Antero-posterior position of the cleat for road cycling

ANTERO-POSTERIOR ADJUSTMENT OF THE CLEAT WITH REGARD TO THE LOWER LIMB FOR ROAD CYCLING AUTHORS: Javier Ramos Ortega, PhD. Lecture at Department of Podiatry. University of Seville. Spain. Pedro Munuera Martinez, PhD. Lecture at Department of Podiatry. University of Seville. Spain. Gabriel Domínguez Maldonado, PhD. Lecture at Department of Podiatry. University of Seville. Spain. CORRESPONDENCE AUTHOR: Javier Ramos Ortega Centro Docente de Fisioterapia y Podología. Universidad de Sevilla. C/ Avicena s/n 41009 Sevilla (España) jror[email protected] KEY WORDS: cleat, cycling, foot. ABSTRACT The aim of this work is to determine the antero-posterior position of the cleat based on various morphological characteristics of the cyclist. The pedal/shoe connection is a crucial element, as many of the non-traumatic lesions to the cyclist’s lower limb are caused by a poor fit between the two, so that it is important to study their relationship. Two tests were used to quantify this position: a photograph and a radiograph, which were digitalized to enable measurements using the program AutoCAD® 2006. Two linear regression models were constructed from the variables cleat/first metatarsal distance and tip/cleat distance, which were invalidated by the low R2 coefficient value (0.106 and 0.057 respectively). All the cyclists presented almost constant values of 3.6 ± 0.8 cm for the cleat/first metatarsal distance and 0.43 for the tip/cleat distance; as the distance from the base of the cleat to the pedal spindle is 3.6 cm. We can state that by positioning the base of the cleat at 43% of the length of the shoe measured from the tip, we are making the pedal spindle coincide with the head of the first metatarsal. INTRODUCTION The most common lesions in cyclists are those affecting the knee, some 25% of all the non-traumatic injuries suffered (1, 2). They can affect cyclists of any category, but are most frequent among those of a high level, because of the substantial kilometrage they cover in training (3). Such lesions can range from slight discomfort on going down steps or after a long ride, to the impossibility of pedaling. There have been few data recorded during recent years on the incidence of discomfort in cyclists’ knees. The most frequent types of lesion from overloading in cycling result in femoropatellar or latero-medial pain in the knee joint (1, 3-5). Different research aimed at preventing possible lesions (6, 7) has analyzed the elements giving the most exact alignment in the fit between cycle and cyclist for each rider. The height of the saddle and handlebars and the length of the crank are the most common, but there is nothing with regard to the exact position of the cleat on the shoe. Cycling lesions can also be due to misalignments between cyclist and cycle. It must be remembered that the pedal restricts the foot to a circular pattern in the sagittal plane, and that the shoe/pedal fixing systems do not allow movements of the two parts in the three planes (although some pedals allow slight movements in the transverse plane). If the segments of the lower limb do not describe a normal trajectory during pedaling, the forces generated in pedaling add loads to the joints that are not associated to the propulsion of the cycle (8). An incorrect anterior-posterior position affects the anterior-posterior forces of the knee (9-11). The shoe/pedal interaction is critical for an effective transmission of the forces generated by the cyclist to the cycle, so that the alignment of these parts is considered an important factor in the management and treatment of lesions caused by overloading at the level of the knee(12). Currently there is no consensus on the ideal longitudinal position of the cleat to prevent possible lesions, while some authors refer to an adjustment based on the coincidence of the pedal spindle with the head of the second metatarsal (9, 11, 13, 14), others claim it should be with that of the first metatarsal (7, 15, 16). This work is designed with the following