Physiological performance capacity in different prepubescent athletic groups

Endurance, strength and speed capacity were investigated among prepubescent male weight lifters (EL), endurance runners (ER) and sprint runners (SR). The subjects were selected by their coaches and all of them were classified as promising and successful junior athletes in the age groups of 10-13 years. Twelve boys belonged to athletic group (AG) and their performance capacity was compared to normally active control (C) boys (n = 9). Biological age was significantly (p less than 0.05) greater in AG (11.3 +/- 0.9 years) than in C (10.2 +/- 1.4 years) but in chronological age there was no difference between the groups. Maximal oxygen uptake was significantly (p less than 0.05) higher in AG (62.3 +/- 3.1 ml.kg-1.min-1) than in C (55.4 +/- 7.7 ml.kg-1.min-1). The endurance runners had the highest value (66.5 +/- 2.9 ml.kg-1.min-1). In anaerobic characteristics there were no significant differences. The rise of centre of gravity (0.26 +/- 0.03 m) of AG in a test for the best drop jump was clearly (p less than 0.05) higher than that (0.22 +/- 0.03 m) of C. The weight lifters and sprint runners were the best in the test for force production. AG had significantly (p less than 0.01) shorter choice reaction time (261 +/- 39 ms) than C (344 +/- 81 ms). Testosterone correlated with jump performances (p less than 0.05), biological age (p less than 0.01) and chronological age (p less than 0.001). Growth hormone correlated significantly only with biological age (p less than 0.05) and testosterone (p less than 0.001). In conclusion, endurance capacity (aerobic) and strength capacity were greater in the athletic group than in the control group and it was suggested that training background and more advanced biological maturation of the athletes affected especially their strength capacity. The parameters used in this investigation can be utilized for talent selection in sport.     

Nutritional conditioning for athletic competition

Diet in itself cannot provide fitness or championship form, but a poor diet can ruin both. Optimal nutrition is a basic component of training that is necessary for the development and maintenance of top physical performance. Appropriate application of recent research findings can have a beneficial impact on exercise performance.     

Protein intake and athletic performance.

For most of the current century, exercise/nutritional scientists have generally accepted the belief that exercise has little effect on protein/amino acid requirements. However, during the same time period many athletes (especially strength athletes) have routinely consumed diets high in protein. In recent years, the results of a number of investigations involving both strength and endurance athletes indicate that, in fact, exercise does increase protein/amino acid need. For endurance athletes, regular exercise may increase protein need by 50 to 100%. For strength athletes, the data are less clear; however, protein intakes in excess of sedentary needs may enhance muscle development. Despite these observations increased protein intake may not improve athletic performance because many athletes routinely consume 150 to 200% of sedentary protein requirements. Assuming total energy intake is sufficient to cover the high expenditures caused by daily training, a diet containing 12 to 15% of its energy from protein should be adequate for both types of athletes.     

Reproduction for the athletic woman. New understandings of physiology and management.

A physically active and athletic lifestyle is not only a healthy but a fulfilling choice for women. Although there is extensive literature on 'athletic amenorrhoea' which implies that exercise causes loss of the menstrual cycle, there is inadequate scientific evidence for a causal relationship. The reproductive system adapts to environmental, nutritional, emotional and physical stressors or 'threats' by downward adjustment towards the premenarcheal pattern. The hormonal milieu of this adaptation is low gonadal steroid and high glucocorticoid levels which synergistically increase the risk for a negative bone balance. Athletic women may become amenorrhoeic if reproductive immaturity, emotional stress and undernutrition coexist with increasing exercise loads. Treatment for athletic women with menstrual cycle changes requires that hypothalamic stressors be identified and decreased. In addition, as progesterone deficiency (from disorders of ovulation, whether flow is regular or absent) is the most prevalent menstrual cycle change, treatment with medroxyprogesterone on days 16 to 25 of their cycle will not only provide regular flow (if estrogen levels are sufficient) but will also promote increased bone density.     

Radiology of athletic injuries: baseball.

