The effects of high-intensity interval training versus continuous moderate-intensity exercise on body composition...

We compared two exercise intensities on lean and fat mass among older people with HIV (PWH). The High Intensity Exercise to Attenuate Limitations and Train Habits (HEALTH) randomized sedentary PWH ≥50 years to 16 weeks of high-intensity interval training (HIIT) or continuous moderate-intensity exercise (CME), both with resistance exercise. Body composition was measured using dual-energy x-ray absorptiometry (DXA) at baseline and week 16. The primary outcome was the percent change in body fat percentage (ratio of fat mass to total mass). Secondary outcomes included percent change in lean, fat, appendicular lean (ALM), and total mass. Linear regression models examined between- and within-group changes from baseline to week 16. Of the 95 participants with pre- and post-DXA scans, the median (interquartile range [IQR]) age was 58 [54-61] years, 14% female, 14% Black, and 14% Hispanic. Fat percentage decreased by -3.3% (95% confidence interval [CI]: -5.2, -1.6) in HIIT and -3.3% (95% CI: -5.3, -1.6) in CME. Fat mass decreased by -3.5% (95% CI: -5.9, -1.0) in HIIT and -3.8% (95% CI: -6.3, -1.3) in CME. Lean mass increased by 1.7% (95% CI: 0.7, 2.7) and ALM by 3.3% (95% CI: 1.3, 5.3) in HIIT and 1.2% (95% CI: 0.2, 2.2) and ALM by 2.6% (95% CI: 0.6, 4.6) in CME. Although both arms had significant improvements compared to baseline, no between-arm comparisons were statistically significant. Supervised HIIT or CME combined with resistance training for 16 weeks is an effective strategy for improving body composition in previously sedentary older PWH. Clinicaltrials.gov: NCT04550676.