Does Medial Arch Height Differs from Barefoot Runners to Shod Runners? an Analytical Study

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1 DOI Number: / Does Medial Arch Height Differs from Barefoot Runners to Shod Runners? an Analytical Study Watson Arulsingh 1, Ganesh Pai 2, Asir John Samuel 3 1 Associate Professor, 2 Professor, 3 Lecturer, Alva s College of Physiotherapy Moodbidri, Dakshina Kannada District. Karnataka. Abstract Introduction and background: The integrity of foot arch plays a vital role in providing shock absorption in lower limb activities. Barefoot running is presumed to help retraining intrinsic foot muscle and causing a well developed medial arch of foot compared shod runners as reported by researchers and allowing proper stretch and recoiling effect on foot arch, thereby preventing injuries in runners. Thus this study was intended to analyze variation in medial arch height of foot among long, middle distance shod and barefoot runners. Study design: cross sectional study. Sampling method: convenient stratified sampling. Methodology: For this purpose, 60 samples were selected. Namely 20 from barefoot runners, 20 from shod runners and 20 from controls in analysing their medial arch height with validated tool named normalized navicular height truncated (NNH) to see if there is real difference exist in arch height static weight bearing posture among these groups. Results: ANOVA test was used to analyze significance of difference among three groups NNH and resulted in p=0.88 for right foot and p=0.34 on left foot. Conclusion: The current study revealed no significant difference between these three groups in the evaluation of navicular height normalized. Keywords: Normalized navicular height, runners, BMI INTRODUCTION Medial arch of foot plays a crucial role in absorption of shock that is encountered in almost all lower limb activities. The arch of foot functions as a spring during running by elongating until midstance and then recoils in second half of stance. The stretch reflexes initiated from this elongation of the foot intrinsic muscles facilitate shock absorption well at the ankle and knee through inhibition of soleus and quadriceps to permit the ankle and knee to adjust slightly as body weight is transferred to the leg 1. In a Corresponding author : Watson Arulsingh watsonarulsingh@yahoo.in. Contact Number much recent study, Lieberman et. al. 2 explained how medial longitudinal arch fla ens and stores elastic energy with foot pronation in ambulation. Lieberman also added that unshod runners who adopt forefoot (FFS) or midfoot (MFS) strike have the advantage of loading medial longitudinal arch during the entire first half and la er half of stance phase in running as the windlass mechanism reaches maximum level of function. In shod runners as they use rearfoot strike (RFS) pa ern, they lose advantage in using this mechanism because the medial longitudinal arch is unable to preload until both rearfoot and forefoot are in contact with the ground. Evidences support forefoot and midfoot strike are commonly adopted by barefoot runners or in

