Successful sprinting depends on covering a specific distance in the shortest time possible. Although external forces are key to sprinting, less consideration is given to the duration of force application, which influences the impulse generated. This study explored relationships between sprint performance measures and external kinetic and kinematic performance indicators. Data were collected from the initial acceleration, transition and maximal velocity phases of a sprint. Relationships were analysed between sprint performance measures and kinetic and kinematic variables. A commonality regression analysis was used to explore how independent variables contributed to multiple-regression models for the sprint phases. Propulsive forces play a key role in sprint performance during the initial acceleration (r = 0.95 ± 0.03) and transition phases (r = 0.74 ± 0.19), while braking duration plays an important role during the transition phase (r = -0.72 ± 0.20). Contact time, vertical force and peak propulsive forces represented key determinants (r = -0.64 ± 0.31, r = 0.57 ± 0.35 and r = 0.66 ± 0.30, respectively) of maximal velocity phase performance, with peak propulsive force providing the largest unique contribution to the regression model for step velocity. These results clarified the role of force and time variables on sprinting performance.

The aim of this study was to investigate spatiotemporal and kinematic changes between the initial acceleration, transition and maximum velocity phases of a sprint. Sagittal plane kinematics from five experienced sprinters performing 50-m maximal sprints were collected using six HD-video cameras. Following manual digitising, spatiotemporal and kinematic variables at touchdown and toe-off were calculated. The start and end of the transition phase were identified using the step-to-step changes in centre of mass height and segment angles. Mean step-to-step changes of spatiotemporal and kinematic variables during each phase were calculated. Firstly, the study showed that if sufficient trials are available, step-to-step changes in shank and trunk angles might provide an appropriate measure to detect sprint phases in applied settings. However, given that changes in centre of mass height represent a more holistic measure, this was used to sub-divide the sprints into separate phases. Secondly, during the initial acceleration phase large step-to-step changes in touchdown kinematics were observed compared to the transition phase. At toe-off, step-to-step kinematic changes were consistent across the initial acceleration and transition phases before plateauing during the maximal velocity phase. These results provide coaches and practitioners with valuable insights into key differences between phases in maximal sprinting.

The aim of this study was to quantify the magnitude of braking impulse induced on the centre of mass by the accelerations at the foot-floor joint during steps three, nine and 19 of maximal sprinting. An induced acceleration analysis was performed to quantify the induced centre of mass accelerations. The accelerations at the foot-floor joint following touchdown generated -0.02 ± 0.01 m.s (143 ± 72%), -0.04 ± 0.01 m.s (80 ± 47%) and 0.07 ± 0.01 m.s (50 ± 13%) of the total relative braking impulse during steps three, nine and 19. A large portion of these foot-floor accelerations resulted from the deceleration of the foot at touchdown. The results suggest that minimising horizontal foot velocities prior to touchdown will result in reduced braking forces. Further research is required to empirically investigate this mechanism in an applied setting.

The aim of this study was to investigate the contributions of the support leg joint moments and non-muscular forces to the horizontal and vertical acceleration of the centre of mass during three different steps in maximal sprinting. An induced acceleration analysis was performed to investigate these contributions during the third, ninth and 19th step. The horizontal and vertical contribution by the ankle joint moment increased from the third to the 19th step while the contribution by the MTP joint moment increased vertically and decreased horizontally from the third to the 19 step. The knee decelerated the centre of mass horizontally while providing vertical support in all three steps with a larger variability observed in steps three and nine. This type of analysis has the potential to quantify the effect of segment orientation on centre of mass acceleration.

The purpose of this study was to identify the effect of a structured training programme on sprint performance and technique in three individual experienced sprinters. Velocity, step length, step frequency, temporal variables and segment angles were gathered from 50 m maximal sprints before and after two high volume four-week training blocks. Participantspecific analyses revealed that athletes’ performance responded differently to training. Changes in velocity between sessions were attributable to different underlying variables across athletes, which matched with expectations based upon coaching observations. These findings have important implications for the design of sprint training programmes and for the timing of applied biomechanical data collection sessions for the purpose of analysis and feedback to coaches and athletes.

Transition steps have previously been identified in the acceleration phase of sprinting. To compare transition steps detected using different measures, three sprinters performed maximal 50 m accelerations from blocks. Sagittal plane kinematics were collected using five 50 Hz cameras while touch-down and toe-off events were identified using a 200 Hz panning camera. Centre of mass height, shin angle and trunk angle at touch-down as well as the step where flight time exceeds contact time were used to detect transitions. Comparable transitions were identified based either on centre of mass height or shin and trunk angles at touch-down. These results provide further knowledge to the way in which the acceleration phase is structured and allows athlete specific biomechanical analysis to aid in the coaching of different sections of the acceleration phase in sprinting.