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Biomedical subjects

J Perry

Publications and source records attributed to J Perry.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Shoulder reaction time and muscle-firing patterns in response to an anterior translation force.

The primary restraint preventing humeral head translation is the capsuloligamentous system. Muscle forces can also decrease translation; however, the timing and magnitude of muscle response has not been previously reported. Fine wire electromyographic analysis of the biceps long head, anterior deltoid, pectoralis major, latissimus dorsi, and rotator cuff muscles was performed after an anterior translation force was applied to 15 normal shoulders. The reflex response time (time to 5% maximal muscle test), the protection response time (time to 20% maximal muscle test), the duration of the protection response, and the magnitude of the protection response were calculated. The shoulder reaction data showed 2 consistent patterns. Activation of the anteriorly located muscles preceded the posteriorly located muscles, and the rotator cuff muscles fired with greater magnitude than the more peripherally located muscles.

Adult↗
PubMedDate not supplied

Electromyographic analysis of shoulder function during the volleyball serve and spike.

The purpose of this study was to describe the electromyographic (EMG) pattern and relative intensities of 8 shoulder muscles during the volleyball serve and spike in 15 professional or collegiate-level athletes. The EMG analysis was synchronized with high-speed cinematography to discern phases of the spike and serve. During the spike, the anterior deltoid and supraspinatus functioned together to elevate and place the humerus throughout all phases. During cocking the infraspinatus and teres minor acted together to rotate the humerus externally. In acceleration, however, these muscles behaved independently; activity of the teres minor remained high, whereas the activity of the infraspinatus declined. The anterior wall muscles functioned to decelerate the humerus during cocking and acted as internal rotators during acceleration. Muscle activities recorded for the serve followed similar patterns as those seen for the spike, but with lower amplitudes. These data illustrate the complex sequence of shoulder muscle activity necessary to play competitive volleyball.

Adolescent↗
PubMedDate not supplied

Temporal-spatial characteristics of wheelchair propulsion. Effects of level of spinal cord injury, terrain, and propulsion rate.

The purpose of this investigation was to compare the temporal-spatial characteristics of wheelchair propulsion (velocity, cycle distance, and cadence) of customary wheelchair users in conditions designed to simulate community settings. Seventy adult males with spinal cord injuries (SCI) were grouped by their level of SCI: low paraplegia (n = 17); high paraplegia (n = 19); C-7 tetraplegia (n = 17); C-6 tetraplegia (n = 17). Testing was performed in a wheelchair that had the right pushrim instrumented with force transducers. Participants propelled the test wheelchair at a self-selected, free, and fast pace over tile and carpeted floors. A wheelchair ergometer was designed to simulate loads encountered during propulsion over graded surfaces. Participants propelled the test wheelchair during ergometer simulation of 4% and 8% grades. Mean velocity, cycle distance, and cadence were calculated for each group in all test conditions. A two-way repeated measures analysis of variance and simple main effects testing for comparison across conditions and between groups were performed. For all test conditions, participants with low paraplegia were the fastest and had the longest cycle distance. With successively higher levels of SCI, velocities were slower and cycle distances shorter. During free propulsion on tile, velocities ranged from 95 m/min in low paraplegics to 55 m/min in C-6 tetraplegics. Fast propulsion velocity increased to 141 and 55 m/min, respectively. There was a significant main effect of surface for velocity such that the carpet condition was slower than the tile for all groups. Differences in velocity were most often the result of changes in cycle distance. High and low paraplegic groups were statistically similar for all test conditions. Participants with C-6 tetraplegia were significantly slower than all other groups for most test conditions. Because their fast propulsion velocities were slower than typical community demands, their ability to function independently outside the hospital setting has been further questioned.

Adult↗
PubMedDate not supplied

Tibialis anterior transfer for calcaneal deformity: a postoperative gait analysis.

We retrospectively evaluated seven children who had low-lumbar-level spina bifida and who had undergone bilateral transfer of tibialis anterior to the calcaneus. The mean age at the time of operation was 8 years (range, 3-12), and the patients were monitored for an average of 40 months (range, 24-60). All children underwent a postoperative gait analysis to assess the function of the transfer and the need for continued postoperative bracing. Transfer of the tibialis anterior muscle to the calcaneus arrested progression of the calcaneal deformity; however, the transfer could not prevent excessive dorsi-flexion of the ankle during stance. The use of a pretibial ankle-foot orthosis improved velocity, increased stride length, decreased quadriceps activity at terminal stance, and led to decreased energy expenditure. We conclude that continued bracing is necessary to provide a more normal appearing and energy-efficient gait.

