Scapulothoracic latent muscle reaction timing comparison between trained overhead throwers and untrained control subjects.

AIM: This study evaluated select scapulothoracic muscles for training-induced latent muscle reaction timing (LMRT) changes. Comparisons were also made between the dominant and non-dominant upper extremities and between individual muscles. MATERIALS AND METHODS: Fifteen male trained overhead throwers (college baseball pitchers) and 15 male untrained, age-matched control subjects participated in this study. Scapulothoracic muscle activation data were collected as subjects attempted to stop a variably timed, sudden glenohumeral joint internal rotation perturbation. RESULTS: Training group differences were not evident for LMRT (P=0.56), however upper extremity dominance (P=0.003) and test muscle (P=0.0002) displayed significant differences. Dominant upper extremity upper trapezius muscle LMRT (72.5+/-26 ms) occurred later than non-dominant upper trapezius muscle LMRT (60.0+/-14.1 ms, P=0.001). Dominant upper extremity middle trapezius-rhomboid muscle LMRT (60.0+/-16.2 ms) occurred later than non-dominant middle trapezius-rhomboid muscle LMRT (50.2+/-12.6 ms, P=0.004). Dominant upper extremity upper trapezius muscle LMRT also occurred later than serratus anterior (55.7+/-16.0 ms, P=0.001) and middle trapezius-rhomboid LMRT (60.2+/-16 ms, P=0.003). Mean overall dominant upper extremity LMRT (62.7+/-19.4 ms) was delayed compared with mean overall non-dominant upper extremity LMRT (53.9+/-12.4 ms, P=0.003). CLINICAL CONSEQUENCES: Although training was not found to influence scapulothoracic LMRT, differences were observed between the dominant and non-dominant upper extremities. Consistent LMRT delays at the dominant upper extremity suggest possible neuromuscular timing differences to enable prolonged glenohumeral joint and scapulothoracic articulation acceleration before deceleration through eccentric muscle activation. Both trained and untrained overhead throwers displayed this response. Variable perturbation test velocities, and in-season testing of larger subject groups may be needed to better elucidate the more subtle differences associated with training.

Relationship between ankle invertor H-reflexes and acute swelling induced by inversion ankle sprain.

STUDY DESIGN: Single group, post-test design using the uninvolved lower extremity as the experimental control. OBJECTIVES: To determine relationships between ankle swelling and flexor digitorum longus and peroneus longus H-reflex amplitude and latency. BACKGROUND: Primary capsuloligamentous injury, neural injury, and joint effusion and swelling may contribute to H-reflex changes following inversion ankle sprain. The relationship between ankle swelling and invertor or evertor H-reflexes has not been reported. METHODS AND MEASURES: Fifteen subjects with acute grade I or II inversion ankle sprains (mean +/- SD) 6.5 +/- 3 days after onset participated in this study. Swelling was estimated using a tape measure and the figure-of-eight girth assessment method. H-reflexes were determined using standard techniques. Paired t-tests were used to compare mean differences in ankle girth (swelling) and ankle invertor or evertor H-reflex amplitude and latency between the involved and uninvolved limbs. Pearson product moment correlations were used to assess relationships between swelling and H-reflex variables. RESULTS: Involved limb ankle girth was increased with respect to the uninvolved limb (1.5 +/- 0.9 cm) and the involved ankle flexor digitorum longus latency was delayed (0.72 +/- 0.7 ms). There was a moderate positive association (r = 0.73) between the latency delay in the involved ankle flexor digitorum longus and swelling. There were no significant differences in H-reflex amplitude and peroneus longus latency between ankles. CONCLUSIONS: Grade I or II inversion sprains and the related swelling appear to delay involved ankle flexor digitorum longus latency to a greater extent than peroneus longus latency. Clinicians need to direct greater attention to the ankle invertors when designing and implementing ankle rehabilitation programs, particularly during the swelling management phase of treatment.

