Abstract
We investigated the association between depression and anaerobic physical activity (while controlling aerobic physical activity), using a nationally representative sample of USA adults (n = 7354) who participated in the cross sectional National Health and Nutrition Examination Survey (NHANES, 1999-2006). We defined depression using the validated "Patient Health Questionnaire" (PHQ(9)) scale of 0-27 as PHQ(9) ≥ 10. Severity of depression was classified by clinically established PHQ(9) levels: mild (5-9), dysthymic (10-14), moderate (15-19), and major depression (≥20). We used logistic regression to estimate adjusted odds ratios of depression associated with distinct types of activity (only aerobic, only anaerobic, combined regime). We used multinomial logistic regression to examine associations of anaerobic activity with various severity levels of depression (mild, dysthymic, moderate, and major depression) with adjustment for aerobic activity. Women had higher prevalence of depression than men (8.4% versus 5.7%), whereas anaerobic muscle strengthening activity was more common in men than women (35% versus 24%). Adjusting for aerobic activity, anaerobic activity was inversely associated with depression (PHQ(9) ≥ 10) in women under 50 (OR = 0.57; 95%CI = 0.41-0.81), all women (OR = 0.59; 0.43-0.80), men under 50 (OR = 0.85; 0.58-1.2), and all men (OR = 0.72; 0.51-1.01). Anaerobic activity was inversely associated with severity level of depressive symptoms in women and men. The combined regimen of anaerobic muscle strengthening activity and meeting the Physical Activity Guideline for America (PAGA) was related to the lowest odds ratio of depression in women (OR = 0.50; 95%CI = 0.33-0.75) and men (OR = 0.39; 95%CI = 0.23-0.62). Independent of aerobic physical activity, anaerobic muscle strengthening activity is significantly and inversely associated with depression among USA adults.