Calcaneus↗
PubMedDate not supplied

Gait abnormalities arising from latrogenic loss of lumbar lordosis secondary to Harrington instrumentation in lumbar fractures.

Six patients with lumbar fractures were studied at the Pathokinesiology laboratory at Rancho Los Amigos Hospital following posterior Harrington distraction instrumentation to identify changes in posture and gait associated with iatrogenic loss of lumbar lordosis. Three patients, all with painful rods, were treated with standard Harrington instrumentation and full length fusion. Three patients were treated with so-called "rodded long-fused short" procedures. It was thought that rod removal in the latter group would result in restoration of lumbar lordosis with concomitant improvement in posture and gait when compared to the full length fusion group. No significant difference between the two groups was found. Rod removal often resulted in kyphotic collapse at the previous fracture site despite solid posterior arthrodesis with net decrease in lumbar lordosis. Hip hyperextension, when available, was the favored compensatory mechanism for loss of lumbar lordosis. Otherwise, hip flexion and forward lean of the trunk was seen.

Adult↗
PubMedDate not supplied

An analysis of posture and gait following spinal fusion with Harrington instrumentation.

This study was stimulated by a paretic spinal injury patient who required crutches for a forward lean, which his trunk developed following spinal instrumentation. Ten patients who underwent Harrington instrumentation to correct scoliosis also displayed reduced lordosis. Partial compensation by increased lumbosacral angle occurred when this joint was open. The patients' standing posture and that of 11 normal adults were assessed with the visible vector system. Five stood with excessive hip hyperextension and three had exaggerated knee flexion. The latter three also demonstrated, during walking, inadequate terminal swing knee extension with excessive knee flexion and ankle dorsi-flexion during stance. There was increased frontal and sagittal sway in four patients.

Adolescent↗
PubMedDate not supplied

Occipito-cervico-thoracic spine fusion in a patient with occipito-cervical dislocation and survival.

A 16-year-old man with occipito-cervical dislocation and survival was treated at Rancho Los Amigos Medical Center. The patient had ligamentous instability between the occiput and the cervical spine. His neurologic level was complete at the C1 level, and he was dependent on a mechanical respirator. Sternocleidomastoid and other neck musculature were not functional. A fusion of the occiput to cervical spine and cervical spine to thoracic spine was performed to obviate the need for external neck support. The patient went on to fuse and is now independently mobile with a tongue-switch driven wheelchair with a respirator trailer 2 years after injury. The patient has no need for external support as a result of his fusion.

Adolescent↗
PubMedDate not supplied

An EMG analysis of the shoulder in throwing and pitching. A preliminary report.

Five male subjects' throwing and pitching motions were analyzed by dynamic electromyography and high speed photography. Electrodes inserted into the deltoid and rotator cuff muscles attempted to define muscle activation patterns during the throwing and pitching cycle. The wind-up or preparation (Stage I) had no consistent pattern. Cocking (Stage II) had a sequential muscle activation pattern of first deltoid activity, followed by the S.I.T. muscles and finally by the subscapularis muscle. Acceleration (Stage III) had a lack of muscle activity, even though the arm was accelerating forward in space. Follow-through (Stage IV) was the most active stage with all the muscles firing intensely. The muscle patterns observed during the cycle were largely characteristic of attempts to decelerate the arm.

Adult↗
PubMedDate not supplied

An EMG analysis of the shoulder in pitching. A second report.

This is the second report in a series of projects dealing with electromyographic (EMG) analysis of the upper extremity during throwing. Better understanding of the muscle activation patterns could lead to more effective preseason conditioning regimens and rehabilitation programs. Indwelling wire electrodes recorded the output from the biceps, long and lateral heads of the triceps, pectoralis major, latissimus dorsi, serratus anterior, and brachialis for four professional baseball pitchers. These signals were synchronized electronically with high speed film records of a fast ball. The EMG signals were converted from analog to digital records. Results showed that wind-up and early cocking phases showed minimal activity in all muscles, and such firing which occurred was of low intensity. Late cocking, which occurred after the front foot was firmly planted, showed moderate activity in the biceps. Cocking was terminated by the pectoralis major and latissimus dorsi. At this point, the trunk began to rotate forward, while the arm remained elevated and the elbow flexed. Also, the shoulder was moving to maximum external rotation. During the acceleration phase, the biceps was notably quiescent, while the pectoralis major, latissimus dorsi, triceps, and serratus anterior were all active. Muscle action at this time terminated external rotation and elbow flexion; i.e., the muscles fired as decelerators and also initiated the opposite actions for ball acceleration, internal rotation and elbow extension. Follow-through was not only a time of eccentric contraction with muscle activity decelerating the upper extremity complex, it was also an active event with the shoulder moving across the body and the elbow into extension with forearm pronation.