Intrarater reliability of selected clinical outcome measures following anterior cruciate ligament reconstruction.

STUDY DESIGN: Single group repeated measures following anterior cruciate ligament (ACL) reconstruction. OBJECTIVES: The purpose of this study was to evaluate the intrarater reliability of selected clinical outcome measures in patients having ACL reconstruction. BACKGROUND: Several investigations have reported the reliability of isokinetic testing and knee ligament arthrometry. Fewer studies have examined the reliability of lower extremity functional tests, with most of these studies evaluating normal subjects. METHODS AND MEASURES: Fifteen physically active males with unilateral ACL-reconstructed knees were evaluated with the KT-1000, Biodex isokinetic dynamometer, and 3 functional hop tests on 5 occasions. RESULTS: Intraclass correlation coefficients (ICCs) revealed good to high intrarater reliability (ICC > 0.80) of the functional hop tests and isokinetic peak torque values ICCs were higher for the involved limb than the uninvolved limb using the scores from the KT-1000 Manual Maximum Test. CONCLUSIONS: The outcome measures examined in this investigation have been shown to be reliable in patients with ACL reconstructions, and support previous investigations in nonimpaired populations. Further research is needed to examine the validity of these postoperative outcome measures in patients with ACL reconstructions.

The effect of quadriceps femoris, hamstring, and placebo eccentric fatigue on knee and ankle dynamics during crossover cutting.

This study attempted to determine the effect of eccentric quadriceps femoris, hamstring, and placebo fatigue on stance limb dynamics during the plant-and-cut phase of a crossover cut. Twenty female college students (task trained) were tested. Hamstring fatigue resulted in decreased peak impact knee flexion moments (p < or = .01), increased internal tibial rotation at peak knee flexion (p < or = .05), and decreased peak ankle dorisflexion (p < or = .05). Quadriceps fatigue resulted in increased peak ankle dorsiflexion moments (p < .01), decreased peak posterior braking forces (p < or .01), decreased peak knee extension moments (p < or = .01), delayed peak knee flexion (p < or = .01), delayed peak propulsive forces (p < .01), and delayed subtalar peak inversion moments (p < or = .05). Fatigue of either muscle group produced earlier peak ankle plantar flexion moments (p < = .05) and decreased peak propulsive knee flexion moments (p < or = .05). Variables requiring further study (p < or = .1) provide discussion data. Soleus, gastrocnemius, tibialis anterior, and deep posterior compartment calf muscles serve as dynamic impact force attenuators, compensating for fatigued proximal muscles.

Ambulatory electromyogram activity in the upper trapezius region: patients with muscle pain vs. pain-free control subjects.

STUDY DESIGN: This study compared the ambulatory electromyogram activity of persons reporting pain in the shoulder and cervical regions with an equal group of persons not reporting such pain. Ambulatory electromyogram data were obtained over 3-day periods. In addition, all participants completed several standard psychological questionnaires. OBJECTIVES: The results were analyzed with inferential statistics to determine whether subjects reporting significant pain in the shoulder and cervical regions had greater ambulatory electromyogram activity than an equal number of subjects not reporting pain. SUMMARY OF BACKGROUND DATA: Considerable controversy exists regarding the role of muscle activity in the etiology and maintenance of muscle pain disorders. Given the availability of ambulatory recording devices that can provide a detailed record of muscle activity over an extended period of time, the present research was conducted to determine whether persons reporting shoulder and cervical pain could be differentiated from a group of normal subjects. METHODS: All subjects (N = 20) completed a battery of tests with standardized psychometric instruments and then were fitted with ambulatory electromyogram monitors to record electromyographic activity of the upper trapezius region of the dominant side; the time, duration, and amplitude of electromyogram activity greater than 2 microV was recorded. The monitors were worn during normal working hours (mean, 6.2 hours per day) over 3 consecutive days. In addition to wearing the monitors, all subjects completed hourly self-ratings of perceived muscle tension during the recording periods. RESULTS: As expected, subjects with muscle pain reported significantly more pain (mean, 4.9) than did the normal control subjects (mean, 0.9), t(15) = 3.29, P < 0.01. However, patients with muscle pain did not have greater average electromyogram activity (mean, 6.4 microV) over the 3-day period as compared to the normal controls (mean, 7.1 microV), t(18) = -0.25, P < 0.80. Self-monitoring of perceived muscle tension also did not reveal differences between pain subjects and the normal control subjects (P < 0.75). CONCLUSIONS: Ambulatory measurements of electromyogram activity did not differentiate persons reporting upper trapezius or cervical pain from those that did not report such pain. Persons reporting pain are also not distinguishable from normal control subjects on a variety of self-report measures. These results raise questions regarding the role of ambulatory electromyogram recordings in the evaluation and treatment of muscle pain disorders.