aims: (1) to analyze the exact position of the cleat with regard to the variables studied for each cyclist, (2) to determine which of the longitudinal variables presents the greatest importance Comentario [j1]: Uno de los comentarios indica que habría que describir las variables, pero entiendo que esto es la introducción y que lo indicado es describirlas en la metodología. Comentario [j2]: idem in the adjustment, and (3) to construct regression models enabling adjustment of the position of the cleat for each cyclist from anthropometric variables. The null hypothesis of this study is that there is not one position of the cleat for each cyclist with regard to the variables of the lower limb. METHODS The target population of our study comprises cyclists who use an automatic pedal and practice the sport intensively. The sample size was calculated with the program nQuery Advisor 4.0, using the number of variables to relate (between 2 and 5), the expected values of the coefficient of multiple correlation (ranging between 0.14 and 0.68 in a pilot study), a value for α of 5%, and a 1-β power of 80%. These data gave a size of 88 feet. The sample comprised 44 individuals (88 lower limbs: 44 right and 44 left), of which 7 were women and 37 men, with a mean age of 34.4 ± 11.1 years. Each participant gave written consent to take part in the study, which was approved by the Experimental Ethics Committee of the University of Seville. We think it opportune to point out that references are always to lower limbs rather than to persons, as the anthropometric variables of the two extremities (right and left) may be different in the same individual, and in clinical practice the need to perform a separate evaluation for each foot is very frequent. As Menz and Munteanu explain (17), the main conceptual and statistical problems generated by this type of approach arise when the inferences derived from the studies are made in relation to persons, having used the extremities as the unit of analysis. As the aim of this study is to analyze and relate the characteristics Comentario [j3]: idem of the lower limb and the cleat, we used as unit of the sample the lower limbs, and not the individuals; thus, we consider the sample to comprise 88 feet. Creemos conveniente señalar que se hace referencia siempre a extremidades inferiores, en lugar de a personas, ya que las variables antropométricas de las dos extremidades (derecha e izquierda) pueden ser distintas en un mismo individuo, y en la práctica clínica es muy frecuente la necesidad de realizar una valoración independiente para cada pie. Como explican Menz y Munteanu (17), los principales problemas conceptuales y estadísticos que generan este tipo de planteamientos ocurren cuando las inferencias derivadas de estos estudios se hacen con respecto a las personas, habiendo utilizado las extremidades como unidad de análisis. Puesto que el objetivo de este estudio es analizar y relacionar las características de la extremidad inferior y la cala, utilizamos como unidad de la muestra los miembros inferiores, y no los individuos, por lo que consideramos que la muestra estuvo constituida finalmente por 88 pies. The criteria for inclusion in this study were the following: cyclists aged more than 20 years old (18-25), not having suffered severe traumatisms to or surgical operations on the lower limb, not having suffered lesions caused by overloading the lower limb during (at least) the previous year, using automatic pedals Look®, and with a sporting intensity of a minimum 5.000 km annually. The variables were recorded using two tests: a photograph and a radiograph, both under a protocol designed so as not to alter the measurements from one subject to another. For the first, a Cyber-shot DSC-P120 digital camera (Sony, San Diego, U.S.A.) was used, with a resolution of 5.1 megapixels and an optical zoom capacity of 3x, placed on a tripod at a distance from the ground of 1 meter, completely vertical to the shoe, which was resting on the ground and centered on the screen such that the tip and the heel of