"Exercise helps produce new red blood cells, and may also strengthen the immune system," explained Atlanta-based fitness trainer Ulrick Bien-Aime. Exercise also improves bone density.

A well-rounded exercise program that includes aerobic exercise, strength training using weights, and flexibility exercises - even when performed regularly in small increments - is key, according to the ACSM report. For those over age 65, such a program can help restore joint and muscle flexibility. Incorporating exercise as a permanent lifestyle change is the ultimate goal, according to the report.

Since it first released exercise guidelines in 1978, the ACSM has found the quantity and quality of exercise needed to attain health-related benefits may differ from what is recommended to attain fitness benefits. "It is now clear that lower levels of physical activity...may reduce the risk for certain chronic degenerative diseases and improve metabolic fitness," the new report stated.

Emphasis on frequency, flexibility
The ACSM's exercise prescription focuses on performing moderately intense aerobic exercise frequently - 3 to 5 times per week - for a total of 20 to 60 minutes each day. However, the exercise can be accomplished in 10-minute increments accumulated during the day. Walking, running, cycling, swimming, and stair climbing are examples of activities that exercise the major muscle groups.

To improve muscular strength and endurance, body composition, and flexibility, the ACSM further recommended a well- rounded program of resistance or strength training. General stretching exercises involving the major muscle and tendon groups can help maintain range-of-motion in joints and overall flexibility as adults age.

Special advice for seniors
Those over age 65 may need longer periods of time to adapt to an exercise program, said the ACSM report, but both healthy and frail elderly individuals can make significant increases in strength and muscle mass through resistance and strength training. By including flexibility training - such as stretching exercises - in their exercise programs, elderly adults can offset naturally occurring muscle and skeletal changes that significantly impair daily life. Flexibility exercises can improve range of motion and function of joints, and can also be key in preventing musculoskeletal injuries in the elderly. The exercise program should provide the proper amount of physical activity to attain a maximum benefit at the lowest risk, the ACSM report said.

Bien-Aime recommended elderly individuals first see their doctor before beginning an exercise program. In some instances, it may be helpful for a family member or friend who knows the individual's history to go along. While he advised that all older people should be up and moving seven days a week, they should also spend time on five of those days doing extra flexibility exercises or walking.

"Start with just five minutes of stretching, then add a little walking," explained Bien-Aime, whose 90-year-old grandmother walks one mile every day. "Exercise helps relieve depression in the elderly," he added. "It also helps reduce deterioration of intellectual processes that often occur as people age."

The American Cancer Society recommends being physically active and maintaining a normal weight at any age. Physical activity can help protect against some cancers by balancing caloric intake with energy expenditure. Some studies suggest regular physical activity can reduce the risk for cancers at several sites including the colon, rectum, prostate, endometrium, and kidney. It may also help prevent breast cancer among postmenopausal women.