ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00001

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00002

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryIncreased serum enzyme activity after exercise was first reported in 1958; subsequent studies have established that many factors determine the degree to which the serum activities of a variety of enzymes increase during and after exercise.The serum activities of those enzymes found especially in muscle, particularly creatine kinase, increase in proportion to the intensity and duration of the preceding exercise, peaking 24 hours after exercise; the effect of duration is dominant, so that the highest postexercise serum enzyme activities are found after very prolonged competitive exercise such as ultradistance marathon running or triathlon events. Weight-bearing exercises which include eccentric muscular contractions such as bench stepping and downhill running induce the greatest increases in serum enzyme activities; serum enzyme activities increase very little even after prolonged participation in those non-weight-bearing activities such as swimming and cycling which do not include eccentric muscular contractions. Prolonged (>2 hours) daily training or competition in weight-bearing activities produces chronically elevated serum enzyme activities. Serum enzyme activities increase more with exercise in males, Blacks and the untrained than th ey do in females, Whites and the trained, respectively; age does not appear to influence the degree to which serum enzyme activities increase with exercise. There is a remarkable individual variability in the degree to which serum enzyme activities increase with exercise; a 50-fold difference in post-race serum creatine kinase activities has been found in healthy and equally trained athletes completing the same 90km ultra-marathon footrace. The biochemical explanation for this degree of individual variability is not currently understood; possibly persons who show abnormally large increases in serum enzyme activities with exercise may have as yet unrecognised subclinical myopathies. No circadian rhythms have been identified for serum enzyme activities; activities rise during the day because of increased physical activity. The rise in serum enzyme activities is greater after exercise at altitude or in the heat than after equivalent exercise at sea level or in the cold.The most likely explanation for the increased serum enzyme activities that follow prolonged weight-bearing activities that also cause marked muscle soreness, is myofibrillar damage in particular sarcomeric Z-disk disruption. Alternate postulates such as sarcolemmal damage due to muscle glycogen depletion or lipid peroxidation seem less likely as they fail to explain the very different responses of serum enzyme activities to equivalent running or cycling exercise, both of which induce the same degree of muscle glycogen depletion and free radical production. The rise in serum enzyme activities that occurs, particularly after prolonged exercise such as marathon running, mimics exactly the changes that occur with acute myocardial infarction; thus the clinical interpretation of increased serum enzyme activities in persons who are physically active must be approached with extreme caution. The value of alternate diagnostic tests including the measurement of the serum content of the acute phase response protein s to distinguish the normal exercise response from that occurring during acute myocardial infarction, has yet to be determined. Serum creatine kinase activity measured both at rest and after exercise is useful in the diagnosis of Duchenne muscular dystrophy and, in particular, in the detection of the female carriers of this condition. There is, as yet, no proven value in the routine measurement of serum enzyme activities in athletes in training. In particular, serum enzyme activities cannot distinguish between appropriate training and overtraining. In addition, especially after very prolonged exercise such as ultra-marathon running, serum enzyme activities return to normal weeks or even months before normal running performance returns. Thus, complete recovery from prolonged exercise cannot be predicted on the basis of serum enzyme activities.At present, the most interesting clinical application for the measurement of serum enzyme activities in the active and apparently healthy population might be the identification of subclinical myopathies, some of which may predispose to the development of acute renal failure or heatstroke during very prolonged exercise.

ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00003

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryAnaerobic tests are divided into tests measuring anaerobic power and anaerobic capacity. Anaerobic power tests include force-velocity tests, vertical jump tests, staircase tests, and cycle ergometer tests. The values of maximal anaerobic power obtained with these different protocols are different but generally well correlated. Differences between tests include factors such as whether average power or instantaneous power is measured, active muscle mass is the same in all the protocols, the legs act simultaneously or successively, maximal power is measured at the very beginning of exercise or after several seconds, inertia of the devices and body segments are taken into account.Force-velocity tests have the advantage of enabling the estimation of the force and velocity components of power, which is not possible with tests such as a staircase test, a vertical jump, the Wingate test and other long-duration cycle ergometer protocols. Maximal anaerobic capcity tests are subdivided into maximal oxygen debt test, ergometric tests (all-out tests and constant load tests), measurement of oxygen deficit during a constant load test and measurement of peak blood lactate. The measurement of the maximal oxygen debt is not valid and reliable enough to be used as an anaerobic capacity test. The aerobic metabolism involvement during anaerobic capacity tests, and the ignorance of the mechanical efficiency, limit the validity of the ergometric tests which are only based on the measurement of work. The amount of work performed during the Wingate test depends probably on glycolytic and aerobic power as well as anaerobic capacity. The fatigue index (power decrease) of the all-out tests is not reliable and depends probably on aerobic power as well as the fast-twich fibre percentage. Reliability of the constant load tests has seldom been studied and has been found to be rather low. In theory, the measure of the oxygen deficit during a constant load test is more valid than the other tests but its reliability is unknown. The validity and reliability of postexercise blood lactate as a test of maximal anaerobic capacity are probably not better than that of the current ergometric tests. The choice of an anaerobic test depends on the aims and subjects of a study and its practicability within a testing session.

ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00004

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

摘要:

SummaryDrugs that induce an increased urine flow are used both legitimately (treatment of hypertension and oedema) and otherwise (rapid weight loss) in sports and exercise. There are 5 major categories of diuretic drugs based on their mechanisms and loci of action. Common to all classes is hypohydration, which has been shown to have an array of adverse effects on performance, including impaired strength, power and endurance. Postural hypotension can be particularly troublesome in the elderly.Also common to all diuretics, except those interfering with the aldosterone mechanism in the distal nephron, is hypokalaemia. Severe symptomatic hypokalaemia (serum K+concentration<3.0 mmol/L) is rare except in clinical situations in which additional hypokalemic factors are present. Moderate levels of hypokalaemia (serum K+concentration 3.0 to 3.5 mmol/L) can increase the risk of adverse reactions as has been shown in a variety of prospective clinical studies. Hypokalaemia has effects on cardiac rhythm, muscle function and integrity, local blood flow, carbohydrate metabolism, and the blood lipid profile.Performance studies generally show diminished exercise tolerance in direct proportion to the degree of hypohydration induced. This is not the case, however, in a clinical setting of compromised cardiopulmonary function, in which diuresis has direct and indirect inotropic effects which augment exercise tolerance and decrease symptoms.The ability of the carbonic anhydrase inhibitor, acetazolamide, to induce a hyperventilatory response to the obligatory metabolic acidosis is taken advantage of in mountaineering to prevent or ameliorate the symptoms of acute mountain sickness, thereby improving exercise performance at high altitude.It is suggested that in clinical situations in which the use of a diuretic is considered appropriate, every effort be made to maintain or restore the serum concentration and the total body store of potassium to normal. To some degree this can be accomplished through diet, although potassium chloride supplements or potassium-sparing diuretics or diuretic combinations may be necessary.

ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00005

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS

ISSN:0112-1642    

DOI:10.2165/00007256-198704040-00006

出版商:Springer International Publishing    

年代:2012

数据来源: ADIS