Comparing the Effectiveness of High Intensity Interval Training vs Continuous Moderate Intensity Exercise on Physical Function Among Older Adults With HIV.

Background: People with HIV (PWH) have accelerated declines in physical function. Although exercise is highly effective for improving function, whether high-intensity interval training (HIIT) imparts greater physical function improvement than continuous moderate-intensity exercise (CME) among older PWH is unknown. Methods: The HEALTH trial (NCT04550676) enrolled sedentary PWH ≥50 years old on stable antiretroviral therapy (ART). Participants were randomized to perform 16 weeks of HIIT or CME, both with resistance exercise. High-intensity interval training sessions included 5 high-intensity (90% of heart rate reserve [HRR] for 4 minutes) and 4 moderate-intensity (50% of HRR for 3 minutes) bouts; the CME arm walked continuously at 60% of HRR. The primary outcome was percent change in 400-meter walk time (400-MWT). Results: Of the 118 randomized participants (n = 57 in HIIT, n = 54 in CME), 111 participants were included in the primary analysis; among these, the median age was 57 (interquartile range, 54-61) years, and 14% of participants were female. Participants in both HIIT (5.9% [95% CI], -7.7, -4.1) and CME (4.6% [95% CI, -6.4, -2.8]) had significant improvements in 400-MWT, with no significant difference between arms (P = .33). Among secondary outcomes of physical function and muscle strength, both arms demonstrated improvement (P < .05 for all), with no significant difference between arms at week 16. Conclusions: Although HIIT demonstrated greater gains in physical function among PWH, the differences from CME were small and not statistically different. Given that both HIIT and CME improved physical function, PWH should be encouraged to select the aerobic exercise according to individual preference.