Impaired Oxygen on-Kinetics in Persons with Human Immunodeficiency Virus Are Not Due to Highly Active Antiretroviral Therapy

Objective: To determine the effects of human immunodeficiency virus (HIV) and highly active antiretroviral therapy (HAART) on oxygen on-kinetics in HIV-positive persons. Design: Quasi-experimental cross-sectional. Setting: Infectious disease clinic and exercise laboratory. Participants: Referred participants (N=39) included 13 HIV-positive participants taking HAART, 13 HIV-positive participants not taking HAART, and 13 noninfected controls. Interventions: Participants performed 1 submaximal exercise treadmill test below the ventilatory threshold, 1 above the ventilatory threshold, and 1 maximal treadmill exercise test to exhaustion. Main Outcome Measures: Change in oxygen consumption (ΔV̇O₂) and oxidative response index (ΔV̇O₂/mean response time). Results: ΔV̇O ₂ was significantly lower in both HIV-positive participants taking (946.5±68.1mL) and not taking (871.6±119.6mL) HAART than in controls (1265.3±99.8mL) during submaximal exercise above the ventilatory threshold. The oxidative response index was also significantly lower (P<.05) in HIV-positive participants both taking (15.0±1.3mL/s) and not taking (15.1±1.7mL/s) HAART than in controls (20.8± 2.1mL/s) during exercise above the ventilatory threshold. Conclusion: Oxygen on-kinetics during submaximal exercise above the ventilatory threshold was impaired in HIV-positive participants compared with a control group, and it appeared that the attenuated oxygen on-kinetic response was primarily caused by HIV infection rather than HAART.