Leveraging Sensor Technology to Characterize the Postural Control Spectrum.

The purpose of this paper is to describe ongoing research on appropriate instrumentation and analysis techniques to characterize postural stability, postural agility, and dynamic stability, which collectively comprise the postural control spectrum. This study had a specific focus on using emerging sensors to develop protocols suitable for use outside laboratory or clinical settings. First, we examined the optimal number and placement of wearable accelerometers for assessing postural stability.

The intra- and interrater reliability of isometric muscle contractions using a novel fixation system for a hand-held dynamometer.

A novel fixation system for a hand-held dynamometer (HHD) was designed to enable isometric muscle measurements on various muscle groups of strong, healthy individuals in a field setting. The objective of this study was to evaluate the intra- and interrater reliability of the system and determine its suitability for use by multiple researchers within large-scale data collections during field activities. Four researchers tested eight healthy subjects, who each completed eight different maximal isometric muscle strength assessments using the HHD fixation system.

Effect of Cold vs Temperate Conditions on Physical Performance During Extended Mountain Warfare Training at Moderate Altitude.

Introduction: The purpose of this study was to investigate the effect of environmental conditions on body composition, upper body power, and lower body power throughout a ∼4-week military mountain training exercise. We hypothesized that countermovement jump and ballistic push-up performance would decrease as a result of extended mountain field training and that winter (cold) conditions would result in greater decrements compared to fall (temperate) conditions. We also expected to observe a strong positive correlation between changes in performance and changes in skeletal muscle mass.

The Association Between Grip Strength, Upper Body Power, and Limb Dominance in a Military Population.

Introduction: Military service members rely on upper body strength and power to accomplish tasks such as carrying heavy weapons and gear, rappelling, combat grappling, and marksmanship. Early identification of the factors that lead to reduced upper body strength and power would enable leadership to predict and mitigate aspects that decrease military operational readiness and increase injury risk. The purpose of this study was to investigate the relationship between grip strength and upper body power in U.

Effect of Fatigue on Movement Patterns During a Loaded Ruck March.

Introduction: Loaded ruck marching is a common training and operational task for many members of the military. It is known to cause fatigue, affect soldier readiness, and can lead to traumatic and overuse injuries. Quantifying the gait changes that occur over the course of a loaded ruck march may provide a better understanding of injury mechanisms and potentially allow for development of individualized injury-prevention training programs.

Association Between Running Shoe Characteristics and Lower Extremity Injuries in United States Military Academy Cadets.

Background: Running-related overuse injuries are very common among recreational runners, with the reported annual injury rates ranging from 39% to 85%. Relatively few large prospective cohort studies have been conducted to investigate injury risk associated with different running shoe characteristics, and the results of the existing studies are often contradictory.

Purpose/hypothesis: The purpose was to investigate the relationship between running shoe characteristics and lower extremity musculoskeletal injury.

Metabolic cost adaptations during training with a soft exosuit assisting the hip joint.

Different adaptation rates have been reported in studies involving ankle exoskeletons designed to reduce the metabolic cost of their wearers. This work aimed to investigate energetic adaptations occurring over multiple training sessions, while walking with a soft exosuit assisting the hip joint. The participants attended five training sessions within 20 days.

Hip muscle response to a fatiguing run in females with iliotibial band syndrome.

Impaired hip muscle function has often been cited as a contributing factor to the development of iliotibial band syndrome (ITBS), yet our full understanding of this relationship is not well established. The objective of this study was to examine the effect of fatigue on hip abductor muscle function in females with ITBS. Female runners, 20 healthy and 12 with a current diagnosis of ITBS, performed a treadmill run to fatigue.

The relationship between foot arch flexibility and medial-lateral ground reaction force distribution.

Background: Overuse running injury susceptibility has previously been associated with the magnitude and slope of ground reaction force profiles, most often in the vertical axis. However, despite the implications of excessive pronation and supination on injury susceptibility, very little research has examined the factors that might affect distribution of force in the medial-lateral directions.

Research Question: The purpose of this study was to consider how foot structure, specifically arch flexibility, affects the distribution of ground reaction force between the medial-lateral and vertical planes of motion.

Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types.

Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel.

The Relationship Between Arch Height and Arch Flexibility.

Background: The correlation between arch structure and injury may be related to the fact that foot structure influences foot function. Foot structure is often defined by arch height, although arch flexibility may be just as important to form a more complete description. We propose an arch flexibility classification system, analogous to arch height classification, and then use the classification system to examine the relationship between arch flexibility and arch height.

