The baby boom is turning out to be a health bust.

Despite growing up at a time of great innovation in health care, the 78 million born in the U.S. between 1946 and 1964 aren't looking all that healthy today, according to a new study.

Medical advances have led to the longest life expectancy ever, but U.S. baby boomers have higher rates of chronic disease, more disability and lower self-rated health than did their parents at a comparable age.

The research may surprise many baby boomers, who have embraced activities such as running, fitness classes and backpacking in unprecedented numbers.

"There seems to be somewhat of a disconnect between the reputation of baby boomers for being healthy and what we see in increasing rates of diabetes, high blood pressure and obesity," said study author Dr. Dana King, a professor of family medicine at West Virginia University School of Medicine. "It's really discouraging that they're not the healthiest generation."

The study, published as a research letter in JAMA Internal Medicine, compared data on people aged 46 to 64 in two time periods -- from 1988 to 1994 for the older generation, and from 2007 to 2010 for the baby boomers.

While 32 percent of their parents' generation described their health as "excellent," only about 13 percent of baby boomers did so.

Obesity was more common among baby boomers than their parents (39 percent versus 29 percent). In addition, 52 percent of boomers said they had no regular physical activity, while only 17 percent in their parents' generation reported inactivity.

There was one area of good news, however. Boomers have lower rates of heart attack and emphysema, and are less likely to smoke cigarettes, the study reported.

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