The effects of toe direction on three-dimensional knee kinematics during closed kinetic chain exercise in patients with anterior cruciate ligament deficient knee

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.

Biomechanical correlation at the knee joint between static lunge and single-leg drop landing - a comparative study among three different toe directions

Background

Toe direction is a critical factor affecting knee biomechanics during various movements including closed kinetic chain (CKC) exercise and landing tasks. Physiotherapists always concentrate on the control of toe direction during CKC exercise as a first step for athletes, as it is believed that correction of toe direction during CKC exercise is important to maintain the appropriate toe position even in high demanding activities such as landing tasks. The purpose of the present study was to investigate knee biomechanics during CKC exercise as well as landing tasks with three different toe directions, and clarify whether biomechanical parameters during CKC exercise would be related to those during landing tasks.

Methods

A total of 23 male recreational level athletes (mean age = 20.0 ± 1.1 yrs) participated. Tegner activity score were 7 for all male subjects. First, the subjects performed weight-bearing static lunge tests (SL) under three different toe directions, including 0 degrees (Toe-neutral: TN), 20 degrees (Toe-In: TI), and - 20 degrees (Toe-out: TO). Thereafter, SLDL was done under three different toe directions. Three-dimensional knee kinematics and kinetics at 60 degrees of knee flexion were calculated. As a statistical analysis, Pearson's correlation coefficient was used to evaluate the relationship between SL and SLDL. The statistical significance level wasset at P=0.05.

Results and Conclusions

Knee abduction angle showed significant correlation between SL and SLDL in all three different directions (TI: r=0.631, p<0.001, TN: r=0.678, p<0.001, TO: r=0.572, p<0.001). In terms of knee internal rotation, strong correlation was also found (TI: r=0.846, p<0.001, TN: r=0.791, p<0.001, TO: r=0.749, p<0.001). In addition, external knee abduction moment presented significant correlation in all three different directions (TI: r=0.574, p<0.001, TN: r=0.499, p<0.01, TO: r=0.469, p<0.01). From the present study, significant correlation between SL and SLDL was found in knee abduction angle, knee internal rotation, and external knee abduction moment under all three different directions including TI, TN, and TO. Physiotherapist should take care of toe direction and reform the movements especially for athletes who present malalignment of the knee joint during SL with TI or TO to prevent ACL injury in landing tasks.