CAT and major depressive disorder: Our main findings were that: (i) the young control group presented greater intensity of depression symptoms in comparison with both the master athletes from sprints and the middle-aged untrained control group; (ii) the young control group did not differ from the endurance runners in terms of intensity of depression symptoms; (iii) CAT activity was negatively associated with the intensity of depression symptoms in master athletes; (iv) the CAT/TBARS ratio was a negative correlation with symptoms of depression.