Improving cardiorespiratory fitness may help prevent depression in adolescents, according to a study of 197 male and 240 female middle schoolers in Texas.

The study participants’ weight, height, physical fitness, and psychological well-being were assessed twice, once during sixth grade and once during seventh grade.

The sixth grade assessments showed strong cross-sectional associations between cardiorespiratory fitness (CRF) and less depression for both the male and female groups.

Examining the data for the girls alone showed more evidence of higher CRF being negatively correlated with depression, in that the girls’ sixth grade CRF was determined to be “a significant predictor of lower depression in seventh grade,” after sixth grade body composition and depression were controlled for. Data for the boys showed this trend as well, but this finding was not statistically significant.

A significant finding from studying the male subset was that sixth grade depression was a predictor of poorer CRF in seventh grade.

“Preexisting levels of depression (i.e., in sixth grade) were the most powerful predictor of subsequent depression. However, even after controlling for sixth grade depression and body composition, higher levels of CRF in sixth grade were associated with significantly less depression by the seventh grade for girls,” according to Camilo J. Ruggero, Ph.D., of the University of North Texas, Denton, and his colleagues.

“Moving forward, stakeholders and researchers concerned about depression during middle school would benefit from regular assessment of not simply physical activity, but levels of CRF as well,” noted the researchers.

Read the full study in the Journal of Adolescent Health .