the shoe exactly fitted the image frame. The dorsoplantar radiographs were made with an inclination of 15 degrees of the X-ray tube to the vertical (26) and with a tube/plate distance of Comentario [j4]: Dice el revisor con respecto a este párrafo que no queda claro, pero yo si lo creo. ¿Qué pensais? Debajo os pomgo el texto concerniente en castellano 1 meter, in accord with the criteria of the Measurements and Terminology Committee of the AOFAS (27, 28) (American Orthopaedic Foot and Ankle Society). All the radiographs were taken with the foot load-bearing, as this is the constant state of the foot in this sport (29). The radiological parameters employed were 65 Kv and 10 mAs. Because of the radiotransparency of the piece under study (the cleat), it was decided to place a rigid metal element at its base to act as a reference in the image of the angle of the shoe when fixed on the pedal (FIGURES 1 and 2). The radiograph thus obtained was digitalized, using a scanner able to explore images on negative films (EPSON EXPRESSION 1680 Pro®, Seiko Epson Corporation, Nagano, Japan) to create a digital image. Measurements were made on the digital image, using the software AutoCAD® 2006 (Autodesk Inc, San Rafael, California). The protocol of digitalization and measurement of the radiographs has previously been used in other studies (30-35). The variables studied were age, gender, annual distance ridden (km), weight, height, body mass index (BMI), angle of adduction of the forefoot, metatarsal formula,(36, 37) shoe size, distance between the cleat and the first metatarsal, and distance between the tip of the shoe and the base of the cleat. The angle of adduction of the forefoot was measured on the cyclist’s radiograph. It was formed by the intersection of the longitudinal axis of the second metatarsal with that of the tarsus minor (38-41)(40, 41). The cleat/first metatarsal distance (FIGURE 3) was measured on the radiograph, as the distance from the first metatarsophalangeal joint to the base of the cleat. The Comentario [j5]: Algunos revisores se preguntan que variable es ésta, así como los conceptos index plus y minus. Si que es cierto que fuera del ambiente podológico, quizás sea un concepto desconocido, por lo que creéis que es necesario con referenciarlos bibliográficamente o habría que explicarlos tip/cleat distance (FIGURE 4) was measured on the photograph, as the ratio between the distance from the tip of the shoe to the base of the cleat and the total length of the shoe. The data analysis was performed using the software SPSS 15.0 for Windows. The intraclass correlation coefficient for the reliability of the measurements was calculated, using 10 randomly chosen cases from the sample, measured 3 times at intervals of a week. A statistical purification was performed to detect atypical values. The Kolmogorov-Smirnov test was used to check whether the data followed a normal distribution; the results of this test showed a normal grouping of the data, validating the use of parametric tests. A Student´s t-test for independent samples was performed on the dependent variables depending on the laterality (right-left) to test the homogeneity of the sample. Lastly, multiple linear regression models were constructed using the cleat/first metatarsal distance as dependent variable in one model, and the tip/cleat distance in another model, and shoe size and metatarsal formula(36, 37) as predictor variables. The value of p was considered significant when below p ≤ 0.05. RESULTS In this study, a total of 44 cyclists took part (88 feet), of whom 7 were women and 37 men. The values for the variables age, weight, height, BMI, and annual km are shown in TABLE 1. TABLE 1. Descriptive variables of the sample For the qualitative variable metatarsal formula(36, 37), there were 26 cases of plus index, 60 of minus index, and 2 of plus-minus index. The shoe size presented minimum and maximum values of 39 and 46 respectively (measured as Paris Points). For the remaining variables, the mean, the typical deviation, and the lower and upper limits