Journal of Sports Sciences, 2000, 18 , 173± 181 Journal of Sports Sciences ISSN 0264-0414 print/ISSN 1466-447X online Ó 2000 Taylor & Francis Ltd http://www.tandf.co.uk/journals/tf/00268976.html The in¯ uence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists DAVID J. SANDERSON, 1 * EWALD M. HENNIG 2 and ALEC H. BLACK 1 1 Biomechanics Laboratory, School of Human Kinetics, University of British Columbia, 6081 University Boulevard, Vancouver, British Columbia V6T 1Z1, Canada and 2 Sportbiomechanik, Universit„t GH Essen, Postfach 103 764, D-45117 Essen, Germany Accepted 7 November 1999 The aim of this study was to determine the response of cyclists to manipulations of cadence and power output in terms of force application and plantar pressure distribution. Two groups of cyclists, 17 recreational and 12 competitive, rode at three nominal cadences (60, 80, 100 rev´min - 1 ) and four power outputs (100, 200, 300, 400 W) while simultaneous force and in-shoe pressure data were collected. Two piezoelectric triaxial force transducers mounted in the right pedal measured components of the pedal force and orientation, and a discrete transducer system with 12 transducers recorded the in-shoe pressures. Force application was characterized by calculating peak resultant and peak eþ ective pedal forces and positive and negative impulses. In-shoe pressures were analysed as peak pressures and as the percent relative load. The force data showed no signi® cant group eþ ect but there was a cadence and power main eþ ect. The impulse data showed a signi® cant three-way inter- action. Increased cadence resulted in a decreased positive impulse, while increased power output resulted in an increased impulse. The competitive group produced less positive impulse but the diþ erence became less at higher cadences. Few between-group diþ erences were found in pressure, notable only in the pressure under the ® rst metatarsal region. This showed a consistent pattern of in-shoe pressure distribution, where the primary loading structures were the ® rst metatarsal and hallux. There was no indication that pressure at speci® c sites in¯ uenced the pedal force application. The absence of group diþ erences indicated that pressure distribution was not the result of training, but re¯ ected the intrinsic relationship between the foot, the shoe and the pedal. Keywords: cycling, eþ ectiveness, force, pressure. Introduction The mechanics of bicycle pedalling involve the transfer of force from the muscles of the legs through the feet and onto the pedal surfaces. Ruby and Hall (1993) examined in detail the link between the foot± pedal interface and loads at the knee joint. They reported that design modi® cations of the pedal could lead to a reduction of forces at the knee joint. Also worthy of examination is the relationship between the load on the structures of the foot and on the pedal. The forces applied to the pedal have been examined by many researchers (Hoes et al., 1968; Davis and Hull, 1981; Lafortune and Cavanagh, 1983; Lafortune et al. , 1983; Broker and Gregor, 1990; Sanderson, * Author to whom all correspondence should be addressed. 1991). Across a range of rider characteristics and riding conditions, a pro® le of the force application during steady-rate cycling has been generated. This pro® le showed that, for steady-rate riding, the resultant pedal force rose to a maximum around 110 ° after top dead centre and decayed by bottom dead centre but not to zero. The recovery phase, or second 180 ° of crank rotation, was often characterized by a force that did not contribute to the positive angular impulse, unless the power output demands were very high. Although the foot is the link between the bicycle and the rider, only limited research has been published on the relationship between pedal force and in-shoe pressure distribution. Sanderson and Cavanagh (1987) showed that there were some changes in the distribution of pressure when cadence was increased from 45 to 90 rev ´min - 1 at a power output of 400 W. These changes