摘要:

From observational studies to clinical trials in a variety of populations and age groups, evidence is mounting in support of the hypothesis that physical activity plays a significant role in the prevention of type 2 diabetes mellitus. Based on the current findings, it is likely that physical activity can reduce the risk of diabetes mellitus development. What is less clear is how much physical activity is necessary, and for how long.Obviously, we are more likely to see the anticipated physiological changes if we maximise the dose. Yet, although maximal is better from a physiological point of view, we ‘in the trenches’ have also recognised the fact that a sedentary individual will most likely not continue to undergo a high intensity activity exercise regimen. In contrast, evidence is mounting regarding long term compliance to moderate levels of activity, which appear to be easier to adopt in one's lifestyle and are less likely to result in injury. More importantly, there appear to be beneficial changes in insulin sensitivity and glucose tolerance in the sedentary individual who incorporates moderate levels of activity such as walking into the their lifestyle, although the onset of beneficial metabolic changes appear to occur much more slowly and less dramatically than what occurs with a high intensity regimen.Even if activity is shown to be beneficial, we are faced with the challenge of reaching the sedentary individuals who would most likely benefit from an increase in physical activity in the first place. This task is a difficult one because of the difficulty in quantifying the sum total of an entire day's worth of movement, rather than that of a few relatively higher intensity leisure activities. What is needed is a measure or combination of measures of physical activity that are simple to use, relatively inexpensive, and adequately capture the subtle changes in physical activity through the day that we are encouraging.It is unlikely that the protective nature of a physically active lifestyle in preventing diabetes mellitus will have a lasting impact once a switch to a sedentary way of life is made. Therefore, from a public health viewpoint, long term commitments to increased activity are required. This is the ultimate challenge.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Critical power (CP) is a fundamental concept describing fatigue and exhaustion. The main physiological determinant of CP is the ability to utilise oxygen. This in turn is dependent primarily on diffusion distance. During exercise, many different tissue systems must increase their metabolic demand. It is argued that each tissue system, such as cardiac, respiratory and leg muscles, has their own CP. Cardiac muscle has the greatest CP relative to its maximum power because it has the shortest diffusion distances. Respiratory muscle also has a substantially higher relative CP than leg muscle. The higher relative CPs of cardiac and respiratory muscle are due in part to the homeostatic functions these tissues provide. This built in protective design can be disrupted in certain conditions such as hypoxia. During high intensity exercise, fatigue and ensuing exhaustion will occur if any contributing physiological system functions above its CP.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Physical activity may play an important role in the management of mild-to-moderate mental health diseases, especially depression and anxiety. Although people with depression tend to be less physically active than non-depressed individuals, increased aerobic exercise or strength training has been shown to reduce depressive symptoms significantly. However, habitual physical activity has not been shown to prevent the onset of depression. Anxiety symptoms and panic disorder also improve with regular exercise, and beneficial effects appear to equal meditation or relaxation. In general, acute anxiety responds better to exercise than chronic anxiety. Studies of older adults and adolescents with depression or anxiety have been limited, but physical activity appears beneficial to these populations as well. Excessive physical activity may lead to overtraining and generate psychological symptoms that mimic depression. Several differing psychological and physiological mechanisms have been proposed to explain the effect of physical activity on mental health disorders. Well controlled studies are needed to clarify the mental health benefits of exercise among various populations and to address directly processes underlying the benefits of exercise on mental health.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

The purpose of this review is to evaluate the effectiveness of commercially available sports drinks by answering the questions: (i) will consuming a sports drink be beneficial to performance? and (ii) do different sports drinks vary in their effectiveness? To answer these questions we have considered the composition of commercially available sports drinks, examined the rationale for using them, and critically reviewed the vast number of studies that have investigated the effectiveness of sports drinks on performance. The focus is on the drinks that contain low carbohydrate concentrations (<10%) and are marketed for general consumption before and during exercise rather than those with carbohydrate concentrations >10%, which are intended for carbohydrate loading.Our conclusions are 3-fold. First, because of variations in drink composition and research design, much of the sports drinks research from the past cannot be applied directly to the effectiveness of currently available sports drinks. Secondly, in studies where a practical protocol has been used along with a currently available sports beverage, there is evidence to suggest that consuming a sports drinks will improve performance compared with consuming a placebo beverage. Finally, there is little evidence that any one sports drink is superior to any of the other beverages on the market.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Participation in rugby football can expose individuals to a variety of infectious diseases both on and off the field of play. The close physical contact and trauma inherent in playing rugby facilitates the transmission of viral, bacterial and fungal pathogens between players and may also lead to the acquisition of potentially lethal infections from the environment, such as tetanus. In the past few years there have been a number of reported outbreaks of infection amongst rugby players in the medical literature. The appearance of HIV infection has focused attention on the potential for transmission of this and other blood-borne viruses such as hepatitis B and C viruses from bleeding wounds sustained on the rugby field. As a result, various expert bodies have produced guidelines on the management of players with bleeding wounds. Opportunities are now available to rugby players to play outside their own countries, including the third world. This can bring them into contact with a wide range of travel-associated infections, some of which may be life threatening. In view of the above it is clear that rugby players and those who coach and manage rugby teams require information and education on the subject of infection and its prevention, as well as access to appropriate medical care and expertise. Many of the infections seen in rugby players are preventable, e.g. by promoting hygienic facilities and conduct in changing rooms and on the field of play, by exclusion of infected players from contact with others and, in some cases, by immunisation or chemoprophylaxis. Players who present with infections should be assessed, correctly diagnosed (using laboratory investigations where appropriate) and treated, and measures should be taken to prevent spread to team-mates and other contacts while respecting the confidentiality of the individual. Any outbreaks of infection should be reported to the appropriate authorities. There is evidence to suggest that strenuous physical exercise such as playing rugby can make individuals susceptible to certain types of infection and prolong time to recovery. More information is required on the true frequency and effects of infection in rugby players.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS