Moderate to high-intensity aerobic exercise increases cardiorespiratory fitness (VO2peak) in younger adults with HIV. There are few studies that show any benefit from varying types of exercise in older adults with HIV. In a pilot study using 22 older men with HIV, half were randomly assigned to one of two groups – moderate-intensity aerobic exercise (Mod-AEX) or high-intensity aerobic exercise (High-AEX). In the High-AEX group, exercise consisted of using a motorized treadmill with occasional substitution using an elliptical machine as needed for joint pain. Duration/intensity was increased 10% weekly. By the 5^th to 7^th week the aerobic exercise sessions lasted 30–45 minutes. In the ModAEX group, participants performed a self-paced 1-mile walk on an indoor track. Initial sessions lasted 20–30 minutes increasing to 45 minutes, similar to the high-AEX group.

This initial study found that moderate to high-intensity aerobic exercise increased endurance and ambulatory function. Only those in the high-intensity aerobic group evidenced an increase in cardiorespiratory fitness.