## 4 Discussion
Moreover, the findings of the current study demonstrate an improvement in jumping performance reliant on a rapid SSC (RJ), specifically in the HG. Although this improvement does not reach statistical significance, the magnitude-based inferential analysis indicates a likely beneficial effect here. To provide a general overview, all results are shown graphically in Figure 3. Based on our findings, it is reasonable to propose that both training strategies have the potential to improve jump and sprint performance through two distinct and potentially complementary mechanisms. Hard surfaces provide a heightened training stimulus for improving the SSC, whereas sand training may elicit greater adaptations to the contractile properties of concentric muscle contractions. The results of the correlation analysis indicate a significant relationship between changes in jumps that rely on the long SSC and sprint performances. The detailed results of the correlation analysis are presented in Figure A3 in the appendix. Accordingly, the results of the present study demonstrate that sand-based training leads to improvements in short sprint performance (10, 20 m), as well. In addition to the highlighted emphasis on concentric force development, the force-absorbing properties of sand impose additional demands,  
Figure 3: Graphical overview of the results (\(\uparrow\) = significant increase; \(\downarrow\) = significant decrease; light green = possibly beneficial effect green = likely beneficial effect; dark green = very likely beneficial effect). potentially contributing to the improved sprint performance observed. The diminished energy return to the body on sand induces altered kinematic movement strategies when compared to exercises performed on solid surfaces. Running at higher speeds on hard surfaces is commonly associated with specific kinematic characteristics, such as an increased stride frequency, greater hip flexion, a forward-leaning trunk posture, and enhanced plantar flexion [22, 54]. Remarkably, similar features were observed in kinematic studies on individuals running on sand [22]. Consequently, the lower vertical push-off velocity on sand leads to an increased stride frequency. In addition, running on sand induces greater hip flexion, which can be attributed to the adoption of a forward-leaning trunk posture. This postural adjustment shifts the body's center of gravity anteriorly during the stance phase, facilitating the generation of a higher horizontal ground reaction force against the shifting sand surface, while the slippery nature of the sand surface necessitates increased plantar flexion [22]. Hence, the improved sprint performance demonstrated by athletes training on sand may be indicative of a deliberate adaptation to their running technique, thus potentially aiding their overall performance. In addition, the recruitment of supplementary motor units, in conjunction with the discussed enhancements in contractile properties pertaining to concentric force development, is likely to exert a synergistic influence on the amplification of sprint performance. Previous studies have supported these assumptions by demonstrating significant increases in muscle activation and force development following pyometric training on sand [55, 56], which is particularly relevant, as the performance of the initial sprint phase heavily relies on the capacity for rapid and high concentric force development [54]. In line with the previous research, the present findings suggest that both sand-based training [27, 49] and training on hard surfaces have the potential to enhance CoD performance [28, 29, 57]. The present study contributes to the existing literature by providing detailed insights into the effects of sand-based training and training on hard surfaces on CoD performance. Further, analyzing the average velocities before and after the CoD maneuver revealed notable differences between the two training conditions.