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Unconfounding the direction of motion in depth, time to passage and rotation rate of an approaching object.

Observers were presented with a set of 216 simulated approaching textured baseballs in random order. In Experiment 1 each had a different combination of time to passage (TTP), direction of motion in depth (dMID) in the vertical plane and total change in angular size (Deltatheta). In Experiments 2 and 3 each had a different combination of TTP, dMID and rate of ball rotation (RR). When required to discriminate TTP and dMID in separate experimental blocks for a non-rotating baseball (Experiment 1), observers could not discriminate dMID independently of variations in TTP but instead showed a bias towards perceiving objects approaching on a trajectory close to the nose as having a shorter TTP than objects approaching on a trajectory that would miss the face. When required to discriminate TTP, dMID and RR in separate experimental blocks (Experiment 2), TTP judgments were again influenced by dMID but could be made independently of RR. Judgments of the relative dMID were affected by variations in RR and rotation direction: for simulated overspin the (i.e., the top of the ball spins towards the observer) perceived ball trajectory was biased towards the ground whereas for simulated underspin the perceived ball trajectory was biased towards the sky. RR could be discriminated independently of both TTP and dMID. When required to make all three of these judgments simultaneously on each trial (Experiment 3) discrimination thresholds were not appreciably different from those found in Experiment 2. We conclude that TTP, dMID and RR can be estimated in parallel but not completely independently within the human visual system.

Depth Perception↗

Catastrophic pediatric sports injuries.

The high school sports of wrestling, gymnastics, ice hockey, baseball, track, and cheerleading should receive closer attention to prevent injury. Safer equipment and sport-specific conditioning should be provided and injuries strictly monitored. Greater attention must also be paid to swimming and diving techniques, and continued observation is needed for heat stroke and heat intolerance in sports such as football, wrestling, basketball, track and field, and cross-country. An increased awareness of commotio cordis in sports other than baseball should include ice hockey, football, track field events, and lacrosse. American football because of the sheer numbers and associated catastrophic injury potential must continue to be monitored at the highest medical levels!

Adolescent↗

Mechanically induced sudden death in chest wall impact (commotio cordis).

Sudden death due to nonpenetrating chest wall impact in the absence of injury to the ribs, sternum and heart is known as commotio cordis. Although once thought rare, an increasing number of these events have been reported. Indeed, a significant percentage of deaths on the athletic field are due to chest wall impact. Commotio cordis is most frequently observed in young individuals (age 4-18 years), but may also occur in adults. Sudden death is instantaneous or preceded by several seconds of lightheadedness after the chest wall blow. Victims are most often found in ventricular fibrillation, and successful resuscitation is more difficult than expected given the young age, excellent health of the victims, and the absence of structural heart disease. Autopsy examination is notable for the lack of any significant cardiac or thoracic abnormalities. In an experimental model of commotio cordis utilizing anesthetized juvenile swine, ventricular fibrillation can be produced by a 30 mph baseball strike if the strike occurred during the vulnerable period of repolarization, on the upslope of the T-wave. Energy of the impact object was also found to be a critical variable with 40 mph baseballs more likely to cause ventricular fibrillation than velocities less or greater than 40 mph. In addition, more rigid impact objects and blows directly over the center of the chest were more likely to cause ventricular fibrillation. Peak left ventricular pressure generated by the chest wall blow correlated with the risk of ventricular fibrillation. Activation of the K(+)(ATP) channel is a likely cause of the ventricular fibrillation produced by chest wall blows. Successful resuscitation is attainable with early defibrillation.

Adolescent↗

Role of streptomycin-sensitive stretch-activated channel in chest wall impact induced sudden death (commotio cordis).

INTRODUCTION: Deaths secondary to low-energy impacts to the precordium in young individuals (commotio cordis) have been reported with increasing frequency. In a swine model, baseball impacts induce ventricular fibrillation when directed at the center of the left ventricle during the vulnerable portion of repolarization just prior to the T-wave peak. It has been hypothesized that activation of stretch-sensitive channels could be crucial for this electrophysiological phenomenon. In this study, a nonselective stretch-activated cation channel was pharmacologically blocked prior to chest blows to determine whether this channel represents a possible pathway by which commotio cordis events occur. METHODS: In a randomized and blinded experiment, 12 swine (mean 17.1 +/- 2.5 kg) received either 2-g streptomycin intramuscularly (mean serum concentration 115 +/- 18 muM) or sterile water prior to chest impact. Each animal received six precordial impacts with a baseball propelled at 40 mph. RESULTS: There was no significant difference in the frequency of induced VF in the animals administered streptomycin (10 of 19 impacts: 53%) compared to those control animals receiving only sterile water (10 of 31: 32%) (P = 0.15). However, the magnitude of ST segment elevation was less in the streptomycin-treated animals (19 +/- 19 mV) versus controls (61 +/- 46 mV) (P = 0.015). CONCLUSION: Streptomycin did not alter the frequency of ventricular fibrillation in our commotio cordis model, indicating that the stretch-activated channel is not implicated in the genesis of chest blow-induced cardiac arrest. However, streptomycin did reduce ST elevation following impact suggesting that the stretch-activated channel may play a role in ST segment elevation following chest wall blows.

