Physical exercise is any bodily activity that enhances or maintains physical fitness Physical fitness comprises two related concepts: general fitness and specific fitness (a task-oriented definition based on the ability to perform specific aspects of sports or occupations). Physical fitness is generally achieved through exercise, correct nutrition and enough rest and overall health At the time of the creation of the World Health Organization , in 1948, health was defined as being "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity" or wellness. It is performed for various reasons. These include strengthening muscles and the cardiovascular system, honing athletic A sport is an organized, competitive, and skillful physical activity requiring commitment and fair play, in which a winner can be defined by objective means. It is governed by a set of rules or customs. In a sport the key factors are the physical capabilities and skills of the competitor when determining the outcome . The physical activity skills, weight loss Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue. It can occur unintentionally due to an underlying disease or can arise from a conscious or maintenance and for enjoyment. Frequent and regular physical exercise boosts the immune system An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function, and helps prevent the "diseases of affluence Diseases of affluence are those diseases which are thought to be a result of increasing wealth in a society, in contrast to diseases of poverty which result from impoverishment" such as heart disease Heart disease or cardiopathy is an umbrella term for a variety of different diseases affecting the heart. As of 2007, it is the leading cause of death in the United States, England, Canada and Wales, killing one person every 34 seconds in the United States alone.[verification needed], cardiovascular disease Heart disease or cardiovascular diseases is the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system (as used in MeSH C14), it is usually used to refer to those related to atherosclerosis (arterial disease). These conditions have similar causes,, Type 2 diabetes Diabetes mellitus type 2 or type 2 diabetes (formerly called non -insulin-dependent diabetes mellitus , or adult-onset diabetes) is a disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and dietary modification. As the and obesity Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. Body mass index , a measurement which compares weight and height, defines people as overweight (pre-obese) when their BMI is between 25 kg/m2 and 30.^[1][2] It also improves mental health, helps prevent depression, helps to promote or maintain positive self-esteem, and can even augment an individual's sex appeal or body image, which again is also linked with higher levels of self-esteem.^[3] Childhood obesity Childhood obesity is a condition where excess body fat negatively affects a child's health or wellbeing. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects it is being recognized as a serious public health is a growing global concern^[4] and physical exercise may help decrease the effects of childhood obesity in developed countries.

Contents 1 Classification 1.1 Types of exercise 1.2 Categories of physical exercise 1.3 Categories of general physical skills 2 Benefits 2.1 Effect on the cardiovascular system 2.2 Effect on the immune system 2.3 Effects on brain function 2.4 Effects on depression 3 Public health measures 4 Common misconceptions 4.1 Targeted fat reduction 4.2 Muscle and fat tissue 5 Excessive exercise 6 Exercise trends 7 Nutrition and recovery 8 History 9 See also 10 References 11 Sources 12 Further reading 13 External links

Classification

Types of exercise

Exercises are generally grouped into three types depending on the overall effect they have on the human body:

• Flexibility exercises, such as stretching Stretching is a form of physical exercise in which a specific skeletal muscle is deliberately elongated (often by abduction from the torso) in order to improve the muscle's felt elasticity and reaffirm comfortable muscle tone. The result is a feeling of increased muscle control, flexibility and range of motion. Stretching is also used, improve the range of motion of muscles Muscle is the contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to produce force and cause motion. Muscles can cause and joints.^[5]
• Aerobic exercises Aerobic exercise is physical exercise that intends to improve the oxygen system Aerobic means "with oxygen", and refers to the use of oxygen in the body's metabolic or energy-generating process. Many types of exercise are aerobic, and by definition are performed at moderate levels of intensity for extended periods of time, such as cycling Cycling, also called bicycling or biking, is the use of bicycles for transport, recreation, or for sport. Persons engaged in cycling are cyclists. or bicyclists. Apart from ordinary two-wheeled bicycles, cycling also includes riding unicycles, tricycles, quadracycles, and other similar human-powered vehicles, swimming Swimming is movement through water, usually without artificial assistance. Swimming is an activity that can be both useful and recreational. Its primary uses are bathing, cooling, fishing, recreation, exercise, and sport, walking Walking is one of the main gaits of locomotion among legged animals, and is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step. This applies regardless of the number of limbs - even arthropods with six, eight or more limbs, skipping rope, rowing Rowing is a sport in which athletes race against each other on rivers, on lakes or on the ocean, depending upon the type of race and the discipline. The boats are propelled by the reaction forces on the oar blades as they are pushed against the water. The sport can be both recreational, focusing on learning the techniques required, and competitive, running Running is a means of terrestrial locomotion allowing a human or an animal to move rapidly on foot. It is defined in human sporting terms as a gait in which at some point all feet are off the ground at the same time. This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight and the, hiking Hiking is an outdoor activity which consists of walking in natural environments, often on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking have been confirmed in studies. The word hiking is understood in all English-speaking countries, but there or playing tennis Tennis is a sport usually played between two players or between two teams of two players each (doubles). Each player uses a racquet that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court, focus on increasing cardiovascular Categories: Medical terms | Sports terminology | Exercise | Greek loanwords endurance.^[6]
• Anaerobic exercises Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass. Muscles trained using anaerobic exercise develop differently compared to aerobic exercise, leading to greater performance in short duration,, such as weight training Weight training is a common type of strength training for developing the strength and size of skeletal muscles. It uses the force of gravity to oppose the force generated by muscle through concentric or eccentric contraction. Weight training uses a variety of specialized equipment to target specific muscle groups and types of movement, functional training Functional training is a classification of exercise which involves training the body for the activities performed in daily life or sprinting Sprints are short running events in athletics and track and field. Races over short distances are among the oldest running competitions. The first 13 editions of the Ancient Olympic Games featured only one event – the stadion race, which was a race from one end of the stadium to the other. There are three sprinting events which are currently, increase short-term muscle strength.^[7]

