Physical activity gives structure and meaning to people’s lives, according to new research.

A study, published in the Journal of Behavioral Medicine, looked at how exercise affected more than 18,000 middle-aged and older men and women in the US.

Researchers examined data from the ongoing Health and Retirement Study, which gathers longitudinal data about the lives, attitudes and activities of American adults aged 50 or older.

Led by Ayse Yemiscigil, a postdoctoral research fellow with the Human Flourishing Program at Harvard University, the study looked at people's responses to questions such as “I have a sense of direction and purpose in life" and “my daily activities often seem trivial and unimportant".

The team then revisited people's attitudes a few years later, correlated with the amount of exercise they did.

The findings suggested that people's exercise habits may influence their sense of purpose in life – while the reverse is also true, as having a sense of purpose seemed to have a positive effect on how much they exercised.

In short, it seems that those with the most steadfast sense of purpose at the start of the study were the most likely to become active over time – and vice versa.

Yemiscigil, said: "People with a greater sense of purpose may be more likely to engage in physical activity.

"At the same time, physical activity can contribute to a sense of purpose.

"We tested these hypotheses using a cross-lagged panel model in a nationally representative, longitudinal panel of American adults.

"An increase in sense of purpose was associated with higher physical activity four years later, above and beyond past activity levels.

"Physical activity was positively associated with future levels of sense of purpose in life, controlling for prior levels of purpose in life.

"The findings demonstrate a bidirectional relationship between sense of purpose in life and physical activity in large samples of middle-aged and older adults tracked over time."

To read more about the study, click here.