Animals↗

Overuse injuries of the upper extremity in the competitive athlete: magnetic resonance imaging findings associated with repetitive trauma.

Overuse injuries are a very common cause of pain in athletes, accounting for a significant loss of training time and missed competitions. Magnetic resonance imaging (MRI) is playing an increasing role in facilitating the expeditious and safe return of these individuals to their preinjury level of physical performance by allowing accurate diagnosis. Sports physicians are increasingly relying on the exquisite anatomic detail afforded by this technique to formulate diagnoses that assist with the optimal management of these athletic injuries. Some upper extremity overuse entities are well recognized; two examples are medial epicondylitis, classically appearing in baseball pitchers, and lateral epicondylitis, in tennis players. Other less well-known injuries of the upper extremity, such as intersection syndrome in rowers and distal clavicular stress fractures in weightlifters, are frequent occurrences in certain circles of athletes. The following article is a pictorial review of the MRI findings of upper extremity overuse injuries encountered in the competitive athlete, with an emphasis on the sports scenarios in which they occur. We will depict mechanisms of injury and applicable anatomy and show characteristic imaging findings. A wide range of entities are addressed, including but not limited to overuse injuries occurring in baseball, swimming, gymnastics, weightlifting, bowling, and cycling.

Athletic Injuries↗

Fragment fixation with a bone graft and dynamic staples for osteochondritis dissecans of the humeral capitellum.

To attain bony union of the fragment in osteochondritis dissecans of the humeral capitellum, fragment fixation was performed with a bone graft and dynamic staples in 4 patients. The staples were inserted not from the articular surface but from the lateral aspect of the capitellum. All patients achieved bony union without complication, and 3 of them returned to playing competitive baseball. At final follow-up after surgery (mean, 7.5 years [range, 2.1-11 years]), 3 patients were able to throw a ball without pain and the remaining patient felt elbow dullness after he played recreational-level baseball as a pitcher. These results suggest that the procedure of fragment fixation with a bone graft and dynamic staples can provide satisfactory results for osteochondritis dissecans of the humeral capitellum with a large osteochondral fragment.

Adolescent↗

An epidemiological study of acute herniated lumbar intervertebral discs.

In an epidemiological study of acute herniated lumbar intervertebral discs in the New Haven, Connecticut (U.S.A.), area, it was found that this condition was most likely to be diagnosed among persons in the age group 30-39 years, and that the most important risk factors among the variable considered in this study were driving of motor vehicles at or away from work, sedentary occupations, suburban residence, and previous full-term pregnancies. Variables for which there was some suggestion of an association but for which the evidence was inconclusive were the male sex, high social class among females, chronic cough and chronic bronchitis, participation in baseball, golf and bowling, the spring and fall seasons, and possibly lack of physical activity other than at work. No increase in risk for this condition was related to race, social class in males, smoking habits, participation in sports other than baseball, golf and bowling, weight or body bulk, recent episodes of emotional stress, pregnancies which were not full-term, and jobs involving lifting, pushing, pulling, or carrying.

Adult↗

What is commotio cordis?

Although thought to be rare, sudden deaths caused by nonpenetrating chest wall impact in the absence of structural injury to the ribs, sternum, and heart (commotio cordis) are reported with increasing frequency. This phenomenon is described in individuals when they are struck by relatively innocent blows to the chest wall. Young male athletes aged 5 to 18 years are particularly at risk for this catastrophe. It has been described after blows to the chest from baseballs, softballs, hockey pucks, and other objects. Death is usually instantaneous, and successful resuscitation is uncommon. A recently reported experimental model provides clues to the mechanisms and inferences for the prevention and treatment of this devastating condition. This swine model shows that a) ventricular fibrillation results from low-energy chest wall impacts during a vulnerable period of repolarization, b) the risk of this event can be decreased with softer-than-standard baseballs, and c) prompt defibrillation is crucial for resuscitation to be successful.

