This is true. FEV1 and FVC for swimmers is higher than other athletes, having a 10% difference is actually huge compared to the general population. Conversel

This is true. FEV1 and FVC for swimmers is higher than other athletes, having a 10% difference is actually huge compared to the general population. Conversely a 20% below average function is what someone with asthma could have or beginning stages of lung disease. Bottom line if you're lungs are functioning even 5% over "normal" for your age, height, and ethnicity you have extremely efficient lungs