Differences in Weight-Acceptance Phase during Landing in Block Jumps: A Pilot Study on Female Volleyball Players

The anterior cruciate ligament (ACL) plays a crucial role in constraining tibiofemoral articulation and preserving the knee joint from harmful aberrations of movement. However, certain high-risk movements, such as landing, can induce ACL injuries. Volleyball practice intrinsically requires performing jumps during attacking and defending phases, with a higher rate of ACL injury occurring during blocking tasks. The execution of these tasks is more subject to variability due to the necessity of adequately counteracting opponents. The type of landing after blocking, as well as gender, has been related to the potential risk of injury. We analyzed two different blocking techniques frequently occurring during volleyball matches: The block jump with double-leg landing and the block jump with single-leg landing (dominant and non-dominant). Synchronized kinematic and kinetic data from female volleyball players were collected using a set of wearable inertial measurement units (IMUs), force platforms, and wireless surface electromyography (EMG). Kinematic and kinetic data were evaluated during the weight-Acceptance phase in each task to determine changes in landing approaches. Block jumping with single-leg landing resulted in changes in the kinematics at the hip, knee, and ankle levels, and higher values of muscular activation during the first instants of weight acceptance, particularly in the biceps femoris and gastrocnemius. Understanding the overall biomechanics associated with different sports tasks allows for a better understanding of personal risk and the definition of proper training programs aimed at injury prevention.