摘要:

Physical fitness is a term describing maximal aerobic capacity adjusted for body size and composition, and is an integrated measure of cardiorespiratory and neuromusculo-skeletal function, oxygen transport and delivery, and psychological drive. Accordingly, high physical fitness requires that all these important body functions function normally, while low physical fitness suggests malfunction of one or more of them.High levels of physical fitness − maintained through heavy daily exercise − has probably been a necessary requirement for survival in the earlier history of humans. In modern, industrialised countries the demand for physical activity to sustain life is declining, and a decline in physical fitness is observed in many populations.Epidemiological studies over the past 50 years have unanimously shown that low physical activity and physical fitness is associated with high cardiovascular and total mortality. Recent data also suggest that low physical activity and physical fitness is followed by an increased incidence of diabetes mellitus and nonfatal cardiovascular diseases. A number of unfavourable biochemical and physiological aberrations following physical inactivity probably explain these observations. However, recent studies also indicate that changes in physical activity, and especially changes that bring increases in physical fitness, can reverse this rather pessimistic scenario.The Global Burden of Disease Study initiated by the World Health Organization included physical inactivity among the most important risk factors threatening global health. A sedentary life style may be as detrimental to health as smoking. Encouragement of physical activity is an important and difficult task, as society is becoming increasingly successful in reducing our need to move.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

Zinc is involved in the biochemical processes supporting life, such as cellular respiration, DNA reproduction, maintenance of cell membrane integrity and free radical scavenging. Zinc is required for the activity of more than 300 enzymes, covering all 6 classes of enzyme activity.Zinc binding sites in proteins are often of distorted tetrahedral or trigonal bipyramidal geometry, made up of the sulphur of cysteine, the nitrogen of histidine or the oxygen of aspartate and glutamate, or a combination. Zinc in proteins can either participate directly in chemical catalysis or be important for maintaining protein structure and stability.The nutritional habits of elite athletes during training and competition are quite different from the recommended diet in the majority of the population. Endurance athletes often adopt an unusual diet in an attempt to enhance performance: an excessive increase in carbohydrates and low intake of proteins and fat may lead to suboptimal zinc intake in 90% of athletes. Mild zinc deficiency is difficult to detect because of the lack of definitive indicators of zinc status. In athletes, zinc deficiency can lead to anorexia, significant loss in bodyweight, latent fatigue with decreased endurance and a risk of osteoporosis.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

The cloning of murine and human obese genes in 1994, and the subsequent identification that the product of the obese gene, leptin, is secreted from adipose tissue, stimulated a tremendous amount of interdisciplinary interest in adipose tissue endocrinology and the potential role of this tissue in the regulation of energy balance. Exercise, with concomitant changes in fuel flux, systemic hormone levels and energy expenditure, may contribute to the regulation of plasma leptin levels and presumably, leptin action. The initial work characterising the leptin-exercise relationship was equivocal. Cross-sectional studies provided some mixed evidence regarding the relationship between aerobic capacity or habitual physical activity and plasma leptin.In contrast, studies on acute bouts of exercise and exercise training interventions have, with few exceptions, suggested that exercise does not alter systemic leptin independent of changes in fat mass. In general, these studies did not carefully control for energy balance, and sampled only a single fasting plasma leptin level. Two recent studies utilising experimental designs in which energy balance was controlled and 24-hour profiles of plasma leptin were determined have provided the most compelling evidence to date of the interaction between exercise, energy balance and systemic leptin in humans. These studies provide a clear explanation for the apparent lack of an acute effect of exercise on systemic leptin and underscore the importance of clearly defining the balance between energy intake and energy expenditure when studying the physiology of leptin. The aim of this brief review is to provide an overview of the interaction between energy expenditure during physical activity and systemic leptin level. Special emphasis will be placed on those studies in which energy intake/balance was carefully controlled.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

With the increase in survival rates of children born prematurely, issues related to their active pursuits and responses to exercise have been gaining increasing attention. In some preterm children with an extremely low birthweight, bronchopulmonary dysplasia or cerebral palsy exercise capacity may be limited, especially in tasks requiring good neuromotor coordination. Deficiencies in aerobic and anaerobic performance, strength and coordination may even occur in children without overt manifestations of a neuromuscular or pulmonary disease. However, as a rule, children born prematurely may engage in physical activities and competitive sports without limitations. Exercise is safe in almost all such children as long as precautions are taken to avoid exercise-induced bronchoconstriction. However, to date there are no studies that have determined the efficacy of training. A wide variety of activities should be encouraged in all children born prematurely at an early age, to support the development of skills and to compensate for the possible effects of their premature birth on coordination.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

A high prevalence of asthma and airway hyperresponsiveness (AHR) has been reported in the athlete population. Factors potentially predisposing athletes to these conditions have not been clearly identified. Although moderate exercise has been shown to be beneficial in patients with asthma, repeated high-intensity exercise could possibly contribute to the development of asthma and AHR. This report provides an overview of the prevalence and possible mechanisms of development of asthma and AHR in the athlete population. The prevalence of asthma and AHR are higher in athletes than in the general population, particularly in swimmers and athletes performing sports in cold air environments. Possible mechanisms involved in the development of asthma in athletes are still uncertain; however, the content and physical characteristics of the inhaled air seem to be important factors, while immune and neurohumoral influences could play a modulatory role. This report stresses the need for further studies to better define the aetiologic factors and mechanisms involved in the development of asthma and AHR in athletes, and proposes relevant preventive and therapeutic measures.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

Since it is generally accepted that the onset of many chronic diseases lies in early childhood, preventive strategies should start as early in life as possible. Physical inactivity is recognised as an important determinant for chronic disease and the prevalence of physical inactivity is increasing during adolescence. Therefore, in the last 10 years much effort has been put into the development of physical activity guidelines for children and adolescents. In this critical review it is shown that the scientific evidence on which these guidelines are based is rather weak. There is only marginal evidence that physical activity during youth is related to adult health status. There is, however, hardly any evidence for a certain dose-response relationship or a particular threshold value from which guidelines can be obtained. Furthermore, it can be suggested that although the value of physical activity guidelines for children and adolescents for public health purposes is beyond doubt, perhaps these guidelines should focus on aspects other than possible health benefits.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS

摘要:

Mild sports-related concussions, in which there is no loss of consciousness, account for >75% of all sports-related brain injury. Universal agreement on concussion definition and severity grading does not exist. Grading systems represent expertise of clinicians and researchers yet scientific evidence is lacking. Most used loss of consciousness and post-traumatic amnesia as markers for grading concussion. Although in severe head injury these parameters may have been proven important for prognosis, no study has done the same for sport-related concussion. Post-concussion symptoms are often the main features to help in the diagnosis of concussion in sport. Neuropsychological testing is meant to help physicians and health professionals to have objective indices of some of the neurocognitive symptoms. It is the challenge of physicians, therapists and coaches involved in the care of athletes to know the symptoms of concussion, recognise them when they occur and apply basic neuropsychological testing to help detect this injury. It is, therefore, recommended to be familiar with one grading system and use it consistently, even though it may not be scientifically validated. Then good clinical judgement and the ability to recognise post-concussion signs and symptoms will assure that an athlete never returns to play while symptomatic.

ISSN:0112-1642    

出版商:ADIS    

年代:2001

数据来源: ADIS