Adult↗
PubMedDate not supplied

Elbow flexion analysis in Bristow patients. A preliminary report.

Seven male nonathletes who had Bristow procedures for shoulder dislocation were analyzed by dynamic electromyography (EMG) and Cybex strength measurement to evaluate the function of elbow flexion. Bilateral strength of elbow flexion also was measured in the 10 controlled subjects to compare the dominant and nondominant arms. The EMG data showed the operated short head of biceps function at low constant intensity, compared with the nonoperated side, while the long head of biceps and brachialis increased their activity. The strength measured by the Cybex demonstrated the elbow flexion on the operated side was not significantly different from the normal group. These data demonstrated that the Bristow procedure reduced the dynamic response of the short biceps which was compensated for by the increase in level of activity of the long heads and brachialis muscle. As a result, normal range of elbow function was restored. Our patients had had intense rehabilitation programs. This appears to be an essential part of the postoperative management to develop the needed compensatory muscle action.

Adult↗
PubMedDate not supplied

Fine wire electromyography analysis of muscles of the shoulder during swimming.

Fine wire EMG of the shoulder was performed on 11 swimmers; 5 performed during dry land studies and 7 during aquatic studies. One individual underwent both studies. A cinematographic analysis was synchronized with the EMG data to determine what muscles were firing at each phase of the swim stroke. Eight muscles were studied: biceps, subscapularis, latissimus dorsi, pectoralis major, supraspinatus, infraspinatus, serratus anterior, and deltoid. Three strokes were analyzed: freestyle, breaststroke, and butterfly. The freestyle and butterfly are frequently associated with impingement type syndromes in swimmers. It was determined that the supraspinatus, infraspinatus, middle deltoid, and serratus anterior were predominately recovery phase muscles. The latissimus dorsi and pectoralis major were predominately pull-through phase muscles. The biceps had mixed inconsistent activity during both phases. From dry land quantifications of the EMG signal it was determined that the serratus anterior functions near maximal muscle test during each stroke, and theoretically may fatigue with repetition. It is hoped that a training program aimed to strengthen the scapular rotators may help alleviate impingement syndrome in swimmers.

Adult↗
PubMedDate not supplied

Functional analysis of anterior cruciate ligament instability.

Eighteen males and two females (mean age, 26.5 years) underwent biomechanical assessment and Cybex evaluation prior to ACL reconstruction. Clinically, all patients had at least a 1+ grade with the Lachman, anterior drawer, and pivot shift tests, the majority being graded as 2+. Footswitch, high speed photography, force plate, and indwelling wire electrode data were collected while each subject performed free and fast walking, running, cutting, and stair climbing activities. During walking, single limb support times did not differ between the subject's involved and uninvolved limbs. Knee joint angles were similar between limbs during walking, running, and stair climbing maneuvers. Dynamic EMG tracings during walking demonstrated similar quadriceps and calf activity between limbs, while greater variation in hamstring firing was evident among subjects. During running, the involved limb had a longer duration of medial hamstring activity compared to the lateral hamstring. No significant differences were seen in either vertical or sagittal shear forces during free walking. During fast walking, higher midstance vertical forces (F2) were present in the involved limb (P less than 0.05). During running, the involved limb experienced lower vertical forces (P less than 0.05), while both anterior and posterior sagittal shear differences were insignificant. Straight cut maneuvers demonstrated significantly lower lateral shear and vertical forces in the involved limb (P less than 0.05). Lower lateral and sagittal shear forces in the involved limb (P less than 0.01 and P less than 0.05, respectively), combined with a reduced angle of the cut during the cross-cut maneuver, may be the first means to assess the functional pivot shift phenomenon ever documented.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

A comparative electromyographic analysis of the shoulder during pitching. Professional versus amateur pitchers.

