摘要:

SummaryLipoprotein abnormalities constitute a major risk for development of cardiovascular disease. These substances, which are comprised of various lipids and proteins (apoproteins), are influenced by specific enzymes which eject their concentrations. It has been demonstrated that elevated total cholesterol and LDL cholesterol are directly associated with the development of coronary artery disease, whereas HDL cholesterol has an inverse relationship with coronary heart disease (CHD). Although more controversial, triglycerides may also be directly associated with coronary atherosclerosis. Favourable changes in lipid levels have been shown to reduce coronary mortality. Exercise may constitute a non-pharmacological approach to lipoprotein therapy.Many exogenous factors also influence lipoprotein concentrations. Changes in diet, body composition, age, as well as medication and akohol usage may directly alter lipid levels. In addition, they can be artificially affected by the analytical method.The immediate effects of one to several bouts of physical activity appear to influence lipoprotein level A reduction in triglycerides has been shown afler physical exertion, especially among trained individuals and those with hypertriglyceridaemia. These acute changes may reflect the utilisation of both muscle and plasma triglycerides as fuels during exertion. After more prolonged training, changes in lipoproteins may also occur. However, since exercise is accompanied by many co-variables which also favourably alter these levels (e.g. lower percentage of body fat, dietary alterations), it is difficult to determine the direct effect of regular physical activity. Initial studies of exercise training’s ejects on total cholesterol did not differentiate changes in HDL and LDL cholesterol. Subsequent research has observed these specific cholesterol fractions. Consistant reduction in LDL cholesterol levels have not been convincingly demonstrated. Although HDL cholesterol has been shown to increase in certain studies, the response has been variable in other investigations. These latter responses may have been due to the fact that HDL cholesterol changes may be dependent on levels prior to conditioning. Assessment of HDL cholesterol subfractions (HDLL2and HDL3), which could additionally impact on cardiovascular risk reduction, have shown favourable increases in HDL2, but as yet these HDL moieties have not been adequately investigated. Reductions in triglyceride levels ajier training among those with elevated values and benecial apoprotein changes post-training have been reported, although few studies exist.Recent research suggests that improved lipid profiles after exercise may be due to alterations in lipoprotein enzyme activity. This area will be important in the future and offers promise for explaining the relationship of exercise and lipoprotein change, as well as the variability of response observed among individuals.Although most studies have considered aerobic training, other forms of exercise such as resistive or strength training, may also evoke favourable lipoprotein changes. Additionally, a preponderance of exercise and lipid research have concerned men. Women have generally shown a lowering of lipoprotein risk factor levels after training. Previously reported contrary data probably reflects women’s pre-exercise low risk lipid profiles.A reduction in coronary mortality has been associated with an active lifestyle. Likewise, an association between exercise and beneficial lipoprotein levels exists. Further prospective randomised studies of individuals with lipoprotein abnormalities, controlled for confounding variables, are necessary before the ejects of physical exertion and lipid metabolism are more clearly understood.

