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Biomedical subjects

G L Soderberg

Publications and source records attributed to G L Soderberg.

At least 37 records · Page 2Linked to original sources
PubMed1987

Electromyographic analysis of knee exercises in healthy subjects and in patients with knee pathologies.

Little information exists about the intensity of contraction required from knee and hip musculature during common therapeutic exercises used for patient populations. This study, therefore, was designed to compare electromyographic data obtained from the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles during maximally resisted straight-leg-raising (SLR) exercises with EMG data obtained from the same muscles during quadriceps femoris muscle setting (QS) exercises in healthy subjects and in patients with knee pathologies. Of the 30 participants in the study, 16 had a history of knee injury or surgery. All participants performed randomly ordered trials of the SLR and QS exercises while the EMG data were recorded from surface electrodes and normalized to values derived from maximal effort isometric contraction trials. An analysis of variance demonstrated significantly greater activity (p less than .05) of the vastus medialis, biceps femoris, and gluteus medius muscles during QS exercises than during SLR exercises. The rectus femoris muscle was significantly more active (p less than .05) during SLR exercises than during QS exercises. The study demonstrated remarkably different degrees of muscle activation between the SLR and QS exercises, indicating that the exercise selected will affect the therapeutic intention.

Adult↗
PubMed1986

Technique for EMG fine wire connections.

A fine wire electrode connector has been developed to incorporate the benefits of on-site pre-amplification, while concurrently providing the ease of repeatable quick connections for fine wires. Results show artifact-free electromyograms in studies of single motor unit action potentials or during functional activities.

Electromyography↗
PubMed1986

Transcutaneous electrical nerve stimulation characteristics for altering pain perception.

The purpose of this study was to determine the effect of conventional low-intensity transcutaneous electrical nerve stimulation (TENS) waveform and frequency characteristics on experimentally induced acute pain. Each of 28 male subjects received six forms of TENS and one control treatment during a single testing session. Treatments used one of two waveforms (monophasic or biphasic) and one of three frequencies (30, 60, or 85 Hz) administered to the forearm. Treatment effects were ascertained from alterations in pain-threshold and pain-tolerance responses induced by noxious electrical stimulation of the ipsilateral fifth digit. The TENS waveform and frequency had a negligible effect on pain threshold. The results indicated that waveform did not influence pain tolerance significantly. Pain tolerance, however, increased significantly at the frequency of 60 Hz but decreased significantly at both 30 and 85 Hz (p less than .05). We concluded that TENS frequency is an important factor in altering the subjects' perception of experimentally induced pain.

Adult↗
PubMed1986

Actions of hip muscles.

This article describes and explains the moment arm vector (MAV) concept, uses the concept for the quantitative classification of hip muscles according to action, and applies the findings to selected clinical problems. A three-dimensional, straight-line model of hip musculature was used. Measurements made on a matched, dry bone specimen provided muscle attachment point location data for the model. Straight lines of muscle action between attachment sites were simulated for a variety of hip configurations during simple hip motions in three principal anatomical planes. We used the MAV concept to identify the three contributions of a muscle (flexion-extension, abduction-adduction, and internal-external rotation) tending to rotate the thigh segment relative to the pelvis. Muscles were classified according to their action or turning effect at 0, 40, and 90 degrees of hip flexion. Certain muscles exhibited significant changes in their action during these simple motions. Model results were verified using an articulated, dry bone specimen with elastic strings stretched between muscle attachment sites. Based on this geometrical model, a "pathological posture" of hip flexion, adduction, and internal rotation was identified, which is a posture prevalent in spastic, brain damaged patients.

Biomechanical Phenomena↗
PubMed1984

Electromyographic analysis of selected muscles during sitting push-ups. Effects of position and sex.

The purpose of this study was to determine if differences in EMG activity of the latissimus dorsi, pectoralis major and triceps brachii occurred between muscles and between the 16 male and 16 female subjects performing push-ups from three different sitting positions. Surface electrodes and associated instrumentation recorded a linear envelope during seated push-ups performed 1) in a wheelchair, 2) in a long-sit position with elbows at 90 degrees, and 3) in a long-sit position with maximum elbow flexion and shoulder abduction. Results showed that women produced greater mean EMG activity than men in all muscles at all positions. Altering the exercise position did not have a consistent effect on level of activity recorded from either sex. The study concludes that use of these exercises should be based on a knowledge of the differences in muscle activity in exercise positions for men and women before treatment objectives can be effectively accomplished.

Adult↗
PubMed1984

Alteration of motor-unit discharge characteristics in aged humans.

