Anything that damages tissue can cause inflammation, such as smoking, high cholesterol or hypertension. When a germ gets into your body, your immunity produces proteins called antibodies, white blood cells and cytokines that kill germs. However, as soon as the germ is gone, your immunity is supposed to shut down. If it does not shut down, these same factors attack and destroy your body tissues; this is called inflammation. Inflammation increases risks for heart attacks, strokes, certain cancers, and diabetes and even worsens diseases such as psoriasis, rheumatoid arthritis, and asthma.
Many scientists have expressed concern that hard exercise damages muscles, so it may turn on inflammation and harm you. However, a study from Verona, Italy shows that hard exercise does not cause inflammation ( Journal of the Canadian Medical Association , October 25, 2005). It measured C reactive protein, a blood test that indicates infection, and showed that there was no difference in levels in sedentary people, those who cycle for fitness, competitive professional bicycle racers and international-class cross country skiers. So muscle damage from hard exercise does not increase inflammation.
We know that regular exercise helps to prevent heart
attacks and strokes. Researchers at Michigan State recently
shown that high-intensity exercise may prevent these diseases
more effectively than low intensity exercise ( Thrombosis
Research , August 2006).
Most heart attacks and strokes occur when plaques
lining the arteries break off and pass down the artery to form a
clot that completely blocks the flow of blood to the heart or brain.
Intense exercise helped prevent clotting by increasing tissue
plasminogen activator and plasminogen activator inhibitor-1 far
more than low-intensity exercise did. Other studies show that
vigor exercise also more effective in helping people lose
weight. However, vigorous exercise can precipitate heart attacks
and strokes, so it's a good idea to get a stress electrocardiogram
before you start a new exercise program or increase the intensity
of your current regimen. If your doctor agreements, typically work up
to the point where you can increase the intensity of your
workouts once or twice a week.