Respiratory impairment and dyspnea and their associations with physical inactivity and mobility in sedentary community-dwelling older persons

Objectives To evaluate the prevalence of respiratory impairment and dyspnea and their associations with objectively measured physical inactivity and performance-based mobility in sedentary older persons. Design Cross-sectional. Setting Lifestyle Interventions and Independence for Elders Study. Participants Community-dwelling older persons (n = 1,635, mean age 78.9) who reported being sedentary (<20 min/wk of regular physical activity and <125 min/wk of moderate physical activity in past month). Measurements Respiratory impairment was defined as low ventilatory capacity (forced expiratory volume in 1 second less than lower limit of normal (LLN)) and respiratory muscle weakness (maximal inspiratory pressure <LLN). Dyspnea was defined as moderate to severe ratings on the modified Borg index, immediately after a 400-m walk test (400-MWT). Physical inactivity was defined according to high sedentary time as the highest quartile of participants with accelerometry-measured activity of <100 counts/min. Performance-based mobility was evaluated using the Short Physical Performance Battery (≤7 defined as moderate to severe mobility impairment) and 400-MWT gait speed (<0.8 m/s defined as slow). Results Prevalence rates were 17.7% for low ventilatory capacity, 14.7% for respiratory muscle weakness, 31.6% for dyspnea, 44.7% for moderate to severe mobility impairment and 43.6% for slow gait speed. Significant associations were found between low ventilatory capacity and slow gait speed (adjusted odds ratio (aOR) = 1.41, 95% confidence interval (CI) = 1.03-1.92), between respiratory muscle weakness and moderate to severe mobility impairment (aOR = 1.42, 95% CI = 1.03-1.95), and between dyspnea and high sedentary time (aOR = 1.98, 95% CI = 1.28-3.06) and slow gait speed (aOR = 1.70, 95% CI = 1.22-2.38). Conclusion Respiratory impairment and dyspnea are prevalent in sedentary older persons and are associated with objectively measured physical inactivity and poor performance-based mobility. Because they are modifiable, respiratory impairment and dyspnea should be considered in the evaluation of sedentary older persons.