ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00001

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryAerobic exercise and training lead to numerous changes and/or adaptations in the normal physiological functioning of the body. The trace minerals chromium, zinc, and copper are directly involved in maintaining and regulating many of these physiological processes, especially those involved in normal carbohydrate, fat and protein metabolism and the ultimate formation of usable energy. Therefore, it is important to establish whether exercise and training alter the functions of these trace elements, and to determine the overall effects of exercise on nutritional status and physical performance.Exercise results in a marked mobilisation of chromium into circulation, while zinc and copper levels have been shown to either remain stable or increase. Exercise also results in large increases in excretion of chromium, zinc and copper. Urinary chromium excretion has been shown to increase on an exercise day compared with a rest day, while increased zinc losses occur in urine and sweat and increased copper losses occur in urine, sweat, and faeces. When exercise-enhanced trace mineral losses are coupled with dietary intakes below the recommended levels, which are commonplace for both sedentary and exercising individuals, the nutritional status and overall health of exercising individuals may be suboptimal. Individuals who train intensively may be at special risk due to repeated increased losses. Trained athletes have lower resting urinary chromium losses, larger increases in urinary chromium losses due to exercise, lower resting serum zinc levels, and possible alterations in copper nutriture compared with sedentary controls. These changes suggest an altered metabolism and/or nutritional status of the trace minerals chromium, zinc, and copper in trained individuals and those who exercise strenuously.

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00002

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryCanoeing and kayaking are upper-body sports that make varying demands on the body, depending on the type of contest and the distance covered. The shorter events (500m) are primarily anaerobic (2 minutes of exercise), calling for powerful shoulder muscles with a high proportion of fast-twitch fibres. In contrast, 10,000m events call for aerobic work to be performed by the arms. Such contestants need a high proportion of slow-twitch fibres, and an ability to develop close to 100% of their leg maximum oxygen intake when paddling. In slalom and Whitewater contests, the value of physiological testing is somewhat limited, since performance is strongly influenced by experience and the ability to make precisely judged rapid paddling efforts under considerable emotional stress. Paddlers face dangers from their hostile cold water environment; causes of fatalities (drowning, cardiac arrest, ventricular fibrillation and hypothermia) are briefly reviewed. Medical problems include provision of adequate nutrition and a clean water supply, effects of repeated immersion (softening of the skin, blistering, paronychial infections, sinusitis, otitis), varicose veins (secondary to thoracic fixation) and hazards of exposure to fibreglass and polystyrene in the home workshop. Surgical problems include muscle sprains and mechanical injuries (haemotomas, lacerations, contusions, concussion, and fractures).

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00003

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryThe problem of menstrual dysfunction in athletes was recognised at about the same time as a theory was developed that a critical fat level was necessary for the onset and maintenance of menstrual function (17% and 22% of bodyweight, respectively). This theory was acceptable because of the frequency of leanness in athletes experiencing menstrual dysfunction and because of the role of adipose tissue in the intraconversion of hormones which could affect hypothalamic and pituitary regulatory centres. Research on this topic has been hampered by the extensive use of surveys, confining sampling to specific sports, use of inaccurate methods of body composition assessment, and lack of data on hormonal changes. Studies using appropriate body composition measures do not support the critical fat theory, but they do not exclude a role for body composition changes in the regulation of menstrual function. The probability of finding menstrual dysfunction in very lean athletes is high, but not absolute, and there is no assurance that dysfunction will improve merely by increasing body weight. Perhaps of more concern, however, is recent research on very lean, long term amenorrhoeic athletes who train intensely and show a loss of bone mineral, apparently related to low oestrogen levels. This mineral deficiency is apparently a factor in stress fractures. The bone mineral content of these athletes is similar to that of post-menopausal women susceptible to osteoporosis. Although the loss of bone due to short term amenorrhoea may be reversible, the prognosis for a long term deficiency is not presently known.

