* on medications that would influence exercise performance such as beta blockers or antiretroviral therapy * enrolled in another interventional clinical research trial * pregnancy * significant hepatic or renal dysfunction * history or cardiac condition as determined by national institutes of health (nih) cardiology to be unsafe for exercise participation (e.g. ischemic heart disease, right- or left-sided heart failure, cor pulmonale or pulmonary hypertension, dilated or hypertrophic cardiomyopathy or non-idiopathic cardiomyopathy) * patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease.

* on medications that would influence exercise performance such as beta blockers or antiretroviral therapy * enrolled in another interventional clinical research trial * pregnancy * significant hepatic or renal dysfunction * history or cardiac condition as determined by national institutes of health (nih) cardiology to be unsafe for exercise participation (e.g. ischemic heart disease, right- or left-sided heart failure, cor pulmonale or pulmonary hypertension, dilated or hypertrophic cardiomyopathy or non-idiopathic cardiomyopathy) * patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease.

on medications that would influence exercise performance such as beta blockers or antiretroviral therapy enrolled in another interventional clinical research trial pregnancy significant hepatic or renal dysfunction history or cardiac condition as determined by national institutes of health (nih) cardiology to be unsafe for exercise participation (e.g. ischemic heart disease, right- or left-sided heart failure, cor pulmonale or pulmonary hypertension, dilated or hypertrophic cardiomyopathy or non-idiopathic cardiomyopathy) patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease.

on medications that would influence exercise performance such as beta blockers or antiretroviral therapy enrolled in another interventional clinical research trial pregnancy significant hepatic or renal dysfunction history or cardiac condition as determined by national institutes of health (nih) cardiology to be unsafe for exercise participation (e.g. ischemic heart disease, right- or left-sided heart failure, cor pulmonale or pulmonary hypertension, dilated or hypertrophic cardiomyopathy or non-idiopathic cardiomyopathy) patients with a current diagnosis of schizophrenia, manic depressive illness, substance abuse, eating disorder or proven organic brain disease.