Patellofemoral alignment: reliability.

Clinical assessment of the patellofemoral alignment is frequently performed, yet the repeatability of these measurements has not been previously investigated. This study examined the reliability of measuring patellofemoral alignment. The Q angle, A angle, and patellar orientation (mediolateral tilt, mediolateral position, superoinferior tilt, and rotation) of 27 healthy subjects were measured over three trials using standardized positioning and operationally defined goniometric, pluri-cal caliper, and visual estimation measurement techniques. Intratester and intertester intraclass correlation coefficients of measurements obtained with the pluri-cal caliper and goniometer ranged from .52 to .86 and .003 to .61, respectively. Intratester and intertester standard errors of the instrumented measurements ranged from 1.6 to 3.5 degrees and 3.2 to 6.8 degrees (.28 and .55 cm for mediolateral position), respectively. Intratester kappa's of visually estimating patellar orientation ranged from .40 to .57. Intertester kappa's were between .03 and .30. The results suggest that both clinical estimation and instrumented measurement of patellofemoral alignment may be unreliable.

Tennis elbow: a review.

Tennis elbow is a common yet sometimes complex musculoskeletal condition affecting many patients treated by physical therapists. The purpose of this article is to review the anatomy, clinical examination, differential diagnosis, conservative care, and surgical treatment for tennis elbow or lateral epicondylitis. Particular attention is given to determining the precise pathological cause of lateral epicondylitis, with consideration of intrinsic and extrinsic factors associated with this condition. This information should assist health care practitioners who treat patients with this disorder.

Electromyographic activity of selected trunk and hip muscles during a squat lift. Effect of varying the lumbar posture.

Electromyographic (EMG) activity of selected hip and trunk muscles was recorded during a squat lift, and the effects of two different lumbar spine postures were examined. Seven muscles were analyzed: rectus abdominis (RA), abdominal obliques (AO), erector spinae (ES), latissimus dorsi (LD), gluteus maximus (GM), biceps femoris (BF), and semitendinosus (ST). The muscles were chosen for their attachments to the thoracolumbar fascia and their potential to act on the trunk, pelvis, and hips. Seventeen healthy male subjects participated in the study. Each subject did three squat lifts with a 157-N crate, with the spine in both a lordotic and kyphotic posture. The lift was divided into four equal periods. EMG activity of each muscle was quantified for each period and normalized to the peak amplitude of a maximal voluntary isometric contraction (MVIC). A two-way analysis of variance (ANOVA) for repeated measures was used to analyze the effects of posture on the amplitude and timing of EMG activity during the lift. Two patterns of EMG activity were seen: a trunk muscle pattern (RA, AO, ES, and LD) and a hip extensor pattern (GM, BF, ST). In the trunk muscle pattern (TP), EMG activity was greatest in the first quarter and decreased as the lift progressed. In the hip extensor pattern (HP), EMG activity was least in the first quarter, increased in the second and third quarters, and decreased in the final phase of the lift. Differences (P < .05) were seen among subjects and in the timing of the muscle activity in all muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of psychologic and physiologic functioning between patients with masticatory muscle pain and matched controls.