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00004

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryTraditionally, the pulmonary system has not been considered the limiting factor in determining maximal oxygen uptake (V̇2max) in healthy individuals since arterial oxygen-haemoglobin saturation is thought to remain high during intense exercise. However, there appears to be a major exception to this rule. Recent evidence suggests that arterial hypoxaemia results during heavy exercise in well trained individuals with a high V̇2max. Further, the degree of arterial desaturation is inversely related to V̇2max. This exercise-induced hypoxaemia does not appear to be due to hypoventilation although athletes who have limited hyperventilation seem to exhibit the lowest arterial oxygen-haemogloblin saturation. A significant venoarterial shunt has been ruled out as a primary cause of the hypoxaemia based on both experimental and theoretical considerations. Therefore, it appears that the exercise-induced hypoxaemia seen in highly trained athletes during heavy exercise is primarily due to diffusion limitations and ventillation-perfusion inequality. It is postulated that incomplete diffusion in the healthy lung may be due to a rapid red blood cell transit time through the pulmonary capillary. In summary, recent findings suggest that the limits of the human pulmonary system may be reached or even exceeded during intense exercise in some individuals. In light of these findings the role of the pulmonary system as a limiting factor during maximal exercise in the highly trained endurance athlete warrants further investigation.

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00005

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryRecreational exercise has achieved great popularity. Possible benefits to participants are increased longevity, decreased risk of cardiovascular disease, improved psychological well-being, and greater fitness. A very important but as yet unanswered concern is whether regular exercise will lead to degenerative joint disease or osteoarthritis. Many factors (e.g. physical characteristics of participants, biomechanical and physical features, nature of the playing surface and sport, manner of participation, preventive measures, and certain medical considerations) might influence the risk of developing osteoarthritis from sports participation. However, none of these have been evaluated. Although studies with animals have identified situations in which articular cartilage degeneration may be accelerated, experimental observations have not found normal joint motion in exercising animals to be harmful to joints. Anecdotal observations in man have suggested relationships between recreational activities and degenerative joint disease. However, those few controlled studies reported indicate that exercise need not be deleterious to joints. We interpret available data as suggesting that reasonable recreational exercise, carried out within limits of comfort, putting joints through normal motions, without underlying joint abnormality, even over many years, need not inevitably lead to joint injury.

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00006

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryStress fractures are commonly found in athletes attending sports medicine clinics for diagnosis of lower limb pain. Plain radiographs are less reliable than the99mTc bone scan for diagnosing stress fractures because of their low sensitivity. While the heightened sensitivity of the bone scan is advantageous as a diagnostic aid, the uptake of99mTc at non-painful sites occurs frequently in the athlete. Although the clinical significance has not been determined, asymptomatic uptake may indicate bone remodelling as part of a continuum of adaptation to physical stress. It is not known whether athletes who have uptake of99mTc in asymptomatic areas represent a separate population from those who do not. This study retrospectively reviewed the medical charts and bone scan reports of 320 athletes diagnosed as having stress fractures, to determine the frequency of asymptomatic focal uptake at sites other than the site of pain. This group was compared with the group who had no asymptomatic uptake on a number of demographic variables and physical findings. Asymptomatic focal uptake was found in 37.5% of athletes with the average number of sites being 1.8 per person. No significant differences between groups with focal asymptomatic uptake and groups with no asymptomatic uptake were found when compared4 for age, height, weight, mileage in runners, times to diagnosis and recovery, frequency of tenderness, swelling, trauma history, varus alignment, and x-ray abnormalities. It is concluded that asymptomatic uptake of99mTc occurs frequently in athletes with stress fractures and there are no significant clinical differences between the group with asymptomatic uptake and the group without. It is suggested that symptomatic uptake of99mTc represents the remodelling response of bone to physical stress.

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00007

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

ISSN:0112-1642    

DOI:10.2165/00007256-198704010-00008

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS