Chronotropic Incompetence among People with HIV Improves with Exercise Training in the Exercise for Healthy Aging Study

BACKGROUND: People with HIV (PWH) have lower exercise capacity compared to HIV-uninfected peers, which may be explained by chronotropic incompetence (CI), the inability to increase heart rate during exercise. METHODS: The Exercise for Healthy Aging Study included adults ages 50–75 with and without HIV. Participants completed 12 weeks of moderate intensity exercise, before randomization to moderate or high intensity for 12 additional weeks. We compared adjusted heart rate reserve (AHRR; CI <80%) on cardiopulmonary exercise testing by HIV serostatus, and change from baseline to 12 and 24 weeks using mixed effects models. RESULTS: Among 32 PWH and 37 controls (median age 56, 7% female, mean BMI 28 kg/m(2)), 28% of PWH compared to 11% of controls had CI at baseline (p=0.067). AHRR was lower among PWH (91 vs 102%; difference 11%, 95% CI 2.5–19.7; p=0.01). At week 12, AHRR normalized among PWH (+8%, 95% CI 4–11; p<0.001) and was sustained at week 24 (+5, 95%CI 1–9; p=0.008) compared to no change among controls (95%CI −4 to 4; p=0.95; p(interaction)=0.004). After 24 weeks of exercise, only 15% PWH and 10% of controls had CI (p=0.70). CONCLUSIONS: Chronotropic incompetence contributes to reduced exercise capacity among PWH and improves with exercise training.