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Auto: In 1-shot AF mode with evaluative metering exposure is locked when focus is achieved. Manual: By AE lock button in creative zone modes. Available range varies by shooting mode.

White balance compensation: 1. Erase: Single image, All images in folder, Checkmarked images, unprotected images Protection: Erase protection of one image at a time.

Windows XP inc. SP2 excl. SP1 excl. Varies depending on the subject, memory card brand and capacity, image recording quality, ISO speed, drive mode, Picture Style, Custom functions etc. Canon Logo. Canon EOS D. Canon Medical Left Right. Print Specification. Effective Pixels. Total Pixels. Aspect Ratio. Low-Pass Filter. Sensor Cleaning. Manual cleaning and Dust Delete Data acquisition. Colour Filter Type. Lens Mount. Focal Length. Equivalent to 1. AF Working Range. AF Modes. AF Point Selection.

Automatic selection, Manual selection. Selected AF Point Display. Superimposed in viewfinder and indicated on LCD monitor. Predictive AF. AF Lock. Locked when shutter button is pressed half way in One Shot AF mode. AF Assist Beam. Intermittent firing of built-in flash or emitted by optional dedicated Speedlite.

Manual Focus. Metering Modes. Metering Range. AE Lock. In terms of healthy and well-motivated young adults, this question was largely answered by the observations of the International Biological Programme Working Party on the standardization of exercise tests; in CE, they demonstrated that plateau values were obtained consistently during repeated testing of 24 young men, irrespective of whether a continuous ramp or discontinuous test protocol was used Shephard et al.

Maximal testing yielded plateaus less consistently in prepubescent children and the elderly. Nevertheless, the IBP Working Party were able to obtain a clear plateau in 35 of a representative sample of 47 young urban children Shephard et al. Likewise, in seniors aged 65—84 years, a plateau was reached in 37 of 55 subjects at their first attempt at maximal exercise, and about a half of the remaining subjects reached a plateau when they were retested Sidney and Shephard Moreover, both in the children and the seniors, failure to reach a plateau was associated with evidence of poor motivation such as a low peak heart rate, a low respiratory gas exchange ratio and low peak lactate readings Sidney and Shephard ; Shephard During the s, capillary blood lactate concentrations were usually determined by the Boehringer enzymatic method Mohme-Lundholm et al.

The portable analyzers also employed an enzymatic electrode system, and their normally acceptable accuracy could be disturbed if they were used at cold temperatures Franklin Respiratory physiologists have continued to examine factors that can limit oxygen transport through much of the Post-Modern Era Table 9. Both the late John Sutton Sutton and Peter Wagner Wagner have had a similar idea of looking at oxygen consumption as a closely linked chain reaction.

By applying the analogue of an electrical conductance Shephard a , and looking at the distribution of gas pressure gradients, I concluded that for oxygen the most important factor limiting oxygen transport in the average healthy individual was blood stream conductance the product of peak muscle blood flow and the oxygen carrying capacity of unit volume of blood Shephard , However, a variety of other factors can limit oxygen transport, both in athletes with a very large maximal oxygen intake, and in individuals with chronic disease Table 9.

Fatigue of the respiratory muscles is a minor factor in most healthy individuals Macklem , but in some people, maximal performance may be limited by the sensation of dyspnoea, which depends in part on the strength of the inspiratory muscles Killian and Campbell In athletes who develop very high respiratory flow rates, during maximal exercise, collapse of the airway and a limitation of expiratory gas flow can also become a significant factor Grimby et al.

The maximal circulatory transport of oxygen depends on pulmonary venous blood being almost fully saturated with oxygen during its passage through the lungs; however, in some athletes, a poor matching of ventilation and perfusion may cause a significant desaturation of pulmonary venous blood during maximal effort Gledhill et al.

In the central circulation, the maximization of stroke volume can be limited by poor venous tone and thus a limitation of venous return, as in vaso-regulatory asthenia Holmgren ; this problem is most likely when a person is exercising in the vertical position, and is avoided when swimming.

Maximal circulatory transport also depends on the peak heart rate; the maximal heart rate decreases with age, and it may also be limited by the administration of beta-blocking drugs. Athletes may attempt to boost their haemoglobin concentration and thus oxygen carriage per unit of cardiac output by high altitude residence Stray-Gunderson et al.

Conversely, anemia can compromise the volume of oxygen transported per unit of cardiac output. When exercising in an urban environment, the oxygen carrying capacity of the blood may be reduced by exposure to carbon monoxide Wright and Shephard Again, the efficiency of circulatory transport depends upon the almost complete removal of oxygen from the capillaries within the active muscles.

The capillary density per muscle fibre can be enhanced by training, thus tending to facilitate tissue diffusion and peripheral oxygen extraction; however, because of associated hypertrophy of the muscle fibres, the average diffusion distance from the capillary to the muscle membrane is not necessarily diminished by aerobic training Hermansen and Wachtlova Finally, the ability of muscle to consume the oxygen that is delivered to it depends on local energy reserves, delivery of substrates and an adequate level of aerobic enzyme activity within the muscle mitochondria.

One important factor influencing the blood transport of any gas is its effective solubility in blood. For oxygen, the sigmoid shape of the dissociation curve has long been recognized; the average solubility factor for oxygen, integrated between arterial and venous blood, is around five Shephard , In contrast, for carbon dioxide, the dissociation curve is such that the effective solubility is only about a fifth of that for oxygen; in consequence, the conductances for carbon dioxide are more evenly distributed between the pulmonary and the circulatory systems Shephard , Although the measurement of oxygen consumption has been greatly facilitated by introduction of the new metabolic equipment, the resulting gains in scientific knowledge are more debatable.