This study explored the physiologic and psychologic distinctions between masticatory muscle pain patients and age and sex-matched normal controls. Subjects completed several standardized psychologic tests. They then underwent a laboratory stress profile evaluation to obtain physiologic measures (EMG, heart rate, systolic and diastolic blood pressure) under conditions of rest, mental stress, and relaxation. The pain patients reported greater anxiety, especially cognitive symptoms, and feelings of muscle tension than did the controls. Under stress, pain patients had higher heart rates and systolic blood pressure than the controls. Electromyogram activity in the masseter regions was not significantly different between the pain and control group. The results are discussed in terms of the likely mechanisms that might account for the observed differences between masticatory pain patients and normal subjects.

Effect of variation in the burst and carrier frequency modes of neuromuscular electrical stimulation on pain perception of healthy subjects.

The purpose of this study was to explore the effect of various combinations of burst and carrier frequencies of neuromuscular electrical stimulation (NMES) on subjects' perception of pain intensity associated with induction of high intensity muscle contractions. Twenty-seven healthy volunteers completed the study. After the initial test session, all subjects were treated in three additional sessions with nine combinations of burst frequencies (50, 70, and 90 bursts per second [bps]) and carrier frequencies (2,500, 5,000, and 10,000 Hz) at an NMES amplitude that produced torque equivalent to 50% of maximal voluntary contraction of their quadriceps femoris muscle. Subjects rated each frequency combination for perceived pain intensity with a visual analog scale. The combinations of burst frequencies (50, 70, and 90 bps) and carrier frequencies (2,500 and 5,000 Hz) do not differ from each other in perceived pain intensity but do differ significantly in perceived pain from the combinations of burst frequencies at the carrier frequency of 10,000 Hz. Thus, the clinician may have to try different stimulus combinations on patients at different current training levels to obtain the least individually perceived pain.

Negative side effects of self-regulation training: relaxation and the role of the professional in service delivery.

Procedures used for relaxation training can resolve or precipitate dysfunction in patients undergoing self-regulation treatments. The present article discusses the role of the clinician in administering relaxation training via thermal biofeedback and coping with unforeseen negative effects of treatment. A case illustration involving the biobehavioral treatment of chest pain is presented and discussed to remind the reader of the significance of the therapist's role in helping tailor treatment programs to unique responses of the individual patient. The case highlights the value of thorough case management and clinical formulation in the successful resolution of relaxation-induced leg pain.

Stretch-based relaxation and the reduction of EMG activity among masticatory muscle pain patients.

This study explored the efficacy of stretch-based relaxation procedures for the reduction of muscle activity in the masseter regions of subjects diagnosed with masticatory muscle pain disorders. Thirty-four subjects with elevated masseter activity were assigned randomly to either a postural relaxation/rest experimental group or a stretch-based relaxation experimental group. Following a psychosocial stressor and application of the relaxation procedure, persons in the stretch-based group showed greater reductions in EMG activity than did those in the postural group for the right masseter region (t = 1.94, P less than .04) and the left masseter region (t = 2.07, P less than .03). The results are discussed in terms of the implications of these findings for further research concerning the etiology and treatment of masticatory muscle pain.

Muscle stretching as an alternative relaxation training procedure.

