Clinical Trials

The loss of muscle mass and function with age leads to high social and economic costs. Lifestyle interventions that can help maintain muscle mass and function can be beneficial to improve health and decrease the costs associated with loss of independence in the elderly. Muscle proteins accumulate damage during aging, which is suggested to lead to loss of function.  The biological processes that remove damaged proteins and synthesis new proteins appear to be decreased with aging.  Exercise is known to increase the processes that remove older and synthesis newer muscle proteins and may be an effect lifestyle intervention to improve muscle quality and function.  Additionally, specific types of proteins appear to decay with age including contractile and mitochondrial proteins.  Different types of exercise training can increase the making of specific proteins.  The investigators will examine the ability for aerobic and resistance training to increase the quality of mitochondrial and contractile proteins between younger and older people.

This research study is designed to help us better understand how the body controls the secretion of adrenocorticotropic hormone (ACTH) in young men and women.

ACTH is a hormone (a chemical that circulates in the blood and influences a person's health) that is made in and released by the pituitary gland in the brain. ACTH increases the production of cortisol by the adrenal gland.

Cortisol is a hormone which allows the body to respond to stress. Thus, ACTH and cortisol are called stress hormones.

Their levels differ in men and women, but doctors do not know why. This study will test how testosterone (male sex hormone) in men and estrogen (female sex hormone) in women control the stress hormones.

This question is important, because sex hormones increase in puberty and decrease with aging.

Accumulation of damaged proteins is thought to underlie many degenerative conditions, including aging, diabetes, Alzheimer's disease, cataracts, and others. Over time, proteins can be irreversibly damaged by a variety of factors, such as reactive oxygen species, and without timely degradation they can accumulate and aggregate. We believe this can contribute to the development of chronic degenerative disorders. The purpose of this study is to develop a novel methodology for measuring protein accumulation and test it in two groups of people: young (18-30 years) and old (≥65 years). This methodology will require that people drink a solution of essential amino acids that includes isotopically labeled L[ring-13C6]phenylalanine. We will then collect blood and muscle samples, to isolate plasma and skeletal muscle proteins. Participants will return to the study center four more times on a weekly interval. We hypothesize that older proteins, which persisted in circulation and accumulated over time, will have a higher degree of post-translational oxidative damage than newly synthesized proteins.

ACTH is a hormone (a chemical that circulates in the blood and influences a person's health) that is made in and released by the pituitary gland in the brain. ACTH increases the production of cortisol by the adrenal gland. Cortisol is a life-supporting hormone, which allows the body to respond to stress. Thus, ACTH and cortisol are called stress hormones. Their levels differ in men and women, but doctors do not know why. This study will test how testosterone (male sex hormone) in men and estrogen (female sex hormone) in women control the stress hormones. This question is important, because sex hormones increase in puberty and decrease with aging.