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Hormones are critical regulatory substances released by the endocrine system to bring about a multitude of physiological responses. The peptide hormone growth hormone and the protein hormone erythropoietin (EPO) are prominent sports-doping agents. Growth hormone, which is highly anabolic, increases skeletal muscle mass and reduces body fat and therefore is used especially by strength and power sports athletes. EPO and associated agents stimulate erythropoiesis, the formation of red blood cells, with a resultant increase in the oxygen-carrying capacity of blood and therefore are used especially by endurance sports athletes. High doses of these agents produce negative effects on health and quality of life, including death.

Doping in sport remains a serious worldwide problem. It is often the subject of news stories; some of them are spectacular, such as the Bay Area Laboratory Co-Operative (BALCO) scandal and the Russian state sponsored doping at the Sochi Olympics. A fundamental question being asked by athletes, scientists, and ethicists is: Do we continue to ban performance-enhancing drugs? If so, how do we enforce the ban? If not, how do we regulate use? Bound up with the issue is the definition of sex and gender in the context of fair play. Sports-governing organizations, antidoping agencies, the public, and athletes will continue to grapple with these matters. The solution will have biological, medical, legal, and ethical implications and seems likely to be neither simple nor permanent.

The World Anti-Doping Code is designed to keep sports free of performance-enhancing drugs. The World Anti-Doping Agency has strict procedures to insure fair assessment of biological specimens from athletes based on scientific research, best clinical chemistry practices, and contemporary investigative procedures. This chapter evaluates analytical techniques, discusses ways by which athletes attempt to avoid detection of drug use, reviews the procedures for evaluation of a positive drug test (an Adverse Analytical Finding), and provides an overview on the consequences of confirmed drug use. A few of the most egregious examples of doping cases such as government-sponsored cheating at the 2014 Winter Olympics in Sochi are presented.

Beta-2 agonists are drugs that selectively mimic the actions of the endogenous catecholamines epinephrine and norepinephrine. As pharmaceuticals, their major role is to reduce signs and symptoms of asthma and chronic obstructive pulmonary disease by bronchodilation, allowing the patient to breathe more easily. As performance-enhancing drugs, they increase pulmonary function and have many downstream actions on the cardiovascular and metabolic systems. High doses also have nonsteroidal anabolic action, increasing muscle mass (clenbuterol is especially popular with athletes). The most serious side effects of high doses involve the cardiac system: arrhythmias, palpitations, and myocardial ischemia. They also raise blood glucose, leading to polyuria and dehydration, and present a slight risk of kidney and blood vessel damage and bone demineralization, leading to stress fractures. The World Anti-Doping Agency prohibits the regular and chronic use of beta-2 agonists, even in asthmatics, without a therapeutic use exemption unless there is a medical emergency.

Stimulants drugs elevate mood, energy, alertness, stamina, and muscle power. Effects are mediated in both the central nervous system and peripheral systems. In a medical context, these effects can be therapeutic, but in athletics, they convey an unfair advantage, so most of them are banned by the World Anti-Doping Agency. The most prominent types used as performance enhancers are amphetamines and caffeine. The neurochemical and physiological mechanism of each class is reviewed briefly. Negative behavioral effects of high doses include agitation, irritability, impaired judgment, and hallucinations. Negative physiological effects include hyperthermia, hyponatremia, and cardiac arrhythmias, which collectively increase the risk for myocardial infarction and hemorrhagic stroke. Repeated use can produce physiological and psychological dependence.

Performance-enhancing substances have been used in athletic competition at least since the ancient Greeks. In the 1920s, sports governing bodies implemented restrictions because of health concerns for the athletes, but they had little effect because no testing was done. The development of synthetic hormones and their widespread abuse by athletes led the International Olympic Committee to issue a list of banned substances. Testing began with the 1968 Olympics, but abuse continued with banned and yet-to-be banned novel substances through the 1990s. To further combat the problem, the World Anti-Doping Agency (WADA) was established in 1999 to take on a full time “policing action” role. Scientists working with WADA developed better detection methods, but cheating remains a serious problem. Exceptions are granted by WADA to allow use of banned substances such as steroids for athletes who can show a legitimate medical need, but exceptions are difficult to obtain.

