The difference between fit older adults and elderly people who are unfit is the amount and intensity of physical activity.

Researchers from Norwegian University found that fitness level had the strongest association with physical activity, followed by gender and season.

"This means that fit older adults were more active than the unfit, females were more active than males and physical activity was higher in the warmer months of the year. In addition we found that higher education was associated with higher physical activity for males, but not for females. Among other interesting results, we found that the social environmental correlates, such as social support and living situation, were not associated with physical activity among the elderly," two first authors of the study, Hallgeir Viken and Nils Petter Aspvik, said in a statement.

For the study, researchers collected and analyzed data from 850 older adults who wore an accelerometer for seven days. Participants were 70-77 years old and living in the city of Trondheim, Norway.

"Correlate studies are important because they examine how background factors can be associated with physical activity behavior. This in turn is important knowledge when developing and adapting physical activity interventions. This is to our knowledge the largest study of physical activity correlates among older adults that has combined objectively measured physical activity and cardiorespiratory fitness (CRF)," researchers said.

The findings are detailed in the Journal of Aging and Physical Activity.