Chronic obstructive pulmonary disease (COPD) can lead to increased dependence on the informal caregiver and, consequently, to distress associated with caregiving burden. In the general population, higher levels of physical activity (PA) are related to lower distress levels; however, this relationship has been scarcely studied in COPD. This study aimed to explore the relationship between distress and PA in informal caregivers of patients with COPD, and the influence of caregivers' (age, sex) and patients' (age, sex, lung function) characteristics and caregiving duration on this relationship. A cross-sectional study was conducted with 50 caregivers (62.7 ± 9.8 years, 88% female; 78% caring for a spouse/partner; 38% caring >40 h/week; patients' FEV1=45.2 ± 21.3% predicted). Data collection comprised questions related to the caregiving context, distress related to caregiving burden assessed with the Informal Caregiver Burden Assessment Questionnaire (QASCI; total score, 7 subscales), and self-reported PA with the Habitual Physical Activity Questionnaire (HPAQ). Spearman's correlation coefficient and linear regressions were used. Significant, negative and moderate correlations were found between the QASCI (28.5 ± 19.8) and the HPAQ (5.2 ± 1.3) (ρ=-0.46; p = 0.01); and between the HPAQ and some QASCI subscales (emotional burden ρ=-0.47; implications for personal life ρ=-0.52; financial burden ρ=-0.44; perception of efficacy and control mechanisms ρ=-0.42; p < 0.01). Two linear regression models were tested to predict QASCI total score including as predictors: 1) HPAQ alone (p = 0.001; r2=0.23); 2) HPAQ and caregiving h/week (p < 0.001; r2=0.34). Higher self-reported PA levels are related to decreased levels of distress associated with caregiver burden in COPD caregivers. Duration of caregiving may negatively influence this relationship.