Vagus Nerve Stimulation And Heart Rate Recovery In Men Living With HIV

People living with HIV (PLHIV) may exhibit alterations in cardiac autonomic control and impaired heart rate recovery after physical exertion. The vagus nerve, primarily responsible for parasympathetic activity, can modulate heart rate when stimulated. PURPOSE: To assess the effect of transauricular Vagus Nerve Stimulationon (taVNS) in heart rate recovery (HRR) and aerobic fitness (VO2max) in PLHIV. METHODS: A total of 12 physically inactive men living with HIV on antiretroviral therapy were randomized into two groups: taVNS and Sham Stimulation. The mean ages were (taVNS = 40.50 ± 12.77 vs Sham = 43.33 ± 12.43) and Body Mass Index (taVNS = 21.77 ± 4.83 vs Sham = 25.91 ± 3.23). Participants underwent 12 stimulation sessions, one per day, lasting 30 minutes each. The taVNS group received electrostimulation in the cymba concha region of the left ear. The stimulation protocol adopted an intensity set at the sensory threshold, a frequency of 10 Hz, and a wavelength of 500 μs. The Sham group received the same protocol, but the stimulator was turned off after identifying the sensory threshold. All participants completed a cardiopulmonary exercise test on a cycle ergometer coupled with a gas analyzer before and after the 12 stimulation sessions. Heart rate was monitored before, during, and after the test using a heart rate monitor. For HRR, Δ60s, Δ120s, and Δ500s were adopted, representing the difference from the maximum heart rate to the recovered heartbeats at 60s, 120 s, and 500 s after the exercise test. A two-way repeated measures ANOVA was applied to compare HRR and VO2max deltas between groups, across times (pre- and post-intervention), and for group × time interaction analysis. RESULTS: Two-way ANOVA showed no significant interaction between the analyzed variables for taVNS vs Sham groups × time (Δ60s: F = 1.87, p = 0.201; Δ120s: F = 0.374, p = 0.554; Δ500s: F = 0.251, p = 0.627; VO2max: F = 1.74, P = 0.216). CONCLUSION: Twelve sessions of taVNS did not effect HRR or VO2max in men living with HIV. taVNS has been used in the treatment of other chronic diseases, and different stimulation parameters may yield different effects. It is suggested that other stimulation protocols be tested in the same population to identify optimal parameters. JAM and PW were financed in part by a scholarship from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil - finance code 001