This experiment involved 12 national-level Slovenian sprinters (age 22.4 ± 3.4 years, body height 177.6 ± 6.9 cm, and body weight 74.9 ± 5.2 kg). Average of the best results in 60-m sprint was 6.93 ± 0.12 seconds (best result 6.65 seconds); average of the best results in 100-m sprint was 10.82 ± 0.25 seconds (best result 10.39 seconds). The subjects have 5 years of active training and competition in sprinting (60, 100, and 200 m) before the experiment. According to the goal of this study, sprinters were divided into 2 groups: elite and sub-elite sprinters. Criteria for group grouping all sprinters were the results from official competition in 60- and 100-m sprint.
- On the basis of kinematic analysis, the following parameters of vertical and depth jumps were calculated: height of takeoff, flight time, duration of take off phase, duration of eccentric phase, duration of concentric phase, velocity of takeoff, and angle in ankle, knee, and hip joints.
- Vertical ground reaction force and other dynamic variables, impulse of force in eccentric and concentric phases, during 2 vertical jumps were recorded using 2 separate force platforms. Ground reaction force was measured unilaterally and bilaterally. Force was further normalized according to the body weight of the measured subjects (N/kg).
In both jumps, the 2 groups of sprinters statistically significantly differentiated into 6 parameters. The height of the CMJ was 65.4 cm in the elite sprinters and only 57.5 in the sub-elite sprinters, with a statistically significant difference of 7.8 cm. In DJ, the difference in the height of jump between the 2 groups amounted to 8.7 cm. Important differences between the groups have also been noticed in the vertical takeoff velocity for both CMJs and DJs. Furthermore, the velocity of body centre of gravity (COG) in the eccentric phase of the DJ importantly discriminated elite sprinters from sub-elite sprinters.
Looking at the force impulse, higher values can be noticed in the category of better sprinters in both absolute impulse of force and force impulse in eccentric and concentric phases of the CMJ.
In this parameter, statistically significant differences have been noticed between the 2 groups of sprinters. Difference in vertical velocity was 0.29 m/s, leading to the conclusion that better sprinters use a proximal-distal principle of muscular chain in vertical jumps in a more optimal way.
In a 45-cm DJ, statistically significant differences between the groups of elite and subelite sprinters were revealed in 3 parameters: height of jump, velocity of COG in eccentric phase, and velocity of COG in concentric phases.
In comparison with the group of subelite sprinters, sprinters from the elite group have shorter cumulative duration of contact phase (elites = 160.4 milliseconds and subelites = 171.2 milliseconds) and shorter duration of eccentric phase in the 45-cm DJ; however, the difference is not statistically significant
In DJ, elite sprinters achieve in average a bilateral ground reaction force 2,984 and subelite even 3,132 N. Unilateral ground reaction force amounts in elite sprinters is 1,492 N and in subelite sprinters is up to 1,566 N. Similarly, the impulse of force in eccentric phase of jump is in average higher in the group of subelite sprinters compared with the group of elite sprinters (elite 149.18 N/s and subelite 156.03 N/s). Apparently, subelite sprinters, despite a higher ground reaction force, are not capable of realizing higher jumps than the elite sprinters.
In summary, the statistically significant (p < 0.05) differences between the sprinters of both groups were revealed in 6 kinematic and dynamic parameters. In CMJ, the differences differences between the groups of sprinters were revealed in parameters (height: elites = 65.39 cm, subelites = 57.55 cm; take off velocity: elites = 3.23 m/s, subelites = 2.94 m/s) height of the jump, vertical velocity of BCG, and the impulse of force in the concentric phase of the jump (concentric impulse: elites = 123.91 N/s; subelites = 108.06 N/s). In DJ, the elite and subelite sprinters differentiated in the realisation of movement velocity in the eccentric and concentric phases (take off velocity: elites = 3.18 m/s, subelites = 2.87 m/s; eccentric velocity: elites = 3.05 m/s, subelites = 2.81 m/s). Elite sprinters better use the stretch reflex, which allows them to more efficiently transfer elastic energy from the first into the second phase of take off action.
Coh, M and Mackala, K. Differences between the elite and subelite sprinters in kinematic and dynamic determinations of countermovement jump and drop jump. J Strength Cond Res 27 (11): 3021–3027, 2013.