Biomedical subjects

Bryan L Riemann

Publications and source records attributed to Bryan L Riemann.

13 recordsLinked to original sources

PubMed2004

Sex comparison of extensibility, passive, and active stiffness of the knee flexors.

OBJECTIVE: To compare extensibility, and passive and active stiffness of the knee flexors between males and females. DESIGN: An experimental design utilized 15 males and 15 females to identify sex differences in active extensibility, and active and passive stiffness of the knee flexors. BACKGROUND: Muscle stiffness appears to contribute to joint stability from both mechanical and neuromuscular perspectives. Differences in knee flexor stiffness may partially explain higher female anterior cruciate ligament injury rates. METHODS: Active knee flexor extensibility was assessed as subjects extend the knee from a fixed hip position, measuring the final knee position. Passive knee flexor stiffness was calculated as the slope of the moment-angle curve resulting from controlled passive knee extension. Active knee flexor stiffness was assessed by loading the lower extremity with 10% total body mass, and measuring the damping effect of the knee flexors on imposed vibratory motion about the knee joint. RESULTS: Females displayed greater active extensibility (P<0.05), while males displayed greater active (P<0.05) and passive (P<0.05) knee flexor stiffness. Sex differences in active and passive knee flexor stiffness were not significant following normalization to anthropometric characteristics. CONCLUSIONS: The knee flexor musculature in males is less extensible and displays greater active and passive stiffness compared to females. However, these differences may be functions of greater mass and height in males.

Adult↗

PubMed2004

The relationships between active extensibility, and passive and active stiffness of the knee flexors.

Insufficient active knee flexor stiffness may predispose the anterior cruciate ligament to injury. Insufficient passive stiffness may result in insufficient active stiffness. Similarly, higher levels of musculotendinous extensibility may inhibit active and passive muscle stiffness, potentially contributing to an increased risk of injury. The literature is both limited and inconsistent concerning relationships between extensibility, passive stiffness, and active stiffness. Extensibility was measured as the maximal active knee extension angle from a supine position with the hip flexed to 90 degrees . Passive stiffness was calculated as the slope of the moment-angle curve resulting from passive knee extension. Active stiffness was assessed via acceleration associated with damped oscillatory motion about the knee. Stepwise multiple regression indicated that passive stiffness accounted for 25% of active muscle stiffness variance. The linear combination of extensibility and passive stiffness explained only 2% more variance compared to passive stiffness alone. Musculotendinous extensibility was moderately related to passive muscle stiffness, and weakly related to active muscle stiffness. The moderate relationship observed between active and passive stiffness emphasizes the dependence of active muscle stiffness on cross-bridge formation, and the relatively smaller contribution from parallel elastic tissues. Additionally, heightened extensibility does not appear to be a predisposing factor for reduced muscle stiffness.

Adult↗

PubMed2004

Effect of lateral ankle ligament anesthesia on single-leg stance stability.

PURPOSE: This study was designed to determine, in isolation, the contribution of lateral ankle ligament mechanoreceptors to postural stability during single leg static (eyes open, eyes closed) and landing tasks. METHODS: Fourteen healthy subjects (nine males, five females) underwent two different treatment conditions (control, anesthesia) in a counterbalanced order (48-h interval). During the anesthetic treatment, lidocaine was injected into the anterior talofibular and calcaneofibular ligament (1.5 cc each) regions. Postural stability was measured using forceplate and kinematic variables. The average of each variable across multiple trials under each treatment for the three tasks was analyzed statistically. RESULTS: Results of all statistical analyses failed to demonstrate significant alterations (P > 0.05) in postural control attributable to the treatment condition. CONCLUSION: These results suggest that lateral ankle ligament mechanoreceptors either do not make a significant contribution to single leg stance stability, do not have a unique, irreplaceable role, or have a role that is too subtle to be detected given the measurement techniques used. Thus, the idea that single leg stability becomes altered after ankle joint injury because of proprioceptive disruption was not supported. This would suggest that reported postural control alterations in persons after repetitive ankle injury more likely occur as a result of alterations in mechanical stability, motor components, and/or central motor programming.

Adult↗

PubMed2003

Kinematic analysis of the hip and trunk during bilateral stance on firm, foam, and multiaxial support surfaces.

