Biomedical subjects

F W Jobe

Publications and source records attributed to F W Jobe.

At least 91 records · Page 5Linked to original sources

PubMedDate not supplied

Rotator cuff function during a golf swing.

A study of bilateral shoulder muscle activity during the golf swing was undertaken using electromyography and high-speed photography. Understanding of the muscle firing patterns could lead to injury prevention and development of appropriate training and conditioning regimens. The swings of seven adult male right-handed professional golfers without shoulder problems were examined. Indwelling electrodes were inserted into the supraspinatus, subscapularis, infraspinatus, latissimus dorsi, pectoralis major, anterior deltoid, middle deltoid, and posterior deltoid on the right side. Each subject was allowed to warm up until he felt comfortable. Films of each subject were taken at 450 frames per second. The swing was broken into four segments to which electromyographic signals were synchronized electronically. The EMG tracings were subjected to analog-to-digital conversion and a relative measure of quantity obtained. All tests were repeated on the left side for each subject. Results indicate that all portions of the deltoid were inactive on the right side throughout the swing. The deltoid was likewise inactive on the left except for a brief spurt from the anterior portion during the milliseconds immediately preceding ball contact. Of the rotator cuff muscles, on the left the supraspinatus fired at a low level throughout the swing, as did the infraspinatus. The latter had a slightly larger burst of activity immediately after ball contact. The subscapularis was more active than any other muscle throughout the swing. The cuff muscles on the right side showed as much activity overall as those on the left. In addition, the latissimus dorsi and pectoralis major seemed to provide power bilaterally, with marked activity during the acceleration phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

An electromyographic analysis of the elbow in pitching.

Elbow injuries are common in baseball pitchers. Curve balls are thought to increase this risk, particularly if the athlete begins throwing this pitch at an early age. The purpose of this paper is to identify forearm muscle firing patterns during the pitching cycle in an effort to understand this etiology. Dynamic EMG was performed on eight collegiate pitchers to evaluate extensor digitorum communis, brachioradialis, flexor carpi radialis, flexor digitorum superficialis, extensor carpi radialis longus, extensor carpi radialis brevis, pronator teres, and supinator. Each subject threw a fast ball and curve ball, which were filmed at 450 frames per second and synchronized with the EMG. These signals were converted from analog to digital records. Results showed low to moderate activity in all muscles during all phases of the pitch. The function is probably positioning to accept the transfer of energy from the larger trunk and girdle structures. The most notable difference between the fast ball and curve ball is a slight increase in the extensor carpi radialis longus and extensor carpi radialis brevis activity during late cocking, acceleration, and follow-through of the curve ball as compared to the fast ball. This difference, however, is not significant. In addition, there was no significant difference between the fast ball and the curve ball in the flexor-pronator group in any phase. We cannot substantiate that medial elbow problems are a result of an increase in the use of flexor muscles during the curve ball pitch.

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

An electromyographic analysis of shoulder function in tennis players.

Shoulder injuries in tennis players are common because of the repetitive, high-magnitude forces generated around the shoulder during the various tennis strokes. An understanding of the complex sequences of muscle activity in this area may help reduce injury, enhance performance, and assist the rapid rehabilitation of the injured athlete. The supraspinatus, infraspinatus, subscapularis, middle deltoid, pectoralis major, latissimus dorsi, biceps brachii, and serratus anterior muscles were studied in six uninjured male Division II collegiate tennis players using dynamic electromyography (EMG) and synchronized high-speed photography. Each subject performed the tennis serve and the forehand and backhand groundstrokes, and each stroke was divided into stages. The tennis serve contains four stages. Three stages characterize the forehand and backhand groundstrokes. Our results indicate that the subscapularis, pectoralis major, and serratus anterior display the greatest activity during the serve and forehand. The middle deltoid, supraspinatus, and infraspinatus are most active in the acceleration and follow-through stages of the backhand. The biceps brachii increases its activity during cocking and follow-through in the serve with a similar pattern noted in the acceleration and follow-through stages of the forehand and backhand. The serratus anterior demonstrates intense activity in the serve and forehand, thus providing a stable platform for the humeral head and assisting in gleno-humeral-scapulothoracic synchrony. The tennis serve and forehand and backhand groundstrokes are accomplished by complex sequences of muscle activity that incorporate contributions from the lower extremities and trunk into smooth, coordinated patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

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↗

PubMedDate not supplied

Electromyographic analysis of the shoulder during the golf swing.

