DIFFERENCE IN EXPLOSIVE STRENGTH BETWEEN ATHLETES AND NON ATHLETES WITH FLAT AND NORMAL FOOT

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1 International Scientific Conference DIFFERENCE IN EXPLOSIVE STRENGTH BETWEEN ATHLETES AND NON ATHLETES WITH FLAT AND NORMAL FOOT Saša Bubanj 1, Mladen Živković 1, Nenad Nikolić 1, Tomislav Gašić 1, Ivana Ćirić Mladenović 1, Hristina Čolović 2 1 Faculty of Sport and Physical Education, University of Niš, Serbia 2 Clinical center of Niš, Serbia Saša Bubanj, Mladen Živković, Nenad Nikolić, Tomislav Gašić, Ivana Ćirić Mladenović, Hristina Čolović UDC SUMMARY Introduction: The aim of this study was to determine whether there is a difference in the manifested explosive strength of the lower limbs, determined by the implementation of the jump with a half squat, between the athletes and non athletes of high school population with normal and flat foot. Methods: The sample of subjects consisted of 240 high school students, 16,67±4,21 years (Mean±SD), and was divided in two sub samples: sub sample of non athletes (N=120) and sub sample on athletes (N=119). Among non athletes, there were 43 subjects of male and 77 subjects of female sex, while among athletes, there were 75 subjects of male and 44 subjects of female sex. Explosive strength of lower extremities, were determined by a wireless device Myotest (Sion, Switzerland), safely attached to a velcro belt of subjects, for the purpose of the vertical jump. All subjects performed five CMJ (countermovement jumps) without the arms' swing. Status of foot were determined by a modern computerized podoscope Podiart (Hungary) along with the appropriate software. Statistical method applied in this research to investigate the difference was t test. Results: Based on the t test it can be concluded that subjects with normal foot and subjects with flat foot do not differ significantly in terms of average values of the explosive strength parameters, nor in the sub sample of non athletes, neither in the sub sample of athletes.simodiossita volor sitium id moluptiame nobisit et fugia dolor sediatemolo et facium restiaecus. Conclusion: Although in previous chapter prevail studies, in which it is concluded that flat foot is not a disadvantage for successful sport performance, parents, health and education workers should be committed in prevention of possible future pain syndromes and injuries of the locomotor apparatus, with children in the period of growth and development, and work on strengthening of their muscles, tendons and ligaments of the foot. Keywords: lower limbs, countermovement jump, status of foot INTRODUCTION In complex movements of human, foot represents a lever and surface with which it is possible to achieve a more effective movement. The pressure of the foot on the ground is not evenly distributed. According to footprints on a flat surface, it is obvious that the main areas of support are calcaneus, heads (distal part) of metatarsal bones and base (proximal part) of the fifth metatarsal bone. The major part of the overall pressure is related to the heel bone and the minor part to the forefoot. During the movement as well as, at various positions, that attitude is changing. Forefoot maximum load is not being on heads of the first and fifth metatarsal bones, i.e., on the outer edges of the distal portion of the longitudinal arch, but in the central area, i.e., on heads of the second, third and fourth metatarsal bones. This is supported by the fact that the first and fifth metatarsal bones are more mobile than other metatarsal bones. These peripheral metatarsal bones move resiliently sideways during increasing pressure, thus performing two useful functions. First, the bearing surface of the frontal plane is increased, and second, by the same moving pressure depreciation becomes more effective. By the mentioned moving most of the pressure is transferred to the secondary metatarsal bone. It is one of the reasons why in case of the increased pressure, for which the mechanism of the 145