The purpose of this program of research was to explore the use of muscle stretching procedures in relaxation training with a clinical population. In the first controlled study, stretching exercises for four muscle groups (obicularis occuli, sternocleidomastoid/trapezius, triceps/pectoralis major, and forearm/wrist flexors) were prepared. A group of people using these procedures (SR, N = 8) was compared to a group using the Bernstein and Borkovec (1973) tense-release (TR; N = 8) techniques for those same muscle groups, as well as compared to an appropriate group of controls (WL; N = 8). Assessment of physiological (multi-site EMG) and subjective (emotions, muscle tension, and self-efficacy) responses showed that persons in the SR displayed less sadness, less self-reported muscle tension at four sites, and less EMG activity on the r.masseter than persons in the TR group. In the second study, 15 subjects were administered an expanded version of the SR relaxation procedures. Results showed that all subjects reported significant decreases in self-reported levels of muscle tension; muscle tension responders showed lowered trapezius EMG and respiration rates and cardiovascular responders showed lowered diastolic blood pressure. The results are discussed in terms of the utility of relaxation procedures based primarily on muscle stretching exercises for lowering subjective and objective states of arousal.

Structural assessment of rat sciatic nerve following tourniquet compression and vascular manipulation.

In a recent study (Nitz et al., Exp Neurol 94:264-279, 1986) the validity of a rat animal model to examine effects of tourniquet compression and vascular occlusion on limb motor function, leg girth, and electrophysiologic changes was established. Here we report observations on sciatic nerve morphologic and morphometric alterations of these same animals. The hindlimbs of 90 rats were compressed by a pneumatic tourniquet at clinically relevant pressures (200 to 400 mm Hg) for 1 to 3 hours, and the sciatic nerve was assessed by light and electron microscopy at 1, 3, and 6 weeks post compression. The nerves were also examined from five additional animals at each of these time intervals following arterial ligation and sciatic nerve epineurectomy (30 rats). Percentage of degenerating myelinated nerve fibers and volume fraction of mast cells and fibroblasts were quantified morphometrically. The percentage of degenerating myelinated nerve fibers after moderate to severe tourniquet compression and vascular manipulation was similar and ranged from 15% to 45%. Tourniquet compression, but not vascular occlusion, resulted in an increase of mast cells and fibroblasts and disruption of endothelial cells of endoneurial vessels. The results suggest that clinically relevant tourniquet compression causes a secondary increase in vascular permeability, intraneural edema, and subsequent prolonged tissue ischemia, resulting in nerve degeneration.

Upper extremity tourniquet effects in carpal tunnel release.

We studied the presence and extent of upper extremity denervation in limb muscles after surgical release of the carpal tunnel. Sixty consecutive patients were randomly assigned to have the procedure performed with (31 patients) or without (29 patients) tourniquet application. Cervical paraspinal and upper extremity muscles were examined electromyographically 3 weeks before and 3 weeks after carpal tunnel release. Three weeks after the operation 77% of the patients in the tourniquet group had denervation in other than thenar muscles. Only one patient in the control (no tourniquet) group had similar electromyographic abnormalities after surgery. Tourniquet time and pressure did not vary significantly between those patients with or without postoperative forearm denervation. Mean operative time for the tourniquet and control groups was nearly identical. These findings indicate that upper extremity tourniquet application results in subclinical, temporary changes in the muscles of the forearm, probably on the basis of nerve changes and denervation.

High intensity electrical stimulation effect on thigh musculature during immobilization for knee sprain. A case report.

We conducted high intensity electrical stimulation of the quadriceps femoris and hamstring muscle groups daily during a three-week period of lower extremity cast immobilization for an athlete who sustained Grade II medial collateral and anterior cruciate ligament sprains. Thigh muscle hypertrophy of the injured (stimulated) leg was suggested by an increase in girth measurement on the day of cast removal. Three weeks after cast removal, single-leg, vertical-leap height was 92% of that accomplished by the dominant, uninjured leg, and the patient was able to return to athletic competition. This case report documents the usefulness of high intensity electrical stimulation for maintaining limb motor function during cast immobilization. Limb stabilization during stimulation and simultaneous excitation of agonist-antagonist muscle pairs also are discussed.

Physical therapy management of the shoulder.