Dynamic, fine-wire, intramuscular electromyography (EMG) was performed on 12 different shoulder muscles in 13 normal male subjects as they pitched a baseball. Seven were major league baseball pitchers and six were amateur pitchers. The act of pitching a fast ball was filmed at 450 frames per second with the EMG signals recorded synchronously. The subscapularis, supraspinatus, and infraspinatus muscles were tested in 13 subjects, the biceps brachii muscle was tested in 12, and other shoulder muscles were tested variously among the subjects. Two groups of muscles were identified. Group I muscles, the supraspinatus, infraspinatus, teres minor, deltoid, trapezius, and biceps brachii, served primarily to position the shoulder and elbow for the delivery of the pitch. These muscles were found to have greater activity during the early and late cooking stages, with less activity during acceleration. Group II muscles accelerated the arm and baseball forward in space. These muscles, the pectoralis major, serratus anterior, subscapularis, and latissimus dorsi, had stronger activity during the propulsive phase of the pitch. The professional pitchers were able to use the muscles about the shoulder in an efficient manner to achieve greater pitching velocities. The subscapularis and latissimus dorsi muscles of Group II had stronger activity among the professionals, whereas the supraspinatus, teres minor, and biceps brachii muscles of Group I had only minimal activity. The amateurs, on the other hand, continued to use all of the rotator cuff muscles and the biceps brachii muscle of Group I through the acceleration stage of the pitch.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Functional analysis of untreated and reconstructed posterior cruciate ligament injuries.

Twenty patients with old ruptures of the PCL were analyzed. Ten patients were untreated, and ten patients had reconstruction of the PCL with the medial head of the gastrocnemius. The patients' gait was analyzed using high speed photography, footswitches, electromyography, and force plate. Patients were studied while walking, running, and stair-climbing. A Cybex muscle strength evaluation was also performed. Clinically, all patients had moderate to severe posterior instability. Five of the 20 patients also had posterolateral instability. Cybex testing showed quadriceps deficits in both reconstructed and untreated groups when comparing involved and uninvolved limbs. The reconstructed group also had deficits on hamstring Cybex testing. Footswitch data showed only minimal abnormalities. Gait velocity of walking was 91% of normal with a normal cadence. There was no significant difference in the single limb support times between the involved and uninvolved limbs in walking, fast walking, or running. The photometric data showed a tendency for increased knee flexion during the midstance phase of the gait cycle in comparing involved and uninvolved limbs. The knee flexion angles during midstance were similar in the patients with posterior instability when compared to the patients with the additional posterolateral instability. Force plate data showed decreased foot-floor reaction in the untreated group during terminal stance while walking. Similar findings were found in the reconstructed group during running.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Electromyographic analysis of elbow function in tennis players.

Muscle activity about the elbow during tennis strokes in nine professional and collegiate level players was studied using indwelling EMG and high speed photography. Eight muscles were evaluated for the serve, forehand, and backhand strokes. The serve was divided into six stages and the ground strokes into four stages. EMG tracings were subjected to analog-to-digital conversion and a relative measure of quantity was obtained. Analysis of variance and Turkey tests were then done to assess statistical significance (P less than 0.05). The ground strokes showed low activity in all muscles tested during the preparation phase. During the acceleration phase, both the backhand and forehand showed a generalized increase in all muscle activity. Both strokes showed marked activity of the wrist extensors and, in addition, the forehand showed high activity in the brachialis and biceps. In the follow-through phase, there was a generalized decrease in muscle activity. The serve showed low activity in all muscles tested during the wind-up phase. The wrist extensors increased their activity in the cooking phase, with marked activity in late cooking. The pronator teres and the triceps showed increased activity in the acceleration phase. Follow-through phase showed low muscle activity except for the biceps, which increased in late follow-through. In conclusion, the muscles of the elbow help stabilize the elbow as a unit during the ground strokes in these high level players. Power in the serve comes from increased activity in the triceps and pronator teres. The predominant activity of the wrist extensors in all strokes may be one explanation for predisposition to injury.

Athletic Injuries↗
PubMedDate not supplied

Electromyographic shoulder activity in men and women professional golfers.

Men and women both enjoy the game of golf. Special considerations are made for women, such as the courses on the professional tours. Thus, one can ask what differences might exist between men and women golfers. This study compares the electromyographic firing patterns of normal shoulder musculature in men and women professional golfers. Eight shoulder muscles (pectoralis major, latissimus dorsi, supraspinatus, infraspinatus, subscapularis, anterior, middle and posterior deltoids) were studied using indwelling electromyography. A visual analysis revealed that women tended to have slightly more activity during the takeaway and forward swing phases, and the men tended to have more activity during acceleration and follow-through. However, an independent two-tailed t-test (P = 0.05) showed these differences not to be statistically significant. This finding is in keeping with injury incidence data from the LPGA Tour, PGA Tour, and Senior PGA Tour, which showed that all three tours have a similar incidence of shoulder injuries. This study does not compare the relative strength of men and women, however.

Adult↗