Animals↗

Etiology and pathophysiology of tendon ruptures in sports.

Of all spontaneous tendon ruptures, complete Achilles tendon tears are most closely associated with sports activities (1-3). Schönbauer (3) reported that 75% of all ruptures of the Achilles tendon are related to sports. In Plecko & Passl (2) the number was 60%. In our material of 430 cases, the number of sports-related Achilles ruptures was very similar (62%), while only 2% of ruptures of other tendons were sports-related (P < 0.001) (1). Also, the majority of Achilles reruptures occurred in sports. The ruptures occurred most often in soccer (34%), track and field (16%) and basketball (14%). The distribution of Achilles ruptures according to different sports varies considerably from country to country, according to the national sport traditions. For example, in northern and middle Europe, soccer, tennis, track and field, indoor ball games, downhill skiing, and gymnastics are the most common; and in North America, football, basketball, baseball, tennis and downhill skiing dominate the statistics (1, 2, 4). In sports, some Achilles ruptures are not spontaneous or degeneration-induced but may occur as a consequence of the remarkably high forces that are involved in the performance (2). Ruptures in the high jump or triple jump are good examples. In such cases, failure in the neuromuscular protective mechanisms due to fatigue or disturbed co-ordination can frequently be found. The spontaneous complete rupture of the supraspinatus tendon of the rotator cuff does not occur very frequently in sports. Those sports that include high-energy throwing movements, such as American and Finnish baseball, American football, rugby and discuss and javelin throwing, may, however, produce this injury. Partial tears and inflammations of the rotator cuff complex are much more frequent in throwing sports. The complete rupture of the proximal long head of the biceps brachii tendon is rare among competitive and recreational athletes. In our material, under 2% of these ruptures were associated with sports activities (5). The rupture (avulsion) of the distal tendon of the biceps muscle is rare. In sports, gymnastics, body building and weight lifting have been said to be able to produce this injury (6). In general, complete ruptures of the quadriceps tendon and the patellar tendon occur most often in older individuals. In our study, the mean age of these patients was 65 years (5). However, these injuries do also occur in younger age groups, especially in athletes. In athletes, the rupture most frequently occurs in high-power sports events, such as high jump, basketball and weight lifting, at the age of 15-30 years. A chronic-patellar apicitis (jumper's knee) may predispose rupture of the tendon (7). As is the case with the rotator cuff complex, overuse inflammation and partial tears of the quadriceps and patellar tendons are one of the most characteristic athletic injuries. Complete spontaneous ruptures of other tendons in sports are rare, although the literature does provide case studies from almost every tendon the human body possesses (8-18).

Athletic Injuries↗

A formula for comparison of selected sport ball compressibility.

The purpose of this study was to develop a formula to determine and compare the compressibility of selected sport balls. Six balls (basketball, volleyball, soccer ball, baseball, handball, golf ball) were dropped ten times from each of four different heights onto a smooth solid surface overlaid with a white sheet of typing paper, overlaid with a sheet of carbon paper. The diameter of the area of contact of each ball imprinted onto the typing paper was measured in millimetres with calipers. From the data, the distance (d) that each ball compressed for each velocity (v) was calculated. It was found that a linear relationship existed between velocity at impact and the distance for each ball studied. The compressibility coefficient (c) for each ball was calculated and a formula was developed to determine the distance each ball would compress at a given velocity. When velocity is measured in metres per second and the distance a ball compresses is measured in millimetres, the formula to determine d for selected balls, in order of compressibility is: basketball d = 3.07v, volleyball d = 2.90v, soccer ball d = 2.80v, baseball d = 0.77v, handball d = 0.53v, and golf ball d = 0.17v.

Equipment and Supplies↗

Closed-Wedge osteotomy for osteochondritis dissecans of the capitellum. A 7- to 12-year follow-up.

This article details a 7- to 12-year follow-up of seven young male baseball players with osteochondritis dissecans of the capitellum that we treated using closed-wedge osteotomy. This procedure was established by Yoshizu in 1986 for the treatment of "Little League elbow." The bone of the capitellum was revascularized and remodeled within 6 months in all seven patients. Six of the patients were able to return to full athletic activity and continued to play baseball. Radiographic assessment during the follow-up study revealed minimal osteoarthritic change and suggests that the treatment is useful for such an injury.