Breath-by-breath analysis of oxygen consumption has certainly become possible. However, it is worth underlining that both the standardization of fitness test methodology that was conducted by the International Working Party Shephard et al. We compared the peak oxygen consumption developed when exercising with one or two legs, the arms and the forearms. We were able to show a gradation of peak oxygen intakes that correlated with anthropometric estimates of the muscle volume that had been activated Shephard et al.

Nevertheless, Tim Noakes , the controversial Professor of Physiology at the University of Cape Town, has recently challenged the usefulness of measuring maximal oxygen intake in athletes Noakes Noakes has drawn upon an idea advanced by C.

Most Exercise Scientists would agree that athletes do limit their energy expenditure in prolonged endurance events, but they regard this as a pacing tactic that has been learned in collaboration with their coaches rather than as the operation of some shadowy Central Governor; the learned objectives of the competitor are to avoid depleting glycogen reserves too early in a prolonged event, and to limit a punishing build-up of tissue lactate until the final sprint.

Practical applications of maximal oxygen intake determinations at the present time include among other items Shephard a :. The Post-Modern Era has seen considerable technical advances in electrocardiography, the use of ultrasound, and techniques for detecting obstruction of the coronary vasculature and injury of myocardial tissue.

Cardiac reactions to both acute and chronic exercise in health and disease have also been understood more clearly. However, a combination of better skin preparation, careful grounding of ancillary equipment, shielding of cables and the development of electronic averaging and filtering devices now permits quite precise measurements of average heart rates and the extent of ST segmental depression during vigorous exercise Jonson et al.

Appearance of more than 0. It was initially hoped that the quantifying of exercise-induced ST depression might identify those apparently healthy individuals who were at particular risk of a heart attack, much as Master had proposed in his study of the recovery ECG following a simple step test Chap. However, a clearer understanding of Bayes theorem and the principles of biological screening quickly dashed such hopes.

During the s, clinical investigators began to apply this mathematical concept to a critical evaluation of various current and proposed biological screening procedures Andermann et al. They soon appreciated that in a healthy population with a low prevalence of cardiac disease, the sensitivity and specificity of most exercise stress tests was such that an unacceptable proportion of patients would inevitably develop false positive test responses.

Such apparently abnormal findings would then require further evaluation, and had the potential to cause long-lasting cardiac neuroses in the individuals who were misdiagnosed Shephard Unfortunately, not everyone has yet recognized the difficulties of ECG screening implicit in Bayes theorem.

For example, a European movement centred in Northern Italy has argued strongly over the last 30 years that all athletes should receive an annual resting ECG, in the hope of detecting and avoiding the sudden exercise-related deaths that have occasionally occurred in young competitors Corrado et al.

Further, many competitors faced the expense and anxiety of undergoing secondary clearance by such techniques such as echocardiography in order to clarify that their ECG test results were false rather than true positive test results.

Italian Cardiologists claimed that as a result of the mandatory ECG screening, there was a small reduction in the number of sudden exercise-related deaths among Italian athletes. However, critics have pointed out that the incidence of such episodes was still no lower in Italy than in North America where preliminary ECG screening of athletes was not mandatory.

Many of the early diagnoses of supposedly abnormal ECGs in Italian competitors were based upon increased voltages of the QRS complex an almost inevitable consequence of a larger heart and a thinner overlying layer of subcutaneous fat.

Vigorous debate continues, but North American cardiologists still reject the idea of universal ECG screening of athletes, largely because it inevitably produces so many worrying and costly false positive test results Maron et al. A commercially available device based upon chest-strap ECG electrodes and recorder transmitting the resultant signal to a wrist-watch type monitor was developed for the Finnish ski team in CE Burke The Italian priest and physiologist Lazarro Spallanzani — CE was apparently aware of the use of sonar by bats, and ever since an Austrian Physician, Josef Leopold Auenbrugger — CE introduced the technique of thoracic percussion, clinicians have exploited the reflection of sound waves by the heart wall as a means of approximating cardiac dimensions.

During the late s, a German Physicist, W. Keidel, attempted to measure the attenuation of sound waves by the heart, but he was apparently unsuccessful in determining cardiac volumes by this technique. The first practical form of echocardiography was developed in CE Krishnamoorthy et al. Working at the University of Lund, Sweden, Inge Edler — CE and his Physicist colleague Carl Hellmuth Hertz — CE designed an ultrasound device that they termed a reflectoscope ; they used this equipment to assess cardiac dimensions in patients with mitral valve disease Edler and Lunstorm Echocardiograohy is now widely used to assess the thickness and movements of the ventricular walls Fig.

The standard clinical M-mode echocardiogram was popularized by Harvey Feigenbaum during the s. He showed that echocardiographic estimates of heart volume compared closely with the values that could be obtained by the more invasive technique of angiography Feigenbaum Dekker and colleagues Dekker et al.

Sports Physicians quickly began to exploit echocardiography, both to evaluate the health of the heart in athletes where supposed abnormalities had been detected during mandatory ECG screening, and also to search for evidence of hypertrophic cardiomyopathy, which some authors claimed was the commonest cause of sudden exercise-induced death in young athletes Maron et al. However, the setting of appropriate goal-posts for diagnosing a pathological ventricular hypertrophy such as the ratio of inter-septal to posterior wall thickness or end-systolic diameter has remained a thorny problem.

