Summary

Investigation of the factors influencing landing performance, in terms of risk of ligament injuries, utilizing exploratory factor analysis and structural equation modeling

Abstract

Introduction

Poor performance on single-leg drop-jump landing has been identified as a potential contributing factor to ligament injuries in the lower limb. This study aimed to explore the factors affecting landing performance using exploratory factor analysis (EFA) and structural equation modeling (SEM).

Methods

The data for the study were collected through field-based preseason screening involving sixty-three male professional and semi-professional football athletes from five teams. The landing activity involved drop-jump landing with the dominant leg from a box of 30 cm height. Kinetic and electromyographic data were obtained using a 40 × 60 cm force plate (Bertec) and surface electromyography (Noraxon), respectively. Outcome measures based on ground reaction forces were the peak vertical ground reaction force (VGRF), center of pressure (COP) standard deviation, and total COP length for 2,5 seconds after landing. The hamstring-to-quadriceps activation ratio was recorded 25-ms before and 70-ms after the landing. The prone and side bridge tests for abdominal muscle endurance (AME), along with the Biering-Sørensen test for back muscle endurance (BME), were used to assess the endurance of the abdominals and back muscles, respectively. Isometric and brake tests of the hamstring muscles and isometric tests for the quadriceps muscles were performed using a handheld dynamometer (MicroFET 2; Hoggan Scientific) to evaluate isometric muscle strength. Subsequently, the performance of the single-leg hop for distance was utilized in the analysis. EFA was employed to identify the underlying grouping of the measured variables, and partial least squares SEM was used to examine the interrelationships among the factors. Data were analyzed using SPSS version 28 and SmartPLS version 4.1.0.6.

Results

Seven latent factors were validated with 14 associated items: VGRF, COP displacement (COPD), back muscle endurance (BME), abdominal muscle endurance (AME), quadriceps performance (QP), Hamstrings to Quadriceps activation ratio (H-Q), and isometric hamstring strength (HS). The measurement items had adequate loadings for each latent factor (>0.7), resulting in appropriate reliability and validity of the latent constructs (Average variance extracted >0.50, Cronbach’s alpha >0.6). The results of the structural model indicated that BME and AME had significant negative effects on VGRF (BME->VGRF path coefficient (PC) -0.274, p=0.011, AME->VGRF PC -0.110, p=0.044) and COPD (BME->COPD PC -0,135, p=0,017, AME->COPD PC -0.259, p=0.006), respectively. On the other hand, QP and HS were interrelated (PC 0.336, p=0.001), and both had a strong positive relationship with AME (QP->AME PC 0.133, p=0.007, HS->AME PC 0.396, p=0.000), while only HS positively influenced BME (PC 0.158, p=0.021). The results also indicated that the H-Q ratio exhibited an inverse relationship with VGRF (PC -0.285, p=0.014), whereas HS had a positive influence on VGRF (PC 0.282, p=0.017). In addition, VGRF had the strongest direct effect on COPD (PC 0.491, p=0.000).

Conclusions

Performance on landing reflects multiple components of neuromuscular control. Therefore, the incorporation of exercises that improve thigh muscle strength, thigh muscle co-activation, and core muscle endurance may exert a significant impact on landing performance and, by extension, on the risk of ligament injuries.