Why Skipping Exercise Can Be Deadly

One day in the summer of 2001, Dan Radin decided to run to the end of his block. For many, that short distance might be conquered in a minute or two. But Radin, a 21-year-old who weighed nearly 275 pounds at the time, barely made it--and hobbled back to his doorstep. Yet, he refused to quit and increased his distance daily; it was three months before he ran a mile, but the challenge changed his life.

Now, Radin, a marketing copywriter in Los Angeles, exercises for an hour most days of the week. He is a lean, muscular 170 pounds. At an annual checkup, his physician remarked that his low blood pressure and cholesterol were likely an improvement from even before he gained excess weight in the late 1990s.

In Pictures: Why Skipping Exercise Can Be Deadly

"Losing a lot of weight and changing your body has a profound impact," Radin says.

More than he may expect, it turns out. According to a study of more than 4,300 people published this summer in the journal of the American College of Sports Medicine, the least-fit individuals had a three-fold increased all-cause mortality risk and a nearly four-fold increased cardiovascular mortality risk when compared to the most fit. In other words, improving your fitness level can better your chances for a longer life.

That study is just one in a recent spate of research in children and adults that draws connections between physical inactivity or obesity and poor health outcomes. It’s no secret that exercise is critical to excellent health, but many of us let the week slip by with nothing more than a brisk walk to the parking lot. Yet, neglecting one's weight and fitness is a certain path to increased risk for life-shortening ailments and conditions.

Exercise as Medicine

While physical activity is just one component of developing fitness--the others include overall health and genetic predisposition--exercise is essential.

The ideal amount, says Jonathan Myers, Ph.D., a co-author of the ACSM study and a health research scientist at the VA Palo Alto Health Care System in northern California, is a half-hour of moderate-intense activity five days of the week. Even better is an hour of exercise most days of the week.

When Myers and his co-authors separated their 4,300 participants into different fitness quintiles and studied them for nearly 20 years, the ones that performed the best reached that five-hour-a-week threshold. Those with the poorest fitness had a three-fold increase in overall mortality risk; 170 participants in this category died of all causes while only 55 in the highest quintile died.

"We've been chasing this for the last 20 years or so," Myers says of the results, "and we've seen it over and over again." Fifty years of epidemiological studies, he says, have demonstrated that people who are more fit or are more physically active have lower mortality rates.

A study published last week in the British Medical Journal found a similar correlation between weight gain and maintaining optimal health into old age. Of the 17,000 women who participated in the 20-year observational study, those who were overweight at age 18 and gained more than 22 pounds by 50 had the worst odds for optimal health. For every 11 pounds gained during that time, the chances for "healthy survival" decreased by 5%.

But it’s never too late to start exercising. Myers' research shows that there are tremendous benefits to be had for the worst-off individuals who can change their ways. When the co-authors compared the least-fit group to the next least-fit group, they noticed a striking difference: The two-fold increase in mortality risk was predominantly due to variations in physical activity, not other risk factors like hypertension and diabetes.

"We don't know yet why exercise has such protective benefits," says Myers, "but your fitness level can outperform the traditional risk factors"--such as smoking and high blood pressure--"in predicting mortality."

The Kids Aren't Alright

Though fitness often becomes a major concern in adulthood, when aging and the onset of chronic disease makes exercise imperative, there's increasing evidence that physical activity in childhood has significant long-term implications for health.

Kathleen F. Janz, a professor in the departments of Health and Sport Studies and Epidemiology at the University of Iowa, found in a recent study that children who lead less active lives are more likely to be overweight years later.

Janz studied 333 5 year olds over eight years by monitoring their physical activity with a device known as an accelerometer and measuring the subjects’ fat mass with body imaging. The protective benefit of physical activity, according to Janz and her co-authors, continued through childhood; the most active children at age five had significantly lower fat mass at eight and 11 compared with those in the lowest quartile.

"It's not unusual that there are windows of opportunity for critical periods where it's most important to do it right," says Janz. Childhood is one of them, she adds.

It's not just fatness that matters, either. A recent study in Circulation found that some Type 2 diabetic and obese teenagers have a thicker carotid artery, an association that had only been seen previously in adults and one that may put them at greater risk for stroke and heart attacks later in life.

Yet, like Jonathan Myers at the Palo Alto Health Care System in northern California, Janz says the protective benefits of exercise are immediate, regardless of how long it's been since the last workout. Certainly, Dan Radin considers himself an example of what can be accomplished with enough determination and direction.

"I hadn't grown up playing sports," he says. "Exercising was something I had to figure out."

But he's far beyond using the corner block as a benchmark or gateway to a longer, healthier life; his next target is a triathlon.

In Pictures: Why Skipping Exercise Can Be Deadly