Energetic Analysis of Landing: A Novel Approach to Understanding Anterior Cruciate Ligament Injuries

Energetic analysis of landing combines kinematic and kinetic parameters across the landing period that have traditionally been evaluated independently and at discrete time points. This coupling of the kinematics and kinetics of multiple joints provides a more comprehensive description of the complex multi-segmental mechanics that occur during landing and in proposed anterior cruciate ligament (ACL) injury mechanisms. The purpose of this investigation was to utilize this form of analysis to 1) elucidate new knowledge regarding biomechanical factors that contribute to sagittal plane energy absorption (EA) patterns that are associated with high risk landing biomechanics related to ACL injury; 2) explore relationships between frontal and sagittal plane EA, and ACL-related landing biomechanics; and 3) clarify previous research regarding potential sex differences in lower extremity EA strategies. 82 volunteer subjects (41 males, 41 females; age = 20.1 ± 2.4 years; height = 1.74 ± 0.10 m; mass = 70.3 ± 16.1 kg) were included in this research study. Subjects had peak isometric strength measured prior to completing double leg jump landing and drop landing tasks during which biomechanics and were assessed. It was found that greater sagittal and frontal plane EA during the 100 ms after ground contact were indicative of biomechanical profiles that likely result in greater ACL loading due to sagittal and frontal plane mechanisms, respectively. However, there is no association between the magnitudes of sagittal and frontal plane EA during landing. Additionally, no sex differences in EA strategy were identified after controlling for initial joint kinematics indicating that landing posture, not sex, influences EA strategy. Finally, the combination of multi-factorial biomechanical parameters is predictive of EA at the hip and ankle, but not at the knee and suggests that interventions aimed at reducing total lower extremity EA and thereby potentially decreasing knee joint loading during landing must facilitate changes across the entire kinetic chain. The results of this investigation provide significant information for understanding the way in which multi-joint lower extremity movement patterns during landing, quantified using EA analyses, affects ACL loading, and provides much-needed evidence for specific biomechanical factors that should be targeted in ACL injury prevention programs

Athletic Training and Public Health Summit

To introduce athletic trainers to the benefits of using a population-based approach to injury and illness prevention and to explore opportunities for partnering with public health professionals on these initiatives

Development of a method to quantitatively measure arthrogenic muscle inhibition in the peroneals

After a joint injury, arthrogenic muscle inhibition (AMI) leads to decreased neuromuscular control and strength, as neural inhibition prevents volitional activation of the entire motor neuron pool. Traditional rehabilitation techniques such as strength training are unable to effectively reduce AMI and there is a need to identify interventions that can improve neuromuscular function in those with AMI. Clinically, Kinesio Tape® is commonly used by sports medicine practitioners to attempt to achieve this neuromuscular improvement. However, whether Kinesio Tape® can reduce AMI has not been established in past research. This may be due in part to previous studies utilizing healthy study subjects who did not demonstrate a neuromuscular deficit. Research has demonstrated that those with functional ankle instability (FAI) exhibit AMI, and thus the overarching purpose of the present project is to determine whether Kinesio Tape® can reduce AMI in those with FAI. However, the completion of this aim required the development and implementation of an appropriate methodology to quantify AMI in the peroneal muscles, as this has not previously been accomplished. The focus of this presentation is to describe AMI, why it is thought to occur following joint injury, and the challenges associated with developing a method to measure AMI consistently in this muscle group. Commonly, the H-reflex is used to evaluate AMI, but pilot testing illustrated that this could not be consistently measured. The central activation ratio of the muscle was then identified as an alternate method for quantifying AMI, but this technique has not previously been applied to the peroneal muscles. After overcoming several challenges, the central activation ratio method was successfully adapted such that it could be used to quantify AMI of the peroneals. As a result, it is now possible to evaluate the efficacy of Kinesio Tape® in facilitating improved neuromuscular control and strength in individuals with AMI

Hamstrings Stiffness and Landing Biomechanics Linked to Anterior Cruciate Ligament Loading

Greater hamstrings stiffness is associated with less anterior tibial translation during controlled perturbations. However, it is unclear how hamstrings stiffness influences anterior cruciate ligament (ACL) loading mechanisms during dynamic tasks

Spinal and Supraspinal Motor Control Predictors of Rate of Torque Development

During explosive movements and potentially injurious situations the ability to rapidly generate torque is critical. Previous research has suggested different phases of rate of torque development (RTD) are differentiately controlled. However, the extent to which supraspinal and spinal mechanisms predict RTD at different time intervals is unknown. RTD of the plantarflexors across various phases of contraction (i.e., 0-25ms, 0-50ms, 0-100ms, 0-150ms, 0-200ms, and 0-250ms) was measured in 37 participants. The following predictor variables were also measured: (a) gain of the resting soleus H-reflex recruitment curve, (b) gain of the resting homonymous post-activation depression recruitment curve, (c) gain of the GABAergic pre-synaptic inhibition recruitment curve, (d) the level of post-synaptic recurrent inhibition at rest, (e) level of supraspinal drive assessed by measuring V waves, and (f) the gain of the resting soleus M Wave. Stepwise regression analyses were used to determine which variables significantly predicted allometrically scaled RTD. The analyses indicated that supraspinal drive was the dominant predictor of RTD across all phases. Additionally, recurrent inhibition predicted RTD in all of the time intervals except 0-150 ms. These results demonstrate the importance of supraspinal drive and recurrent inhibition to RTD.Keywords: Neuromuscular control, Rate of force development, V wav