Attempting to increase male sex hormone levels by transplantation of gonadal tissue dates at least as far back as 1786. Modern androgen therapy was started when testosterone was chemically synthesized in 1935, and testosterone and its derivatives saw substantial use in sports doping in the 1960s and 1970s. Prevalence of sports use seems not to have declined since then despite health warnings. This chapter gives an overview of presumed mechanisms of action, though experimental study is hampered by the ethical restriction on dose levels. Commonly used agents with their trade and popular names are given. Major side effects in skin, muscle, joint, circulatory system, liver, brain, gastrointestinal system, and bone are noted, as are behavioral and psychological effects. Two other anabolic substances, androstenedione and dehydroepiandrosterone, are also discussed briefly.

Selective androgen receptor modulators (SARMs) and selective estrogen receptor modulators (SERMs) are performance-enhancing drugs used by doping athletes to stimulate anabolism and thereby increase muscle mass, strength, and recovery from exercise training. SARMs are intended to have the same effects as androgenic anabolic drugs such as steroids and hormones such as testosterone. SERMs act as estrogen receptor agonists or antagonists depending on the type of tissue; they interfere with the negative feedback loop of the hypothalamic–pituitary–gonadal axis, thereby allowing testosterone levels to rise, and so are used mainly by male athletes. Animal data support the assumption of physiological and performance enhancement by SARMs and SERMs, but human data are less conclusive. These drugs are banned by the World Anti-Doping Agency. Both types have detrimental side effects but not to the extent seen with more potent anabolic agents such as testosterone and steroids.

Energy is essential for life and all functions of the body. This energy must be in the chemical form of adenosine triphosphate (ATP). This chapter presents an overview of the biochemical pathways used in energy metabolism for the conversion of the chemical energy in food to ATP. It explains how the macronutrients carbohydrate, fat, and protein are used in the processes of substrate and oxidative phosphorylation to yield ATP for use in exercise.

This chapter looks forward to the research questions, advancing technologies, and methods that will inform exercise science in the near future—what needs to be studied and how to study it. Two fields of inquiry are focused on, genetics, with its subdiscipline epigenetics, and proteomics. Diseases related to lifestyle and aging are emphasized. Specific research objectives are recommended to point the way forward, such as exploiting genomics to personalize treatment therapies by establishing multidimensional, integrated clinical research; and, translating the findings of basic science to practical application through a team effort of engineers, physicians, pharmacists, and other concerned parties. It is suggested that a large part of the solution to much current morbidity and unnecessary mortality is simple, economical, already available to most people, and proven effective: sensible diet, regular exercise, adequate rest, and recreation.

This chapter relates the technical matters covered in the preceding chapters and provides a summation of the key scientific and practical rationales for the benefits of engaging in an exercise program. In section “What to Expect When Everything Goes Right,” specific positive effects are reviewed: control of body weight, treatment and avoidance of major diseases, improvement of mood, increase in energy, improvement of sex life, enhancement of social life, and increase in life expectancy. In section “What to Expect When Everything Goes Wrong,” specific negative effects are reviewed: incidence of injury associated with various exercises, and the types of injuries and their causes. The final section offers advice on injury avoidance.

Energy is expended constantly as long as the body is alive. This chapter discusses the concept of total daily energy expenditure (TEE) and its components. How TEE is influenced by altering the levels of spontaneous and voluntary physical activity (VPA) is discussed. The basal metabolic rate (BMR) is characterized and used as a benchmark by which changes can be measured. Formulas for calculating energy expenditure in the resting state, activities of ordinary living (spontaneous physical activity) and VPA (exercise) are presented, as is a table showing calculated energy expenditure values for various levels of many activities. Persistent conditions (age, gender, chronic obesity) and transient conditions (food intake, drugs, fever-inducing illness) that can affect BMR are noted.

