###### Abstract  
The incidence of knee injuries during firefighter training is high, but there is a lack of research on predictive factors and risk assessment for such injuries. Biomechanical assessments can provide a better understanding of how the body's load changes during exercise, which may alter the risk of injury. Ten firefighters were recruited for our study. Each participant completed the FMS test and the single- and double-leg jump tasks. Motion information was collected and musculoskeletal models of the participants were constructed using OpenSim 4.4 to obtain the joint angle and joint moment. The peak GRF and CoM-CoP angle were also calculated. The findings showed a significantly larger PKFM (\(p=0.0195\)), VAFM (\(p=0.0039\)), and peak AP GRF (\(p=0.0039\)) during the single-leg jump. The opposite performance was observed for KFA (\(p=0.0098\)) and MPA (\(p=0.0273\)). A stepwise multiple linear regression analysis was used to explore the relationship between these parameters and both the FMS score and the times of injuries. The risk of injury is higher in the single-leg jump compared to the double-leg jump. The biomechanical parameters of these two jumps can be used to assess sports injuries and to provide methods and references for injury risk monitoring during firefighter occupational training. s +
Footnote †: journal: Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China; jingwen1013@tju. real-time monitoring [10]. Therefore, in addition to the FMS, more objective parameters are needed to predict and evaluate the risk of sports injuries accurately. In previous research on lower limb sports injuries, demographic information is typically considered as an objective influencing factor. Specifically, kinematic parameters such as smoking habits [11], anthropometrics [12], body mass index (BMI) [13], aerobic/anaerobic ability [14], joint rotation angle [15], and center of mass (CoM)-center of pressure (CoP) inclination angle [16] are often overlooked when focusing on health behavior variables. Biomechanical assessments can provide a deeper understanding of how the body experiences changes in load during exercise, thereby revealing potential injury risk factors during exercise, which has been confirmed in studies of different populations and various types of exercise. For example, a series of studies have pointed out the following: biomechanical dynamics and kinematic factors were shown to have an impact on anterior cruciate ligament (ACL) load and risk of ACL injury [17]; several key biomechanical factors (vertical ground reaction force (vGRF), hip flexion moment, and peak knee evasion moment) differed significantly between individuals with and without ACL injury [18]; knee joint abduction impulse and other biomechanical factors were identified as predictive factors for lower limb injuries during running [19]; and knee joint moment was one of the main predictive factors for ACL injury [20]. Similarly, the ground reaction force (GRF) was also an important factor in lower limb dynamics, providing an approximate measurement of the load on the lower limb musculoskeletal system [21]. As one of the biomechanical factors that are intuitive and easy to measure, the GRF is believed to be associated with overuse injuries in the lower limbs [22]. Another study explored the association between vGRF and running-related injuries and found that vGRF may be a risk factor for injuries in young runners [23]. It can be seen that biomechanical parameters play an irreplaceable role in predicting the risk of sports injuries and have been proven effective in many fields of injury risk prediction and assessment but have not yet been applied to the safety monitoring of firefighter training. This study was focused on risk factors for sports injuries and the insufficient attention to biomechanical parameters in the field of firefighter training safety monitoring.