The influence of exercise on single leg jump-cut and double leg jump landing biomechanics

An important field of study within the exercise science realm lies in identifying risk factors for musculoskeletal injuries to inform injury prevention programs. One of the more serious injuries in sports, especially sports involving cutting and jumping, is sprain of the anterior cruciate ligament (ACL). Previous research has found that women are at greater risk for ACL injuries and this injury most commonly occurs during a deceleration movement. For this study, we measured landing biomechanics before and after an exercise protocol to gain insight on the influence of fatigue on knee position and loading during a single leg jump-cut and a double leg jump landing. Forty female participants between the ages of 18-30 who were free of musculoskeletal injury, had no history of ACL injury, and engaged in at least 150 minutes of moderate exercise per week were enrolled. Subjects performed two landing tasks: 1) a double leg landing from a 30 cm high box placed a distance of 50% of their height from the edge of two force platforms and 2) a single leg jump-cut over a small hurdle from a distance of 50% of their max height behind the force platforms prior to completing an exercise protocol. For the exercise protocol, subjects performed 6 cycles of treadmill walking at a self-selected speed between 3.0-3.5 mph for 5 minutes followed by one minute of jumping activities. Following the 30-minute exercise protocol, landing biomechanics were again measured as the subjects repeated the two landing tasks. The results presented in this poster will compare changes in single leg jump-cut and double leg jump landing biomechanics due to exercise. The specific variables of interest are: knee flexion angle at initial contact, peak internal knee extension and varus moments, knee valgus angle at initial contact, and peak knee valgus angle. These factors have previously been identified as significant predictors of ACL injury. By comparing the effects of exercise on knee biomechanics throughout both the single leg jump-cut and the double leg jump landing tasks we aim to identify if the biomechanical changes that occur from exercise are similar between tasks or if they are task dependent.This project was presented at Oregon State University's Celebrating Undergraduate Excellence 2015

Ankle-Dorsiflexion Range of Motion and Landing Biomechanics

A smaller amount of ankle-dorsiflexion displacement during landing is associated with less knee-flexion displacement and greater ground reaction forces, and greater ground reaction forces are associated with greater knee-valgus displacement. Additionally, restricted dorsiflexion range of motion (ROM) is associated with greater knee-valgus displacement during landing and squatting tasks. Because large ground reaction forces and valgus displacement and limited knee-flexion displacement during landing are anterior cruciate ligament (ACL) injury risk factors, dorsiflexion ROM restrictions may be associated with a greater risk of ACL injury. However, it is unclear whether clinical measures of dorsiflexion ROM are associated with landing biomechanics

Factors influencing high school coaches’ adoption of injury prevention programs

OBJECTIVES: Despite documented efficacy of injury prevention programs (IPPs) to reduce sport-related lower extremity injury risk, there is evidence of a lack of widespread IPP adoption by high school coaches. This study identified factors related to non-adoption of IPPs by assessing coaches’ knowledge, attitudes, and behaviors related to prevention programs and comparing attitudes between adopter and non-adopter coaches. DESIGN: Cross-sectional METHODS: Head soccer and basketball coaches (n=141) from 15 Oregon high schools were invited to complete a web-based survey assessing their IPP-related knowledge, attitudes, and behaviors. RESULTS: Of the 66 coach respondents, 52% reported being aware of IPPs; 21% reported using an IPP with their team; and 9% reported having their student-athletes perform the IPP exactly as designed. No apparent differences in the attitudes towards the importance of injury prevention or the effectiveness of IPPs were identified between coaches that did and did not adopt an IPP. Perceptions that efficacious IPPs do not offer a relative advantage over coaches’ existing practices, do not align with coaches’ needs (compatibility), and are difficult to implement in their setting (complexity) emerged as key factors underlying coaches’ decisions not to adopt a program. Of those that did report adopting an IPP, just 43% (6/14) reported implementing the program as designed. CONCLUSIONS: Improving preventative practices of high school coaches requires more than improved dissemination to increase coach awareness. To improve the rate of IPP adoption and implementation fidelity, coach education should directly address issues related to relative advantage, compatibility, and complexity.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The article is published in the Journal of Science and Medicine in Sport and available at: https://doi.org/10.1016/j.jsams.2015.03.00

Lower Extremity Energy Absorption and Biomechanics During Landing, Part II: Frontal-Plane Energy Analyses and Interplanar Relationships

Greater sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing is consistent with sagittal-plane biomechanics that likely increase anterior cruciate ligament (ACL) loading, but it does not appear to influence frontal-plane biomechanics. We do not know whether frontal-plane INI EA is related to high-risk frontal-plane biomechanics

Lower Extremity Energy Absorption and Biomechanics During Landing, Part I: Sagittal-Plane Energy Absorption Analyses

Eccentric muscle actions of the lower extremity absorb kinetic energy during landing. Greater total sagittal-plane energy absorption (EA) during the initial impact phase (INI) of landing has been associated with landing biomechanics considered high risk for anterior cruciate ligament (ACL) injury. We do not know whether groups with different INI EA magnitudes exhibit meaningful differences in ACL-related landing biomechanics and whether INI EA might be useful to identify ACL injury-risk potential