2 160 Indian Journal of Physiotherapy and Occupational Therapy. January-March 2015, Vol. 9, No. 1 minimalists in order to protect the feet and lower limbs from specific impact- related injuries as they are reported to be high among runners. 2 In rear foot strikers foot arch does not lengthen even after the ball of the foot contacted the ground, 3 whereas the longitudinal arch of the foot is loaded in three- point bending for forefoot strikers immediately as foot contacts the ground. Hence fore foot strikers uses extrinsic and intrinsic muscles of the arch differently than a rear foot strikers. If foot muscles respond in this way when running barefoot or in minimal, it is presumed to strengthen the arch s muscles more than shod running with arch supports. Another hypothesis raised by researcher 4 that running shoes with arch supports might limit amount of arch collapse as well as arch lengthening that might be entirely opposite to the mechanics of barefoot running and presumed to have negative effect on arch muscles in shod runners. Hence it is assumed that FFS running might strengthen foot arch muscles more than RFS running. On this basis, one has to consider forefoot and barefoot running likely to require more foot muscle strength to avoid injury. A study has reported that runners who trained for five months in minimal shoes had significantly larger and stronger extrinsic muscles 5. Barefoot runners are reported to have less morphological changes in arch of the foot including lesser number of pesplanus 6 and a lesser frequency of foot abnormalities. 7 Some authors exclaimed that strong foot may be more supple and should be able to control excess pronation and other movements subsequently in preventing specific running injuries. 8,9 Robbins & Hanna (1987) 10 studied on 17 runners who increased barefoot activity in the last four month, found to have had shorter arches of feet. He further suggested that modern running shoes are contributing to higher injury rate as they blocked sensory feedback from contact with ground, whereas barefoot runners reported fewer injuries and did not had longer arches. Hence barefoot running could be possible means rehabilitating intrinsic muscles of foot. Though modern foot wears have originally evolved from simple foot coverings which meant to protect feet from thermal and colder climates as well as mechanical protection from all environments 1, also reflecting different cultures, fashion. Researchers reported that modern footwear alters the way of running and that may decondition the feet. Cushioning and motion control features are needed in order to protect runners from injury. But recent studies have reported despite of the peculiar selection shoe type on the basis of foot morphology no changes in injury occurrence are observed with appropriately matching runners. 11,12,13 Numerous studies have recommended that a habitually barefoot is healthier compared to the habitually shod foot. Schul- man 14 reported that people who are habitually barefooted have relatively few foot disorders. Fiolkowskiet al. (2003) 15 have analysed navicular drop (ND) pre and post with the induction of lidocaine (1% with epinephrine) by a orthopedic surgeon on tibial nerve. Abductor hallucis muscle electrical activity was monitored in his study. Their study demonstrated increase in navicular drop compared pre nerve block data. This increase in navicular drop after inducing nerve block with decreased intrinsic foot muscle activity indicates that intrinsic foot muscles play a vital role in support of the medial longitudinal arch in relaxed standing. Thus Reflection of arch integrity is might be seen by the measurement of arch height. Headlee D al (2008) 16 induced fatigue on foot intrinsic muscle by specific exercises and monitored abductor hallucis activity through surface electromyography correlating with navicular drop(nd) during static stance before and after induction fatigue. Subjects demonstrated more ND after fatigue (p<0.0005).this again supports that intrinsic muscles of foot play a role in maintaining of the medial longitudinal arch in static stance. When these muscles get disrupted through fatigue, it led to increase in pronation through navicular drop test. Foot Arch height usually determined by visual method, arch index, navicular height measurement and navicular drop test (ND), truncated navicular height normalized and still new evolving clinical methods are being evolved and tested for validity, reliability. George S et al in his study compared arch index and truncated navicular height with

3 Indian Journal of Physiotherapy and Occupational Therapy. January-March 2015, Vol. 9, No gold standard radiological arch measurement in characterizing medial arch height of foot, reported that truncated navicular height correlated closely with radiological finding especially in calcaneal inclination angle compared to other clinical foot arch measurement he used. Ator 18 et al. (1991) and Vicenzino 19 et al. (2000) reported good reliability for measurement of NH (intraclass correlation coefficients (ICCs) greater than 0.94). But in order to get accurate NH according to various foot length, NH has to be normalized. Rasch and Burke 20 reported that when foot is enclosed in shoe, small plantar muscles goes for atrophy as though they are immobilized, so with wearing supportive shoes compromises efficiency. When these muscles do not function strongly or efficiently, causes excessive pronation of the foot. When the intrinsic muscles are not able to convert the foot from a force absorber to a force transducer through stance, efficiency and power is lost, thus the body may have to seek other ways to gain speed. The result of these is often compensatory recruitment from the anterior musculature of the hip, which is already overactive. According to Robbins (1987) and Bruggeman 21 (2005), absence of arch support results in strengthening of the arch musculature. Morimoto and Okada 22 (1985) reported long distance runners to have lower dorsal arch than throwers, jumpers and sprinters, and they speculated the cause to be the mechanical stress. M. Kouchi 23 et a l (2003) reported through their study that the runners had narrower heel, lower dorsal arch height, shorter heel to medial and lateral malleoli lengths, shorter heel to the base of 5 th metatarsal than non-athletes of the same foot length. However, there is now considerable evidence that shoe-wearing also accentuates the height of the medial longitudinal arch. 3, 24 Thus this study was mainly intended to analyze the variation medial arch height of feet among bare foot runners, shod runners and controls. Method: Subjects were stratified in to three groups namely shod runner, barefoot runners and non runners. Overall sample size of 60 determined for this study with 20 from shod runner group, 20 from barefoot runner group and 20 from controls at convenient sampling method. Ethical review Board commi ee approval certificate obtained. Consent was obtained from every participant. Runners and controls who fulfills inclusion criteria chosen for this study. Long, middle distance habitually shod and barefoot runners with minimum of three years participation are selected for this study. Age group between 18 to 25 years and nonathletes of same age group included. Both genders were selected. Subjects were excluded if they had any congenital lower limb deformities, trauma in the feet other than event related, athlete with auto immune disorder and athlete with metabolic diseases, Smokers, participant with suspected or known cardiac problem, any other neurologically affected foot. Participants BMI were calculated. To measure medial arch height of foot normalized, truncated navicular height measure was used. Subject was made to assume relaxed standing position with feet positioned shoulder width apart. Navicular tuberosity was marked with water soluble marker. Navicular height was calculated by measuring distance from the most medial prominence of the navicular tuberosity to the supporting surface. Then subjects were made to stand on two graph sheets placed in front of them after dipping their feet in ink diluted tray for generating foot print. Demarcation of first MTP joint in foot print is made when subjects were maintaining their position on the graph. To calculate truncated foot length, distance between the two lines perpendicularly drawn from first MTP joint and from the most posterior aspect of the heel calculated ( Figure 1). Then navicular height was divided by truncated foot length to derive normalized foot arch height.values are documented as normal arch foot if NNH value fall within If NNH values were less than 0.18 was documented as Flat foot 17. MATERIAL AND METHOD Materials used: Metal ruler, plastic tray, ink, graph sheets, water soluble marker, pencil, scientific calculator, stadiometer, weighing scale, data sheet.

4 162 Indian Journal of Physiotherapy and Occupational Therapy. January-March 2015, Vol. 9, No. 1 Figure.1: Normalized navicular height truncated. Figure 3 Statistical analysis: SPSS v-20 was used for data analysis. ANOVA test of significance was used to compare normalized navicular height (medial arch height of foot) among the three groups analyzed for this study. Pearson rank correlation coefficient (r) was used to establish correlation between BMI and NNH among these groups analyzed. RESULTS Data collected and NNH was compared among shod, barefoot runners and controls. ANOVA test was used to analyze right foot NNH among three groups, resulted in p=0.88 and left foot p value 0.34 reveals no significant difference NNH(medial arch height) between these three groups. Figure 2 When correlating BMI to left foot NNH on non runners, r value was (p=0.47). Figure 4 When correlating BMI to left foot NNH on shod runner group resulted in Pearson value of r= (p=0.76). Figure 5 When correlating BMI to left foot NNH on barefoot runner group resulted in Pearson value of r= (p=0.29). When correlating BMI to right foot NNH on non runner group resulted in Pearson value of r= (p=0.29).

5 Indian Journal of Physiotherapy and Occupational Therapy. January-March 2015, Vol. 9, No Figure 6 shock absorbing function in preventing lower limb injuries in runners. 4, 6,10,20,21. Possibly in future if more number of samples added in each selected group may give more clear scenario to address all existing controversy in this issue. When correlating BMI to right foot NNH on barefoot runner group resulted in Pearson value of r= (p=0.63), Figure 7 When correlating BMI to right foot NNH on shod runner group resulted in Pearson value of r= (p=0.99). While correlating BMI to NNH on both feet of control groups resulted in Pearson value of r= (p=0.37), in barefoot runners r= (p=0.56) and shod runners r= (p=0.38). Result of these correlations from Figure 2 to 7 reveals no correlation of BMI to NNH among samples analyzed. DISCUSSION The result of this study infers no significance of difference on medial foot arch height between shod,barefoot long and middle distance runners and controls. This is completely contrary to all claims made by researchers for the health benefit of barefoot running causing a well-developed foot arch and Current study also revealed no correlation of BMI to medial foot arch height (NNH) among samples analyzed. Me e K Nilsson 25 et al (2012) reported lack of evidence in confirming whether BMI associate with medial arch height in static measures. Sneha sameer 26 et al (2012) reported obesity lowers the medial longitudinal arch of foot in young adult. Emma Cowley 27 et al (2013) reported that BMI did not predict the change in arch height. When comparing gender variance to NNH by Independent T-test with 2 tailed significance analyses revealed on the right foot with the values of and left foot value of 0.49 with an average value of 0.63 which reveals no significant difference in NNH among both gender indicates NNH (truncated) validated tool in measuring medial arch height for both gender despite of some morphological change in feet between both gender as reported in earlier studies 28, 29. CONCLUSION This study concluded that there is no significance of different exists in foot medial arch height between shod, barefoot runners and non runners. There was no correlation exist between BMI to arch height among three groups observed and analysis of this study revealed no significant difference of foot arch height (NNH) variation among both gender. Acknowledgement: Authors express sincere gratitude to Joseph Oliver Raj (PT), Principal, Alva s College of Physiotherapy and Pitchaiah (PT) Associate professor, Alva s College of Physiotherapy who rendered their support in crucial aspects of this study. Conflict of Interest authors declared no conflict of interest in this study. Authors declared no biased results influenced by academic institution or any personal relationships. Source of Funding- Self funded.

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