Golf is a popular sport throughout the world, yet there is little in the literature that discusses the mechanics of the swing. The purpose of this study is to analyze the EMG activity in eight shoulder muscles of both the right and left arms during the golf swing. The results reveal that the infraspinatus and supraspinatus act predominantly at the extremes of shoulder range of motion, the subscapularis and pectoralis major during acceleration, the latissimus dorsi during forward swing, and the anterior deltoid during forward swing and follow-through. The middle and posterior deltoids appear to be relatively noncontributory, without any specific timing patterns. This data is an expansion of an earlier pilot study and allows us to more accurately develop an exercise program for optimal performance as well as for prevention and rehabilitation.

Adult↗

PubMedDate not supplied

Electromyographic analysis of the glenohumeral muscles during a baseball rehabilitation program.

Many exercises are used to strengthen the glenohumeral muscles, but there have been limited studies to evaluate the exercises. Thus, the purpose of this study was to decide how the muscles responsible for humeral motion can best be exercised in a rehabilitation program for the throwing athlete. Dynamic, fine wire, intramuscular electromyography was carried out in 15 normal male volunteers performing 17 shoulder exercises derived from a shoulder rehabilitation program used by professional baseball clubs. The four rotator cuff muscles were studied, as well as other positioners of the humerus, including the pectoralis major, latissimus dorsi, and three portions of the deltoid. The electromyographic activity was synchronized with cinematography and averaged over 30 degrees arcs of motion. An exercise was considered to be a significant challenge for a muscle if it generated at least 50% of its predetermined maximum contraction over three consecutive arcs (i.e., a 90 degrees range). Four exercises were consistently found to be among the most challenging exercises for every muscle. These shoulder exercises consisted of 1) elevation in the scapular plane with thumbs down, 2) flexion, 3) horizontal abduction with arms externally rotated, and 4) press-up. This study documents that the minimum for an effective and succinct rehabilitation protocol for the glenohumeral muscles would include these exercises.

Adult↗

PubMedDate not supplied

Anterior capsulolabral reconstruction of the shoulder in athletes in overhand sports.

From April 1, 1985, through June 30, 1987, 25 skilled athletes with shoulder pain secondary to anterior glenohumeral instability that had failed to improve with conservative therapy had an anterior capsulolabral reconstruction. All but one athlete completed a formal rehabilitation program with an average followup of 39 months. The results at followup were rated excellent in 68%, good in 24%, fair in 4%, and poor in 4%. Seventeen patients returned to their prior competitive level for at least 1 year. This operation and rehabilitation program may allow many athletes who participate in overhand activities or throwing sports to return to their prior level of competition.

Adolescent↗

PubMedDate not supplied

The painful shoulder during freestyle swimming. An electromyographic cinematographic analysis of twelve muscles.

The purpose of this paper is to describe the patterns of activity of 12 shoulder muscles in painful shoulders, and compare those patterns of activity with normal shoulders. The results show significant differences in 7 of the 12 muscles. Those muscles included the anterior deltoid, middle deltoid, infraspinatus, subscapularis, upper trapezius, rhomboids, and the serratus anterior. There were no significant differences between muscle activity patterns of normal versus painful shoulders in the latissimus dorsi, pectoralis major, teres minor, supraspinatus, or the posterior deltoid. This information will contribute to the development of muscle conditioning programs to optimize performance and prevent injury, as well as develop programs for scientific rehabilitation strengthening.

Adult↗

PubMedDate not supplied

EMG analysis of the scapular muscles during a shoulder rehabilitation program.

The purpose of this study was to determine which exercises most effectively use the scapular muscles. Eight muscles in 9 healthy subjects were studied with indwelling electromyographic electrodes and cinematography while performing 16 exercises. The 8 muscles studied were the upper, middle, and lower trapezius; levator scapula; rhomboids; pectoralis minor; and the middle and lower serratus anterior. Each exercise was divided into arcs of motion and the electromyographic activity was quantified as a percentage of the maximal manual muscle test. The optimal exercises for each muscle were identified based on intensity (greater than 50% maximal manual muscle test) and duration (over at least 3 consecutive arcs of motion) of the muscle activity. Twelve of the exercises qualified as top exercises for all of the muscles. On further analysis, a group of 4 exercises was shown to make up the core of a scapular muscle strengthening program. Those 4 exercises include scaption (scapular plane elevation), rowing, push-up with a plus, and press-up.

