## 1 Introduction
[15] found large negative associations between IMTPF and 0-5 m, 10-20 m, and 0-30 m sprint performances (r = \(-\)0.63, r = \(-\)0.53, r = \(-\)0.60, correspondingly) in high-level male sprinters. On the other hand, [PERSON] et al. [21] reported no significant relationships between IMTPF and sprinting performance in collegiate rugby league players. In contrast, authors observed a weak inverse relationship (r = \(-\)0.37) between IMTPF normalized to body mass with 10 m sprint time. Similarly, [PERSON] et al. [22] reported moderate correlations between IMTP normalized peak force and 5 m (r = \(-\)0.44) and 10 m sprint time (r = \(-\)0.45) in male adolescent basketball players. Furthermore, [PERSON] et al. [23] observed no significant correlations between IMTPF and sprint times of 5 m and 10 m in collegiate rugby union players. Finally, another study indicated a lack of correlations between IMTPF and sprint acceleration performance from 0 to 40 m-distance intervals in national- and international-level sprinters [24]. The observed differences in the relationships between IMTPF and acceleration performance may be attributed to the fact that the IMTP primarily assesses the ability to generate force in the vertical direction. However, this may have limited relevance for team sport athletes, who are trained to execute movements in the horizontal, frontal, and transverse planes. Additionally, variations in factors such as contact time, running distance, running posture, surface type, and footwear may also contribute to these differences. In contrast with the availability of studies documenting the relationships between isometric strength and sprinting performance, few have investigated their relationships with sprint mechanical properties. [PERSON] et al. [20] found large relationships between IMTPF and average values of force, velocity, and power from 5 to 20 m of sprinting performance (r = 0.48-0.69, 0.50-0.70, and 0.62-0.73, respectively) in basketball players. Moreover, [PERSON] et al. [24] reported a significant relationship between IMTPF and P\({}_{\mathrm{max}}\) (r = 0.61) in male sprinters. Nevertheless, the authors indicated an absence of correlation between maximal strength assessments and sprint mechanical characteristics in female sprinters. It remains uncertain whether the ability of elite sprinters to generate and apply horizontal force and power during the specific phases of sprint acceleration is linked to their ability to produce isometric maximal force, as evaluated by the IMTP. Further observations are warranted to define the relationship of IMTPF assessments in the specific acceleration phases with their underlying mechanical variables. In particular, incorporating mechanical characteristics into the analysis of sprint performance could provide valuable insights for coaches and practitioners, enhancing their understanding of the lower limbs' maximal force capacities and their relevance to sprint acceleration phases. Therefore, this study aimed to examine the relationships between IMTP, sprint acceleration performance, and its underpinning mechanical properties in national-level track and field athletes during the competitive period of the season. It was hypothesized that the IMTPF would be related to the sprint acceleration performance and its underpinning mechanical properties.