Middle school-aged girls who are physically fit could be less prone to depression, according to preliminary university-led research.

Conducted by Camilo Ruggero, an assistant professor of psychology from the University of North Texas, the initial findings have indicated that girls who exercised regularly during the American sixth grade were less likely to be depressed in the following school year.

The research has been unable to reason as to why fitness, weight and depression interact with each other, however specialists have suggested that the onset of depression could be related to BMI.

As well as observing girls, the study also saw that boys who became the subject of depression during the sixth grade were then more likely to be less physically active during the seventh.

The study has had its critics though, with some stating that causation is yet to be properly determined, essentially pointing out that increasing fitness does not mean that a person’s mental health will improve in due course.

If the research does stand up to become featured in a peer-reviewed journal, the findings would provide growing weight to a body of evidence that highlights the important impact of fitness levels and physical activity on the function of the brain, as well as the development of mental illness.

Research published recently has suggested that exercise could help children to improve their language skills, while other findings show that physical fitness could have links to the academic performance of young people.