There is a lack of studies investigating gender differences in whole-body kinematics during single-leg landings from increasing vertical heights and horizontal distances. This study determined the main effects and interactions of gender, vertical height, and horizontal distance on whole-body joint kinematics during single-leg landings, and established whether these findings could explain the gender disparity in non-contact anterior cruciate ligament (ACL) injury rate. Recreationally active males (n=6) and females (n=6) performed single-leg landings from a takeoff deck of vertical height of 20, 40, and 60 cm placed at a horizontal distance of 30, 50 and 70 cm from the edge of a force platform, while 3D kinematics and kinetics were simultaneously measured. It was determined that peak vertical ground reaction force (VGRF) and the ankle flexion angle exhibited significant gender differences (p=0.028, partial η 2 =0.40 and p=0.035, partial η 2 =0.37, respectively). Peak VGRF was significantly correlated to the ankle flexion angle (r= −0.59, p=0.04), hip flexion angle (r= −0.74, p=0.006), and trunk flexion angle (r= −0.59, p=0.045). Peak posterior ground reaction force (PGRF) was significantly correlated to the ankle flexion angle (r= −0.56, p=0.035), while peak knee abduction moment was significantly correlated to the knee flexion angle (r= −0.64, p=0.03). Rearfoot landings may explain the higher ACL injury rate among females. Higher plantar-flexed ankle, hip, and trunk flexion angles were associated with lower peak ground reaction forces, while higher knee flexion angle was associated with lower peak knee abduction moment, and these kinematics implicate reduced risk of non-contact ACL injury.

Competitive swimmers have a high incidence of breaststroke-related knee injuries. Although previous investigators have implicated the terminal phase of the kick in the injury mechanism, athletes often complain of pain during the initial phase of rearward thrust. Disagreement in the current literature surrounds the precise anatomical derangement(s) constituting "breaststroker's knee." The purpose of this investigation was to delineate the epidemiology, anatomy, and pathobiomechanics of breaststroke knee injuries. Descriptive data were obtained by surveying 391 athletes. An extremely high incidence of knee pain was documented both among breaststroke specialists (73%) and nonbreaststrokers (48%). Age, years of competitive swimming, and specific training characteristics were positively correlated with knee pain. Both the medial collateral ligament and the inferomedial patellar border were involved. A further 21 swimmers were assessed in detail using four methods: interview, physical examination, Cybex II isokinetic quadriceps and hamstring testing, and cinematographic analyses. The interview and physical examination data supported the conclusions derived from the descriptive data, while Cybex testing and kinematic film analyses failed to demonstrate statistical differences between the injured and noninjured groups. Although kinematic film analyses did not demonstrate statistical differences between cases and controls, dramatic differences in the injury rate were noted when hip abduction angles at kick initiation were less than 37 degrees or greater than 42 degrees. This bimodal increase in injury rates suggests that modification of hip abduction at kick initiation, in conjunction with altered training regimens, will lead to a reduction in medial knee joint stress and hence fewer breastroke injuries.

Introduction: The understanding of abnormalities in biomechanical parameters of gait in individuals with vision loss (i.e., blindness or low vision) has clinical importance. The aims of this study were to compare the spatiotemporal and ground reaction force variables of sighted individuals with those with vision loss. Methods: Ten sighted males and 10 young males with congenital vision loss were recruited. A Vicon motion analysis system with four cameras and two Kistler force plates was used to quantify spatiotemporal and ground reaction force components of both groups during walking without shoes. Sighted individuals walked in eyes-open and eyes-closed conditions. Results: Results showed that the stride and step length, walking speed, the vertical and posterior–anterior reaction forces in heel contact and push-off phase, and the impulse of the control group during walking with the open- and closed-eyes conditions were significantly smaller than those in persons with vision loss ( p < .05). Discussion: Vision loss is associated with decreased step and stride length, slower walking, and smaller propulsive reaction force. These kinematic and kinetics alterations suggest an adaptation to a new neuromuscular response for dynamic postural control as a result of lack of vision. These alterations in the long term may result in rigidity and muscle weakness. Implications for practitioners: A rehabilitation program to enhance mobility and strength is suggested for individuals with vision loss.

Background: Previous attentional focus literature suggests that adopting an external focus (EF) results in greater force production through a variety of mechanisms. Objective: The purpose of the present study was to examine the effects of attentional focus and dual-tasking when performing heavily loaded barbell movements that are specific to strength-based sports. Method: Fifteen resistance-trained males (age = 23.3 ± 3.4 years) reported to the laboratory for three visits. The first visit consisted of a five-repetition maximum (5RM) test on the conventional deadlift. During the subsequent sessions, the participants performed a total of twelve single conventional deadlift repetitions while adopting an internal focus (IF), an external focus (EF), or while performing the cognitive task (COG). The IF and EF consisted of focusing on activating the quadriceps and maintaining a straight bar path, respectively. The COG consisted of counting the total occurrence of two single-digits in a sequence of three-digit numbers, separately. Three-dimensional motion capture and force platforms were used to collect kinematic and kinetic data. Results: No significant differences were found between the IF, the EF and the COG for lift duration, peak barbell velocity, peak vertical ground reaction force, area of 95% confidence ellipse, peak hip moments and peak hip powers. Adopting an EF significantly reduced variability of the barbell trajectory and centre of pressure (COP) in the anterior-posterior direction. Mean velocity of COP was also significantly lower for the EF. Conclusion: Our findings suggest that adopting an EF may lead to greater postural stability when performing heavily loaded barbell movements.

A multidisciplinary design optimization (MDO) approach is proposed to aid in the prediction of non-contact anterior cruciate ligament (ACL) injury mechanisms and risk factors. In this investigation the need for such an approach is argued based on an exhaustive evaluation of diverse factors that cause non-contact ACL injury, and the similarly numerous and different existing study approaches that have been carried out to investigate injury. The proposed MDO approach fuses patient data and existing study approaches via an artificial intelligent (AI) technique—absent in previous biomechanics investigations—so as to offer new insights into ACL injury prevention.