OBJECTIVE: To differentiate hip and trunk motion during double-leg stance. DESIGN: Trunk and hip angular position variances were measured on different support surfaces with and without vision. BACKGROUND: Postural control results from motion about the hips and trunk during bilateral stance. While the hip joint has been studied extensively, information concerning relative amounts of hip and trunk motions during postural control is limited. METHODS: Trunk flexion/extension, trunk lateral flexion, right and left hip flexion/extension and abduction/adduction angular position variances were assessed in 14 normal subjects using an electromagnetic tracking system during bilateral stance on firm, foam, and multiaxial support surfaces with and without vision. RESULTS: Significantly greater amounts of motion occurred at all joints for the multiaxial-eyes closed condition compared to all other surface-vision conditions. No significant differences were found between any other surface-vision conditions. Within the multiaxial-eyes closed condition, right and left hip flexion/extension and abduction/adduction magnitudes were significantly greater than those of trunk flexion and lateral flexion, and left hip flexion/extension motion was significantly greater than that of the right hip. CONCLUSIONS: Postural control mechanisms involve similar amounts of motion at the hips and trunk, except for conditions under which a rigid base of support becomes unstable and vision is eliminated. RELEVANCE: These results suggest that the trunk and hips should be considered separately during kinematic analysis of postural control. This information may be useful in providing a more sensitive assessment of postural control to identify balance-related pathologies associated with stroke, concussion, and somatosensory deficits.

Abdomen↗

PubMed2003

Comparison of the ankle, knee, hip, and trunk corrective action shown during single-leg stance on firm, foam, and multiaxial surfaces.

OBJECTIVE: To compare the quantity of ankle, knee, hip, and trunk corrective actions shown during single-leg stance. DESIGN: Counter-balanced crossover design. Single-leg stance under the conditions of eyes open on firm, foam, and multiaxial surfaces and eyes closed on a firm surface were recorded for 12 seconds in 18 participants. SETTING: A university neuromuscular research laboratory. PARTICIPANTS: Eighteen healthy and recreationally active college students. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Average angular displacement magnitude between successive sampling instances for the ankle, knee, hip, and trunk. RESULTS: A significant condition by joint interaction was revealed. Post hoc comparisons revealed that the ankle dominated as the source of corrective action across each of the testing conditions. As the challenge became greater because of foam surface or eyes closed, more corrective action occurred at proximal joints (hip and/or knee). CONCLUSIONS: The ankle is of primary importance during single-leg stance on firm, foam, and multiaxial surfaces, with proximal joints having an increased role under more challenging conditions. These results provide a scientific basis for clinicians' and researchers' decisions about support surface and visual condition during single-leg postural control testing and training.

Adolescent↗

PubMed2003

Shoulder muscle reflex latencies under various levels of muscle contraction.

Previous research in relaxed muscles shows that muscle reflex latencies are too slow to protect the shoulder. However, during athletic activity when injury occurs, some level of shoulder muscle contraction typically exists. The purpose of the current study was to assess shoulder muscle reflex latencies under various levels of muscle contraction. Seventeen healthy subjects participated. A perturbation consisting of an external rotation collision force to the anterior forearm in a position of apprehension under various levels of muscle contraction (0%, 20%, and 50% of a maximum voluntary muscle contraction) was applied. Muscle reflex latencies were measured as the time from perturbation application to onset of muscle activity. Electromyography measured activity onset of the rotator cuff muscles and the primary humeral movers. During 0%, the latissimus dorsi muscle reflex latency was significantly slower than most other muscles. No difference existed between muscles in the 20% and 50% conditions. For the rotator cuff muscles, the reflex latencies significantly quickened for 20% and 50% compared with the relaxed state (0%). Overall, introducing muscle contraction significantly quickened muscle reflex latencies. These results provide clinicians with a better understanding of the role that these reflexes play in joint stability in a position of injury vulnerability like a position of apprehension.

Adult↗

PubMed2002

Gender differences in strength and lower extremity kinematics during landing.

