Inclusion Criteria:  Subjects will be men and women of all races and ethnic backgrounds aged 40-75 years with documented HIV-1 infection. Subjects will be HIV-1-seropositive individuals on a stable DHHS approved ART regimen for at least 6 months, with documented virologic suppression (<50 copies HIV-1 RNA/mL) for at least 3 months. All subjects must have CD4+ T cell counts >200 cells/mm3 at the time of study entry. Subjects will be free of overt CVD as assessed by: a) medical history; b) physical examination; c) electrocardiogram and BP at rest and maximal exercise; d) complete blood chemistries, lipid and lipoprotein, glucose, insulin and hematological evaluation. All candidates will be sedentary as determined from the Stanford Physical Activity Questionnaire (<35 kcal/wk) and will not have engaged in any program of regular physical activity for at least 6 months prior to the study.  Exclusion Criteria:  Receiving hormone replacement therapy (HRT) currently or in the preceeding 3-year period. Pre- or peri-menopausal women