Many cardiologists have expressed concern if the ratio of interventricular septum to posterior ventricular wall thickness exceeds 1. Upper limits for the dimensions of interest have thus undergone frequent adjustment Shephard and as with other screening tests, it has been difficult to establish clear norms that are effective in distinguishing the physiological hypertrophy seen in all endurance athletes from the pathological changes associated with hypertrophic cardiomyopathy Pelliccia et al.

A recent ultra-sound study of Olympic athletes, spanning their participation in two to five Olympic Games, emphasized that despite large left ventricles, top endurance competitors normally showed no cardiovascular symptoms, and little change of left ventricular morphology or function as their sport participation continued Pelliccia et al.

In the future, a new technique that may help to differentiate physiological from pathological hypertrophy is the use of ultrasound speckle tracking; this calculates the global longitudinal strain in the ventricular muscle Butz et al.

Differentiation of transient from long-term pathologies may also emerge from ultrasound and magnetic resonance imaging of right ventricular and atrial dimensions before and after endurance competition Neilan et al. The use of ultra-sound continues to expand in the clinical sports medicine laboratory, with other applications that now include the diagnosis and treatment of musculo-skeletal injuries, the diagnosis of splenomegaly, and the estimation of bone density Yim and Corrado The detection and quantification of myocardial injury has been greatly facilitated as exercise biochemists have developed an ability to distinguish the extra-cellular release of a myocardial protein cardiac troponin from similar proteins that are released by the injury of skeletal muscle Roth et al.

Some investigators have argued that a small leakage of myocardial protein is a normal component of the process of cardiac hypertrophy Shave and Oxbrough and that magnetic resonance and echocardiographic techniques show no associated deterioration of myocardial function following a bout of prolonged endurance exercise Wilson et al.

Others have insisted that if there is release of cardiac troponin, there must be some injury to heart muscle; they have linked their findings to small immediate changes in ventricular function that resolve within a week or so following endurance competition LaGerche et al.

This debate has yet to be resolved. The mortality from acute coronary disease has been greatly reduced through the development and widespread distribution of cardiac defibrillators in public areas, particularly gymnasia and sports facilities. New techniques to visualize the coronary blood supply have also helped in detecting coronary stenosis in those individuals who develop symptoms suggestive of myocardial ischaemia, and this has served as a prelude to rapid angioplasty or by-pass surgery in those with significant vascular obstruction.

His patient was a year-old boy undergoing surgery for a congenital cardiac defect, and the direct application of an alternating current by paddles placed on the ventricles restored a normal sinus heart rhythm. In the mids, two Russian Cardiologists V.

Klimov began to experiment with applying larger alternating voltages 1, V or more to the exterior of the chest cage. In CE, Bernard Lown — of Harvard University suggested the alternative of applying a single direct current shock; this had a potential of perhaps 1, V, and an energy content of — J, discharged over 5 ms Eisenberg Lower voltages were also required for the biphasic device, thus reducing its weight, and allowing the development of portable versions for use outside of hospitals.

A further improvement was the design of an automated defibrillator that could be used by untrained lay personnel; the new equipment was able to analyze the heart rhythm, determine chest impedance and apply a shock of appropriate magnitude. Angiography was first used to examine the cerebral vasculature in CE. Introduction of radio-contrast material into the heart was facilitated by the development of cardiac catheterization Chap.

However, the first injection of radio-contrast material into the coronary artery occurred accidentally at the Cleveland Clinic in CE, when the left ventricular catheter of Mason Sones — CE slipped into one of the coronary vessels.

The patient went into cardiac arrest, but this was quickly reversed, and the potential value of the intra-coronary injection was quickly recognized.

Over the next 6 years, Sones and his colleagues reported angiographic findings in a series of over 1, patients Proudfit et al. However, magnetic resonance imaging of the heart was not applied clinically until around , with early protagonists including Goldman et al.

The idea behind this technique is that powerful magnets align hydrogen protons along the same vector, and radio wave pulses knock the protons out of alignment.

As the protons return to their original position, they send out signals. These are fed to a computer, and images of the underlying tissue are created. Cardiac and respiratory movements initially complicated imaging of the heart, but this difficulty was largely solved in the s by the use of an ECG-based gating of the image. For cardiac investigations, a contrast agent such as gadolinium is usually administered intravenously.

One can thus visualize areas of heart muscle where the contrast material does not penetrate due to coronary narrowing or occlusion. Following infarction, the area of scarred muscle appears white, in contrast with dark, normally-perfused cardiac muscle. Thallium scintigraphy was first introduced in the late s, although since the early s many investigators have preferred to use technetium, because the images are of better quality and the marker has a shorter radioactive half-life.

Despite increasing use of computed tomography and magnetic resonance imaging, in the year CE, 8. The radioactive material generates a local pulse of electromagnetic radiation that can be detected by a photomultiplier.

CT is not used routinely in clinical practice. The patient receives an intravenous injection of iodine, and the heart is then scanned by a high-speed CT scanner. It is thus more useful in ruling out coronary disease than in diagnosing it. It may also be useful in demonstrating the severity of coronary narrowing Fig. Although this range of new technology looks impressive, diagnosis and prognosis have shown quite small improvements relative to the taking of a careful clinical history. Thus, Ladenheim et al.