ISSN:0112-1642    

DOI:10.2165/00007256-198704050-00001

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryA variety of beverages formulated to provide fluid, carbohydrates, and electrolytes during and following exercise are commercially available. Such ‘sport drinks’ commonly contain 4 to 8% carbohydrate (as glucose, fructose, sucrose or maltodextrins) and small amounts of electrolytes (most often sodium, potassium, and chloride). The efficacy of consuming such beverages has been questioned primarily because of concern that beverage carbohydrate content may inhibit gastric emptying rate and fluid absorption during exercise, thereby jeopardising physiological homeostasis and impairing exercise performance.Gastric motor activity, and consequently gastric emptying rate, is governed by neural and humoral feedback provided by receptors found in the gastric musculature and proximal small intestine. Gastric emptying rate may be influenced by a variety of factors including, but not limited to, the caloric content, volume, osmolality, temperature, and pH of the ingested fluid, diurnal and interindividual variation, metabolic state (rest/exercise), and the ambient temperature. The caloric content of the ingested fluid appears to be the most important variable governing gastric emptying rate, providing a mean caloric efflux from the stomach of 2.0 to 2.5 kcal/min for ingested fluid volumes less than 400ml.At rest, gastric emptying is inhibited by solutions containing calories in a manner independent of the nutrient source (i.e. carbohydrate, fat or protein). Consequently, plain water is known to empty from the stomachs of resting subjects at rates faster than solutions containing calories. Gastric emptying is increasingly inhibited as the caloric content of the ingested fluid increases.During moderate exercise (2 hours). Many commercially available carbohydrate-electrolyte beverages provide electrolytes in quantities that may reduce the risk of fluid/electrolyte imbalances. Yet, the electrolyte content of most carbohydrate-electrolyte beverages is sufficiently dilute that hyperelectrolytaemia in response to consuming even large quantities of these beverages is highly unlikely.Cardiovascular and thermoregulatory function during prolonged exercise are as well maintained when subjects consume carbohydrate-electrolyte beverages as with plain water alone. Core temperature, mean skin temperature,.plasma volume, heart rate, plasma osmolality, and plasma electrolyte content change similarly during prolonged exercise in the heat whether subjects consume plain water or a carbohydrate-electrolyte beverage.Performance, as assessed by exercise time to exhaustion or by time to complete a predetermined exercise task, has frequently been shown to be enhanced by carbohydrate feeding during prolonged exercise. Whether this ergogenic effect is linked to sparing of muscle and liver glycogen, maintenance of plasma glucose concentration or other factors remains to be determined.The organoleptic properties of fluid replacement beverages are important and often overlooked elements in preventing dehydration. Voluntary fluid consumption during exercise in the heat is known to be greater with sweetened, flavoured beverages than with plain water.

ISSN:0112-1642    

DOI:10.2165/00007256-198704050-00002

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryWith increasing involvement of young children in competitive sports there have been many studies on the cardiorespiratory response of children to endurance training. There were many methodological and design restrictions which limited the depth of studies in this area and made comparisons across studies difficult. Sufficient experimental progress has been made to draw the following conclusions. Trained children exhibit higher V̇2maxvalues than do untrained children. These differences are present irrespective of the ages of the children but are more pronounced in many cases in older children. Exercise programmes which are of sufficient intensity, frequency and duration lead to improvements in cardiorespiratory capacity. The minimum and optimum levels for intensity, frequency and duration have not yet been identified. The majority of the current literature assumes that children respond to endurance training in a manner similar to that of adults. This point needs further verification. The age or maturity level during which exercise training exerts its greatest effect on the cardiorespiratory system has not been clearly identified.

ISSN:0112-1642    

DOI:10.2165/00007256-198704050-00003

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryThe management of ligamentous injuries to the ankle is controversial. Neither the methods for classification and diagnosis, or the procedures for treatment are clear cut.Ankle sprains are a common occurrence, with the majority involving the lateral ligament complex. Within this complex, the anterior talofibular ligament is injured most frequently, usually while the foot is in the plantar flexed position.Ankle injuries can be diagnosed through physical exam, including the anterior drawer test and/or a stress exam, or through roentgenographic evaluation. The purpose of the stress roentgenogram is to measure the degree of talar tilt. However, it does not always yield consistent, reliable results. This inconsistency has led to the use of arthrography. There is debate over its use as well, howeverAnkle sprains can be classified into three groups, according to functional loss. Treatment for first and second degree sprains is usually non-operative. The best approach to Grade III sprains is debatable. The issues in the treatment of Grade III sprains are first, whether treatment should be operative or non-operative, and second, whether non-operative treatment should emphasise immobilisation or mobilisation. Brostrom’s work is cited as noteworthy. He recommended adhesive strapping followed by mobilisation as the treatment of choice, and reserves surgery for cases of chronic instability. Results demonstrated that strapping yielded shorter disability periods, while surgery produced less instability. The prevention of functional instability is a major concern in the treatment of ankle injuries.There is no consensus for treating a lateral ligament rupture. The authors suggest immobilisation followed by a rehabilitative programme. Three methods of immobilisation are plaster casting, adhesive strapping, and the air-stirrup. The physiological mechanism of cryotherapy and thermotherapy are discussed briefly and recommendations for their use are provided. Aspiration is also discussed.Loss of motion is designated as a primary cause of chronic pain and reinjury, and exercises intended to restore range of motion are provided. Exercises aimed at restoring strength and proprioception are also presented. This allows for return to activity and serves to prevent reinjury.

ISSN:0112-1642    

DOI:10.2165/00007256-198704050-00004

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS