60) A recent study (61) further demonstrated decreased arteriovenous oxygen difference during peak treadmill exercise in a group of individuals with HIV who received HAART compared with a group of individuals with HIV who did not receive HAART and with a non-HIV-infected control group, indicating a deleterious effect of HAART on peak peripheral muscle oxygen extraction and utilization during exercise.

55 Effects include increased exercise duration, increased peak oxygen consumption, and increased peripheral arteriovenous oxygen difference.

[98-100] Peripheral adaptations include (1) an increase in the number and size of mitochondria, (2) improved extraction of oxygen from circulating blood by the exercising muscles, (3) increased muscle strength, (4) increased mitochondrial enzymatic activity, (5) proliferation of capillaries, (6) an increase in the mean transit time of blood through muscle capillaries, (7) a lowering of peripheral vascular resistance, and (8) an increased arteriovenous oxygen difference.