Categories of physical exercise

• Strength training Strength training is the use of resistance to muscular contraction to build the strength, anaerobic endurance, and size of skeletal muscles. There are many different methods of strength training, the most common being the use of gravity or elastic/hydraulic forces to oppose muscle contraction. See the resistance training article for information
• Agility training Agility is the ability to change the body's position efficiently, and requires the integration of isolated movement skills using a combination of balance, coordination, speed, reflexes, strength, endurance and stamina

Sometimes the terms 'dynamic' and 'static' are used. 'Dynamic' exercises such as steady running, tend to produce a lowering of the diastolic Diastole is the period of time when the heart fills with blood after systole (contraction). Ballistics accurately describes diastole as recoil opposed to coil or systole. Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing. The term diastole originates blood pressure during exercise, due to the improved blood flow. Conversely, static exercise (such as weight-lifting) can cause the systolic Systole , is a phase of the cardiac cycle where the myocardium is contracting in a coordinated manner in response to an endogenous electrical stimulus, and pressure is being generated within the chambers of the heart driving blood flow. Experimental and clinical measurements of systolic contraction are often based on ejection fraction and cardiac pressure to rise significantly (during the exercise).

Categories of general physical skills

Physical exercise is used to improve physical skills.

Physical skills fall into the following general categories, per CrossFit CrossFit is a strength and conditioning fitness methodology that promotes broad and general overall physical fitness. CrossFit combines weightlifting, sprinting, and gymnastics. CrossFit says that proficiency is required in each of ten fitness domains: cardiovascular/respiratory endurance, stamina, strength, flexibility, power, speed, agility,:

• Endurance Endurance is the ability for an animal to exert itself for a long period of time. In humans, it is usually used in aerobic or anaerobic exercise. The definition of 'long' varies according to the type of exertion - minutes for high intensity anaerobic exercise, hours or days for low intensity. Training for endurance can have a negative impact on
• Stamina
• Speed In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero
• Strength Physical strength, also know as Muscular strength, is the ability of a person to exert force on physical objects using muscles. Increasing physical strength is the goal of strength training
• Flexibility Flexibility refers to the absolute range of movement in a joint or series of joints that is attainable in a momentary effort with the help of a partner or a piece of equipment. Flexibility in some joints can be increased to a certain degree by stretching
• Power
• Co-ordination
• Agility Agility is the ability to change the body's position efficiently, and requires the integration of isolated movement skills using a combination of balance, coordination, speed, reflexes, strength, endurance and stamina
• Balance In biomechanics, balance is an ability to maintain the center of gravity of a body within the base of support with minimal postural sway. When exercising the ability to balance, one is said to be balancing
• Accuracy In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to its actual value. The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same

Benefits

A common elliptical training machine An elliptical trainer is a stationary exercise machine used to simulate walking or running without causing excessive pressure to the joints, hence decreasing the risk of impact injuries US Marines The United States Marine Corps is a branch of the United States armed forces responsible for providing force projection from the sea, using the mobility of the United States Navy to rapidly deliver combined-arms task forces. It is one of seven uniformed services of the United States. In the civilian leadership structure of the United States exercising on the USS Bataan USS Bataan is a Wasp-class amphibious assault ship commissioned in 1997. She is named to honor the defense of the Bataan Peninsula on the western side of Manila Bay in the Philippines during the early days of US involvement in World War II

Physical exercise is important for maintaining physical fitness Physical fitness comprises two related concepts: general fitness and specific fitness (a task-oriented definition based on the ability to perform specific aspects of sports or occupations). Physical fitness is generally achieved through exercise, correct nutrition and enough rest and can contribute positively to maintaining a healthy weight, building and maintaining healthy bone density, muscle strength, and joint mobility, promoting physiological well-being, reducing surgical risks, and strengthening the immune system.