The purpose of this study was to determine and compare the discharge characteristics of single motor-unit action potentials (SMUAPs) in young and aged subjects during 5, 10, and 20 percent of maximum voluntary contraction (MVC) of the abductor digiti minimi manus muscle. Three decades of aged subjects ranging from 60 to 90 years of age were compared with a group of 20 to 35 year olds. Specially constructed fine-wire bifilar recording electrodes were used, and SMUAPs were identified by interactive computer processing. Although the results did not reach a statistically significant level, they showed the 70- to 79-year-old age group had the longest mean interspike intervals (ISI) in each of the three percentages of MVC. The prolonged ISI indicate a slow motor-unit discharge rate. In addition, the 70- to 79-year-old group had a statistically significant floating standard deviation, indicating increased variability of discharge, and a significantly different negative floating serial correlation coefficient. All three factors describing motor-unit discharge behavior in the 70- to 79-year-old age group suggest possible substitution of larger motor units for smaller motor units normally active at low tensions.

Action Potentials↗
PubMed1984

Electromyography in biomechanics.

The purpose of this paper is to discuss the use of EMG as related to biomechanical function and dysfunction. The uses and limitations of this technique are described and instrumentation features and methods of data collection and interpretation are presented. We also discuss factors that influence the relationship of EMG to biomechanical measurements and cite as examples studies that have used EMG. Emphasis is placed on improving the ability of the physical therapist to use and interpret EMG data in kinesiology and biomechanics.

Biomechanical Phenomena↗
PubMed1984

Electromyographic analysis of selected muscles during the lateral step-up exercise.

The purpose of this study was to determine electromyographically if significant differences in level of electrical activity in the vastus medialis, rectus femoris, biceps femoris, and semimembranosus/semitendinosus muscles occurred during the concentric and eccentric phases of a 4- and 8-in lateral step-up exercise. Twenty-nine subjects with no pathological condition of the knees participated in the study. The surface electromyograms obtained were processed by linear envelope detectors and normalized, in percentage, to a maximum voluntary contraction of each subject. Within-muscle differences, step height, and contraction type were tested with a two-way analysis of variance. Results revealed that the average values for muscular activity, depending on the height and direction, ranged from 24 percent to 60 percent for vastus medialis, 8 percent to 23 percent for rectus femoris, 3 percent to 9 percent for biceps femoris, and 4 percent to 9 percent for semimembranosus/semitendinosus muscles. All muscles were significantly more active at the 8-in height than at the 4-in height. The concentric phase produced significantly greater activity (p less than .001) than the eccentric phase at each height except for semimembranosus/semitendinosus muscles, where no significant difference existed. The results of this study are discussed with respect to the limited role that the tested hamstrings and quadriceps femoris muscles play in preventing anterior shear of the tibia during the lateral step-up exercise.

Adolescent↗
PubMed1984

Alterations in ankle dorsiflexion torque as a result of continuous ultrasound to the anterior tibial compartment.

Although considerable documentation of the physiologic effects of ultrasound (US) exists, little information is available concerning direct effects of US on muscle, particularly when the US is applied immediately before muscle performance. The purpose of this study was to determine the effect of continuous US to the anterior tibial muscle compartment on ankle dorsiflexion torque assessed immediately posttreatment, at 30 minutes, and at 60 minutes posttreatment. Seventeen healthy subjects were tested performing isometric contractions at dynamometer velocities of 60 and 180 degrees/sec. Subjects first received either a placebo or a 1.5 W/cm2 15-minute US treatment. One week later, the protocol was repeated with the administration of a second treatment. Analysis of variance showed no significant interactions for time and treatment for any contraction; time, for isometric contraction, was the only significant main effect. Follow-up analyses were all nonsignificant for comparisons of pretreatment to posttreatment and posttreatment to 30- and 60-minute intervals within treatment groups. The study concludes that in spite of known physiologic effects, one treatment of US does not have an immediate or latent effect on peak torque.

Adult↗
PubMed1983

Laser etched bifilar fine wire electrode for skeletal muscle motor unit recording.

To selectively record a limited number of skeletal muscle motor unit action potentials, a bifilar fine wire electrode was developed. Two 8 micrometers wires were braided together, a hook formed, and ends insulated. A round beam, pulsed laser, etched a 5 micrometers piece of insulation from each wire near the hooked end. Bipolar recordings from a select number of skeletal muscle motor units were obtained from these two uninsulated 5 micrometers areas. Reactive and capacitative components for each set of electrodes were measured. These electrodes were selective in recording from 3 to 5 single motor unit action potentials at low isometric tension levels.

Electrodes↗
PubMed1983

Comparison of skeletal muscle motor unit discharge characteristics in young and aged humans.

