Physical Exercise

Physical exercise is any bodily activity that enhances or maintains physical fitness and overallhealth and wellness. It is performed for various reasons. These include strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance and for enjoyment. Frequent and regular physical exercise boosts the immune system, and helps prevent the "diseases of affluence" such as heart disease, cardiovascular disease, Type 2 diabetes and obesity.^[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 is a growing global concern^[4] and physical exercise may help decrease the effects of childhood obesity in developed

Classification

[edit]Types of exercise

Physical exercises are generally grouped into three types^{[citation needed]} depending on the overall effect they have on the human body:

• Flexibility exercises, such as stretching, improve the range of motion of muscles and joints.^[5]
• Aerobic exercises, such as cycling, swimming, walking, skipping rope, rowing, running, hiking or playing tennis, focus on increasingcardiovascular endurance.^[6]
• Anaerobic exercises, such as weight training, functional training, eccentric training or sprinting, increase short-term muscle strength.^[7]

[edit]Categories of physical exercise

• Strength training
• Agility training
• Eccentric Training

Sometimes the terms 'dynamic' and 'static' are used. 'Dynamic' exercises such as steady running, tend to produce a lowering of the diastolicblood pressure during exercise, due to the improved blood flow. Conversely, static exercise (such as weight-lifting) can cause the systolicpressure to rise significantly (during the exercise).

Benefits

A common elliptical training machine

US Marines exercising on theUSS Bataan

Physical exercise is important for maintaining physical fitness 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.^{[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.^[9]

Frequent and regular aerobic exercise has been shown to help prevent or treat serious and life-threatening chronic conditions such as high blood pressure, obesity, heart disease, Type 2 diabetes,insomnia, and depression.^[10] Endurance exercise before meals lowers blood glucose more than the same exercise after meals.^[11] 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.^[12]

^{source: Google, Physical Edu}