Effects of Toe Direction on Biomechanics of Trunk, Pelvis, and Lower-Extremity During Single-Leg Drop Landing

Time course of biomechanics during jump landing before and after two different fatigue tasks

Objective

Muscle fatigue contributes to anterior cruciate ligament (ACL) injuries, with increased knee and hip abduction observed during fatigue. However, there have been no reports revealing the differences between fatigue tasks or the duration of these changes. In this study, we conducted single-leg drop landings before and after hip and knee fatigue tasks to elucidate the changes in lower limb biomechanics over time.

Methods

Twenty-two male participants performed single-leg drop landings before, immediately after, and 5, 10, and 15 min after fatigue tasks involving isokinetic hip abduction/adduction (hip fatigue task [HFT]) and knee extension/flexion (knee fatigue task [KFT]). Hip and knee kinematic and kinetic data were collected using a three-dimensional motion analysis device and two force plates. A two-way ANOVA was performed with both the fatigue task (HFT and KFT) and time point (Time 1 to Time 4) as factors, and the main effects and interactions were calculated.

Results

The knee adduction angle after the HFT was significantly greater than that after KFT immediately following the fatigue task. The knee flexion moment was significantly lower in the KFT, whereas the knee adduction and internal rotation moments were significantly higher in the HFT immediately after the fatigue task.

Conclusion

This study revealed distinct kinematic and kinetic changes specific to each fatigue task, particularly in the frontal plane for hip joint tasks and the sagittal plane for knee joint tasks. These findings could assist in the development of ACL injury prevention programs tailored to the functional improvement and exercise capacity of each joint.

Effects of Dual Task Interference on Biomechanics of the Entire Lower Extremity During the Drop Vertical Jump

The dual task is an important factor affecting knee biomechanics during jump-landing tasks. Athletes often have trouble in performing two tasks concurrently and a dual task can deteriorate landing performance. However, it is still unknown whether a dual task will affect the entire lower extremity. The purpose of this study was to clarify the effects of cognitive task interference on biomechanics of hip and ankle joints as well as the knee joint during the drop vertical jump (DVJ). A total of 20 female collegiate athletes participated in the study. Athletes performed a DVJ with or without a cognitive task. The DVJ was captured using a motion analysis system. Mental arithmetic of 2-digit addition was used as a cognitive task. Maximum vertical ground reaction force (vGRF), joint angles at initial contact (IC), joint moments within 40 milliseconds (ms) after IC, and joint angles and moments at peak vGRF were assessed. The data were statistically compared between with and without a cognitive task condition using a two-tailed paired t-test or the Wilcoxon singed rank test. The peak external knee abduction moment on both limbs within 40 ms after IC during the DVJ was significantly larger in the dual task than in the single task with less knee and hip flexion at initial contact. In addition, all moments of hip and ankle joints within 40 ms after IC were significantly larger in the dual task than in the single task accompanied with greater vGRF, except for the hip internal rotation moment. Cognitive tasks during a DVJ will result in biomechanical changes of the entire lower extremity in female athletes.

Effects of foot progression angle on kinematics and kinetics of a cutting movement

Purpose

Foot progression angle is a key factor for biomechanical knee load, which is associated with noncontact anterior cruciate ligament (ACL) injury during sports-specific tasks. The purpose of the present study was to assess the biomechanics of trunk, pelvis, and lower extremities during a cutting maneuver under different foot progression angles.

Methods

Nineteen male collegiate athletes (ages 18–24) participated in the present study. Cutting motion was analyzed using eight infrared cameras (250 Hz), two force plates (1250 Hz), and 44 reflective markers. Subjects performed 45-degree side cutting maneuvers under three foot progression angles, including 20 degrees (toe-out: TO), 0 degrees (neutral: TN), and − 20 degrees (toe-in: TI). Peak values of each biomechanical parameters in trunk, pelvis, hip, and knee within a first 40% stance phase and each parameter at the timing of the peak vertical ground reaction force were assessed. A statistical analysis was performed to compare data among the three-foot progression angles using the Friedman test.

Results

Peak angles of knee abduction, tibial internal rotation, hip internal rotation, and hip adduction were significantly greater for TI position than for TO position (p < 0.01). Peak moments of knee abduction and tibial internal rotation under TI position were also significantly larger than TO position (p < 0.01). Moreover, greater peak pelvis-trunk rotation was found for TI position than for TN and TO positions (p < 0.01).

Conclusion

From the present study, TI position could lead to an increased risk of ACL injury during a pre-planned cut maneuver, compared to TO position.