Obese women might better manage their weight by slowing their walking speeds, according to two Colorado researchers.

“Walking slower for a given distance can burn more calories that walking at a normal pace,” said study co-author Raymond C. Browning, of the University of Colorado in Boulder. “This may also reduce the risk of musculoskeletal injury,” he added.

Although the amount of energy used while walking depends on the speed of the walker, researchers had not previously determined the amount of energy obese adults used as they walked at different speeds.

Walking speeds are greatly influenced by the amount of energy required. Normal-weight individuals typically walk about 1.4 meters per second, or 3 miles per hour, the speed that requires the least amount of energy. Studies of obese adults, however, suggest they prefer to walk more slowly than normal-weight adults. Yet they have also been shown to burn up to 33 percent more calories while walking.

Thus, it was not known whether the preferred walking speeds of obese adults also corresponded to the speed that required the least amount of energy.

To investigate, Browning, a doctoral student in integrative physiology, and Dr. Rodger Kram, an associate professor in the department, studied 20 women, half of whom were moderately obese. They measured the women’s preferred walking speeds as well as the amount of energy they used to walk a set distance.

The researchers had thought that the obese women would prefer to walk at slower speeds than their normal-weight peers, but they did not find this to be true. The obese women walked slightly less fast, but the difference was not statistically significant, the team reports in the journal Obesity Research.

Preferred walking speed for women in both groups was about 1.4 meters per second, as indicated in previous research. Also, the obese women did burn much more calories while walking than did the normal-weight women

Browning and Kram had expected the obese women to use more energy due to their heavier mass. Their wider stance and wider leg swings to the side as they walked would suggest the obese women burn more calories per minute than their peers.

Still, the difference in calorie consumption between the two groups was only 11 percent, much lower than expected, the researchers note.

“Our findings suggest that the walking movement is not as expensive for obese women as we thought it would be and that obese individuals are probably adjusting their gait to conserve energy,” Browning noted.

“We thought that the obese women would walk more slowly than the normal weight to reduce the effort, but instead they appear to choose a walking speed that minimizes how much energy they need to expend to walk a given distance,” Browning noted.

Thus, while both groups burned a similar amount of calories while walking at their preferred speeds, the obese women used more effort - i.e., they consumed more oxygen.

In order to burn calories while using the same amount of aerobic effort used by normal-weight women at their preferred walking speeds, obese women should reduce their speed to 1.0 meter per second, according to Browning and Kram.

“Our results suggest that walking slower for a set distance may be an appropriate exercise recommendation for a weight management prescription in obese adults,” they write.

Due to the reduced health benefits of slower, less aerobic walking speeds, however, Browning suggests that “non-weight bearing activities be prescribed to reduce the risk of cardiovascular diseases.”

SOURCE: Obesity Research, May 5, 2005.