~~Exercise and how it affects the body~~

People have always believed that exercise is good for them, says Dr. John O'Kane, University of Washington sports-medicine expert and lead physician to the UW's athletic teams. What the latest research is doing is showing just how good for us it is.

Health experts also say you don't have to run marathons or hit the gym for endless hours to gain significant benefits. Probably the best-known benefit is heart health, and for that, a program of regular, moderate exercise will do just fine, O'Kane said.

"If you can just get yourself to start walking 30 minutes a day, that's a good start," he said.
"You do get benefits from more vigorous exercise," O'Kane added. You burn more calories and gain endurance, for instance. And one study suggested that women who exercised vigorously had lower rates of prostate cancer.

Exercise does its best work when teamed with healthy eating. But studies now show exercise has its own beneficial impact, even when you're not also following an ideal diet, he said.

The brain/

Mental sharpness: Exercise may help preserve it as you age. A recent study found that among women 65 and older, the least amount of cognitive decline over eight years occurred in those who exercised the most (walking 18 miles per week), while decline was greatest in those who exercised the least (walking half a mile per week). Decline decreased with each added mile.

Diabetes: Many studies show regular physical activity helps prevent or control diabetes.

Exercise works on diabetes in two ways: By burning energy in the form of blood sugar and by reducing body fat.

Bones: Many studies indicate that regular exercise,including strength training,may help older people avoid falling and breaking their bones.

Arthritis: Both aerobic exercise and strength training, in moderation, can reduce joint swelling and pain and extend mobility.

Heart: Like all muscles, the heart becomes stronger and larger as a result of exercise so it can pump more blood through the body with every beat and sustain its maximum level with less strain. The resting heart rate of those who exercise is also slower because less effort is needed to pump blood.People who exercise the most often and vigorously have the lowest risk for heart disease, but any exercise is beneficial. Studies consistently find that light to moderate exercise is even beneficial in people with existing heart disease. However, anyone with coronary artery disease should seek medical advice before beginning a workout program.

*chemical changes in the blood during exercise*

During exercise, the muscles use up oxygen as they convert chemical energy in glucose to mechanical energy. This O2 comes from hemoglobin in the blood. CO2 and H+ are produced during the breakdown of glucose, and are removed from the muscle via the blood. The production and removal of CO2 and H+, together with the use and transport of O2, cause chemical changes in the blood. These chemical changes, unless offset by other physiological functions, cause the pH of the blood to drop. If the pH of the body gets too low (below 7.4), a condition known as acidosis results. This can be very serious, because many of the chemical reactions that occur in the body, especially those involving proteins, are pH-dependent. Ideally, the pH of the blood should be maintained at 7.4. If the pH drops below 6.8 or rises above 7.8, death may occur. Fortunately, we have buffers in the blood to protect against large changes in pH.