ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Congestive heart failure is a widely prevalent sequel to myocardial infarction and other chronic conditions (including ischaemia without infarction, hypertension, various infections, toxic metabolic and endocrine disorders). Exercise tolerance is severely limited; the cardiac ejection fraction is often less than 20% and the peak oxygen intake may be less than 10 ml/kg • min, with a resulting deterioration in the quality of life.Possible factors contributing to the poor tolerance of exercise include: (i) disturbances of myocardial function (damage to the ventricular wall; decreased inotropic response, mitral valve regurgitation and increased diastolic pressures); (ii) peripheral vascular factors (decreased metaboreceptor discharge, reduced vasodilator response, increased activity of sympathetic afferents and less efficient distribution of cardiac output); (iii) hormonal disturbances (increases of catecholamines, renin/angiotensin/aldosterone, antidiuretic and natriuretic factors, endothelin and decreased endothelium-relaxing factor); (iv) impaired muscle function (loss of lean tissue, increase of type II fibres, increased impedance to perfusion, enzyme changes); (v) ventilatory disturbances (increased oxygen cost of activity, pulmonary congestion, increased ventilatory drive, mismatching of ventilation and perfusion, increased anaerobic effort); and (vi) psychological factors (anxiety, depression and iatrogenic limitation of effort).The prognosis with conventional treatment is poor, but patients with stable congestive heart failure respond favourably to a progressive exercise programme. Reported gains depend on the cause of congestive failure, initial status, study duration and compliance, and the type of training programme. Most studies to date have been short term (4 to 16 weeks), and relatively few have adopted a randomised controlled design. Suggested bases for the enhancement of aerobic performance of up to 20% include an increased intensity of peak effort, an enhanced matching of ventilation to perfusion, improved cardiac function, a strengthening of skeletal muscle and an increase of aerobic enzyme activity in the muscles.A few studies have continued for a year or longer and it appears that the gains realised over the first 16 weeks of training can be sustained for this period; the quality of life is enhanced, but data are as yet insufficient to judge effects upon mortality rates.Useful clinical information can be obtained from a 6-minute walk, but the choice for more precise evaluation lies between a measurement of ventilatory threshold or peak oxygen intake. Given initial muscle wasting, prescribed exercise should include both aerobic activity and resisted muscle exercises.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Ergospirometry is a diagnostic procedure to continuously measure respiration and gas metabolism during ergometer exercise. It enables judgement of function and performance capacity of the cardiopulmonary system and metabolism. Ergospirometry is made up of the 2 components spirometry and ergometry. The first attempts to measure human gas metabolism while performing quantified physical work can be traced back to the year 1790. The development of procedures to measure gas metabolism and respiration as well as the construction of ergometers in the nineteenth and twentieth centuries are described.Ergospirometry and routinely performed clinical performance diagnosis were introduced in 1929, but it was not until the 1950s when the first ergospirometry apparatus which met all scientific requirements was developed. The parameters used and the physiological and pathophysiological findings by ergospirometry are given in an historical frame. Numerous medical fields have profited from the technique of ergospirometry, for example: cardiology, pneumology, sports medicine, exercise physiology, biochemistry, clinical pharmacology, surgery, orthopaedics, paediatrics and gerontology, besides such global disciplines as preventive medicine, exercise therapy and rehabilitative medicine.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Overtraining is defined as an increase in training volume and/or intensity of exercise resulting in performance decrements. Recovery from this condition often requires many weeks or months. A shorter or less severe variation of overtraining is referred to as overreaching, which is easily recovered from in just a few days. Many structured training programmes utilise phases of overreaching to provide variety of the training stimulus. Much of the scientific literature on overtraining is based on aerobic activities, despite the fact that resistance exercise is a large component of many exercise programmes. Chronic resistance exercise can result in differential responses to overtraining depending on whether either training volume or training intensity is excessive. The neuroendocrine system is a complex physiological entity that can influence many other systems. Neuroendocrine responses to high volume resistance exercise overtraining appear to be somewhat similar to overtraining for aerobic activities. On the other hand, excessive resistance training intensity produces a distinctly different neuroendocrine profile. As a result, some of the neuroendocrine characteristics often suggested as markers of overtraining may not be applicable to some overtraining scenarios. Further research will permit elucidation of the interactions between the neuroendocrine system and other physiological systems in the aetiology of performance decrements from overtraining.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS

摘要:

Squash is a moderate to high intensity sport which demands specific fitness. Squash at any level places a high demand on the aerobic system for energy delivery during play and recovery. In addition, the sport requires bursts of intense, anaerobic physical activity involving the lactic anaerobic energy system. Players must possess appropriate levels of local muscular endurance, strength, power, flexibility and speed, combined with agility, balance and co-ordination. Irrespective of the standard of play, aerobic fitness training and specific anaerobic training should be undertaken by all who play or intend to play squash. Aerobic fitness for the individual who is new to the game and has little training background can be improved using low intensity continuous running. Training sessions and matches should be preceded by warm-up and flexibility exercises which may reduce the chance of injury and enhance readiness to perform.Despite squash being an indoor sport, it is likely that play in hot and humid weather may generate significant thermal loads with the associated elevations in heart rate. Fluid losses of 2 L/min and rectal temperatures of 39°C may occur, thereby increasing the cardiovascular stress of participation and the risk of heat illness. Sudden death and other manifestations of heart disease can occur in squash, therefore advice regarding the safe participation for those with, or who have the potential to develop disease appears essential. For those under 40 years of age who are well and have no known heart disease, medical clearance is not mandatory prior to taking up squash; for such individuals, regular medical monitoring may be unnecessary. For healthy individuals older than 40 years of age irrespective of health status, but particularly for those with coronary disease or relevant risk factors, a medical checkup is recommended prior to, and at least annually after taking up squash. Healthy individuals older than 40 years of age with one or more risk factors require a medical checkup prior to commencing squash for the first time and at regular intervals (every 2 years) thereafter. These individuals should also have a medically supervised exercise test. Those individuals older than 40 years of age who have a known history of heart disease, most commonly coronary artery disease, may play squash if it is demonstrated that, on examination or following therapy or surgery, they can exercise safely to a high workload.Most eye injuries which occur in squash are related to eye/ball and eye/racquet contact. The incidence of injury is very low but such injuries may be totally preventable. Ideally, all players should wear protective eye apparatus. The ‘ideal’ protective apparatus should comply with the Australian/New Zealand Standard for eye protectors for racquet sports.It should be recognised at the outset that there is a paucity of specific data regarding squash and pregnancy. Most women with normal pregnancies may continue to exercise and play squash particularly in the early stages of pregnancy but should notify their physician of their intention to do so.Musculo-skeletal injuries to the lower limb dominate most studies and common injuries include sprains and strains to the back and ankles. Of particular interest is the development of degenerative hip disease in elite squash players necessitating retirement or curtailment of activity in the third decade.Dealing with injuries and illness that are attributed to squash requires an approach based on prevention as well as on appropriate injury management.

ISSN:0112-1642    

出版商:ADIS    

年代:1997

数据来源: ADIS