2 FIS Communications 2014 foot is not prepared, the middle metatarsal bones are being often broken. It is necessary to mention that this function of the metatarsal bones, especially of the first and fifth metatarsal bones, is a consequence of the need for a greater bearing surface; this is particularly emphasized when changing the direction of movement or moving in the curved line, when the foot is more reliant on the ground by its side edges, mainly at the front of the feet (Bubanj, 1997). The function of the foot of a man is to by its firmness provide the locomotor apparatus a solid ground, and by its elasticity to enable amortization of the increased pressures, that is, to participate in resisting (reflection) by its elastic forces, when the mentioned pressures decrease (Bubanj, 1997). In its broadest sense, the foot comprises the two different shape and function arches, longitudinal and transverse ones. According to the mechanical function, the longitudinal arch is formed by two arcs, external and internal ones. The outer arc is formed by the calcaneus, cuboid bone and the fourth and fifth metatarsal bones. The inner arch is formed by ankle bone, navicular bone, three cuneiform bones of the foot and the first three metatarsal bones. The outer arch is stronger and lower, and the inner arch is more flexible and higher. According to such properties one determines also their functions. In the outer arch prevalent is the support function and in the internal arch prevailing function is that of depreciation. Longitudinal arch sustains the entire weight of the body. The most important connections that are part of the arch system are long plantar arch connections (lig. plantare longum) and plantar calcaneus navicular connection (lig. calcaneonaviculare plantare). In maintaining the longitudinal arch participate muscles whose tendons pass under the foot system and the metatarsus. The same muscles by their contractions increase the arch curvature. It is assumed that the long leaf muscle is one of the main active holders of the longitudinal arch of the foot, because its paralysis causes changes in the foot that are characteristic for the flat feet (pes planus). Flat foot is described as the loss of the medial longitudinal arch of the foot, valgus deformity of the heel and medial talar prominence (Herring, 1990). Muscular strength and power are important components of fitness essential for the execution of a variety of daily and sporting activities (Beunen & Thomis, 2004). Explosive strength is defined as the ability of the neuromuscular system to produce dynamic force rapidly in an open kinetic chain movement, such as jumping, in which rate of force development is at or near maximum (Kinser et al., 2008). Countermovement jumps (CMJ) contain an eccentric and concentric phase that constitute a stretch shortening cycle, and they are associated with many dynamic movements, including running, bounding, and tumbling. CMJ depend both on contractile elements and elastic properties of the muscle and connective tissue (Schmidtbleicher, 1992). Flat feet, as a postural morphology, have long been associated with pain and disability and thus are often a concern to parents from a preventative perspective of their children's health and mobility (Evans, Nicholson, & Zakaris, 2009). Changes may occur during the embryonic development and may be the result of some rickets disorders that contribute to bone lesions and deformities. Acquired factors contributing to the emergence of flat feet are: excessive obesity in the developmental age of the child (Milenkovic, 2007; Bordin et al., 2001); rickets and rickets phenomena; atonic or flaccid paralysis of certain muscle groups of the lower leg or foot; various mechanical injuries or diseases; physical inactivity; hygienically unsuitable footwear (Milenkovic, 2007). Studies have shown that the longitudinal arch develops spontaneously during the first decade of life, when it gets higher (Staheli, Chew, & Corbett 1987, Taussig & Pillard, 1987). However, according to Pfeiffer, Koty R, Ledl, T., Hauser, G., & Sluga (2006), children who start walking earlier also bear a risk factor to the occurrence of foot deformities. It is important to note that most people with flat feet confront almost no problems during their lifetime because of the abovementioned deformity. Individuals, however, develop clinical symptoms which can be divided into subjective and objective ones. We are certain to claim that both of them are important, regardless of their origin. There has been a suggested link between muscle strength and type arch of the foot. However, a distinct cause and effect dependence has yet to be established (Lysis, Posadzki, & Smith, 2010). In this context, the aim of this study was to determine whether there is a difference in the manifested explosive strength of the lower limbs, determined by the implementation of the jump with a half squat, between the athletes and non athletes of high school population with normal and flat foot. 146

3 International Scientific Conference METHODS Sample of examinees The sample of subjects consisted of 240 highschool students, and was divided in two subsamples: sub sample of non athletes (N=120) and sub sample on athletes (N=119), with body height 172,31±7,46 cm, body mass 65,27±10,58 kg, aged 16,67±4,21 years (Mean±SD). Athletes were engaged in different sport activities. Among non athletes, there were 43 subjects of male and 77 subjects of female sex, while among athletes, there were 75 subjects of male and 44 subjects of female sex. Sample of measuring instruments Explosive strength of lower extremities, were determined by a wireless device Myotest (Sion, Switzerland), safely attached to a velcro belt of subjects, for the purpose of the vertical jump. All subjects performed five CMJ without the arms' swing. The sample of the variables, processed and RESULTS mistreated by the device Myotest consisted of the: 1) CMJ height (HEIGHT, in cm); 2) power manifested upon occasion of CMJ (POWER, in W/kg); 3) force manifested upon occasion of CMJ (FORCE, in N/kg) and 4) subject velocity effectuated upon occasion of CMJ (VELOCITY, in cm/s). By using a modern computerized podoscope Podiart (Hungary) along with the appropriate software, the following variables of the foot were determined: 1) normal foot (PESNOR); and 2) flat foot (PESPL). Statistical analysis For the statistical analysis and interpretation of the results, the statistical package SPSS version 11.0 was in use. Results were expressed by descriptive statistics, while in aim to calculate statistically significant difference in the explosive strength of lower extremities between subjects in relation to their sport activity and foot status, t test was used (Pallant, 2007). Statistical significance was set at level p < 0, 05. Table 1. Descriptive statistics of explosive strength among non athletes with normal foot and flat foot. Non-athletes Height in cm Power in W/kg Force in N/kg Velocity in cm/s PESNOR PESPL N Mean 23,76 41,81 29,34 215,13 Std. Dev. 5,90 8,33 3,43 26,46 Min. 15,10 26,30 19,80 172,00 Max. 42,20 67,40 36,60 289,00 N Mean 23,92 42,98 36,35 214,73 Std. Dev. 5,98 8,31 41,37 24,38 Min. 11,50 21,40 21,10 183,00 Max. 38,00 61,30 319,00 273,00 Table 2. Descriptive statistics of explosive strength among athletes with normal foot and flat foot. Athletes Height in cm Power in W/kg Force in N/kg Velocity in cm/s PESNOR PESPL N Mean 30,41 46,61 30,58 231,30 Std. Dev. 22,44 7,89 3,61 26,75 Min. 14,90 24,80 21,80 171,00 Max. 207,00 62,10 38,90 302,00 N Mean 27,97 47,41 30,41 232,50 Std. Dev. 6,51 9,17 4,01 28,28 Min. 14,30 22,20 19,90 167,00 Max. 38,70 68,00 37,50 275,00 147

4 FIS Communications 2014 Table 3. Kolmogorov Smirnov test (120 non athletes and 119 athletes). Height in cm Power in W/kg Force in N/kg Velocity in cm/s Non-athletes,043,300,000,123 Athletes,000,889,977,741 Table 4. Difference in explosive strength among non athletes with normal foot and flat foot (t test). Non-athletes PESPL N Mean Std. Deviation p Height in cm PESNOR 71 23,76 5,90,885 PESPL 49 23,92 5,98 Power in W/kg PESNOR 71 41,81 8,33,451 PESPL 49 42,98 8,31 Force in N/kg PESNOR 71 29,33 3,43,157 PESPL 49 36,35 41,37 Velocity in cm/s PESNOR ,13 26,45,935 PESPL ,73 24,38 Table 5. Difference in explosive strength among athletes with normal foot and flat foot (t test). Athletes PESPL N Mean Std. Deviation p Height in cm PESNOR 69 30,41 22,44,456 PESPL 50 27,97 6,51 Power in W/kg PESNOR 69 46,61 7,89,611 PESPL 50 47,41 9,17 Force in N/kg PESNOR 69 30,58 3,61,809 PESPL 50 30,41 4,01 Velocity in cm/s PESNOR ,30 26,75,815 PESPL ,50 28,28 By application of Kolmogorov Smirnov test, the postulate about normal distribution of data in subsamples of non athletes and athletes was tested. Three measurements of totally 8 do not have normally distributed data, and that should not affect the credibility of the tests. Based on the t test it can be concluded that subjects with normal foot and subjects with flat foot do not differ significantly in terms of average values of the explosive strength parameters, nor in the subsample of non athletes, neither in the sub sample of athletes. DISCUSSION It is difficult to make a systematization of previous studies in which difference (or correlation) in