Another commonly used multi-joint maximal isometric force test, in the field of sports performance, is the isometric squat push test (ISqT). Athletes can maintain a squat position at knee angles of 90\({}^{\circ}\), 120\({}^{\circ}\), or 140\({}^{\circ}\), providing a maximum isometric effort for a given period. Although IMTP is more widely used due to its strong scientific background [8], ISqT also provides highly reliable and low-variable PF results (ICC = 0.97\(-\)0.99, CV = 3.6%), with an SDC of approximately \(\sim\)11% [17; 18; 25]. An isometric squat push test, like IMTP, has been compared with dynamic maximum strength tests and other sports tasks, showing similar correlations [25; 26]. However, absolute and relative force values in ISqT have been found to be significantly higher compared to IMTP, even when using the same knee angle (140\({}^{\circ}\)) [27]. Researchers theorize that this may be due to the elimination of upper limb involvement as a means of anchoring and pulling on the bar, along with instructions to push instead of pull [24; 27]. To date, and to our knowledge, few studies have explored the possibility of evaluating multi-joint maximal isometric force by eliminating the bar as an object of traction (IMTP) or push (ISqT). [PERSON] et al. [28] included the isometric belt squat test (IBSqT) and compared kinetic variables with those of ISqT. The authors reported that the isometric belt squat test produced higher values in all variables (Relative peak Force [N/kg] 2.67 \(\pm\) 0.56 vs. 3.15 \(\pm\) 0.82), except for hip angular moment, where no significant differences were found (\(p\) > 0.05). Although the study by [PERSON] et al. [28] provides information on interesting variables, it does not provide data on important metrics for sports performance, nor does it address the reliability and consistency of these results. On the other hand, [PERSON] et al. [29] conducted a validation study of a commercial device using an isometric belt squat test in different positions and angles (90\({}^{\circ}\), 105\({}^{\circ}\), and 120\({}^{\circ}\)) but did not report the reliability data for time-dependent variables. Given that prior studies, such as those by [PERSON] et al. [28] and [PERSON] et al. [29], did not address the reliability and consistency of isometric belt squat test results or time-dependent variables, there remains a clear need for further research to establish the reliability of this method in evaluating multi-joint maximal isometric force across various conditions. The isometric belt squat test exhibits distinct methodological approaches to evaluating lower limb strength compared to IMTP and the isometric squat. The IBSqT isolates the lower body by removing upper-body involvement, avoiding grip strength limitations, and enabling higher force outputs [27]. Its hip-based load placement minimizes lumbar torque, enhancing safety and accessibility [28]. However, direct comparisons of the reliability of force production between these tests are absent in the scientific literature, necessitating further research to establish their relative reliability. Identifying an accessible, efficient, and reliable method like the IBSqT could streamline testing and reduce the reliance on specialized equipment used in protocols like the IMTP. Furthermore, the IBSqT offers a safer, time-efficient alternative for assessing strength, which is crucial for in-season monitoring where minimizing athlete fatigue and injury risk is paramount. Therefore, this study aims to compare the intra- and inter-session reliability of kinetic variables at several time windows between the IBSqT and the IMT in strength-trained individuals.