The effects of fatigue on lower extremity kinematics, kinetics and joint coupling in symptomatic female runners with iliotibial band syndrome.

Background: Altered hip and knee kinematics and joint coupling have been documented in runners with iliotibial band syndrome. Symptoms often present themselves after several minutes of running, yet the effect of fatigue warrants further exploration. The purpose of this study was to determine the effect of a run to fatigue in runners with iliotibial band syndrome, as compared to healthy controls.

The effects of limb dominance and fatigue on running biomechanics.

Purpose: To establish whether lower extremity limb dominance has an effect on overground running mechanics.

Background: In attempts to resolve unilateral pathology, physical therapists often use the restoration of symmetry as a clinical milestone. While lower limb dominance has been shown to affect lower extremity mechanics during dynamic tasks such as jump landing, its effect on running gait is poorly understood.

Are joint structure and function related to medial knee OA pain? A pilot study.

Background: Although the severity of knee osteoarthritis (OA) usually is assessed using different measures of joint structure, function, and pain, the relationships between these measures are unclear.

Purpose: Therefore, we: (1) examined the relationships between the measures of knee structure (flexion-extension range of motion, radiographic tibiofemoral angle, and medial joint space), function (Knee Osteoarthritis Outcome Scores [KOOS], peak adduction angle, and moment), and pain (visual analog scale [VAS]); and (2) identified variables that best predicted knee pain.

Methods: We assessed 15 patients with medial knee OA using VAS pain, KOOS questionnaire, 3-D gait analysis, and radiographic examination.

A comparison of rearfoot motion control and comfort between custom and semicustom foot orthotic devices.

Background: Motion control and comfort are primary objectives in orthotic intervention. Semicustom orthotic devices have been presented as a more cost-effective solution than custom orthotic devices. However, no studies have compared their function or comfort to that of custom orthotic devices.

A comparison of semi-custom and custom foot orthotic devices in high- and low-arched individuals during walking.

Background: Orthotic devices can be a successful treatment for lower extremity injuries. However, the high cost of custom devices prevents some patients from purchasing them. Some orthotic companies have begun to offer a less expensive, semi-custom alternative.

Side-to-side differences in overuse running injury susceptibility: a retrospective study.

Despite the number of studies examining factors associated with overuse running injury, little is known about why an individual gets injured on a particular side of the body. Abnormal levels of several strength, structural, kinetic, and kinematic factors have been attributed to injury susceptibility. However, while most studies have compared the injured limb of injured runners to an arbitrary limb of healthy controls, there is some evidence to suggest that injury risk is related to characteristics on both sides of a runner.

The symmetry angle: a novel, robust method of quantifying asymmetry.

Quantification of asymmetry is a common objective in both research and clinical settings. The most common method for quantification of asymmetry of discrete variables is calculation of the symmetry index. Essentially a measure of the percent difference between sides, the symmetry index requires the choice of a reference value.

Non-consecutive versus consecutive footstrikes as an equivalent method of assessing gait asymmetry.

Asymmetry of gait is often studied to characterize populations and assess the efficacy of treatment protocols. However, despite the continuous nature of gait, many studies have made comparisons between data from non-consecutive footstrikes. This is typically considered a limitation of these studies.

The effect of gender, age, and lateral dominance on arch height and arch stiffness.

Background: Arch structure is known to vary widely. However, it may be linked to intrinsic factors such as gender, age, and lateral dominance. Understanding the association between these factors and arch structure may be useful in understanding injury biases that exist between individuals with different foot types.

Kinetic asymmetry in female runners with and without retrospective tibial stress fractures.

Gait asymmetry may be linked to the tendency for runners to sustain chronic overuse injuries. This paper compares gait asymmetry in female runners who have never sustained a running-related injury to those who have sustained unilateral tibial stress fractures. The symmetry index was used to characterize asymmetry in the kinetics of both subject groups.

Investigation of the validity of modeling the Achilles tendon as having a single insertion site.

Objective: To assess the propriety of modeling the Achilles tendon insertion on the calcaneus as a single point when musculoskeletal models are used to predict subtalar joint moment arms.

Design: The sensitivity of model-predicted subtalar joint moment arms to insertion site position was investigated and measurements of Achilles tendon function were made in cadaver specimens.

Background: The insertion site of the Achilles tendon is typically modeled as having a single-point insertion.