phys Ther Sport. 2015;16(1):2933. PubMed ID: 24894762 doi:10.1016/j.ptsp.2014.02.005

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Zifchock RA, Davis I, Hillstrom H, Song J. The effect of gender, age, and lateral dominance on arch height and arch stiffness. Foot Ankle Int. 2006;27(5):367372. PubMed ID: 16701058 doi:10.1177/107110070602700509

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15.

    Butler RJ, Hillstrom H, Song J, Richards CJ, Davis IS. Arch height index measurement system: establishment of reliability and normative values. J Am Podiatr Med Assoc. 2008;98(2):102106. PubMed ID: 18347117 doi:10.7547/0980102

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16.

    Comalli PE Jr, Wapner S, Werner H. Interference effects of Stroop color-word test in childhood, adulthood, and aging. J Genet Psychol. 1962;100(1):4753. doi:10.1080/00221325.1962.10533572

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    Cohen J. Statistical Power Analysis for the Behavioral Sciences. Cambridge, MA: Academic Press Inc; 1988.

  • 18.

    Nilsson J, Thorstensson A. Ground reaction forces at different speeds of human walking and running. Acta Physiol Scand. 1989;136(2):217227. PubMed ID: 2782094 doi:10.1111/j.1748-1716.1989.tb08655.x

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19.

    Williams DS, McClay IS, Manal KT. Lower extremity mechanics in runners with a converted forefoot strike pattern. J Appl Biomech. 2000;16(2):210218. doi:10.1123/jab.16.2.210

    • Crossref
    • Search Google Scholar
    • Export Citation

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The authors are with the Spaulding National Running Center, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Cambridge, MA, USA.

Johnson (cdjohnson@mgh.harvard.org) is corresponding author.
  • View in gallery

    —Mean impulse ratios by arch flexibility grouping and foot strike pattern. Error bars represent 95% confidence intervals. FFS indicates forefoot strikers; RFS, rearfoot strikers. *Statistical significance at P < .05.

  • 1.

    Nakhaee Z, Rahimi A, Abaee M, Rezasoltani A, Kalantari KK. The relationship between the height of the medial longitudinal arch (MLA) and the ankle and knee injuries in professional runners. Foot. 2008;18(2):8490. doi:10.1016/j.foot.2008.01.004

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 2.

    Kudo S, Hatanaka Y. Forefoot flexibility and medial tibial stress syndrome. J Orthop Surg. 2015;23(3):357360. doi:10.1177/230949901502300321

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Williams DS 3rd, McClay IS, Hamill J. Arch structure and injury patterns in runners. Clin Biomech. 2001;16(4):341347. doi:10.1016/S0268-0033(01)00005-5

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Kaufman KR, Brodine SK, Shaffer RA, Johnson CW, Cullison TR. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med. 1999;27(5):585593. PubMed ID: 10496574 doi:10.1177/03635465990270050701

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5.

    Cowan DN, Jones BH, Robinson JR. Foot morphologic characteristics and risk of exercise-related injury. Arch Fam Med. 1993;2(7):773777. PubMed ID: 7906597 doi:10.1001/archfami.2.7.773

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6.

    Beard JH. Physical rejection for military service; some problems of reconstruction. Sci Monthly. 1919;9(1):514.

  • 7.

    Zifchock RA, Theriot C, Hillstrom HJ, Song J, Neary M. The relationship between arch height and arch flexibility: a proposed arch flexibility classification system for the description of multidimensional foot structure. J Am Podiatr Med Assoc. 2017;107(2):119123. PubMed ID: 28198638 doi:10.7547/15-051

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8.

    Williams DB III, Tierney RN, Butler RJ. Increased medial longitudinal arch mobility, lower extremity kinematics, and ground reaction forces in high-arched runners. J Athl Train. 2014;49(3):290296. PubMed ID: 24840580 doi:10.4085/1062-6050-49.3.05

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9.

    Zifchock R, Parker R, Wan W, Neary M, Song J, Hillstrom H. The relationship between foot arch flexibility and medial-lateral ground reaction force distribution. Gait Posture. 2019;69:4649. PubMed ID: 30660951 doi:10.1016/j.gaitpost.2019.01.012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10.

    Kleindienst FI, Campe S, Graf ES, Michel KJ, Witte K. Differences between fore-and rearfoot strike running patterns based on kinetics and kinematics. In: ISBS-Conference Proceedings Archive, Vol 1; 2007:252255.

    • Search Google Scholar
    • Export Citation
  • 11.

    Stearne SM, Alderson JA, Green BA, Donnelly CJ, Rubenson J. Joint kinetics in rearfoot versus forefoot running: implications of switching technique. Med Sci Sports Exerc. 2014;46(8):15781587. PubMed ID: 24500531 doi:10.1249/MSS.0000000000000254

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12.

    Kelly LA, Farris DJ, Lichtwark GA, Cresswell AG. The influence of foot-strike technique on the neuromechanical function of the foot. Med Sci Sports Exerc. 2018;50(1):98108. PubMed ID: 28902682 doi:10.1249/MSS.0000000000001420

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13.

    de Almeida MO, Saragiotto BT, Yamato TP, Lopes AD. Is the rearfoot pattern the most frequently foot strike pattern among recreational shod distance runners? Phys Ther Sport. 2015;16(1):2933. PubMed ID: 24894762 doi:10.1016/j.ptsp.2014.02.005

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Zifchock RA, Davis I, Hillstrom H, Song J. The effect of gender, age, and lateral dominance on arch height and arch stiffness. Foot Ankle Int. 2006;27(5):367372. PubMed ID: 16701058 doi:10.1177/107110070602700509

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15.

    Butler RJ, Hillstrom H, Song J, Richards CJ, Davis IS. Arch height index measurement system: establishment of reliability and normative values. J Am Podiatr Med Assoc. 2008;98(2):102106. PubMed ID: 18347117 doi:10.7547/0980102

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16.

    Comalli PE Jr, Wapner S, Werner H. Interference effects of Stroop color-word test in childhood, adulthood, and aging. J Genet Psychol. 1962;100(1):4753. doi:10.1080/00221325.1962.10533572

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17.

    Cohen J. Statistical Power Analysis for the Behavioral Sciences. Cambridge, MA: Academic Press Inc; 1988.

  • 18.

    Nilsson J, Thorstensson A. Ground reaction forces at different speeds of human walking and running. Acta Physiol Scand. 1989;136(2):217227. PubMed ID: 2782094 doi:10.1111/j.1748-1716.1989.tb08655.x

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19.

    Williams DS, McClay IS, Manal KT. Lower extremity mechanics in runners with a converted forefoot strike pattern. J Appl Biomech. 2000;16(2):210218. doi:10.1123/jab.16.2.210

    • Crossref
    • Search Google Scholar
    • Export Citation
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