Indiana University researchers have found that physical activity throughout the day like simply moving is linked to positive feelings.
However, they found no similar relationship between physical activity and negative moods.
"In the study, if people are more active, they tend to report a more positive mood. Really low levels of activity are related to lower levels of positive affect," said Bryan McCormick, associate professor in IU Bloomington's School of Health, Physical Education and Recreation.
For the study, physical activity was considered movement beyond resting -- not formal exercise.
"People often see physical activity as having to be exercise, but it doesn't have to be exercise. Physical activity beyond a resting state does appear to be related to mood," McCormick said.
The study is exceptional because it tracks moment-by-moment physical activity throughout the day and compares it to reports study participants make throughout the day of their activities and feelings.
For the study, the 25 participants wore uniaxial accelerometers during waking hours for seven days so their physical activity could be recorded.
They also wore wristwatches with pre-programmed alarms that signalled them seven times per day during this period so they could fill out brief reports.
If the participants responded more than 20 minutes after the alarm, their report was disregarded in order to eliminate the ambiguity of "recall."
Majority of studies involving mood and physical activity rely on recall, and compare it to overall physical activity levels, not moment-by-moment activity.
"Most research distinguishes between positive and negative mood. In our study, the moment-by-moment activity is related to positive mood -- but not related to negative mood state," McCormick said.
Physical activity and exercise is drawing more attention as a possible way to influence mild depression.
"In some ways, it might treat mild depression in that it increases our positive feelings, but it doesn't necessarily take away our negative feelings," McCormick said.
Georgia Frey, associate professor in the School of HPER's Department of Kinesiology and lead author of the study, said: "The results of this study were modest and based on a relatively small sample but the findings are encouraging."