How to improve and protect your health through exercise

Exercising may not be on your priority list, but the health benefits from getting up and moving makes it well worth the effort. Here are some health improvements you're likely to see in as little as six months if you begin exercising regularly.

Ever notice that people who work out a lot tend to get fewer colds and bouts of flu than those who avoid the gym? There's a reason for that. Every time you exercise, it puts stress on your entire body, stimulating the release of certain immune system hormones and chemicals. If you exercise too much, this has a negative effect, increasing inflammation and eventually suppressing the immune system. But if you exercise moderately on a regular basis, you're able to maintain a higher level of immune activity without triggering that suppression response.

Again, this is not a lifetime-of-exercise-needed kind of response. The response of your immune system to a single physical workout is intense enough to supercharge the effects of a pneumonia or influenza vaccine, particularly in the elderly, who tend to have weaker immune systems to begin with. Exercise regularly, and those vaccines are more likely to work in you. (It's a little-known fact that flu vaccines simply don't work in many people, particularly the elderly.) With or without a vaccine, physical activity significantly reduces your risk of developing an infection, studies find.

When researchers examined the risk of hospitalization for infectious disease in 1,365 women ages 55 to 80, they found that those who were inactive were more than three times as likely to be hospitalized for infections. Other studies find a much lower risk of upper respiratory tract infections like colds and bronchitis, as well as pneumonia, among older adults who remain physically active. Again, we're not talking about training for a marathon. Something as gentle as the ancient Chinese martial art of tai chi can boost your immune system enough that it can better fight off the virus that causes shingles, a painful nerve disease more common in those over 50.

Exercise has other brain benefits beyond improved memory and reasoning. A long-term study that followed nearly 1,500 people for an average of 21 years found that just two rounds of leisure-time physical activity each week cut their risk of Alzheimer's in half. You can get benefits in an even shorter amount of time; exercising just three or more times a week during a six-year period, one study found, reduced the risk of dementia by a third in older people compared to those who exercised less. Some of this risk reduction is thought to be related to changes in the hippocampus, the part of the brain that controls higher thought and the part first affected by the physical changes that lead to Alzheimer's.

The bottom line is that physically active people have healthier hippocampuses. So do rats. When rats specially bred to develop Alzheimer's get steady exercise over several months, they show a remarkable reduction in the plaques and other brain changes that signal the development of the disease.

If you're on the younger end of the aging spectrum and still haven't gone through menopause, you have yet another reason to lace up your Nikes:

• A Spanish study at the University of Granada found that three hours of exercise a week could significantly reduce severe hot flashes and other menopausal symptoms, increasing a woman's overall quality of life.
• While half of the exercising group had severe symptoms when they began working out, after a year, just 37 percent did (and no, they hadn't reached menopause yet).
• Meanwhile, the percentage of women with severe menopausal symptoms in a control group that didn't exercise rose from 58 to 67 percent.