ISSN:0112-1642    

DOI:10.2165/00007256-199112020-00001

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

ConclusionThe neuroendocrine system plays an integral function in the development and maintenance of muscle tissue. Numerous investigations have confirmed the effects of both aerobic exercise and heavy resistance exercise upon the neuroendocrine system. Although there has been great progress in the area of exercise and neuroendocrinology, many questions regarding hormonal responses to exercise remain unanswered. In particular, there is a need for additional research that will reveal the specific mechanisms by which different exercise protocols induce hormonal responses.

ISSN:0112-1642    

DOI:10.2165/00007256-199112020-00002

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryThe issue of discrimination in physically demanding employment, such as police, firefighters, prison guards and military personnel, is contentious. In terms of oxygen transport, the ‘action limit’ (calling for personnel selection or task redesign) is a steady oxygen consumption of 0.7 L/min, while the maximum permissible limit is 2.1 L/min. Note is taken of the commonly expressed belief that public safety duties are physically demanding, calling for personnel with an aerobic power of at least 3 L/min, or 42 to 45 ml/kg/min. The actual demands of such work can be assessed on small samples by physiological measurements (using heart rate or oxygen consumption meters), but the periods sampled may not be typical of a normal day. A Gestalt can also be formed as to the heaviness of a given job, or a detailed task analysis can be performed; most such analyses of public safety work list distance running and other aerobic activities infrequently. An arbitrary requirement of ‘above average fitness’ is no longer accepted by courts, but a further approach is to examine the characteristics of those currently meeting the demands of public safety jobs satisfactorily. Young men commonly satisfy the 3 L/min standard, but this is not usually the case for women or older men; in the case of female employees, it also seems unreasonable that they should be expected to satisfy the same standards as men, since a lower body mass reduces the energy cost of most of the tasks that they must perform.A second criterion sometimes applied to physically demanding work (a low vulnerability to heart attacks) is examined critically. It is concluded that the chances that a symptom-free public safety officer will develop a heart attack during a critical solo mission are so low that cardiac risk should not be a condition of employment.Arbitrary age- and sex-related employment criteria are plainly discriminatory, since some women and 65-year-old men have higher levels of physical fitness than the average young man of 25 years. Neither laboratory nor field tests offer a satisfactory means of distinguishing such individuals, and the only equitable basis of selecting personnel for physically demanding work seems a probationary period of employment.

ISSN:0112-1642    

DOI:10.2165/00007256-199112020-00003

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryThe posterior cruciate ligament (PCL) is the strongest ligament about the knee and is approximately twice as strong as the anterior cruciate ligament. Its main function is to prevent the posterior dislocation of the tibia in relation to the femur, providing 95% of the strength to resist the tibial posterior displacement. Along with the anterior cruciate ligament (ACL) the PCL controls the passive ‘screw home’ mechanism of the knee in terminal knee extension. It also provides mechanical support for the collateral ligaments during valgus or varus stress of the knee.PCL ruptures are uncommon apparently due to its strong fibre structure. The most frequent injury mechanism in isolated PCL tears is a direct blow on the anterior tibia with the knee flexed thus driving the tibia posteriorly. Automobile accidents (in which the knee hits the dashboard) and soccer injuries (in which an athlete receives a blow to the anterior surface of the tibia during knee flexion) characteristically produce this type of injury. In other PCL injury mechanisms (hyperextension, hyperflexion or rotational injuries with associated valgum/varum stress), other knee structures are also often damaged.The most characteristic diagnostic finding in a knee with a PCL rupture is the ‘posterior sag sign’ meaning the apparent disappearance of the tibial tubercle in lateral inspection when the knee is flexed 90°. This is due to gravity-assisted posterior displacement of the tibia in relation to the femur. A positive posterior drawer test performed at 90° of flexion and a knee hyperextension sign are sensitive but nonspecific tests. False negative findings are frequent, especially in acute cases. If necessary, the clinical diagnosis of the PCL tear can be verified by magnetic resonance imaging, examination under anaesthesia, arthroscopy, or a combination of these modalities.If a PCL avulsion fragment has been dislocated, surgical treatment is recommended. In isolated, complete midsubstance tears of the PCL the majority of the recent studies recommend conservative treatment, since abnormal residual posterior laxity in most of these knees is consistent with functional stability and minimal symptoms. This has been the case even in athletes. In isolated PCL tears, the outcome seems to depend more on the muscular (quadriceps) status of the knee than on the amount of residual posterior laxity. Therefore, the conservative treatment protocol emphasises intensive quadriceps exercises, and only a short (under 2 weeks) immobilisation period followed by early controlled activities and early weightbearing.According to the current concept, acute phase surgery (primary PCL repair with augmentation, or primary PCL reconstruction) is indicated in fresh injuries of the PCL associated with disruptions of other major ligaments or capsular structures. Simultaneously with the PCL surgery, all the other damaged structures should also be repaired. Even with surgery, however, the prognosis is poorer than in isolated PCL tears. In chronic PCL insufficiency a reconstruction with bone-patella tendon-bone autograft or allograft can be considered, if the patient suffers from repeated giving way symptoms which are not resolved by rehabilitation.

ISSN:0112-1642    

DOI:10.2165/00007256-199112020-00004

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryAs many as 1.5 million young men participate in American football in the United States. An estimated 1.2 million football-related injuries are sustained annually. Since the 1970s epidemiological studies have shown that the risk of injury is higher in older athletes and lower in teams with more experienced coaches and more assistant coaches. 51% of injuries occurred at training; contact sessions were 4.7 times more likely to produce injuries than controlled sessions. Injury rates were reduced by wearing shorter cleats and preseason conditioning.Overall, lower extremity injuries accounted for 50% of all injuries (with knee injuries accounting for up to 36%). Upper extremity injuries accounted for 30%. In general, sprains and strains account for 40% of injuries, contusions 25%, fractures 10%, concussions 5% and dislocations 15%.Cervical spine injuries have the potential to be catastrophic, but they declined dramatically in the decade 1975 to 1984, due to the impact of rule changes modifying tackling and blocking techniques and improved fitness, equipment and coaching. Appropriate diagnostic evaluation of cervical injuries is mandatory.The evidence supporting prophylactic knee bracing is not compelling and does not mandate compulsory or routine use.Return to play criteria include: full range of motion; normal strength; normal neurological evaluation; no joint swelling or instability; ability to run and sustain contact without pain; no intake of pain medication; player education about preventive measures and future risks. These criteria should be strictly observed.In addition to ankle and knee rehabilitation, lumbar spine injuries present a challenge for the physician. Repetitive flexion, extension and torsional stresses predispose the lumbar spine to injury. Rehabilitation consists of pain control and training. The training phase aims to eliminate repetitive injuries by minimising stress at the intervertebral joint.Football is a high risk sport. Coaches, players, trainers and physicians must all become aware of the proper means to prevent injuries.

ISSN:0112-1642    

DOI:10.2165/00007256-199112020-00005

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS