Anthony J. House

Knee Proprioception and Strength and Landing Kinematics During a Single-Leg Stop-Jump Task

CONTEXT The importance of the sensorimotor system in maintaining a stable knee joint has been recognized. As individual entities, knee-joint proprioception, landing kinematics, and knee muscles play important roles in functional joint stability. Preventing knee injuries during dynamic tasks requires accurate proprioceptive information and adequate muscular strength. Few investigators have evaluated the relationship between knee proprioception and strength and landing kinematics. OBJECTIVE To examine the relationship between knee proprioception and strength and landing kinematics. DESIGN Cross-sectional study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Fifty physically active men (age = 26.4 ± 5.8 years, height = 176.5 ± 8.0 cm, mass = 79.8 ± 16.6 kg). INTERVENTION(S) Three tests were performed. Knee conscious proprioception was evaluated via threshold to detect passive motion (TTDPM). Knee strength was evaluated with a dynamometer. A 3-dimensional biomechanical analysis of a single-legged stop-jump task was used to calculate initial contact (IC) knee-flexion angle and knee-flexion excursion. MAIN OUTCOME MEASURE(S) The TTDPM toward knee flexion and extension, peak knee flexion and extension torque, and IC knee-flexion angle and knee flexion excursion. Linear correlation and stepwise multiple linear regression analyses were used to evaluate the relationships of both proprioception and strength against landing kinematics. The α level was set a priori at .05. RESULTS Enhanced TTDPM and greater knee strength were positively correlated with greater IC knee-flexion angle (r range = 0.281-0.479, P range = .001-.048). The regression analysis revealed that 27.4% of the variance in IC knee-flexion angle could be accounted for by knee-flexion peak torque and TTDPM toward flexion (P = .001). CONCLUSIONS The current research highlighted the relationship between knee proprioception and strength and landing kinematics. Individuals with enhanced proprioception and muscular strength had better control of IC knee-flexion angle during a dynamic task.

Reliability and precision of hip proprioception methods in healthy individuals

Objective:The goal of this study was to establish the intrasession and intersession reliability and precision of threshold to detect passive motion (TTDPM), force sense (FS), and active joint position sense (JPS) tests for the hip in healthy individuals. Design:Descriptive laboratory study. Setting:Research laboratory. Participants:Data were collected on 20 subjects between the ages of 18 and 30 years. They were physically active and had no history of major lower extremity injury or surgery or hip injuries. Interventions:Threshold to detect passive motion, FS, and active JPS were measured using a Biodex System 3 and a Vicon Motion Analysis System. Main Outcome Measures:Error scores were calculated as the absolute difference between the reference and reproduction values. Intraclass correlation (ICC) and standard error of measurement (SEM) were used to assess intrasession and intersession reliability and precision. Results:Adduction showed good reliability for JPS, with an intersession ICC (SEM) of 0.753 (0.248 degrees). For TTDPM, abduction showed an intrasession ICC (SEM) of 0.825 (0.256 degrees) and adduction had an intrasession ICC (SEM) of 0.765 (0.266 degrees). The intersession ICCs (SEM) were as follows: flexion 0.810 (0.143 degrees), extension 0.777 (0.195 degrees), abduction 0.906 (0.176 degrees), and adduction 0.893 (0.144 degrees). Flexion showed a good intersession ICC for FS: 0.764 (0.932 Nm). Conclusions:Results indicate that a reliable and precise method of measuring hip TTDPM has been established. Further investigation is necessary to develop reliable and precise measurement methods for FS and active JPS of the hip and to identify if TTDPM is related to hip kinematics, hip kinetics, and muscle activation about the hip during functional tasks.

Physiological Differences between Male and Female Army Soldiers Matched on Age and Years of Service: 1609

US Army Soldiers must optimize physical readiness to minimize the risk of unintentional musculoskeletal injury and optimize performance. All Soldiers follow similar physical training (PT) guidelines and perform gender-integrated PT. In order to optimize performance, male and female athletes train differently; therefore it is possible that traditional PT may not specifically address the unique physical and physiological needs of female Soldiers. PURPOSE: To determine if physiological differences exist between genders in US Army Soldiers of the 101st Airborne Division (Air Assault), controlling for age and years of service (YOS). METHODS: Data were collected on 53 female Soldiers (age= 25.8± 4.4 years, height= 1.65±0.06 m, mass= 65.9±10.3 kg) and matched with 53 male Soldiers (age= 25.5±4.2 years, height= 1.76±0.06 m, mass=83.5±13.6 kg) based on age (±3 years) and YOS (± 0.5 years). Variables analyzed were: percent body fat, total mass, lean mass, and fat mass; anaerobic power (AP)/capacity (AC); and maximal oxygen uptake (VO 2max)/lactate threshold (LT). Paired t-tests were used to compare all variables between genders. Statistical significance was set at p<0.05 a priori. RESULTS: differences in physiological variables do exist in US Army Soldiers of the 101st Airborne Division (Air Assault). These differences have important implications for potential changes or augmentation to current PT in order to optimize physical performance. Future research should investigate other physical characteristics that may relate to injury and if targeted PT that addresses the identified suboptimal characteristics in female Soldiers mitigates the risk of unintentional musculoskeletal injury and optimizes physical readiness.