## 4 Discussion
### Limitations  
Despite the promising findings, this study has several limitations that should be acknowledged. The sample size, although adequate for reliability analyses, was relatively small, especially in the asymptomatic control group (\(n\) = 15) when compared to the LBP group (\(n\) = 38). However, the recruitment of a sample twice the size for the LBP group was performed with the objective of studying LBP and adjusting for possible differences between the subjects with pain due to their heterogeneous characteristics and conditions (e. g. determining the influence of variables such as BMI, age or disability), while the asymptomatic subjects were considered a more homogeneous sample. Nevertheless, this analysis was not performed in this study, highlighting the importance of its development in future research. In addition, the gender distribution of the total sample was not balanced (with only 35% being males). The distinction of gender characteristics could influence the reliability of the measurements. Also, there was a significant difference in weight and BMI between the LBP group and the asymptomatic controls, with the LBP group exhibiting higher values. However, the increase in BMI is usually a common finding in this population. These differences could have influenced the hip flexion angles during the SLR test due to biomechanical or physiological factors associated with higher BMI. The study did not control these variables, which may have introduced confounding effects on the measurements and their reliability. This limited sample may affect the generalizabilityof the results to broader populations. Future studies with larger sample and controlling gender and BMI are necessary to confirm these findings and enhance external validity.  
Furthermore, only two examiners participated in the measurements--one experienced and one novice. While this design allowed for the assessment of the impact of examiner experience on measurement reliability, it does not capture the variability that might occur with a larger and more varied group of clinicians. Including multiple examiners with varying levels of expertise in future research could provide a more comprehensive understanding of inter-examiner reliability and enhance the generalizability of the results.  
Moreover, the study focused solely on the reliability of the Kinoveea software for measuring hip flexion angles during the SLR test and did not assess the validity of these measurements against a gold standard such as three-dimensional motion capture systems or other reliable methods such as digital inclinometer or goniometer. Without validation against a criterion standard, the accuracy of the Kinovea measurements remains uncertain. Future studies should aim to establish the concurrent validity of Kinovea by comparing its measurements with those obtained from advanced motion analysis technologies.  
Also, the study did not evaluate the diagnostic utility of the SLR test when analyzed with Kinoveea software, such as its sensitivity, specificity or predictive values for identifying neural tissue involvement in LBP patients. Assessing these diagnostic parameters would provide valuable insights into the clinical applicability of Kinovea-enhanced SLR assessments and their potential impact on patient management.