There is little question concerning the value of early coronary angioplasty or surgical grafting when narrowed vessels are detected; the balloon-dilation of the stenosed artery or the by-pass operation also relieve chest pain more rapidly than medical therapy.

New techniques that have facilitated the description of muscle function during the post-modern era include the development of isokinetic dynamometers, force plates, needle biopsy and non-invasive assessments of muscle metabolism. Some historians trace the origins of isokinetic equipment back to the mechanical exercise machines of Gustav Zander that appeared during the nineteenth century Chap.

Early versions of the isokinetic dynamometer allowed only concentric contraction. Pioneers included T. Hettinger , and H. Thistle, a physician interested in muscular rehabilitation Thistle et al. In CE, Perrin introduced the Cybex I isokinetic dynamometer Perrin , and this became commercially available three years later.

The equipment was enhanced by adding a variety of servo-motors and microprocessors. Several forms of isokinetic dynamometer capable of assessing both concentric and eccentric effort became commercially available during the s Abernethy et al. Because of the high retail cost and large profit margins associated with modern isokinetic equipment, various civil court actions have debated patent rights to the underlying concepts.

The use of isokinetic equipment has now become an important component of assessments undertaken in well-equipped strength testing laboratories. Machines such as the KinCom , Cybex and Biodex allow subjects to exercise at computer-controlled speeds over a pre-determined range of motion, with measurements made most easily at the knee and arm joints.

One immediate objection to the isokinetic testing of a single joint is that the results may not be representative of muscle strength in other body regions. Thus, one study of Australian football players found little relationship between the isokinetic strength of the quadriceps and their likelihood of developing hamstring injuries Bennell et al. The nature of the movement also bears little relationship to that experienced in most forms of athletic endeavour Abernethy et al.

The first force platform was used by Etienne Jules Marey Chap. The introduction of force platforms has greatly facilitated examination of the explosive force developed by the muscle groups of the legs, largely replacing the earlier jump tests of physical educators. Piezo-electric crystals measure ground reaction forces, and facilitate studies of balance and gait.

Other current methods of assessing muscle function are the Wingate test, and the calculation of force-velocity curves. Use of the Wingate test as a simple measure of the anaerobic power and capacity of the leg muscles was discussed in Chap. The force-velocity test developed by Henri Vandewalle and Hugues Monod during the s allows the extrapolation of cycle ergometer data to both the peak power at zero velocity and the peak velocity at zero loading, when using either the legs or the arms to drive the ergometer Vandevalle et al.

Needle biopsies of muscle have given new insights into both fibre types and muscle metabolism, with implications for the selection of athletes, training and sports nutrition. Throughout the s, muscle fibres were classified as having either fast or slow twitch properties, with the distinction based simply on estimations of their myoglobin content Lawrie However, in the s, classification began to be based on enzyme profile, typing fibres as slow or fast twitch based upon their content of either myosin vs.

For a while, there was considerable debate as to whether humans had an intermediate fibre type IIx , but advances in muscle protein chemistry during the s allowed resolution of this question.

A variety of fibre types were defined very precisely in terms of their main protein constituents Moss et al. He demonstrated that intramuscular stores normally provided a total body reserve of some g of glycogen, but that these reserves could be boosted by a specific dietary regimen that comprised a heavy, glycogen-depleting bout of work and three days of a fat and protein diet, followed by three days of a high carbohydrate intake Saltin and Hermansen With minor variations and simplifications, this dietary technique has become very popular as a means of boosting intramuscular glycogen stores and thus preparing endurance athletes for events lasting longer than about 90 min.

Needle biopsy of the muscles was never very pleasant for the subjects involved. Towards the end of the s, it was found that non-invasive assessments of liver and muscle glycogen could be made by nuclear magnetic resonance spectroscopy Zang et al.

Determination of overall and localized muscle volumes has been helped by the development of several techniques such as the measurement of creatinine excretion or isotopic creatine dilution, body potassium determinations based on the gamma emissions of the naturally occurring isotope 40 K, neutron activation of muscle nitrogen, dual energy x-ray absorptiometry, and nuclear magnetic resonance technology Shephard d.

Such measurements have been useful in the diagnosis of sarcopenia Park et al. Sarcopenia has been diagnosed when data for an individual fell 1 SD or more below the norms for a young and healthy reference population. Such techniques have also allowed the monitoring of rehabilitation Fiatarone et al. But for Sports Scientists without access to expensive equipment, it has also been shown that the muscle volume of the limbs can be estimated from simple anthropometric measurements of limb circumferences, bone diameters and skinfold assessments of the thickness of overlying fat Jones and Pearson ; Shephard et al.

Anthropometric estimation of lean tissue mass in lower limbs Shephard et al. New technology has allowed more precise determinations of body fat content and bone density, important pieces of information in the evaluation of both athletes liable to the female athletic triad disordered eating, amenorrhoea and osteoporosis and older sedentary populations.

New methods of estimating body fat available in hospital laboratories include the use of ultra-sound, magnetic resonance imaging, computerized tomography and dual photon absorptiometry Shephard d. In fitness laboratories, the bio-electrical impedance method has proven popular since the s Lukaski It is a safe, inexpensive and portable tool, and it allows the fitness professional to make quite rapid determinations.

Originally conceived for blood flow measurements, it was first applied to the determination of total body water and thus lean tissue mass by Hoffer et al.