exerted explosive strength between subjects with flat foot and those with normal longitudinal foot arch were determined (due to methodological differences, heterogeneity of the sample in relation to gender, age, body mass index, history of sport activities, test conditions, and other characteristics). However, prevail studies, given as follows, in which it is concluded that flat foot is not a disadvantage for successful sport performance: Because the controversy about the relation of foot morphology and foot function is still present, Tudor, Ruzic, Sestan, Sirola, & Prpić, T. (2009) conducted a study, dealing with motor skills and athletic performance in flat footed school children. They aimed to determine if there is an association between the foot flatness and several motor skills that are necessary for sport performance. The feet of 218 children aged 11 to 15 years were scanned, and the arch index was determined. The value of the arch index was corrected for the influence of age, and then the entire sample was categorized into four groups according to the flatness of their feet. The children were tested for eccentric concentric contraction and hopping on a Kistler force platform, speed coordination polygon (Newtest system), balance (3 tests), toe flexion (textile crunching), tip 148

5 International Scientific Conference toe standing angle, and repetitive leg movements. Altogether, 17 measures of athletic performance were measured. No significant correlations between the arch height and 17 motor skills were found, i.e., no disadvantages in sport performance originating from flat footedness were confirmed. Children with flat and children with normal feet were equally successful at accomplishing all motor tests. Thus, authors suggested that there is no need for treatment of flexible flat feet with the sole purpose of improving athletic performance, as traditionally advised by many. Lizis, Posadzki, & Smith (2010) found any association between longitudinal arch of the foot with the explosive power of lower limb muscles among five hundred seventy four young adults (n = 574) who participated in a study and were divided into three arch height groups and three muscle strength groups, respectively. The purpose of this study was to compare the outcomes from selected explosive strength tests with different medial longitudinal arch heights measured by using a Clarke's angle method. Petrović, Obradović, Golik Perić, & Bubanj (2013) conducted a study with a purpose to compare the differences in explosive strength related to foot type (flat feet and normal feet) in three different age groups. The status of the longitudinal foot arch was measured with the computerized digitalized Pedikom System. Explosive strength of the legs was measured by the Kistler force plate expressed in the squat jump, CMJ and continuous jumps with straight legs. Authors hypothesized that foot type therefore may alter the efficiency of such a kinetic chain and subsequently affect explosive strength. Three different populations of subjects were tested: 80 athletes (age 10±1), 60 adolescent athletes (age 15±1), and 164 students of the Faculty of Sport (age 20±1, Mean±Std.Dev.). All three age groups were divided into sub groups according to the measured status of longitudinal arch (Group A with presence of flat feet and Group B with normal feet). There were no statistically significant differences in the explosive strength of the legs between the groups. These findings suggest that flat foot is not a disadvantage in performing sport activities, but can certainly cause other postural deformities. On the other side, Živković et al. (2014) conducted a study which included 114 elementary school children, all males, aged 11 and 12, divided in two sub samples: the first consisted of children suffering from varying degrees of deformities of the foot, while the second consisted of children with normal arches of the feet. The purpose of this study was to compare the outcomes from explosive strength tests and speed running tests selected according to Kurelić (1975), with different medial longitudinal arch heights measured by using a Thomson's method. Children with normal arches of the feet achieved statistically significantly better results while performing explosive strength tests, while children suffering from varying degrees of deformities of the foot achieved statistically significantly better results while performing speed