Ray Browning, a doctoral student in CU-Boulder's integrative physiology department and lead author on the new study, said the results show that people who walk a mile at a leisurely pace burn more calories than if they walk a mile at their normal pace. In addition, those who walk at 2 miles per hour rather than 3 miles per hour reduce the loads on their knee joints by up to 25 percent.
"The message is that by walking more slowly, obese individuals can burn more calories per mile and may reduce the risk of arthritis or joint injury," he said.
Browning and his CU colleagues also found the number of calories burned per pound of body weight is similar for obese adults as normal sized adults walking at the same speed. Because obese people generally have heavier legs, wider stances and swing their legs in a wider arc, the researchers expected the cost of walking for obese people to be significantly higher.
"This was a surprise," said Browning. "The subjects probably are unwittingly altering their posture and walking with straighter legs, conserving calories in the process."
A paper by Browning, CU-Boulder integrative physiology Associate Professor Rodger Kram and undergraduates Emily Baker and Jessica Herron was presented at the June 2005 meeting of the American College of Sports Medicine meeting in Nashville and published recently in the journal, "Obesity Research."
The CU-Boulder researchers based their expectations that obese adults would have a greater energy cost when walking on previous studies by Kram's lab team. In one study, energy expenditure increased by about 25 percent when normal-weight people walked with a deliberately wider stance, said Browning.
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