The radiographs and medical records of 29 professional basebell players from several teams were reviewed. Each player had been selected because of radiographic abnormalities. Abduction views of the shoulder were employed in pitchers and outfielders who complained of shoulder pain. Upper extremity abnormalities predominated and accounted for 22 injuries including avulsion injuries of the origin of the long head of the triceps at the infraglenoid tubercle of the scapula and traction injuries at the origin of the pronator muscles at the medial epicondyle of the humerus. Trauma to the lower extremities was caused by collision with a fixed barrier in one man and by running and sliding in 13 others.     

The zone diet and athletic performance.

The Zone diet is the latest eating regimen marketed to improve athletic performance by opposing traditional high carbohydrate sports diets. The 40/30/30 diet is centred primarily on protein intake (1.8 to 2.2 g/kg fat free mass; i.e. total bodyweight-fat weight) and promises a change in the body's insulin to glucagon ratio through its macronutrient alterations. Changes in the existing hormonal milieu are said to result in the production of more vasoactive eicosanoids, thus allowing greater oxygen delivery to exercising muscle. This favourable condition, known as the Zone, is anecdotally reported to benefit even the most elite endurance athletes. Applying the Zone's suggested protein needs and macronutrient distributions in practice, it is clear that it is a low carbohydrate diet by both relative and absolute standards, as well as calorie deficient by any standard. Reliable and abundant peer reviewed literature is in opposition to the suggestion that such a diet can support competitive athletic endeavours, much less improve them. The notion that a 40/30/30 diet can alter the pancreatic hormone response in favour of glucagon is also unfounded. The Zone is a mixed diet and not likely to affect pancreatic hormone release in the same way individual nutrients can. Although the postprandial insulin response is reduced when comparing a 40% with a 60% carbohydrate diet, it is still a sufficient stimulus to offset the lipolytic effects of glucagon. Many of the promised benefits of the Zone are based on selective information regarding hormonal influences on eicosanoid biology. Contradictory information is conveniently left out. The principle of vasodilating muscle arterioles by altering eicosanoid production is notably correct in theory. However, what little human evidence is available does not support any significant contribution of eicosanoids to active muscle vasodilation. In fact, the key eicosanoid reportedly produced in the Zone and responsible for improved muscle oxygenation is not found in skeletal muscle. Based on the best available scientific evidence, the Zone diet should be considered more ergolytic than ergogenic to performance.     

The assessment of athletic hip injury.

The differential diagnosis of athletic hip pain is extensive. The physical demands of sport place the athlete at increased risk to injure the hip. The basis of successful treatment of the athlete with hip pain lies in the ability of the physician to assess and diagnose the etiology accurately. A thorough understanding of the evaluation of the athlete with hip pain allows for an earlier diagnosis, earlier treatment, and ultimately an earlier return to sport.     

Radiology of athletic injuries: football.

During a 17-year period, 33 injuries produced radiographic abnormalities in 26 members of a professional football team. Sites of injury were correlated with playing position and protective equipment worn at the time of injury. Fractures of multiple transverse processes of the lumbar spine are reported in offensive halfbacks and offensive ends. Two linebackers and one center sustained fractures of the mid-forearm. Several related reports of the morbidity and mortality of football injuries are also discussed.     

Hazard of deceptive advertising of athletic footwear.

OBJECTIVES: Athletic footwear are associated with frequent injury that are thought to result from repetitive impact. No scientific data suggest they protect well. Expensive athletic shoes are deceptively advertised to safeguard well through "cushioning impact", yet account for 123% greater injury frequency than the cheapest ones. This study tested the hypothesis that deceptive advertising creates a false sense of security with users of expensive athletic shoes, inducing attenuation of impact moderating behaviour, increased impact, and injury. METHODS: Fifteen young healthy male volunteers confronted four surfaces: a bare force moment platform, and three with this platform covered by identical shoe sole material made to appear different and advertised divergently. Advertising messages suggested superior impact absorption and protection (deceptive message), poor impact absorption and high injury risk (warning message), and unknown impact absorption and safety (neutral message). Ground reaction forces were recorded for 10 barefoot footfalls, according to a protocol requiring stepping forward from perch to a surface 4.5 cm below. RESULTS: Impact varied as a function of advertising message (p < 0.001). Deceptive message equalled neutral message in eliciting higher impact than the warning message and the bare platform. Differences grew with repetitions (p < 0.001). CONCLUSIONS: These data provide a plausible mechanism explaining higher injury frequency in users of expensive athletic shoes. This is the first report to suggest: (1) deceptive advertising of protective devices may represent a public health hazard and may have to be eliminated presumably through regulation; (2) a tendency in humans to be less cautious when using new devices of unknown benefit because of overly positive attitudes associated with new technology and novel devices.     