The purpose of this study was to determine the discharge characteristics of motor unit action potentials. Three decades of aged subjects ranging from 60 to 90 yr of age were compared to a group of 20-35 yr olds. Motor unit behavior was described by the interspike interval (ISI) and expressed statistically as a mean, a floating standard deviation (FSD), and a floating serial correlation (FRHO). The 70- to 79-yr-old group tended to have a slow motor unit discharge rate, an increased variability of discharge (FSD) and a negative serial correlation coefficient (FRHO). All three factors describing motor unit discharge behavior possibly suggest substitution of larger motor units for small motor units normally active at low tensions for the 70-79 age group.

Action Potentials↗
PubMed1983

Ultrasound effects on electroneuromyographic measures in sensory fibers of the median nerve.

The purpose of this study was to clarify the available literature and study the influence of ultrasound on the conduction velocity and amplitude of evoked sensory potentials in the median nerve. Thirteen subjects were assigned to either Experimental or Control Groups for ultrasound or placebo treatments. We compared sensory-nerve conduction velocity in the median nerve after 10 minutes of ultrasound treatment at three intensity levels (0.5, 1.0, and 1.5 W/cm2) with sensory-nerve conduction velocity in the median nerve after 10 minutes of placebo ultrasound treatment (0.0 W/cm2). No significant differences were noted between groups at any of the three ultrasound intensity levels, nor were the interaction effects significant. A hypothetical model, based on the available literature, proposes that ultrasound-induced changes in sensory-nerve conduction velocity may not progress in a direct linear fashion relative to the duration of treatment.

Adult↗
PubMed1983

Muscle mechanics and pathomechanics. Their clinical relevance.

This article reviews pertinent mechanical characteristics of the human musculotendinous unit. Contractile and elastic elements of muscle are discussed, primarily in relationship to their length-tension and force-velocity properties. Evidence from a variety of recent studies of muscle function and dysfunction is presented. Clinical implications for physical therapy practice are discussed, and examples of pathological conditions are cited. A primary conclusion reached is that the degree and duration of muscle elongation are important factors in immobilization and important considerations in therapeutic programs.

Humans↗
PubMed1983

An electromyographic analysis of quadriceps femoris muscle setting and straight leg raising.

Physical therapists routinely advise patients to perform quadriceps femoris muscle setting or straight leg raising or both following knee surgery or trauma from knee injury. Little information exists, however, about the intensity of effort required from knee and hip musculature during the exercises. This study was designed to compare the level of electromyographic activity during maximally resisted straight leg raises with the level during quadriceps femoris muscle setting exercises for the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles. Forty healthy young adult men and women performed randomly ordered trials of each exercise in the supine position. Electromyographic activity was recorded from surface electrodes and normalized to values derived from maximal isometric trials. Statistical analysis demonstrated significantly greater (p less than .0001) vastus medialis, biceps femoris, and gluteus medius muscle activity during quadriceps femoris muscle setting. The rectus femoris muscle was significantly more active (p less than .0001) during the straight leg raise. The study demonstrated remarkably different muscle activation levels between the exercises studied and clearly indicates that selection of the exercises needs to be based on the therapeutic objectives.

Adult↗
PubMed1982

An adaptable, multiple plate dynamometer and electromyograph for the study of quadruped postural responses.

An EMG-force measurement system which can be placed inside a sound dampened testing chamber to study subtle postural responses in the standing quadruped is described. The dynamometer is adjustable to accommodate different foot placement strategies and to afford a more natural standing posture. A non-telemeterized method of recording EMG from an unrestrained animal is also discussed.

Animals↗
PubMed1981

Relationship between perception of joint position sense and limb synergies in patients with hemiplegia.

The purpose of this study was to determine if patients with hemispheric brain lesions and subsequent paresis demonstrated a correlation between the perception of joint position sense and the ability to combine component parts of the limb synergies. Twenty-one adult patients with 6-week to 87-month histories of unilateral, hemispheric, paralytic brain lesions were evaluated by each of two tests. The first test evaluated the subject's ability to combine components of the limb synergies. A pilot investigation was performed which established the reliability of the testing instruments. The correlation between the perception of joint position sense and synergy test results, .83, was significant at p less than .01. Implications for therapeutic management of the patient with hemiplegia are discussed.

Adult↗
PubMed1978

A light-emitting diode system for the analysis of gait. A method and selected clinical examples.

The purpose of this study was to design, develop, and test a comprehensive and potentially clinically useful system for the objective evaluation of sagittal-plane motion and temporal and distance factors during gait. A light-emitting diode and a 35 mm single-frame color slide photographic technique were utilized. The method of data collection and reduction produced values that are similar to reports in previous literature. High reliability was shown both within and across investigators testing normal subjects. Across-investigator comparisons when taking angular measurements demonstrated lower reliability. Specific clinical examples are presented to demonstrate the applicability of the light-emitting diode system.

Gait↗