The importance of the regional distribution of body fat to cardiovascular health was first noticed by Jean Vague, a physician from Marseille, in CE, with an English-language publication of his observations some 9 years later Vague He found a greater risk of various metabolic complications in individuals with a central male distribution of body fat.

His research was initially regarded with some scepticism, and it was not until the s that epidemiological research in Sweden and the U. Many options for the assessment of bone health have become available during the last fifty years, including single and dual photon absorptiometry, single and dual x-ray absorptiometry, neutron activation, computerized tomography and ultrasound Shephard d.

Methods that have proven particularly helpful in population surveys have included dual energy x-ray absorptiometry Park et al. Dual energy x-ray absorptiometry was introduced by Jay A. Stein of M. It is presently the most frequently used approach.

The relative absorption of two x-ray beams of differing energy levels allows the investigator to distinguish soft tissue from bone.

Radiation exposure is minimal, in contrast with dual photon absorptiometry, where there are problems with slowly decaying isotopes. The ultrasound approach was developed to monitor fracture healing in the s, and in CE Michael Liebschner of Rice University pioneered its application to the monitoring of bone loss in astronauts.

The osteosonic index OSI, closely correlated with dual energy X-ray energy absorptiometry data is calculated as the product of the transmission index T and the speed of transmission of the sound wave through the bone S. Both dual x-ray absorptiometry and ultrasonic data are interpreted in terms of T scores relative to normal values for healthy young adults. Until the s, few Exercise Science laboratories had the equipment to investigate immune responses to exercise, although there were occasional epidemiological studies suggesting relationships between upper respiratory infections and either a single bout of heavy endurance exercise or a period of particularly arduous training Chap.

Proof even of this relationship was somewhat tenuous, since most studies were based upon reports of respiratory symptoms rather than clinically diagnosed and virologically proven episodes of rhinovirus infection Shephard a. Development of Exercise Immunology over the past 3 decades has been spurred by new technology, with an increased study of mucosal immunoglobulins, establishment of a parallel between strenuous exercise and sepsis, appreciation of the importance of leukocyte demargination, discovery of a metabolic role for cytokines, application of reverse transcription techniques to cytokine detection, and an understanding of a complicated cascade of humoral secretions Shephard Progress in Exercise Immunology was greatly stimulated by several technical developments Chap.

Assessments of cytotoxicity became more precise as methods developed to isolate natural killer NK cells; it is now possible to express rates of lysis relative to both the NK cell count and to a unit volume of blood.

Decreases in the number and toxicity of circulating natural killer cells may contribute to an increased susceptibility to upper respiratory infections following a demanding bout of exercise. However, in recent years, interest has shifted from the NK cells towards exercise-induced changes in the protective role of the mucosal immune system, where immunoglobulins offer the primary physical, biochemical and immunological barriers to most hostile micro-organisms Tharp and Barnes The first observations on immunoglobulin responses to heavy exercise were made by Tomasi et al.

Others soon confirmed these findings, noting also some chronic suppression of salivary immunoglobulins with periods of heavy training Gleeson Laurel Mackinnon and associates were able to relate the exercise-related decreases in immunoglobulin levels to episodes of upper respiratory infection.

Camus and associates first drew attention to a possible parallel between sepsis and the immune reactions to very heavy exercise. Further, they suggested that exercise might prove a useful model for those interested in countering problems of sepsis. Three years later, an international symposium in Toronto was devoted to this question Hoffman-Goetz et al.

Although there was agreement with the concept of Camus and colleagues, encouraging continued animal experimentation, it was not thought ethical to require human volunteers to undertake an intensity of exercise sufficient to cause a long-term suppression of immune function.

Substantial changes in the circulating leukocyte count have long been observed during and immediately following a bout of vigorous exercise. Vejlens further demonstrated an association between margination and erythrocyte aggregation.

Much of the margination was flow dependent, but Crary et al. This conclusion spurred an extensive study of the modulation of the activity of adhesion molecules by hormones such as the catecholamines Shephard et al. One of the current leaders in Exercise Immunology, Bente Klarlund-Pedersen of Copenhagen, opened up a new line of enquiry with the fascinating discovery that exercise activated the IL-6 gene in skeletal muscle.

IL-6 was thus released into the blood as intramuscular glycogen stores became depleted. It appears that in addition to playing important roles in controlling responses to infection and injury, secretion of the cytokine IL-6 may make a significant contribution to metabolic regulation Pedersen et al.

The IL-6 gene is rapidly activated during exercise, and the IL-6 released from muscle can induce lipolysis, suppress TNF production and stimulate cortisol production, particularly when muscle stores of glycogen are low.

Cytokines also seem to be important regulators of muscle protein turnover Zoico and Roubenoff Determinations of plasma cytokine concentrations have proven challenging, since the circulating concentrations of these compounds are very low. Most cytokines also bind strongly to receptor molecules, have a short half-life, and are readily neutralized by circulating inhibitors. Assay methods have included radioimmunoassay, enzyme-linked immunosorbent assay ELISA , and competitive binding to a receptor molecule,.

But recently, cytokine determinations have been facilitated by the transcription of cytokine mRNAs Moldoveanu et al. The new sensitivity of methods for cytokine detection has led to the realization that circulating cytokines may be derived from sites other than circulating leucocytes. Thus, the in vitro production of cytokines by mitogen- or phytohaemagglutinin-stimulated cells may give only a partial picture of what happens in vivo.

