Content area
Full Text
ABSTRACT
Brughelli, M, Cronin, J, and Chaouachi, A. Effects of running velocity on running kinetics and kinematics. J Strength Cond Res 25(4): 933-939, 2011-Sixteen semiprofessional Australian football players performed running bouts at incremental velocities of 40, 60, 80, and 100% of their maximum velocity on a Woodway nonmotorized force treadmill. As running velocity increased from 40 to 60%, peak vertical and peak horizontal forces increased by 14.3% (effect size [ES] = 1.0) and 34.4% (ES = 4.2), respectively. The changes in peak vertical and peak horizontal forces from 60 to 80% were 1.0% (ES = 0.05) and 21.0% (ES = 2.9), respectively. Finally, the changes in peak vertical and peak horizontal forces from 80% to maximum were 2.0% (ES = 0.1) and 24.3% (ES = 3.4). In addition, both stride frequency and stride length significantly increased with each incremental velocity (p < 0.05). Conversely, contact times and the vertical displacement of the center of mass significantly decreased with increased running velocity (p < 0.05). A significant positive correlation was found between horizontal force and maximum running velocity (r = 0.47). For the kinematic variables, only stride length was found to have a significant positive correlation with maximum running velocity (r = 0.66). It would seem that increasing maximal sprint velocity may be more dependent on horizontal force production as opposed to vertical force production.
KEY WORDS sprinting, vertical force, horizontal force, stiffness, stride length
INTRODUCTION
Of interest to many strength and conditioning practitioners, coaches, and athletes is the best training practice for the improvement of running sprint speed. One approach that may provide useful information in terms of exercise selection, assessment, and program design is to investigate the contribution of incremental running velocities on peak vertical and peak horizontal force production. It has been well established that peak vertical (F^sub v^) and peak horizontal forces (F^sub h^) increase (50-100% and >200%) with increasing running velocities from slow to moderate values (i.e., 1.5-6.5 m-s^sup -1^) (20,21). However, little is known about how F^sub v^ and F^sub h^ are affected by greater running velocities (>6.5 m).
Three recent studies have directly investigated the effects of running velocity above 6.5 m-s^sup -1^ on F^sub v^. These studies reported that F^sub v^ and relative F^sub v^ (RF^sub v^...