Exercise also reduces levels of cortisol Cortisol, also known as hydrocortisone, is a steroid hormone or glucocorticoid produced by the adrenal gland. It is released in response to stress, and to a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis, suppress the immune system, and aid in fat, protein and carbohydrate metabolism.^{[citation needed]} Cortisol is a stress hormone that builds fat in the abdominal region, making weight loss difficult.^{[citation needed]} Cortisol causes many health problems, both physical and mental.^[8]

Frequent and regular aerobic exercise has been shown to help prevent or treat serious and life-threatening chronic conditions such as high blood pressure Hypertension or high blood pressure is a chronic medical condition in which the systemic arterial blood pressure is elevated. It is the opposite of hypotension. It is classified as either primary (essential) or secondary. About 90–95% of cases are termed "primary hypertension", which refers to high blood pressure for which no medical, obesity Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. Body mass index , a measurement which compares weight and height, defines people as overweight (pre-obese) when their BMI is between 25 kg/m2 and 30, heart disease Heart disease or cardiopathy is an umbrella term for a variety of different diseases affecting the heart. As of 2007, it is the leading cause of death in the United States, England, Canada and Wales, killing one person every 34 seconds in the United States alone.[verification needed], Type 2 diabetes Diabetes mellitus type 2 or type 2 diabetes (formerly called non -insulin-dependent diabetes mellitus , or adult-onset diabetes) is a disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and dietary modification. As the, insomnia, and depression Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities. The term "major depressive disorder" was selected by the American Psychiatric Association to designate this symptom cluster as a mood disorder.^[9] Endurance exercise before meals lowers blood glucose more than the same exercise after meals.^[10] According to the World Health Organization, lack of physical activity contributes to approximately 17% of heart disease and diabetes, 12% of falls in the elderly, and 10% of breast cancer and colon cancer.^[11]

There is some evidence that vigorous exercise (90–95% of VO₂ Max VO2 max is the maximum capacity of an individual's body to transport and use oxygen during incremental exercise, which reflects the physical fitness of the individual. The name is derived from V - volume per time, O2 - oxygen, max - maximum) is more beneficial than moderate exercise (40 to 70% of VO₂ Max VO2 max is the maximum capacity of an individual's body to transport and use oxygen during incremental exercise, which reflects the physical fitness of the individual. The name is derived from V - volume per time, O2 - oxygen, max - maximum).^[12] Some studies have shown that vigorous exercise executed by healthy individuals can increase opioid peptides (a.k.a. endorphins, naturally occurring opioids that in conjunction with other neurotransmitters are responsible for exercise-induced euphoria and have been shown to be addictive), increase testosterone and growth hormone,^[13] effects that are not as fully realized with moderate exercise. More recent research^[14][15] indicates that anandamide may play a greater role than endorphins in "runner's high".

Both aerobic and anaerobic exercise also work to increase the mechanical efficiency of the heart by increasing cardiac volume (aerobic exercise), or myocardial thickness (strength training). Such changes are generally beneficial and healthy if they occur in response to exercise.

Not everyone benefits equally from exercise. There is tremendous variation in individual response to training: where most people will see a moderate increase in endurance from aerobic exercise, some individuals will as much as double their oxygen uptake, while others can never augment endurance.^[16][17] Similarly, only a minority of people will show significant muscle growth after prolonged weight training, while a larger fraction experience improvements in strength.^[18] This genetic variation in improvement from training is one of the key physiological differences between elite athletes and the larger population.^[19][20] Studies have shown that exercising in middle age leads to better physical ability later in life.^[21]

Effect on the cardiovascular system

The effect of exercise on the cardiovascular system is well documented.

There is a direct relation between physical inactivity and cardiovascular mortality, and physical inactivity is an independent risk factor for the development of coronary artery disease. There is a dose-response relation between the amount of exercise performed from approximately 700 to 2000 kcal of energy expenditure per week and all-cause mortality and cardiovascular disease mortality in middle-aged and elderly populations. The greatest potential for reduced mortality is in the sedentary who become moderately active. Most beneficial effects of physical activity on cardiovascular disease mortality can be attained through moderate-intensity activity (40% to 60% of maximal oxygen uptake, depending on age). ... persons who modify their behavior after myocardial infarction to include regular exercise have improved rates of survival. ... Persons who remain sedentary have the highest risk for all-cause and cardiovascular disease mortality. [1]

Effect on the immune system

Although there have been hundreds of studies on exercise and the immune system, there is little direct evidence on its connection to illness. Epidemiological evidence suggests that moderate exercise has a beneficial effect on the human immune system while extreme exercise impairs it, an effect which is modeled in a J curve. Moderate exercise has been associated with a 29% decreased incidence of upper respiratory tract infections (URTI), but studies of marathon runners found that their prolonged high-intensity exercise was associated with an increased risk of an infection, although another study did not find the effect. Immune cell functions are impaired following acute sessions of prolonged, high-intensity exercise, and some studies have found that athletes are at a higher risk for infections. The immune systems of athletes and nonathletes are generally similar. Athletes may have slightly elevated natural killer cell count and cytolytic action, but these are unlikely to be clinically significant.^[22]

Vitamin C supplementation has been associated with lower URTIs in marathon runners.^[22]

Biomarkers of inflammation such as C-reactive protein, which are associated with chronic diseases, are reduced in active individuals relative to sedentary individuals, and the positive effects of exercise may be due to its anti-inflammatory effects. The depression in the immune system following acute bouts of exercise may be one of the mechanisms for this anti-inflammatory effect.^[22]

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