running tests. Results of motor tests for the evaluation of the explosiveness confirmed the significance of the muscles of the longitudinal arch of the foot and thus confirmed the lack of explosiveness of the participants suffering from this type of weakness. Never the less, once speed as a cyclical motor activity is analyzed, significantly better results were obtained by children suffering from flat feet, and this in turn led authors to consider the degree of significance of the muscles of the feet, their influence in activities such as running, in relation to the significance and importance of the muscles of the m. quadriceps femoris, m. biceps femoris, m. triceps sure or the flexors and extensors of the upper leg. According to authors, it is evident that afore mentioned muscles take on significant function in running, so that their function in cyclical movements of the lower extremities is more significant than the activity of the muscles of the feet. CONCLUSION Although in previous chapter prevail studies, in which it is concluded that flat foot is not a disadvantage for successful sport performance, parents, health and education workers should be committed in prevention of possible future pain syndromes and injuries of the locomotor apparatus, with children in the period of growth and development, and work on strengthening of their muscles, tendons and ligaments of the foot. Acknowledgments We gratefully acknowledge that the Ministry of Education, Science and Technological Development of the Republic of Serbia supported and financed the current study within project

6 FIS Communications 2014 REFERENCE Beunen, G., & Thomis, M. (2004). Gene powered? Where to go from heritability (h2) in muscle strength and power? Exercise and Sport Sciences Reviews, 32(4), Bordin, D., De Giorgi, G., Mazzocco, G., Rigon, F. (2001). Flat and cavus foot, indexes of obesity and overweight in a population of primary school children. Minerva Pediatrica, 53 (1), Bubanj, R. (1997). Osnovi primenjene biomehanike u sportu (The fundaments of applied biomechanics in sport). Niš: SIA. Evans, A. M., Nicholson, H., & Zakaris, N. (2009). The paediatric flat foot proforma (p FFP): improved and abridged following a reproducibility study. Journal of Foot and Ankle Research, 2, 25. doi: / Herring, J. A. (1990). Flexible pesplanovalgus (flat foot). Pediatric Orthopedics. 2nd ed. Philadelphia: WB Saunders, Kinser, A.M., Ramsey, M.W., O'Bryant, H.S., Ayres, C.A., Sands, W.A., & Stone, M.H. (2008). Vibration and stretching effects on flexibility and explosive strength in young gymnasts. Medicine and Science in Sports and Exercise, 40(1), Lizis, P., Posadzki, P., & Smith, T. (2010). Relationship between explosive muscle strength and medial longitudinal arch of the foot. Foot & Ankle International, 31(9), Pallant, J. (2007). SPSS survival manual. Third Edition, Allen & Unwin. Petrović, M., Obradović, B., Golik Perić, D., & Bubanj, S. (2013). Jumping abilities are not related to foot shape. Facta Universitatis series Physical Education and Sport, 11 (3), Pfeiffer, M., Koty, R., Ledl, T., Hauser, G., & Sluga, M. (2006). Prevalence of flat foot in percolated children. Pediatrics, 118 (2), Schmidtbleicher, D. (1992). Training for power events. Strength and power in sport, 1, Staheli, L.T., Chew, D.E., & Corbett, M. (1987). The longitudinal arch. A survey of eight hundred and eightytwo feet in normal children and adults. J Bone Joint Surg, 69, Taussig, G., & Pillard, D. (1987). Pied plat statique de l'enfant (Statično ravno stopalo kod dece). In: Dimeglio, H., & Claustic, J. (Eds). Monographies de Podologie. Masson, 8, Tudor, A., Ruzic, L., Sestan, B., Sirola, L., & Prpić, T. (2009). Flat footedness is not a disadvantage for athletic performance in children aged 11 to 15 years. Pediatrics, 123(3), e386 e392. Živković, M., Živković, D., Bubanj, S., Milenković, S., Karaleić, S., &. Bogdanović, Z. (2014). The dependence of explosive strength and speed on feet posture. HealthMed, 8 (2),

ANKLE JOINT ANATOMY 3. TALRSALS = (FOOT BONES) Fibula. Frances Daly MSc 1 CALCANEUS 2. TALUS 3. NAVICULAR 4. CUBOID 5.

ANKLE JOINT ANATOMY 3. TALRSALS = (FOOT BONES) Fibula. Frances Daly MSc 1 CALCANEUS 2. TALUS 3. NAVICULAR 4. CUBOID 5. ANKLE JOINT ANATOMY The ankle joint is a synovial joint of the hinge type. The joint is formed by the distal end of the tibia and medial malleolus, the fibula and lateral malleolus and talus bone. It is