This article presents an overview of physical therapy management for patients with pathological musculoskeletal conditions of the shoulder. The importance of a thorough physical examination is stressed because proper treatment is based on this information. The primary goals of management should include the alleviation of acute inflammation and pain and the avoidance of subsequent soft tissue shortening. Medical and surgical treatments for common shoulder disorders also are discussed.

Pneumatic tourniquet application and nerve integrity: motor function and electrophysiology.

Limb motor function, leg girth, spontaneous potentials, and compound muscle action potentials were evaluated in a rat animal model at various times after tourniquet application and occlusion of blood flow to the sciatic nerve. The thighs of the animals were compressed by a pneumatic tourniquet at clinically relevant pressures (200, 300, and 400 mm Hg) for 1 to 3 h. Extrinsic blood supply was occluded by ligation of the common iliac and femoral arteries and intrinsic by removing a 12-mm segment of the epineurium from the sciatic nerve. Motor function deficits were noted for 1 to 5 weeks in limbs of animals subjected to tourniquet compression and from 2 to 4 weeks following vascular manipulation. Control leg girths did not change during the experiment whereas girths of tourniquet-compressed legs increased initially and then decreased and remained below control values. Girths of limbs subjected to vascular manipulation were unaltered during the 1st week but decreased in a similar fashion to those of tourniquet-compressed limbs at 3 and 6 weeks. Spontaneous potentials were present and compound muscle action potentials were reduced in animals after tourniquet application and vascular manipulation compared with control values. These electrical abnormalities were most pronounced 1 week after the treatments, progressed toward normalcy during the course of the experiment, but failed to attain control values at the termination of the study. Analysis of electrophysiologic data indicated that magnitude of pressure and duration of compression-produced nerve injury occurred independently in an additive fashion.

Effects of short-term electrical stimulation on the ultrastructure of rat skeletal muscles.

The purpose of this study was to determine the effects of short-term, 2,500-Hz carrier-wave frequency electrical stimulation on the ultrastructure of fast-twitch rat skeletal muscles. Thirteen Sprague-Dawley male rats were divided into three groups: daily treatment (Group 1), every-other-day treatment (Group 2), and control (Group 3). The medial quadriceps femoris and hamstring (semitendinosus and semimembranosus) muscles of the right thigh were treated with short-term electrical stimulation. After treatment, the animals were sacrificed, and their treated and sham quadriceps femoris and hamstring muscles were removed, fixed by immersion, and processed for electron microscopy. Morphometric measurements were made on electron micrographs using a Videoplan computer system, and the results were analyzed statistically. The results revealed that mitochondria, triads, and glycogen content of the fast-twitch muscles changed to resemble those of slow-twitch muscles. In view of these results, clinicians should consider the possibility that similar changes also might occur in human subjects under clinical conditions.

Comparison of muscle spindle concentrations in large and small human epaxial muscles acting in parallel combinations.

A small short muscle acting across a joint in parallel with vastly larger and longer muscles is clearly unable to play more than a minimal mechanical role in such a "parallel muscle combination" (PMC). This research investigates a feed back role for the small muscles of PMCs, proposing a significantly higher muscle spindle concentration therein to be consistent with this role. Epaxial PMCs (semispinalis and multifidus versus rotatores brevis) from the C5-C6, T6-T7, and L4-L5 regions of three 36-week-old male fetuses and two adult cadavers were removed and fixed in Carnoy's fluid. Tissue samples were embedded in paraffin, cut into 10 microns thick sections perpendicular to the muscle's longitudinal axis and stained by Harris' hematoxylin and eosin. Representative tissue sections were projected onto a sterological grid and the percentage volume of spindles determined. Data were analyzed with Student's unpaired t test. In all PMCs, rotators brevis spindle percentage volumes ranged from 4.58 to 7.30 times higher than those of multifidus and semispinalis. Differences in mean spindle percentage volumes between large and small members of all PMCs were significant (P less than .0001). Our findings are consistent with the notion of a "kinesiological monitor" or feedback role for rotatores brevis.