for a confidence interval of 95% are detailed in TABLE 2. TABLE 2. Mean, typical deviation, and confidence interval to 95% for the quantitative variables. N Minimu m Maximu m Mean Typ. Dev. Age (years) 88 19.00 62.00 34.41 11.09 BMI 88 18.62 26.99 23.20 1.92 Height (m) 88 1.57 1.84 1.72 0.08 Weight (kg) 88 52.00 84.00 68.79 7.92 Annual km (km) 88 5000 30000 12470.45 6243.58 Confidence interval to 95% Variable Media ± DT Lower limit Upper limit Angle of adduction of the forefoot (º) 13.3 ± 0.4 12.4 14.2 Cleat/I-metatarsal distance (cm) 3.6 ± 0.8 3.4 3.7 Tip/cleat distance (%) 0.43 0.42 0.43 The results of the Student´s t-test for independent samples on the dependent variables depending on the laterality did not show significant differences in the sample, or in the variable cleat/first metatarsal distance (p = 0.251), or in the tip/cleat distance (p = 0.246). The linear regression was intended to illustrate the effects of the independent variables on a dependent variable, so that two models were constructed depending on whether the dependent variable was the cleat/first metatarsal distance or the tip/cleat distance. CLEAT/FIRST METATARSAL DISTANCE MODEL The values of R and R2 for this first model were 0.326 and 0.106 respectively, with p = 0.002. The multiple linear regression procedure (TABLE 3) yielded the following formula for the determination of the position: first metatarsal distance = -22.624 + (1.379 · shoe size). TABLE 3. Coefficient of correlation of model 1 Model Nonstandardized coefficients Confidence interval for B to 95% B Typ. Error Lower limit Upper limit Constant Shoe size -22.624 1.379 18.240 0.431 -58.884 0.522 13.636 2.236 10. Cavanagh PR, Sanderson DJ. The biomechanics of cycling: Studies of the pedalling mechanics of elite pursuit riders. En: Burke ER. Editor. Science of Cycling. Campaign, IL: Human Kinetics Books; 1986. p. 91-122. 11. Ericson MO, Nisell R. Tibiofemoral joint forces during ergometer cycling. Am J Sports Med. 1986 Jul-Aug; 14 (4): 285-90. 12. Wheeler JB, Gregor RJ, Broker JP. The effect of clippless float design on Shoe/Pedal interface kinetics and overuse knee injuries during cycling. J Appl Biomech. 1995; 11 (2): 119-41. 13. Ericson MO, Bratt A, Nisell R, Nemeth G, Ekholm J. Load moments about the hip and knee joints during ergometer cycling. Scand J Rehabil Med. 1986; 18 (4): 165-72. 14. Mandroukas K. Some effects of knee angle and foot placement in bicycle ergometer. J Sports Med Phys Fitness. 1990 Jun; 30 (2): 155-9. 15. Ruby P, Hull ML, Kirby KA, Jenkins DW. The effect of lower-limb anatomy on knee loads during seated cycling. J Biomech. 1992 Oct; 25 (10): 1195-207. 16. Callaghan MJ, Phil M. Lower body problems and injury in cycling. Journal of Bodywork and Movement Therapies. 2005; 9: 226-36. 17. Menz HB, Munteanu SE. Radiographic validation of the manchester scale for the classification of hallux valgus deformity. Rheumatology (Oxford). 2005 Aug; 44 (8): 1061-6. 18. Cheng JC, Chan PS, Chiang SC, Hui PW. Angular and rotational profile of the lower limb in 2,630 chinese children. J Pediatr Orthop. 1991 Mar-Apr; 11 (2): 154-61. 19. Fabry G, MacEwen GD, Shands AR,Jr. Torsion of the femur. A follow-up study in normal and abnormal conditions. J Bone Joint Surg Am. 1973 Dec; 55 (8): 1726-38. 20. Kling TF,Jr, Hensinger RN. Angular and torsional deformities of the lower limbs in children. Clin Orthop Relat Res. 1983 Jun; (176) (176): 136-47. 21. Kumar SJ, MacEwen GD. Torsional abnormalities in children's lower extremities. Orthop Clin North Am. 1982 Jul; 13 (3): 629-39. 22. MacEwen GD. Anteversion of the femur. Postgrad Med. 1976 Oct; 60 (4): 154-6. 23. Staheli LT, Corbett M, Wyss C, King H. Lower-extremity rotational problems in children. normal values to guide management. J Bone Joint Surg Am. 1985 Jan; 67 (1): 39-47. 24. Wynne-Davies R. Talipes equinovarus. a review of eighty-four cases after completion of treatment. J Bone Joint Surg Br. 1964 Aug; 46: 464-76. 25. Khermosh O, Lior G, Weissman SL. Tibial torsion in children. Clin Orthop Relat Res. 1971 Sep; 79: 25-31. 