We hypothesize that a mixed regimen of exercise (including both resistance and aerobic exercise) and L-carnitine supplementation will improve mitochondrial dysfunction in HIV/HAART patients, and therefore, alleviate dysmetabolic symptoms such as dyslipidemia and insulin resistance. In this randomized, placebo-controlled study, we will explore whether a mixed regimen of exercise, including both resistance and aerobic exercise, and L-carnitine supplementation affect lipids and remnant lipoproteins, adipokines, insulin resistance; blood lactate levels and VO2max; and kinetics of leucine and triglyceride-rich lipoproteins among African-American and Hispanic HIV-positive subjects undergoing HAART. Effects on muscle mitochondrial function will be assessed using exercise tests and body composition assessment (DEXA and Bioimpedance), while effects on hepatic mitochondrial function will be assessed measuring the relation between leucine and VLDL-apoB metabolism. We believe that the proposed study will help to elucidate underlying mechanisms for metabolic complications and will offer new possibilities for intervention to reduce negative metabolic effects in HIV/HAART patients.