Our lungs may start to lose their steam earlier in life than we thought. Research out today suggests that lung function tends to peak in young adulthood and only gets worse from there.

Scientists at the Barcelona Institute for Global Health (ISGlobal) led the study, published Thursday in The Lancet Respiratory Medicine. After analyzing data from earlier population studies, the researchers found that peak lung function is usually reached by our early 20s and—contrary to current wisdom—continues to steadily decline as we age.

According to lead author Judith Garcia-Aymerich, co-director of the Environment and Health over the Life Course program at ISGlobal, it’s been assumed that our lungs follow a specific trajectory: they gradually get stronger until our mid-20s, reach a steady plateau over the next few decades, then decline as we reach middle age. But this assumption was based on studies that only examined lung function at certain time periods, rather than over the course of an entire life.

To bridge this knowledge gap, Garcia-Aymerich’s team combined and analyzed data from eight different population studies in Europe and Australia. These studies collectively involved around 30,000 people from the ages of four to 82, and lung function was measured through forced spirometry, a test where people blow out as much air as possible after taking a deep breath.

The researchers first identified two broad stages of lung development: a phase of rapid growth in early childhood, followed by slower, steady growth through the early 20s. On average, this peak was reached around age 20 for women and age 23 for men. Unlike other research, they failed to find any evidence of a steady period of lung function following this peak.

“Previous models suggested a plateau phase until the age of 40, but our data show that lung function starts to decline much earlier than previously thought, immediately after the peak,” said Garcia-Aymerich in a statement released by ISGlobal.

The findings, somber as they are, might help improve how respiratory health is tracked and maintained, the researchers say.

They found that certain risk factors for poor lung health, such as asthma and smoking, might affect lung function a bit differently than suspected, for instance. Chronic asthma appears to weaken lung health at an early age, a weakness that then persists throughout a person’s life. Smoking, on the other hand, seems to rapidly worsen a person’s lungs starting in the mid-30s. Equipped with this knowledge, it might be possible to intervene early on, the researchers say.

“Early detection of low lung function may allow interventions to prevent chronic respiratory diseases in adulthood,” said Garcia-Aymerich.

While our lungs might not stay in tip-top shape as long as hoped, there are things most anyone can do to keep them as healthy as possible, such as regular physical exercise.