26. McCrea JD, Clark WD, Fann T, Venson J, Jones CL. Effects of radiographic technique on the metatarsophalangeal joints. J Am Podiatry Assoc. 1977 Dec; 67 (12): 837-40. 27. Smith RW, Reynolds JC, Stewart MJ. Hallux valgus assessment: Report of research committee of american orthopaedic foot and ankle society. Foot Ankle. 1984 Sep-Oct; 5 (2): 92-103. 28. Saltzman CL, Brandser EA, Berbaum KS, DeGnore L, Holmes JR, Katcherian DA, et al. Reliability of standard foot radiographic measurements. Foot Ankle Int. 1994 Dec; 15 (12): 661-5. 29. Renton P. Radiology of the foot. En: Klenerman L. Editor. The Foot and Its Disorders. 3ª. Oxford: Blackwell Scientific Publications; 1991. p. 259-345. 30. Munuera PV. Factores morfológicos en la etiología del hallux limitus y el hallus abductus [Tesis Doctoral]. Sevilla: Escuela Universitaria de Ciencias de la Salud; 2006. 31. Domínguez G. Estudio de la protusión metatarsal en el adulto criterios de normalidad [Tesis Doctoral]. Sevilla: Escuela Universitaria de Ciencias de la Salud; 2006. 32. Munuera PV, Dominguez G, Castillo JM. Radiographic study of the size of the first metatarso-digital segment in feet with incipient hallux limitus. J Am Podiatr Med Assoc. 2007 Nov-Dec; 97 (6): 460-8. 33. Munuera PV, Domínguez G, Reina M, Trujillo P. Bipartite hallucal sesamoid bones: Relationship with hallux valgus and metatarsal index. Skeletal Radiol. 2007 Nov; 36 (11): 1043-50. 34. Domínguez G, Munuera PV, Lafuente G. Relative metatarsal protrusion in the adult: A preliminary study. J Am Podiatr Med Assoc. 2006 May-Jun; 96 (3): 238-44. 35. Munuera PV, Domínguez G, Polo J, Rebollo J. Medial deviation of the first metatarsal in incipient hallux valgus deformity. Foot Ankle Int. 2006 Dec; 27 (12): 1030-5. 36. Viladot A. The metatarsals. En: Jahss MH. Editor. Disorders of the foot. Philadelphia: Saunders; 1982. p. 659-710. 37. Viladot A. Anatomía y biomecánica. En: Viladot A. Editor. Quince lecciones sobre patología del pie. 2ª. Barcelona: Springer-Verlag Ibérica; 2000. p. 1-33. 38. Laporta G, Melillo T, Olinsky D. X-ray evaluation of hallux abducto valgus deformity. J Am Podiatry Assoc. 1974 Aug; 64 (8): 544-66. 39. Palladino SJ. Preoperative evaluation of the bunion patient: Etiology, biomechanics, clinical and radiographic assessment. En: Gerbert J. Editor. Textbook of bunion surgery. 2ª. New York: Futura Publishing Company; 1991. p. 1-87. 40. Engel E, Erlick N, Krems I. A simplified metatarsus adductus angle. J Am Podiatry Assoc. 1983 Dec; 73 (12): 620-8. 41. Ferrari J, Malone-Lee J. A radiographic study of the relationship between metatarsus adductus and hallux valgus. J Foot Ankle Surg. 2003 Jan-Feb; 42 (1): 9-14. 42. Hannaford DR, Moran GT, Hlavac HF. Video analysis and treatment of overuse knee injury in cycling: A limited clinical study. Clin Podiatr Med Surg. 1986 Oct; 3 (4): 671-8. 43. Sanderson DJ, Hennig EM. In-shoes pressure distribution in cycling and running shoes during steady-rate cycling. EnSecond north american congress on biomechanics; August 24-28; Chicago. ; 1992. p. 247-8. 44. Sanderson DJ, Hennig EM, Black AH. The influence of cadence and power output on force application and in-shoe pressure distribution during cycling competitive and recreational cyclist. J Sports Sci. 2000; 18: 173-81. 45. Venning P. Sources of error in the production and measurement of standard radiographs of the foot. Br J Radiol. 1951 Jan; 24 (277): 18-26. 46. Gonzalez H, Hull ML. Multivariable optimization of cycling biomechanics. J Biomech. 1989; 22 (11-12): 1151-61. 47. Gregor RJ, Wheeler JB. Biomechanical factors associated with shoe/pedal interfaces. implications for injury. Sports Med. 1994 Feb; 17 (2): 117-31. 48. Ericson MO, Ekholm J, Svensson O, Nisell R. The forces of ankle joint structures during ergometer cycling. Foot Ankle. 1985 Dec; 6 (3): 135-42. 49. O'Brien T. Lower extremity cycling biomechanics. A review and theoretical discussion. J Am Podiatr Med Assoc. 1991 Nov; 81 (11): 585-92. 50. Timmer C. Cycling biomechanics: A literature review. J Orthop Sports Phys Ther. 1991: 106-13.