New methodology for determining lower limb asymmetries through force analysis during countermovement jumps

Objective: This study employed an innovative method to determine lower limb asymmetries using countermovement jumps, force platforms, and a kinematic system with 30 reflective markers. Methods: The sample included three doctoral students with an average age of 42.3 ± 15 years. The corresponding number of data points analyzed for each participant was: Subject 1 (n = 3669), Subject 2 (n = 3344), and Subject 3 (n = 3584). According to the impulse (IM) and landing (LA) phases, the data were distributed as follows: Subject 1 (IM: n = 2000; LA: n = 1669), Subject 2 (IM: n = 1891; LA: n = 1693), and Subject 3 (IM: n = 2102: LA: n = 1246). Force platforms recorded data during the impulse and landing phases, while the asymmetry index was calculated as the difference between the right and left leg, divided by the right leg value, and multiplied by one hundred. Results: The analyses showed significant differences between the right and left legs (p < 0.001), with an asymmetry index ranging from 5.07% to 14.22%. The effect size was moderate to large (0.59 to 0.85). Significant differences were also found between the impulse and landing phases (p < 0.001), except in one case (p = 0.069), with effect sizes ranging from trivial to large (0.37 to 0.99). Conclusions: The results indicate that this method provides valuable insights into lower limb asymmetries, potentially aiding in the detection of imbalances between the dominant and non-dominant sides before and after the flight phase, particularly in sports requiring explosive movements. Although the sample was limited, the findings highlight the importance of regularly monitoring asymmetries in both athletic and at-risk populations. This study also emphasizes the need for standardized protocols to assess asymmetries, contributing to improved injury prevention strategies.