Adolescent↗

Orthopaedic injuries in athletes (ages 6 to 17). Comparison of injuries occurring in six sports.

A prospective study of orthopaedic injuries to children (ages 6 to 17) was conducted for a calendar year in the controlled environment of a military post. Data were collected on the number of participants, the hours of participation, and the number of injuries for six supervised sports (football, soccer, basketball, baseball, swimming, and gymnastics). An injury index factor was derived by a formula: (number of injuries x 10(4)) divided by [(number of participants) x (average number of hours of participation) x (number of weeks in the season of the sport)]. When the injury index factors were compared, the risk a participant has for sustaining an injury in football was twice as high (1.72) as its nearest competitors, basketball (0.88) and gymnastics (0.85). Soccer had an index factor of 0.29; baseball, 0.14; and swimming had a factor of zero. Eighty percent of all sports-related orthopaedic injuries involved the upper extremities. Lower extremity orthopaedic injuries occurred only in football and gymnastics. The evidence suggests that those persons concerned with reducing the number of injuries to the growing athlete in supervised sports should focus their attention on reducing the risk of injury to the upper extremities.

Adolescent↗

Arterial abnormalities of the hand in athletes.

Vascular lesions of the hand may be seen in athletes exposed to repetitive blunt trauma. Thirteen athletes seen from 1983 to 1988 experienced symptoms related to hand ischemia. Nine were professional baseball catchers. The majority of patients complained of chronic symptoms, including cold hypersensitivity (four patients), finger numbness (one), finger coolness (three), and finger blanching (three). Two patients had acute symptoms with sudden posttraumatic hand ischemia with finger and palmar pain. Diagnosis was established by history and physical examination and confirmed by noninvasive testing. Testing included use of Doppler examination and cold tolerance examination with thermistors. Two athletes required angiographic evaluation because of severe ischemia and continuous pain. All patients in this group were managed nonoperatively. Those with chronic complaints were counseled regarding cold avoidance and instructed to increase their glove padding. The two patients with acute symptoms required vasodilator (papaverine chloride) infusion, followed by intravenous heparin and dextran. All baseball catchers returned to their sport with dissipation of symptoms.

Arteries↗

Sports injuries: An important cause of morbidity in urban youth. District of Columbia Child/Adolescent Injury Research Network.

INTRODUCTION: Sports injuries account for substantial morbidity and medical cost. To direct intervention, a population-based study of the causes and types of sports injuries was undertaken. METHOD: An injury surveillance system was established at all trauma center hospitals that treat residents 10 to 19 years old in the District of Columbia and the Chief Medical Examiner's Office. Medical record abstractions were completed for those seen in an emergency department, admitted to the hospital, or who died from injury June 1996 through June 1998. FINDINGS: Seventeen percent (n = 2563) of all injuries occurred while participating in 1 of 6 sports (baseball/softball, basketball, biking, football, skating, and soccer) resulting in an event-based injury rate of 25.0 per 1000 adolescents or 25.0/1000 population year. Rates were higher in males for all sports. The most common mechanisms were falls (E880-888) and being struck by or against objects (E916-918). Hospitalization was required in 2% of visits and there were no deaths. Of those requiring hospitalization, 51% involved other persons, 12% were equipment-related, and 8% involved poor field/surface conditions. Of all baseball injuries, 55% involved ball or bat impact often of the head. Basketball injuries included several injuries from striking against the basketball pole or rim or being struck by a falling pole or backboard. Biking injuries requiring admission included 2 straddle injuries onto the bike center bar and collision with motor vehicles. Of all football injuries, 48 (7%) involved being struck by an opponent's helmet and 63 (9%) involved inappropriate field conditions including falls on or against concrete, glass, or fixed objects. In soccer there were 4 goal post injuries and a large proportion of intracranial injuries. There were 51 probable or clear assaults during sports and an additional 30 to 41 injuries from baseball bat assaults. CONCLUSIONS: Many sports including noncontact sports involved injuries of the head suggesting the need for improved head protection. Injuries involving collisions with others and assaults point to the need for supervision and enforcement of safety rules. The 16% of sports injury visits and 20% of hospitalizations related to equipment and environmental factors suggest that at least this proportion of injury may be amenable to preventive strategies. Design change may be warranted for prevention of equipment-related injuries. The many injuries involving inappropriate sports settings suggest the need for and use of available and safe locations for sports.

Adolescent↗

Unsafe and violent behavior in commercials aired during televised major sporting events.

