Physical inactivity has become the biggest public health problem of this century, but consistent exercise can drastically reduce mortality risks, a health and lifestyle expert said Monday.

“Low fitness is a powerful determinant of mortality,” said Steven N. Blair, professor of exercise science, epidemiology and biostatistics at the University of South Carolina’s Arnold School of Public Health.

Blair spoke at the lecture sponsored by the kinesiology department to an audience of about 250 people.

Blair is the president and CEO of the Cooper Institute in Dallas, where he has conducted many observational studies about the relationship between cardiorespiratory fitness and mortality.

Participants in these studies were divided into three groups according to their level of physical activity. Mortality rates in the low group were twice as high as those in the moderate group. Blair said low-fitness men and women had even higher mortality rates than smokers.

Blair said moderate exercise consists of 130-150 minutes of walking per week. Higher-intensity activities such as jogging or aerobics require less time.

“Three 10-minute walks a day, five days a week will produce moderate fitness,” he said.

He said Body Mass Index isn’t important in measuring an individual’s fitness. Unfit people are twice as likely to die as fit people in every category.

He said there are easy ways to increase fitness.

He explained the differences between the “Sedentary Way” and the “Active Way.” The “Sedentary Way” involved heavy reliance on TV remotes, pizza delivery and riding lawn mowers, which he termed “abominations.”

The “Active Way” outlined easy ways to incorporate exercise into everyday life, like getting up to change the TV channel, making your own pizza and using a push-mower.

“I thought the differences between low and moderate fitness were the most striking thing,” Nina Dobbs, a sophomore health promotions major from Bainbridge, said after the lecture. “Although I think I get moderate exercise just from walking to class everyday.”

Blair concluded the lecture with some final advice: “Walk the dog every day, even if you don’t have one.”