The increase in life expectancy has exposed the population to greater intrinsic and extrinsic factors that affect the whole organism and that can influence the respiratory function of the elderly, which is already suffering from aging-related alterations. Changes such as replacement of muscle fibers by fat and increased rib cage rigidity affect the function of respiratory muscles, leading to strength deficit, represented by decreased values of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP), which may reflect in dyspnea and fatigue.

To analyze the factors associated (sociodemographic characteristics, lifestyle habits, and health conditions) with respiratory muscle strength (RMS) among community-dwelling older adults.

Cross-sectional, population-based study conducted among community-dwelling elderly residents in the urban area in the municipality of Macapá-AP. The associated factors evaluated were sociodemographic characteristics (structured questionnaire with information about sex, age, education, individual income and housing), lifestyle habits (self-report of smoking; and level of physical activity - through the International Physical Activity Questionnaire-IPAQ) and health conditions (body mass index; self-report of hospital admissions and falls in the last 12 months; associated diseases; medication use; self-perception of health; depressive symptoms - measured by the Geriatric Depression Scale; functional capacity - using the Katz Scale and the Lawton and Brody instrument; and physical performance through the Short Physical Performance Battery). The MIP and MEP were evaluated by means of manovacuometry. Factors associated with RMS were identified by means of multivariable analysis in the multiple linear regression model, considering a significance level of 5%.

A total of 383 elderly people with a mean age of 70.01 (SD±7.3) years participated in the study, 251 being female (65.5%) and 132 male (34.5%). The adjusted linear regression model analysis pointed out that being female and having advanced age were associated with lower values of both MIP (β= -0.330; p= <0.001 and β= -0.150; p= 0.003, respectively) and MEP (β= -0.410; p= <0.001 and β= -0.190; p= <0.001, respectively). Elderly insufficiently active (β= -0.120; p= 0.008), with lower BMI values (β= 0.140; p= 0.002) and worse physical performance (β= 0.120; p= 0.020) showed association with lower MIP values and those less independent were associated with lower MEP values (β= -0.130; p= 0.005).

Older age and being female, insufficiently active, poorer physical performance, having a lower BMI value, and being less independent were factors associated with RMS in community-dwelling elderly.

The identification of factors that are associated with RMS in the elderly population enables health professionals to promote actions to change lifestyle habits, such as physical exercise, as well as to improve health conditions during the aging process, because our results demonstrated that these factors could bring impairment to respiratory function in community-dwelling elderly.