878 Journal of Strength and Conditioning Research, 2004, 18(4), 878–884  2004 National Strength & Conditioning Association THE IMPORTANCE OF ISOMETRIC MAXIMUM STRENGTH AND PEAK RATE-OF-FORCE DEVELOPMENT IN SPRINT CYCLING MICHAEL H. STONE, 1,2 WILLIAM A. SANDS, 1 JON CARLOCK, 1 SAM CALLAN, 3 DES DICKIE, 3 KAREN DAIGLE, 1 JOHN COTTON, 1 SARAH L. SMITH, 1 AND MICHAEL HARTMAN 1 1 Sports Science, United States Olympic Committee, Colorado Springs, Colorado 80909; 2 School of Biomedical and Sports Science, Edith Cowan University, Perth, Australia; 3 USA Cycling, Colorado Springs, Colorado. ABSTRACT. Stone, M.H., W.A. Sands, J. Carlock, S. Callan, D. Dickie, K. Daigle, J. Cotton, S.L. Smith, and M. Hartman. The importance of isometric maximum strength and peak rate-of- force development in sprint cycling. J. Strength Cond. Res. 18(4): 000–000. 2004.—This study was designed to investigate the re- lationship of whole-body maximum strength to variables poten- tially associated with track sprint-cycling success. These vari- ables included body composition, power measures, coach’s rank, and sprint-cycling times. The study was carried out in 2 parts. The first part ( n = 30) served as a pilot for the second part (n = 20). Subjects for both parts ranged from international-caliber sprint cyclists to local-level cyclists. Maximum strength was measured using an isometric midthigh pull (IPF). Explosive strength was measured as the peak rate-of-force development (IPRFD) from the isometric force-time curve. Peak power was estimated from countermovement (CMJPP) and static vertical jumps (SJPP) and measured by modified Wingate tests. Athletes were ranked by the U.S. national cycling coach (part 1). Sprint times (from a standing start) were measured using timing gates placed at 25, 82.5, 165, 247.5, and 330 m of an outdoor velo- drome (part 2). Maximum strength (both absolute and body- mass corrected) and explosive strength were shown to be strong- ly correlated with jump and Wingate power. Additionally, max- imum strength was strongly correlated with both coach’s rank (parts 1 and 2) and sprint cycling times (part 2). The results suggest that larger, stronger sprint cyclists have an advantage in producing power and are generally faster sprint cyclists. KEY WORDS. sprinting, cycling, explosiveness INTRODUCTION F rom the perspective of this discussion, it may be argued that there are three variables of primary importance for most strength/power sports. These variables are (a) maximum strength, (b) power output, and (c) the peak rate-of-force development (PRFD). Strength can be defined as the ability to produce force (38, 40). Thus, strength can have a direction and a mag- nitude, ranging from 0 force production to maximum. Maximum strength is the greatest force possible under specified conditions (34). Power is the rate of doing work (P = force  distance/time) and can be expressed as the product of force and speed (P = force  velocity). Power can be calculated as an average over a range of motion or as an instantaneous value occurring at a particular instant during the displacement of an object. Peak power (PP) is the highest instantaneous power value found over a range of motion under a given set of conditions. Activ- ities in which a movement sequence results in maximum achievable velocities, such as sprint cycling, are strongly related to power production (46). The PRFD is associated with the concept of explosive strength and is directly related to the ability to accelerate objects, including body mass (37). Thus, a greater PRFD can increase acceleration capabilities. It can be argued that maximum strength is the basic quality that affects power output (16, 18, 25, 37). There are several possible reasons why maximum strength may affect peak power output, including (a) a given load would represent a smaller percentage of maximum strength for a stronger person, thus, this load would be easier to ac- celerate; (b) it is possible that a person with greater max- imum strength would have a greater percentage or larger type II fibers. Type II fibers are the primary motor units that contribute to high power output; and (c) it is possible that, as a result of strength training (i.e., greater maxi- mum strength), additional alterations can occur simul- taneously, which would affect power. These alterations could include hypertrophy of type II fibers, increases in the Type II/I cross-sectional area ratio and alterations in the nervous system (3, 13, 42). Nervous-system adapta- tions could include alterations in motor unit activation, such as increased rate-of-force production (1, 2, 42). Ad- aptations such as these would affect greater explosive strength and higher power outputs and could affect su- perior performance. Furthermore, some data indicates that maximum strength affects power in a hierarchical manner with di- minishing influence as the external load decreases to a point at which other factors, such as rate-of-force devel- opment, may become more important (36, 37). Therefore, it might be expected that maximum strength would have a greater affect in sports in which relatively large loads must be overcome (i.e., throwing events and sprint cy- cling). However, the exact associations between measures of maximum strength and various types of performance are not well understood. Coaches and sports scientists usually agree that, in sports such as weightlifting and particularly powerlifting, continuous increases in maximum strength would be ad- vantageous. However, there is little or no agreement with regard to how much strength is necessary for most sports, including sprint cycling, that may have a need for strength, power, and speed. The purpose of these inves- tigations was to describe the potential relationship be- tween measures of isometric maximum strength (IPF) and isometric peak rate-of-force development (IPRFD)