Longer-term, moderate exercise improves immune activity

Older men and women who performed moderate resistance exercise at home 30 minutes a day, three times a week, for eleven months, showed a significant increase in natural killer cell activity, the immune system's first line of defense against viral infection, according to a study by researchers at Acadia University in Nova Scotia. The sustained exercise may be the key, say the researchers, since earlier studies using shorter periods of up to three months did not find this significant increase in immune system activity with resistance training.

In addition to enhanced immune response, the adults also showed significant improvements in muscle strength and lipid profiles, with decreased total cholesterol and LDL concentrations.

Jennifer DiPenta, a student working in the labs of Dr. Rene J. L. Murphy and Dr. Julia Green-Johnson, reported the study at Experimental Biology 2004, as part of the scientific sessions of The American Physiological Society.

Baseline immunological and physiological functions as well as lipid profiles were obtained from 10 men and 12 women, ages 54 to 82 years (median age 63.5), all retired. They then were trained in simple, moderate intensity resistance exercises, involving tubing and exercise balls, which they could do alone at home. During the next eleven months, the participants were monitored with bi-weekly phone calls and monthly home visits, during which the programs were altered, based on their abilities. At the end of approximately 11 months of training, they returned to the Centre of Lifestyle Studies at Acadia University for another series of physical and immune function tests.

Muscle strength increased significantly. There were no changes in weight, but total cholesterol and plasma LDL decreased significantly (HDL remained unchanged). To measure immune activity, lymphocytes from each participant were incubated with K562 tumor cells known to be targeted by natural killer cells. After eleven months of participating in the study, the participants showed a higher response.

Dr. Green-Johnson says, "It was gratifying to see the improvement in these older people in ways that should enable them to maintain their health and independence with advancing age." Dr. Murphy adds, "We believe the take home message is that there are several important health benefits for older people who choose to participate in a simple home-based exercise program."

The study was funded by the Nova Scotia Health Research Foundation, and the exercise equipment was provided by Theraband. Ms. DiPenta holds a fellowship provided by The American Physiological Society.

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