In November, 1,000 U.S. adults were asked daily about their exercise habits as part of the Gallup-Healthways Well-Being Index.
Typically, Americans exercise the most in the summer and taper off in the fall and exercise the least in December.
The Gallup-Healthways Index indicated the percentage of adults who reported exercising frequently -- for at least 30 minutes three or more days per week -- slipped to 49.8 percent last month, down from 50.5 percent in November 2010. The percentage also was down from 52.2 percent in October and from the year's high of 54.5 percent in July, the survey found.
The percentage of Americans reporting they exercise frequently was relatively low through the fall of 2008 and much of 2009, amid the worst of the economic crisis.
However, the percentage who reported frequent physical activity was generally higher in 2010 and has since remained at somewhat higher levels, Gallup officials said.
The 29,285 telephone interviews conducted as part of the Gallup-Healthways Well-Being Index survey Nov. 1 to 30 has a margin of error of 1 percentage point.