Energy is essential for life, and the type of energy required is very specific. The body is designed to take chemical energy from food and convert it to the useful form, adenosine triphosphate (ATP). This conversion is critical for the performance of exercise. This chapter presents an overview of the principles of energy interconversion and how the body uses this principle to enable it to expend energy and perform the muscular work called exercise. Units of measurement are specified, anaerobic and aerobic pathways of ATP production and use are described, and a one-page “close-up” on the historical progression of methods for sampling and studying ATP processes is presented.

Humans consume and expend energy daily. This chapter focuses on how the changes in food consumption and expenditure influence overall energy stores, which are represented by total body mass (weight). Mathematically this relationship can be expressed by the energy balance equation (EBE), which accounts for factors that control the relationship among consumption (energy intake), storage (energy storage), and expenditure (energy output) in the calculation of EBE. Major influences on each of these factors are detailed, with a focus on physical activities and exercise. The crossover concept—the divergence of the relative contributions by lipids and carbohydrates to energy production as the intensity of exercise increases—is explained in the framework of its impact on energy expenditure.

This chapter discusses the effects of pharmacologic and nutritional supplements to enhance performance by altering biochemical processes or to produce weight loss by increasing energy expenditure. The examples discussed are adaptogenic herbs, amino acids, anabolic steroids, caffeine, ephedrine, erythropoietin, levothyroxine, metrileptin, sibutramine, and vitamins and minerals. Many performance-enhancing drugs have been banned in sport because they constitute an unfair advantage for users over nonusers or because long-term use damages the body (or both), but the list of substances and methods of administration changes rapidly and regulatory agencies must deal with a moving target. Treatment of the subject here is necessarily brief; this complex topic warrants a book of its own.

The human body has a tremendous capacity to produce ATP from the intrinsic energy metabolism pathways. This large capacity is necessary as exercise can result in greater than 20-fold increase in the rate of energy expenditure. This chapter provides an overview of the central and peripheral mechanisms by which the body induces and regulates the increase in energy metabolism with exercise.

This chapter reviews the principles of exercise training and relates aerobic and anaerobic programs to the underlying metabolic phenomena. The major aspects of all training are defined—frequency, intensity, time, type, volume, and progression—and each is elaborated. Aerobic and anaerobic programs are differentiated by the physiological and biochemical adaptations dominant in each, though some mechanisms and effects are common to both. The shift in preference between carbohydrate and lipid as an exercise fuel source, as a function of training adaptation, is discussed, as are complexities in this generalization. Type I and Type II skeletal muscle fibers, mitochondrial density, maximal oxygen uptake, and other key factors at the cellular level are discussed, and suggestions about the mechanism of muscular fatigue are offered.

Accurate measurement and determination of energy expenditure are critical in understanding the energy metabolism status and capacity of an individual. This chapter presents some primary analytical procedures used in the laboratory and the field to determine expenditure at rest and during physical activity: direct calorimetry, indirect calorimetry by measuring respiratory gas exchange (oxygen uptake using O 2 and CO 2 concentration; specifically, O 2 and CO 2 analysis by infrared absorption spectroscopy, refractometry, and mass spectrometry), the doubly labeled water technique for isotopes in the laboratory, and calculation formulas and questionnaires in the field. Heart rate monitors and motion sensors (pedometers and accelerometers) are also reviewed. The strengths and limitations of the various methods are discussed.

The endocrine system has profound regulatory effects within the human body and thus the ability to control and maintain appropriate function within many physiological systems (i.e., homeostasis). The hormones associated with the endocrine system utilize autocrine, paracrine, or endocrine actions on the cells of their target tissues within these physiologic systems to adjust homeostasis. The introduction of exercise as a stressor to disrupt homeostasis can greatly amplify and impact the actions of these hormones. To that end, the endocrine response to an acute exercise session occurs in a progression of phases with the magnitude of the response being relative to the exercise work intensity or volume. Various physiologic mechanisms are considered responsible for these responses, although not all are completely understood or elucidated. Chronic exercise training does not eliminate the acute exercise response but may attenuate the overall effect of the responsiveness as the body adapts in a positive fashion to the training stimulus. Regrettably, an excessive intensity and/or volume of training may lead to maladaptation and is associated with inappropriate endocrine hormonal responses. The mechanisms leading to a deleterious maladaptive state are not well understood and require additional research for elucidation.