## 7 Conclusions
### Limitations and Future Research  
The model presented does not enable the assessment of HSI with people running or jumping. This limitation is linked to one of the main restrictions of normal walking implemented in this model, which requires that at least one of the pedestrian's feet is in contact with the ground, contrary to the activity of running, where there may be moments where both feet are in flight. Therefore, future work will extend this study by eliminating restrictions on the duration and length of double support such that activities other thanwalking can be considered. Another potential area of research is to consider other types of load associated with humans crossing pedestrian bridges, such as those due to bicycles or strollers.  
Biomechanical models of human gait that use reverse dynamics have been validated in previous research by proving their feasibility in predicting the kinematics and kinetics of gait (Movements and Forces) [29; 31]. However, the validation of these models considering vibrating surfaces in real environments has not been addressed. The collection of experimental data where the complete body movements of the gait are recorded under HSI conditions and simultaneously structural vibrations in real bridges are configured as the next step to validate and comprehensively evaluate the approach proposed in this research. In addition, a detailed statistical study of anthropometric characteristics is just as important. This analysis will allow defining key anthropometric parameters that can be integrated into the proposed human-structure interaction models, such as the one proposed in this study, and performing comprehensive comparisons and validations, reducing the uncertainty of the physical parameters of the human system.  
Finally, it is known that anthropic loads are not the only dynamic loads to which pedestrian bridges are subjected, in that sense the integration of this model with wind or earthquake effects becomes an interesting field of research that is worth exploring.  
A future key aspect to be perfected within the model presented in this research is related to the kinematic model assumed for the body segment of the foot (Section 2.1.1). This is due to the biological variability of the dynamics of the foot, where the kinematics and kinetics are different according to the anthropometric conditions of the person, such as the anatomical structure of the foot, body weight, body mass index (BMI), joint range of ankle motion, or age. In this sense, a robust model that can be implemented in this model that reduces the uncertainty gap of biological variability is of great importance.  
Conceptualization, J.M.; methodology, B.C., J.M. and P.T.; software, J.D.A.; validation, J.D.A.; formal analysis, J.D.A.; investigation, J.D.A., B.C. and P.T.; writing--original draft, J.D.A.; writing--review & editing, J.D.A., B.C., J.M. and P.T.; supervision, J.M. and P.T.; project administration, P.T. All authors have read and agreed to the published version of the manuscript.  
0 This work is part of the research project: Formation and insertion of high-level human capital for the regions biennium 2021-2022, Universidad del Valle, Valle del Cauca, CT 15-2021 FAN SGR--BPIN: 2021000100099. The authors would like to express their gratitude to the Universidad del Valle and the Ministerio de Ciencia Tecnologia e Innovacion (Mincinciencias), who financed the project.  
Not applicable.  
The data that support the findings of this study are available from the corresponding author upon reasonable request.  
The authors declare no conflicts of interest.