OBJECTIVE: Injuries are the leading cause of death in children, and media exposure seems to increase children's risk-taking behavior. Televised sports are commonly viewed by children. The objective of this study was to determine the proportion of commercials that depict violence or other unsafe behavior during major televised sporting events that are aired before 9:00 pm. METHODS: We obtained a list of the 50 sports programs that were most highly rated by Nielsen Media Research and that were televised between September 1, 2001, and September 1, 2002. These 50 programs included Winter Olympics events (n = 15), National Football League (NFL) regular season games (n = 14), NFL playoff games (n = 10), Major League Baseball World Series and playoff games (n = 7), the NFL Super Bowl (n = 1), the National Basketball Association Western Conference Final Game (n = 1), the College Football Rose Bowl (n = 1), and the National Collegiate Athletic Association Basketball Championship game (n = 1). Two other events were reviewed as well: the final round of the Masters Golf Championship, because it was the only sporting event rated in the top 50 of the previous year that was not represented by a similar sporting event in the study year, and the Daytona 500 National Association for Stock Car Auto Racing race, because it was the only event rated among the top 75 of the study year that was not represented by a similar event (ie, there were no other golfing or auto racing events reviewed). These events were included because different sporting events may attract different viewers and different advertisements; thus, their inclusion provides a more comprehensive evaluation of the topic. For sporting events with >3 programs in the top 50 (NFL regular season games, NFL playoff games, Winter Olympic events, and Major League Baseball World Series), representative samples of events were assessed. Surrogate events were analyzed for programs that were aired after 9:00 PM (Eastern Time) to control for the reduced likelihood of viewing by children after 9:00 PM. For example, afternoon telecasts of the National Collegiate Athletic Association Regional Final and National Semifinal games were assessed in place of the Championship game, which started after 9:00 PM. Weekend afternoon telecasts of the Winter Olympics (3 successive weekends) were assessed as surrogates for all Olympics telecasts. For the World Series, the Super Bowl, and the National Basketball Association Conference Championship games, which began before 9:00 PM but ended after that time, we evaluated only commercials that aired before 9:00 PM. All commercials that were aired during these programs were reviewed at standard speed for unsafe behavior or violence. Commercials that were aired during pregame, postgame, or halftime periods were not assessed. Commercials were categorized according to the product being advertised. Unsafe behavior was simply defined as any action that could have harmful consequences or that contravened the injury prevention recommendations of national organizations. Violence was defined as any intentional physical contact by an aggressor that had the potential to inflict injury or harm or the legitimate threat of such action. All commercials were reviewed by at least 2 investigators; when the 2 could not agree on the findings, a third investigator was used to resolve differences. The percentage of commercials and of commercial breaks that portrayed violent or unsafe behavior was determined for each category of event and advertised product. A commercial break was defined as a series of commercials shown during a single break from the sporting event. chi2 analysis was used for all analyses, and relative risks with 95% confidence intervals were determined. The proportion of commercials that depicted unsafe behavior and/or violence during each sporting event was compared with the proportion of such commercials that were observed during the Masters Golf Tournament (which had the lowest proportion of commercials depicting such behavior). The proportion of commercials that contained violent/unsafe behavior for each advertised product was compared with the proportion of such commercials that advertised food or nonalcoholic beverages. Food and nonalcoholic beverage commercials were selected as the reference because they are a well-defined, common category of commercial. RESULTS: Of the 1185 commercials assessed, 14% (n = 165) displayed unsafe behavior and 6% (n = 66) depicted violence. Of the 322 commercial breaks, 158 (49%) contained at least 1 commercial showing unsafe behavior or violence. Sixty-three commercials required review by a third investigator to adjudicate violence or unsafe behavior; 20 of 52 were ultimately judged to portray unsafe behavior, and 4 of 11 were ultimately judged to portray violence. Sporting events differed in the proportion of commercials that showed violence or unsafe behavior. The Super Bowl had the highest proportion of such commercials, and the Masters Golf Tournament had the least (relative risk: 4.3; 95% confidence interval: 1.4-12.5). The Masters Golf Tournament was noteworthy for the complete absence of violent commercials. Only 18% of reviewed commercials advertised movies or television programs, yet these commercials accounted for 86% of all violent commercials. Forty-eight percent of commercials that contained violence were for movies, and an additional 38% were for television programs. Nearly two thirds of all commercials for movies contained violence, whereas 15% of all commercials for television programs contained violence, a rate that increased to 22% when commercials for other sporting events were excluded. Several categories of commercials portrayed unsafe behaviors; commercials for automobiles accounted for the most. In 8 different categories, 10% or more of the commercials depicted unsafe behavior, and 7 were significantly more likely to depict such behavior than a food or beverage commercial. CONCLUSIONS: Children who watch televised sports view a significant amount of violent and unsafe behavior. In accordance with American Academy of Pediatrics recommendations for television viewing, parents should both limit and directly supervise children's viewing of these events. Our findings suggest that parents should remain present during commercials or should consider implementing commercial-skipping technology. In addition, efforts should be made to regulate the content of commercials that promote television programs and movies on the basis of the hour at which the sporting event is aired. Moreover, the sports, movie, and television industries should be encouraged to adopt models of advertising that limit or eliminate such content. These efforts could help to ensure that the viewing of televised sporting events is a safe and positive experience for children.