Adult↗

PubMedDate not supplied

The subscapularis muscle and its glenohumeral ligament-like bands. A histomorphologic study.

The subscapularis muscle and the distribution of its tendinous bands is of significance in the surgical management of the shoulder joint. This distribution pattern has not been previously described in detail. We feel that, in any anterior approach to the glenohumeral joint for fracture fixation, joint replacement, and soft tissue reconstruction, a thorough understanding of the distribution pattern of the subscapularis bands is essential. We examined the subscapularis muscles from five cadavers. Four sections from the lateral one-half of each muscle were custom-mounted and stained with Masson's trichrome. We found a consistent pattern in which the tendinous bands were evenly interspersed in the midportion of the muscle and condensed laterally into a single large, flat tendon in the superior two-thirds of the muscle. The inferior one-third remained muscular. Understanding this pattern should help the surgeon have confidence that he/she has obtained a more secure repair in procedures involving the subscapularis muscle.

Humans↗

PubMedDate not supplied

An electromyographic analysis of the elbow in normal and injured pitchers with medial collateral ligament insufficiency.

Electromyography and high-speed film were used to examine the muscle activity in the elbows of pitchers with medial collateral ligament insufficiency compared to the activity in uninjured elbows. Ten competitive baseball pitchers with medial collateral insufficiency and 30 uninjured competitive pitchers were tested while throwing the fastball and the curveball. The extensor carpi radialis brevis and longus in the injured pitchers showed greater activity than in the uninjured pitchers for both pitches. The triceps, flexor carpi radialis, and pronator teres all showed less activity in the injured pitchers during the fastball, but only the triceps had less activity during the curveball. The differences were seen during the late cocking and acceleration phases, which place the greatest stress on the medial collateral ligament. If the flexor carpi radialis and pronator teres were substituting for the deficient medial collateral ligament and functioning as dynamic stabilizers, one would expect enhanced muscle activity. However, the opposite was found. This pattern of asynchronous muscle action with medial collateral ligament injury may predispose the joint to further injury. The muscular differences seen are critical to the understanding of the pathomechanics of patients with medial collateral ligament deficiency, and provide a basis for rehabilitation.

Adolescent↗

PubMedDate not supplied

Electromyographic analysis of the trunk in golfers.

Golf is a popular sport for both men and women. The trunk is the most common area of injury during the golf swing. The purpose of this study was to describe and compare the muscle firing patterns in the trunk during the golf swing. Twenty-three golfers with handicaps of five or below volunteered for this study. Surface electromyographic electrodes were placed on the abdominal oblique and erector spinae muscles bilaterally. High-speed cinematography was used in conjunction with the electromyographic electrodes. The results demonstrated relatively low activity in all muscles during takeaway (below 30% of maximal muscle test), and relatively high and constant activity throughout the rest of the swing (above 30% maximal muscle test, with the exception of the contralateral erector spinae during late follow-through, which was 28% maximal muscle test). This high and constant activity demonstrated the importance of the trunk muscles during a golf swing. These results indicate the need for an effective preventive and rehabilitative exercise program for the golfer.

Abdominal Muscles↗

PubMedDate not supplied

Electromyographic and cinematographic analysis of elbow function in tennis players using single- and double-handed backhand strokes.

It is generally believed that tennis players using a double-handed backhand rarely develop lateral epicondylitis since the helping arm appears to absorb more energy and changes the mechanics of the swing. The purpose of this paper was to compare muscle activity about the elbow in single- and double-handed backhand strokes in competitive tennis players. Muscle activity in 3 elbow extensors, a wrist flexor, and a forearm pronator of the dominant arm was compared during the single-handed (N = 14) and double-handed (N = 13) backhand ground strokes using indwelling electromyography and high-speed cinematography. Significantly higher activity was seen in the double-handed technique in the flexor carpi radialis muscle in the preparation phase and in the pronator teres muscle in the acceleration phase. Higher flexor carpi radialis muscle activity in preparation of the double-handed stroke appeared to be a function of the double-handed grip used on the racquet, and the increased pronator teres muscle activity in acceleration indicated maintenance of greater pronation provided by the grip of the non-dominant hand. The decreased occurrence of lateral epicondylitis in players using a double-handed backhand may not be caused by decreased extensor activity, but rather by factors associated with flawed stroke mechanics more often seen in the single-handed technique.