Investigations by Northoff et al. Illustration of the complex interaction of hormones and cytokines involved in the healing process Reprinted from Northoff et al. In the planning of health and fitness interventions, it is important to ascertain how far all individuals will react in a uniform manner. If responses show substantial and genetically-related differences, this may be helpful both in selecting competitors for particular athletic events, and in understanding why some clients fail to respond to treatment despite seemingly good compliance with a prescribed lifestyle regimen.

The understanding of genetic issues during the Post-Modern Era has been advanced by twin and family studies of fitness characteristics, an analysis of inter-individual differences in training response, genome mapping, and a growing interest in epigenetic influences. Attempts at quantitative study of the genetics of physical fitness began in the early s, with comparisons of fitness levels between similar and dissimilar twins who had been exposed either to similar or to dissimilar environments during their years of growth.

Vassilis Klissouras, a Greek immigrant to Montreal, was an early pioneer in this line of research Klissouras However, different investigators obtained strikingly dissimilar data from such analyses, particularly with respect to the intra-class correlations for variables such as the maximal oxygen intake in monozygous and dizygous twin pairs Table 9. Intra-class correlations for maximal oxygen intake in monozygous MZ and dizygous DZ twin pairs see Bouchard et al.

Unfortunately, the repetition of apparently very similar analyses yielded widely differing verdicts on the partition of this variance, in part because of unmeasured interactions between genetic and environmental influences. Nevertheless, there now seems little doubt that some individuals are born with a higher maximal oxygen intake than others.

One factor that encouraged a continued search for substantial genetically determined differences in the response to training was what seemed large inter-individual differences in the gains of maximal oxygen intake when apparently similar young men followed an identical week aerobic conditioning regimen.

The immediate conclusion drawn from these experiments was that some members of the group lacked any ability to improve their physical condition by training. However, there were still substantial inter-individual differences in response after correcting for regression to the mean. Plainly, the inheritance of a high initial aerobic power and an above-average response to aerobic training give some individuals a substantial advantage in athletic events that require a large maximal oxygen intake.

The mapping of the human genome has given further impetus to the research of Sports Geneticists; a consortium of investigators led by Claude Bouchard in Quebec City is conducting research looking at linkages of specific gene configurations with the risks of cardiovascular and metabolic disease, and with fitness attributes such as maximal oxygen intake, muscle strength and the response to various training programmes Bouchard et al.

Initial studies at the Mexico City Olympic Games in CE yielded essentially negative findings in terms of inter-individual genetic differences; participants in the Games were not distinguished by allelic variations in red cell antigens or enzyme variants of red blood cells deGaray et al. Further observations at the Montreal Olympic Games in CE again disclosed no differences of red cell antigens or enzymes between athletes and controls Chagnon et al.

Individual gene variants have been linked to such factors as physical activity behaviour, cardiorespiratory fitness and endurance performance, muscle strength and power, body mass and adiposity, and characteristics of glucose and lipid metabolism.

But in most cases, individual genes seem to account for only a very small fraction of the total variance in data relating to health, fitness and training responses The discovery of substantial new information that can help the practitioner of Sports Medicine as yet remains a tantalizing distant dream.

Further advances await a better understanding of possible interactions between individual genes, and clarification of epigenetic factors that can activate and deactivate particular segments of the human genome.

The Post-Modern Era has seen important advances in our understanding of acclimation to high altitudes, to hot and cold environments, and to disturbances of circadian rhythm, with implications for those including competitive athletes planning to exercise or compete in the face of such challenges. The hosting of the Olympic Games in Mexico City CE was a major factor sparking interest in the speed with which athletes could adapt to low ambient pressures of oxygen.

At least two weeks was required to maximize the adaptive increase in haemoglobin concentration; Heath and Williams found that despite a reduction in aerodynamic resistance, endurance athletes were initially running 8. Some competitors found negative effects from a disturbance of their normal training routines and life in an unaccustomed environment; moreover, tissue bicarbonate reserves were reduced, and at least initially there was a reduction of blood volume at altitude Shephard b.

Thus, some Sports Scientists argued that athletes who were travelling to high altitudes could achieve a better performance by arriving immediately before competition, and racing before their buffering capacity and blood volume were depleted Kirkendall The Mexico City Games raised the issue of more permanent adaptations to low oxygen pressures, since the first five places in the 10, m run were taken either by high altitude natives or those who had lived for long periods at high altitude.

Specific advantages of these individuals appeared to include not only a high haemoglobin concentration, but also a reduced sensitivity of the carotid chemoreceptors thus avoiding excessive respiratory effort and an increased activity of aerobic enzymes in the skeletal muscles thus allowing muscular activity to be maintained at lower partial pressures of oxygen Milledge , Continued study of Kenyan and Ethiopian competitors has suggested that other factors may also contribute to their advantage- distance walking and running from an early age, a favourable somatotype, and a strong motivation to succeed as a means of social and economic advancement Wilber and Pilsiladis It was quickly appreciated that when a competitor returned to sea level, the increase of haemoglobin concentration that had developed in Mexico City allowed more oxygen to be carried with every litre of blood that was pumped by the heart.

Moreover, this physiological advantage persisted for several weeks, as the haemoglobin concentration only gradually reverted to its sea level norm.

Tactics included transfusion of their own autologous blood and administration of the erythropoietin that stimulates red cell production in the bone marrow erythropoietin was first identified and extracted from urine in CE. Investigators at York University in Toronto played an important role in demonstrating the potential impact of this abuse upon maximal oxygen intake Buick et al.