This study evaluated kinematic, vertical ground reaction forces, and strength variables in healthy collegiate female basketball, volleyball, and soccer players compared with matched male subjects. Thirty athletes did single-leg landing and forward hop tasks. An electromagnetic tracking device synchronized with a force plate provided kinematic data and vertical ground reaction force data, respectively. Maximum angular displacement and time to maximum angular displacement kinematic variables were calculated for hip flexion, abduction, rotation, knee flexion, and lower leg rotation. Vertical ground reaction force data normalized to body mass provided impulse, maximum force, time to maximum force, and stabilization time variables. An isokinetic device measured quadriceps and hamstring peak torque to body mass at 60 degrees /second. With both tasks, females had significantly less knee flexion and lower leg internal rotation maximum angular displacement, and less knee flexion time to maximum angular displacement than males. For the single-leg land, females had significantly more hip internal rotation maximum angular displacement, and less lower leg internal rotation time to maximum angular displacement than males. For the forward hop, females had significantly more hip rotation time to maximum angular displacement than males. Females also had significantly less peak torque to body mass for the quadriceps and hamstrings than males. Weaker thigh musculature may be related to the abrupt stiffening of the knee and lower leg on landing in females.

Adult↗

PubMed2002

Effect of ankle taping and bracing on vertical ground reaction forces during drop landings before and after treadmill jogging.

STUDY DESIGN: Single-group repeated-measures experimental design. OBJECTIVES: The purpose of this study was to evaluate the effects of prophylactic ankle stabilization on vertical ground reaction forces before and after treadmill jogging. BACKGROUND: Previous research has demonstrated acute effects of ankle taping and bracing on ankle joint kinematics and vertical ground reaction forces during drop landings. Based on the number of investigations demonstrating increased range of motion of the braced or taped ankle following exercise, it may be plausible that the aforementioned landing alterations may return to normal following an exercise bout. METHODS AND MEASURES: Fourteen healthy recreational participants performed stiff and soft drop landings before and after a 20-minute treadmill exercise bout under 3 different ankle stabilizer conditions (no stabilizer, ankle brace, and ankle tape). A forceplate was used to collect ground reaction force data under the dominant foot. The first and second peak impact force, as well as the time to each of the 2 peak forces, were determined for each trial and used as dependent variables. RESULTS: The time to reach peak forces were significantly less under the ankle brace and tape conditions in comparison to the control (no-stabilizer) condition. CONCLUSIONS: It appears that ankle taping and bracing decrease the time to reach peak impact forces. These alterations indicate that during dynamic activity the musculoskeletal structures of the body may be subjected to loads within shorter time periods. Whether these effects are detrimental over time remains speculative at this point and requires further research.

Adaptation, Physiological↗

PubMed2002

Is There a Link Between Chronic Ankle Instability and Postural Instability?

OBJECTIVE: To provide clinicians and researchers with an expanded perspective on the association between functional ankle instability and postural control. DATA SOURCES: I searched MEDLINE and SPORT Discus for the years 1966-2001 using the key words ankle, instability, and balance. Additional information was obtained from cross-referencing pertinent articles. DATA SYNTHESIS: Conflicting reports have been published about whether postural control is disrupted in people with chronic ankle instability. The variety of testing methods and operational definitions used by various investigators make drawing a consensus difficult. In contrast, the results of investigations considering postural-control strategy disruptions in persons with chronic ankle instability have been compatible. Depending upon the effectiveness of an altered strategy, postural-control deficiencies may fail to be revealed in the absence of challenging tasks and environmental conditions. CONCLUSIONS/RECOMMENDATIONS: If we accept the idea that postural control is disrupted after orthopaedic injury, the next step becomes identifying the causative factors within the postural-control system. Experimental evidence surrounding the role of lateral ankle-ligament mechanoreceptors in posture suggests that they cannot be the sole source of the alterations revealed. Consideration should be directed to other potential areas within the postural-control system, as outlined in the text, during ankle evaluations and rehabilitation.

Journal Article↗

PubMed2002

The sensorimotor system, part I: the physiologic basis of functional joint stability.

OBJECTIVE: To define the nomenclature and physiologic mechanisms responsible for functional joint stability. DATA SOURCES: Information was drawn from an extensive MEDLINE search of the scientific literature conducted in the areas of proprioception, neuromuscular control, and mechanisms of functional joint stability for the years 1970 through 1999. An emphasis was placed on defining pertinent nomenclature based on the original references. DATA SYNTHESIS: Afferent proprioceptive input is conveyed to all levels of the central nervous system. They serve fundamental roles in optimal motor control and sensorimotor control over functional joint stability. CONCLUSIONS/APPLICATIONS: Sensorimotor control over the dynamic restraints is a complex process that involves components traditionally associated with motor control. Recognizing and understanding the complexities involved will facilitate the continued development and institution of management strategies based on scientific rationales.