Elbow↗

PubMedDate not supplied

Infraspinatus muscle-splitting incision in posterior shoulder surgery. An anatomic and electromyographic study.

Standard posterior shoulder surgical approaches include infraspinatus tendon detachment and infraspinatus-teres minor interval development. Cadaveric and clinical investigation of a new infraspinatus-splitting approach to the posterior glenohumeral joint was undertaken to assess efficacy in providing exposure, preserving tendon attachment, and avoiding neurologic compromise. Infraspinatus musculotendinous and neural anatomy was examined in 20 cadavers. Four patients with posterior shoulder instability underwent posterior capsulorrhaphy through this infraspinatus-splitting approach, followed by electrodiagnostic testing. Infraspinatus muscle was bipennate in all specimens, the tendinous interval an average 14 mm inferior to the scapular spine at the glenoid rim. The infraspinatus-splitting interval bisected the posterior glenoid rim at its midpoint, whereas the infraspinatusteres minor interval crossed the glenoid rim's lower quarter. The suprascapular nerve provided sole innervation to the infraspinatus muscle in all specimens, entering the infraspinous fossa at the notch as a single trunk 22 mm medial to the glenoid rim. Minimum branching variability was observed. Electrodiagnostic testing showed no evidence of axonal damage or muscle denervation in either infraspinatus pennate bundle. Limiting infraspinatus-splitting dissection medially to 1.5 cm from the posterior glenoid rim prevents damage to any interval-crossing suprascapular nerve branches. Posterior shoulder surgery through a horizontal, longitudinal infraspinatus tendon-splitting approach provides excellent exposure of posterior capsule, labrum, and glenoid, without requiring tendon detachment or causing neurologic compromise.

Acromion↗

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Functional outcomes in athletes after modified anterior capsulolabral reconstruction.

During a 7-month period, 32 consecutive athletes underwent anterior capsulolabral reconstruction with modifications, consisting of a horizontal capsulotomy (rather than a T-capsulotomy) and suture anchors (rather than drill holes); 31 patients were available for follow-up examinations. At preoperative examinations all patients demonstrated positive relocation tests; 22 were diagnosed with recurrent anterior subluxation and 9 with recurrent anterior dislocation. After surgery, all patients underwent a rehabilitation program. Followup included physical examination, subjective questions, and radiographs. At a minimum of 24 months' followup, results measured by modified Rowe score were 24 patients (77%) excellent, 6 (19%) good, and 1 (3%) failure. Eighty-one percent of the patients returned to the same sport at the same level of competition, 13% returned to the same sport at a lower level of competition, and 6% did not return to the preinjury sport. Radiographic analyses at 2 years' followup revealed all Mitek anchors were well seated in the bone of the glenoid neck. No complications of the suture anchors occurred. This modification of anterior capsulolabral reconstruction simplified the procedure and allowed a more aggressive early rehabilitation program with 97% good or excellent results.

Adolescent↗

PubMedDate not supplied

The normal and the painful shoulders during the breaststroke. Electromyographic and cinematographic analysis of twelve muscles.

The purpose of this study was to describe and compare electrical activity patterns in 12 shoulder muscles during the breaststroke in 25 competitive swimmers who had normal shoulders and in 14 who had painful shoulders while they performed this stroke in a pool. The electromyographic analysis was synchronized with high-speed cinematography to discern phases of the breaststroke. Means, standard deviations, and t-tests were done for each phase. The differences in muscle activity between the two groups of swimmers demonstrated an increase in the internal rotators in the group with painful shoulders. They also demonstrated a decrease in the teres minor, supraspinatus, and the upper trapezius muscles. These factors increase the risk of impingement. Both the serratus anterior and teres minor muscles in the swimmers with normal shoulders consistently fired at or above 15% manual muscle test throughout the breaststroke cycle and were thus subject to fatigue. Based on these results, exercises for the breaststroke swimmer should be directed toward endurance training of the serratus anterior and teres minor muscles while balancing the internal and external rotators of the shoulder as well as the deltoid and supraspinatus muscles.

Adult↗