The disadvantage of prolonged residence at altitude is that training intensity is often curtailed. The most effective technique thus seems to live at altitude or the simulated high altitude conditions of a tent or room where the partial pressure of oxygen is reduced , but to continue training at sea level so that the normal vigour of conditioning programmes can be maintained Levine and Stray-Gundersen Issues of optimal techniques and speed of heat acclimation gained prominence during the s.

Not only were athletes travelling to compete in hot environments, but the British government also wanted to deploy their troops from English barracks to tropical colonies and dependencies when emergencies developed. South African companies also wished to dig ever deeper gold and diamond mines, thus increasing the thermal stress on their labourers. Robinson and his associates maintained that heat acclimatization could be achieved by an appropriate regimen of endurance training, even if this was undertaken in a cool environment Piwonka et al.

Certainly, a high level of fitness increases tolerance of hot environments, but in the early s Wyndham and his colleagues demonstrated categorically that maximum acclimation required a combination of physical activity and heat exposure Wyndham et al. Moreover, and unfortunately for the British military commanders, the full adaptive potential realized by residence in a tropical environment could not be achieved simply by exercising in a hot chamber Edholm and Bacharach One environmental issue that has attracted considerable controversy over the last 50 years has been the quantity of fluids that endurance athletes should ingest when competing under warm conditions Table 9.

Ekblom et al. However, much depends upon whether the exercise depletes muscle and liver reserves of glycogen. Fluid intake could usefully include a modest pre-event drink of mL, and a further mL of fluid should be ingested in each subsequent 15 min of running, to match the likely rate of fluid absorption from the gastro-intestinal tract during vigorous exercise Shephard and Kavanagh In terms of maintaining hydration during competition, water was shown to be as effective a replacement fluid as proprietary sports drinks Costill et al.

Weighing offered a simple means of estimating final over- or under-dehydration, if due allowance was made for the water liberated from stored glycogen a total of up to 2 l. Changes seen in post-coronary patients after running a 42 km marathon event in 4—5 hours. Based on the data of Shephard Some athletes and coaches possibly encouraged by the manufacturers of proprietary sports beverages ignored these simple guidelines, reasoning that if a little fluid was good for a runner, more would be even better.

Problems were particularly likely in the slowest runners and under cool conditions. World-wide, there have been at least 8 deaths from over-hydration of endurance competitors. Tim Noakes stirred up considerable controversy on this question, making the as yet unsubstantiated allegation that both companies manufacturing sports drinks and the scientific agencies that received grants from these companies were actively conspiring to suppress information on the dangers of hyponatraemia.

In his view, this condition had become epidemic Noakes and Speedy ; Noakes ; Shephard b. The field diagnosis of disturbances in body electrolyte balance has been greatly facilitated by the development of portable sodium ion meters during the late s. Shephard b. Exercise in a very cold environment can enhance fat loss. However, it may have a negative impact upon habitual physical activity, provoking bronchospasm and also angina in cardiac patients.

Potential acclimatization to cold seems quite limited. The issue of cold-induced angina came into prominence around , as North American cardiac patients began to undertake some of their prescribed physical activity not only in the gymnasium, but also in parks and streets. The inhalation of cold air was found to precipitate angina; possibly, a reflex spasm of the coronary vessels was initiated by the stimulation of vagal receptors in the trachea Hattenhauer and Neill ; Shephard Cold exposure also increases the work-load of the heart through vasoconstriction of the skin blood vessels, and thus a rise in blood pressure.

All violent Exercise makes the Asthmatic to breathe short … and if the Exercise be continued it occasions a Fit. Modern research on this topic began some fifty years ago; Simon Godfrey at the Hadassah Hospital in Jerusalem and Ken Fitch in Australia were pioneers in this field Fitch and Morton ; Godfrey et al. However, debate continues on medications that can be administered to high-performance athletes without conferring systemic benefits by boosting function in other parts of the body Fitch et al.

The existence of non-shivering thermogenesis, possibly based upon the activation of brown fat, was demonstrated by T.

Davis This type of fat is mobilized during cold exposure, and it produces heat rather than the energy that is required for exercise. The potential for cold acclimatization was examined in the late s. Evidence of adaptation was seen in the Korean Ama pearl divers Hong et al. Eric Glaser and I also established that it was possible to acclimatize to hot and cold conditions simultaneously Glaser and Shephard , with the subjects feeling more comfortable and shivering less under cold conditions.

The body temperatures of those who have been acclimatized often drop to lower temperatures than in those who are not accustomed to cold conditions, suggesting that much of the apparent benefit may be no more than habituation to various unpleasant sensations. Factors increasing the likelihood of facing disturbances of circadian rhythm during the Post-Modern Era have included the need for shift-work to keep industrial plants and associated services operating 24 h per day, and ever-increasing international air travel for business, leisure and world-wide athletic competitions.

The repeated disturbance of circadian rhythms can have adverse health consequences, and Physiologists have sought to speed the process of circadian adjustments through exposure to artificial light and the administration of melatonin. Abnormal working hours are not a new phenomenon. In the seventeenth century, Ramazzini Chap. But by CE, it was estimated that a fifth of European workers were engaged in shift work, and about one in 20 employees worked extended hours, sometimes associated with a compressed working week Harrington Studies of alternative shift arrangements have suggested that the least harmful is a rapid clockwise 8-h rotation morning, afternoon, night ; attention must also be paid to the recreational, dietary and transportation needs of the night shift, and the provision of bright lighting may possibly help night-time adaptation Harrington Attempts to speed the adaptation of circadian rhythms by exposure to bright lights an intensity of 5,—12, lux began in the early s Czeisler et al.