Differences in plantar loading between flat and normal feet during different athletic tasks

The purpose of this study was to determine if foot type (flat or normal) resulted in loading differences during four sport-specific tasks (cross-cut, side-cut, shuttle run, and landing from a simulated lay-up). Twenty-two healthy subjects (12 normal feet and 10 flat feet) completed five trials in each condition, while in-shoe pressure data was collected at 50 Hz. Contact area, maximum force, and the force time integral were analyzed under the entire foot and in eight-foot regions. Foot type was determined by examining navicular height, arch angle, rearfoot angle, and a clinical score. A series of independent sample t-tests were used to determine statistical differences (α < 0.05). During the cross-cut, flat feet demonstrated an increase in medial midfoot contact area. During the side-cut, flat feet demonstrated an increase in contact area, force time integral and maximum force in both the medial and lateral midfoot. During the shuttle run, flat feet demonstrated an increase in force time integral in the lateral midfoot and increases in maximum force in both the medial and lateral midfoot. During the landing task, flat feet demonstrated an increase in maximum force in the medial midfoot. However, flat feet demonstrate a decrease in middle forefoot maximum force. All results were statistically significant (p < 0.05). Therefore, individuals with a normal foot could be at a lower risk for medial and lateral midfoot injuries such as metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.     

Enhancement of athletic performance with drugs. An overview.

Drug use among athletes has become a recognised problem in sports. Athletes may use drugs for therapeutic indications, for recreational or social reasons, as ergogenic aids or to mask the presence of other drugs during drug testing. Stimulants were some of the first drugs used and studied as ergogenic aids. Amphetamines may increase time to exhaustion by masking the physiological response to fatigue. Caffeine may improve utilisation of fatty acids as a fuel source thereby sparing muscle glycogen. Cocaine and other sympathomimetic drugs have little or no effect on athletic performance. Anabolic steroids appear to have the potential to increase lean muscle mass and strength under certain conditions. Human growth hormone may also be used for an anabolic effect, but data on this effect are lacking. Erythropoietin may represent a pharmacological alternative to blood doping by increasing red blood cell mass. The use of narcotic analgesics is not necessarily ergogenic but can be harmful if used to allow participation of an athlete with a severe injury. According to the American College of Sports Medicine alcohol does not possess an ergogenic effect. However, it may be used to reduce anxiety or tremor prior to competition. Marijuana does not increase strength. Tobacco products may produce psychomotor effects or control appetite which may be beneficial to some athletes. Other drugs used by athletes include beta-blocking agents, diuretics, and a variety of nutritional supplements. In addition, diuretics and probenecid may be taken to mask drug contents in the urine. Whether the ergogenic effects are real or perceived, the potential for adverse effects exists for all of these drugs. Potential health complications represent a serious risk to an otherwise healthy population. Further research on the long term health risks in athletes taking ergogenic drugs is needed.     

Arthroscopy for athletic foot and ankle injuries

The development of arthroscopic techniques began in the early 1900s. Today, there are several techniques available for treating athletic injuries of the foot and ankle. This article describes arthroscopic techniques for the great toe, subtalar arthroscopy, anterior ankle impingement exostoses (footballer's ankle), posterior ankle arthroscopy, endoscopic calcaneoplasty, and osteochondral lesions of the talus. New techniques for arthroscopic repair of chronic ankle instability are reviewed, and the authors present their results with thermal-assisted capsular modification for chronic lateral ankle instability.