Journal Article↗

PubMed2002

The Sensorimotor System, Part II: The Role of Proprioception in Motor Control and Functional Joint Stability.

OBJECTIVE: To discuss the role of proprioception in motor control and in activation of the dynamic restraints for functional joint stability. DATA SOURCES: Information was drawn from an extensive MEDLINE search of the scientific literature conducted in the areas of proprioception, motor control, neuromuscular control, and mechanisms of functional joint stability for the years 1970-1999. DATA SYNTHESIS: Proprioception is conveyed to all levels of the central nervous system. It serves fundamental roles for optimal motor control and sensorimotor control over the dynamic restraints. CONCLUSIONS/APPLICATIONS: Although controversy remains over the precise contributions of specific mechanoreceptors, proprioception as a whole is an essential component to controlling activation of the dynamic restraints and motor control. Enhanced muscle stiffness, of which muscle spindles are a crucial element, is argued to be an important characteristic for dynamic joint stability. Articular mechanoreceptors are attributed instrumental influence over gamma motor neuron activation, and therefore, serve to indirectly influence muscle stiffness. In addition, articular mechanoreceptors appear to influence higher motor center control over the dynamic restraints. Further research conducted in these areas will continue to assist in providing a scientific basis to the selection and development of clinical procedures.

Journal Article↗

PubMed2002

Sensorimotor system measurement techniques.

OBJECTIVE: To provide an overview of currently available sensorimotor assessment techniques. DATA SOURCES: We drew information from an extensive review of the scientific literature conducted in the areas of proprioception, neuromuscular control, and motor control measurement. Literature searches were conducted using MEDLINE for the years 1965 to 1999 with the key words proprioception, somatosensory evoked potentials, nerve conduction testing, electromyography, muscle dynamometry, isometric, isokinetic, kinetic, kinematic, posture, equilibrium, balance, stiffness, neuromuscular, sensorimotor, and measurement. Additional sources were collected using the reference lists of identified articles. DATA SYNTHESIS: Sensorimotor measurement techniques are discussed with reference to the underlying physiologic mechanisms, influential factors and locations of the variable within the system, clinical research questions, limitations of the measurement technique, and directions for future research. CONCLUSIONS/RECOMMENDATIONS: The complex interactions and relationships among the individual components of the sensorimotor system make measuring and analyzing specific characteristics and functions difficult. Additionally, the specific assessment techniques used to measure a variable can influence attained results. Optimizing the application of sensorimotor research to clinical settings can, therefore, be best accomplished through the use of common nomenclature to describe underlying physiologic mechanisms and specific measurement techniques.

Journal Article↗

PubMedDate not supplied

Effect of peripheral afferent alteration of the lateral ankle ligaments on dynamic stability.

BACKGROUND: The sensorimotor influence of the lateral ankle ligaments in muscle activation is unclear. HYPOTHESIS: The lateral ankle ligaments have significant sensorimotor influence on muscle activation. STUDY DESIGN: Controlled laboratory study. METHODS: Muscle-firing characteristics in response to a high-speed inversion perturbation and during gait were assessed in 13 normal subjects. Solutions (1.5% lidocaine or a placebo of saline) were injected bilaterally into the anterior talofibular and calcaneofibular ligaments (1.5 ml per ligament) to alter peripheral afferent influence. Subjects were again tested with the same protocol. RESULTS: The protective response of the anterior tibialis and peroneal muscles during inversion perturbation and mean muscle activation amplitude decreased during running after both injections. After injection, no significant differences were seen for muscle reflex latencies, maximum amplitude, time to maximum amplitude during inversion perturbation, or mean amplitude during walking. CONCLUSION: The lateral ankle ligaments have a sensorimotor influence on muscle activation. CLINICAL RELEVANCE: Induced edema from the injected solutions may have altered the sensorimotor influence of the lateral ankle ligaments, thereby inhibiting the dynamic ankle stabilizers. This finding suggests that dynamic stability may be compromised because of swelling after joint injury.

Adult↗