Even moderate exercise by older people cuts the risk of developing a syndrome which increases heart disease and diabetes risk, US researchers say.
The research reinforces the benefits of exercise
The Johns Hopkins University team said cutting body fat can offset metabolic syndrome in those aged 55 to 75.
The Journal of Preventive Medicine said 100 over-55s were prescribed exercises ranging from weightlifting to walking.
Lead researcher Kerry Stewart said: "Exercise can be as effective as what is accomplished today with drugs."
The study provides more evidence of the benefits of exercise to the middle-aged and elderly.
Up to a quarter of adults in the UK are estimated to have one or more of the risk factors for developing metabolic syndrome.
In the US study, a group of more than 100 people aged 55 to 75 were monitored for a period of six months.
None had shown any previous signs of cardiovascular disease, apart from slightly raised blood pressure.
Half the participants took part in exercise sessions for an hour three times a week, including aerobic exercise and weightlifting.
The rest were given a booklet that encouraged increased activity, such as walking, to promote good health.
The researchers found that, as might be expected, if middle-aged people stuck to an exercise programme, it improved overall fitness.
The metabolic syndrome is essentially the preence of a number of factors including:
Excessive fat tissue in and around the abdomen
High levels of unhealthy cholesterol in the blood
Raised blood pressure
An inability to use sugar in the blood properly
But the reduction in the number of cases of metabolic syndrome was linked more strongly to reductions in total and abdominal body fat and increases in muscle leanness, rather than improved fitness.
At the beginning of the study, 43% of all participants had the metabolic syndrome.
By the end of the study, there were no new cases of metabolic syndrome in the exercise group, and the condition had resolved in nine of them, a reduction of 41%.
In the control group, eight participants no longer had the syndrome, while four new cases appeared, resulting in an overall reduction of 18%.
Kerry Stewart, professor of medicine and director of clinical exercise physiology and heart health programs at The Johns Hopkins University School of Medicine and its Heart Institute, said: "Older people are very prone to have the metabolic syndrome.
"While each component of metabolic syndrome increases disease risk by itself, when combined, they represent an even greater risk for developing heart disease, diabetes and stroke."
He added: "Older people can benefit greatly from exercise, especially to reduce their risk for developing metabolic syndrome.
"Our results show that this population can be motivated to follow through with a moderate exercise programme, and for some risk factors, such as abdominal fat, exercise can be as effective as what is accomplished today with drugs."
Professor Stewart said: "Because so many older persons have or are at risk for metabolic syndrome, this study provides a very strong reason for individuals to increase their physical activity levels.
"They will reduce their fatness, and increase their fitness and leanness, while reducing their risk for heart disease and diabetes."