Benefit was optimized if the light exposure continued for 6—8 h per night for 4 days before the shift of rhythm, and dark glasses were worn during the daytime to minimize exposure to natural sunlight. Although the secretion of melatonin is involved in setting the circadian rhythm, attempts to speed adjustments by therapeutic use of melatonin have had only limited success, in part because of side effects of the drug, and in part because of unfavourable pharmacokinetics when it is administered orally Turek and Gillette We will examine briefly the attitudes of some recent governments to issues of health and fitness, focussing particularly upon the initiatives and personal lifestyles of leaders in the United States and Canada.

President in However, as a schoolboy he had suffered from various bouts of illness, and had lived under the shadow of his brother Joe, who was the local football star Dallek In , JFK recuperated from one bout of illness by serving as a farm hand on a 40,acre Arizona ranch.

John F. Kennedy, U. At Harvard, Kennedy tried out for football, golf, and swimming, earning a spot on the Varsity swim team. Despite a medical disqualification for lower back problems, he used the powerful influence of his family to be allowed to serve as Captain of a torpedo boat during World War II. This condition, together with severe back pain, led to use of a multiplicity of drugs, sudden mood swings, and periods of impaired judgment which may have contributed to a plethora of extra-marital affairs.

An early positive contribution of the Kennedy administration to international health was the establishment of the U. Under this programme, some 10, volunteers provided help in education, farming, health care, and construction to underdeveloped nations.

The option of retirement at age 62 was introduced, social security benefits were increased, food distribution to the needy was augmented, services for those with mental disorders was improved, and millions of children were vaccinated against various diseases Bernstein He was himself a major proponent of fitness, lending his name to articles in magazines such as Sports Illustrated Chap.

At high school he was known for his prowess in both debate and baseball. Johnson continued in office through CE. Lyndon B. Johnson, U. He also claimed to Parker :. However, he was not himself famous for an overall healthy lifestyle. He reputedly smoked 60 cigarettes per day and worked 18—20 h per day with no obvious leisure pursuits, until he sustained a near-fatal heart attack in CE. He then stopped smoking, but he became overweight, particularly after leaving his Presidential office. At this point, he also resumed smoking heavily.

He suffered further massive heart attacks in and CE, the last proving fatal. The latter encountered fierce opposition Patel and Ruchefsky :. Nevertheless, the proposal was enacted in July, CE. The Medicare programme offered low cost medical services to tens of millions of elderly Americans; Harry and Bess Truman received the first two Medicare Cards as the bill was signed into law at the Truman Library in Independence, Missouri.

Low-income groups also began to receive government-sponsored medical coverage through the Medicaid programme. Official statistics suggested that the number of U. Nixon enrolled in junior varsity football, but was rarely asked to play, because of his short stature. However, he was a member of his college basketball team. Richard Nixon, U. His term in office ran from to CE. He is perhaps best known for his impeachment, and he is the only American President to have resigned from office.

The EPA was created on January 1st CE, in response to mounting public concern over the impact of human activities upon the environment, and a Council on Environmental Quality was established within the office of the President; this Council required environmental impact statements for all new major Federal initiatives.

In CE, Senator Edward Kennedy was motivated by dramatic increases in the costs of medical treatment to propose a universal, federally-run health insurance scheme. Nixon responded with a health care plan that provided Medicaid for low-income families with dependent children, and required that all employees be provided with health care.

However, the Nixon plan still left some forty million people without coverage, and the Democrats thus declined to support it. His 3-year term was marked by a depressed economy, inflation, and few new policy initiatives. He died at the age of 93 years Greene He was also an avid golfer, shooting a hole in one during a Pro-Am competition, and he was a boxing coach while studying at Yale University. As an adult, he maintained a strong interest in the Boy Scouts of America , and he was the only U.

President to attain the rank of Eagle Scout. Despite his athletic career, Ford tripped on one occasion when leaving the Presidential plane in Austria, and in consequence he was often lampooned as a klutz by cartoonists. President from to CE. Before entering politics, he had been a Naval Officer and then a Georgia peanut farmer. After rehearsing the operation on a tennis court, Carter and a team of 23 men entered the damaged reactor to carry out repairs.

Following the death of his father, Carter returned to Georgia to help with the family farm. At this time he was sufficiently poor to qualify for subsidized public housing. By applying scientific methods to his farming, Carter quickly became relatively wealthy. After leaving office, Carter himself worked tirelessly to improve housing and eradicate disease in developing countries.

The Carter Center , opened in , has played a major role in the control and eradication of Guinea worm disease, river blindness, malaria, trachoma, lymphatic filariasis, and schistosomiasis Gherman At school, he had been a member of the football team and captain of the swim team.

He brought to the White House the skills of a radio, television and movie actor, mostly in the B-grade film unit and notoriously he was featured in commercials for Chesterfield cigarettes. Thus, in CE his message ran Jonas and Nissenson :. As President, Reagan was the simplistic front-man for those pushing the Reaganomics agenda. He sought deregulation of the economy, a lowering of taxes, and the cutting of government services, with an implicit faith that the goodness of humanity would make the system work.

His changes reduced Medicaid , food stamps, and funding of the Environmental Protection Association.

However, many observers think that mental deterioration may have set in earlier, albeit masked by skilful assistance from his wife.