Over a lifetime, the unhealthful effects of sitting add up. Alpa Patel, an epidemiologist at the American Cancer Society, tracked the health of 123,000 Americans between 1992 and 2006. The men in the study who spent six hours or more per day of their leisure time sitting had an overall death rate that was about 20 percent higher than the men who sat for three hours or less. The death rate for women who sat for more than six hours a day was about 40 percent higher. Patel estimates that on average, people who sit too much shave a few years off of their lives.

Another study, published last year in the journal Circulation, looked at nearly 9,000 Australians and found that for each additional hour of television a person sat and watched per day, the risk of dying rose by 11 percent. The study author David Dunstan wanted to analyze whether the people who sat watching television had other unhealthful habits that caused them to die sooner. But after crunching the numbers, he reported that “age, sex, education, smoking, hypertension, waist circumference, body-mass index, glucose tolerance status and leisure-time exercise did not significantly modify the associations between television viewing and all-cause . . . mortality.”

Sitting, it would seem, is an independent pathology. Being sedentary for nine hours a day at the office is bad for your health whether you go home and watch television afterward or hit the gym. It is bad whether you are morbidly obese or marathon-runner thin. “Excessive sitting,” Dr. Levine says, “is a lethal activity.”

The good news is that inactivity’s peril can be countered. Working late one night at 3 a.m., Dr. Levine coined a name for the concept of reaping major benefits through thousands of minor movements each day: NEAT, which stands for Non-Exercise Activity Thermogenesis. In the world of NEAT, even the littlest stuff matters. McCrady-Spitzer showed me a chart that tracked my calorie-burning rate with zigzagging lines, like those of a seismograph. “What’s that?” I asked, pointing to one of the spikes, which indicated that the rate had shot up. “That’s when you bent over to tie your shoes,” she said. “It took your body more energy than just sitting still.”

In a motion-tracking study, Dr. Levine found that obese subjects averaged only 1,500 daily movements and nearly 600 minutes sitting. In my trial with the magic underwear, I came out looking somewhat better — 2,234 individual movements and 367 minutes sitting. But I was still nowhere near the farm workers Dr. Levine has studied in Jamaica, who average 5,000 daily movements and only 300 minutes sitting.

Dr. Levine knows that we can’t all be farmers, so instead he is exploring ways for people to redesign their environments so that they encourage more movement. We visited a chairless first-grade classroom where the students spent part of each day crawling along mats labeled with vocabulary words and jumping between platforms while reciting math problems. We stopped by a human-resources staffing agency where many of the employees worked on the move at treadmill desks — a creation of Dr. Levine’s, later sold by a company called Steelcase.

Dr. Levine was in a philosophical mood as we left the temp agency. For all of the hard science against sitting, he admits that his campaign against what he calls “the chair-based lifestyle” is not limited to simply a quest for better physical health. His is a war against inertia itself, which he believes sickens more than just our body. “Go into cubeland in a tightly controlled corporate environment and you immediately sense that there is a malaise about being tied behind a computer screen seated all day,” he said. “The soul of the nation is sapped, and now it’s time for the soul of the nation to rise.”