Physical activity alleviates stress and benefits women psychologically, which in turn aids their memory, the study said.
"Our research suggests these self-reported memory problems may be emotionally related. These women are frightened, stressed, fatigued, tapped out emotionally and have low self-confidence, which can be very mentally taxing and can lead to perceived memory problems," said Siobhan Phillips, Assistant Professor, Northwestern University Feinberg School of Medicine in Chicago.
The findings were published in the journal Psycho-Oncology.
The researchers looked at memory and exercise in breast cancer survivors in two study arms - one in self-reported data for 1,477 women; the other in accelerometers worn by 362 women. The findings linking improved memory to higher levels of physical activity were consistent across both groups.
In the study, more physical activity was associated with higher levels of self-confidence, lower distress and less fatigue, which in turn is associated with lower levels of perceived memory impairment. Breast cancer survivors who had higher levels of moderate and vigorous physical activity - brisk walking, biking, jogging or attending an exercise class -- had fewer subjective memory problems. Subjective memory is an individual's perception of his/her memory.