Advertising↗

Snuffing tobacco out of sport.

Use of oral snuff has risen sharply among baseball players following a tobacco industry marketing campaign that linked smokeless tobacco with athletic performance and virility. Millions of adolescents have copied these professional role models and, today, are at risk of developing oral cancer and other mouth disorders. New policies and programs are needed to break the powerful grip that the tobacco industry has on professional sport. Health agencies, including the National Cancer Institute and the National Institute for Dental Research, have teamed up with major league baseball to help players quit and reduce public use of oral tobacco. If these efforts are successful, our national pastime will once again become America's classroom for teaching health and fitness, not nicotine addiction.

Adolescent↗

Shoulder MR arthrography: which patient group benefits most?

OBJECTIVE: We sought to compare the diagnostic accuracy of conventional MRI versus MR arthrography of the shoulder in the assessment of high-performance athletes (professional baseball players) and to compare our findings in these patients with the conventional MRI and MR arthrographic findings in an age-matched control group of nonprofessional athletes. MATERIALS AND METHODS: Conventional MRI and MR arthrographic examinations of the shoulder in 20 consecutive professional baseball players with shoulder pain were reviewed retrospectively by two musculoskeletal radiologists in consensus. These interpretations were compared with retrospective consensus interpretations of conventional MRI and MR arthrographic examinations of the shoulder obtained in a control group of 50 consecutive nonprofessional athletes with shoulder pain. MR images were assessed for full- or partial-thickness supraspinatus tendon tears, superior labral anteroposterior (SLAP) tears, and anterior or posterior labral tears. RESULTS: In the 20 consecutive professional athlete patients, two full-thickness and six partial-thickness undersurface supraspinatus tendon tears were seen on MR arthrography but not seen on conventional MRI as well as six SLAP tears, two anterior labral tears, and one posterior labral tear. Three patients had both SLAP tears and full- or partial-thickness supraspinatus tendon tears. Of 14 patients with findings on MR arthrography that were not seen on MRI, 11 had arthroscopic correlation. In all 11, arthroscopic findings confirmed findings on MR arthrography. In the group of 50 nonprofessional athlete patients, five had additional findings on MR arthrography not seen on conventional MRI: two anterior labral tears, two partial-thickness supraspinatus tendon tears, and two SLAP tears. One patient had both a partial-thickness supraspinatus tendon tear and a SLAP tear seen on MR arthrography. The five patients with additional findings on MR arthrography had arthroscopy. In all five, arthroscopic findings confirmed the findings on MR arthrography. CONCLUSION: MR arthrography is considerably more sensitive for detection of partial-thickness supraspinatus tears and labral tears than conventional MRI. MR arthrography showed injuries in addition to those seen on conventional MRI in 14 of 20 patients in the high-performance athlete group. These results suggest high-performance athletes may be a subgroup of patients for whom MR arthrography yields considerably more diagnostic information than conventional MRI.

Adolescent↗

Long-term working memory in text production.

In reading and other high-level cognitive tasks, Ericsson and Kintsch (1995) proposed that the limited capacity of short-term working memory (STWM) is supplemented by long- term working memory (LTWM) for individuals with a high degree of domain-specific knowledge. In Experiment 1, college students (N = 80) wrote persuasive and narrative texts concerning baseball; domain-specific knowledge about baseball and verbal ability was assessed. The results showed that verbal ability and domain-specific knowledge independently affected writing skill, supporting the view that literacy depends on both knowledge sources and refuting one argument raised in support of the LTWM hypothesis. Experiment 2 (N = 42) replicated this outcome and tested the prediction that a high degree of domain-specific knowledge would lessen interference on a secondary task. The data supported the interference prediction, offering evidence that LTWM plays a role in the production of text.

Adult↗