title: The effects of testosterone and insulin-like growth factor 1 on motor system form and function.
abstract: In this perspective article, we review the effects of selected anabolic hormones on the motoric system and speculate on the role these hormones may have on influencing muscle and physical function via their impact on the nervous system. Both muscle strength and anabolic hormone levels decline around middle age into old age over a similar time period, and several animal and human studies indicate that exogenously increasing anabolic hormones (e.g., testosterone and insulin-like growth factor-1 (IGF-1)) in aged subjects is positively associated with improved muscle strength. While most studies in humans have focused on the effects of anabolic hormones on muscle growth, few have considered the impact these hormones have on the motoric system. However, data from animals demonstrate that administering either testosterone or IGF-1 to cells of the central and peripheral motor system can increase cell excitability, attenuate atrophic changes, and improve regenerative capacity of motor neurons. While these studies do not directly indicate that changes in anabolic hormones contribute to reduced human performance in the elderly (e.g., muscle weakness and physical limitations), they do suggest that additional research is warranted along these lines.
authors: Ohio Musculoskeletal & Neurological Institute, Ohio University, Athens, OH, USA; Department of Biomedical Sciences, Ohio University, Athens, OH, USA. Electronic address: okik@ohio.edu.
authors: Kentaro
authors: K
authors: Oki
authors: Ohio Musculoskeletal & Neurological Institute, Ohio University, Athens, OH, USA; Department of Family Medicine, Ohio University, Athens, OH, USA.
authors: Timothy D
authors: TD
authors: Law
authors: Ohio Musculoskeletal & Neurological Institute, Ohio University, Athens, OH, USA; Department of Biological Sciences, Ohio University, Athens, OH, USA.
authors: Anne B
authors: AB
authors: Loucks
authors: Ohio Musculoskeletal & Neurological Institute, Ohio University, Athens, OH, USA; Department of Biomedical Sciences, Ohio University, Athens, OH, USA; Department of Geriatric Medicine, Ohio University, Athens, OH, USA.
authors: Brian C
authors: BC
authors: Clark
mesh_terms: D000375:Aging / Q000502:physiology*; D000728:Androgens / Q000502:physiology*; D000818:Animals; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D008297:Male; D009043:Motor Activity; D053580:Muscle Strength; D013739:Testosterone / Q000502:physiology*
chemical_list: D000728:Androgens; D013739:Testosterone; D007334:Insulin-Like Growth Factor I
keywords: Aging; Insulin-like growth factor 1; Motor system; Muscle strength; Testosterone