Determinants affecting physical activity levels in animal models.
Weight control is dependent on energy balance. Reduced energy expenditure (EE) associated with decreased physical activity is suggested to be a major underlying cause in the increasing prevalence of weight gain and obesity. Therefore, a better understanding of the biological determinants involved in the regulation of physical activity is essential. To facilitate interpretation in humans, it is helpful to consider the evidence from animal studies. This review focuses on animal studies examining the biological determinants influencing activity and potential implications to human. It appears that physical activity is influenced by a number of parameters. However, regardless of the parameter involved, body weight appears to play an underlying role in the regulation of activity. Furthermore, the regulation of activity associated with body weight appears to occur only after the animal achieves a critical weight. This suggests that activity levels are a consequence rather than a contributor to weight control. However, the existence of an inverse weight-activity relationship remains inconclusive. Confounding the results are the multifactorial nature of physical activity and the lack of appropriate measuring devices. Furthermore, many determinants of body weight are closely interlocked, making it difficult to determine whether a single, combination, or interaction of factors is important for the regulation of activity. For example, diet-induced obesity, aging, lesions to the ventral medial hypothalamus, and genetics all produce hypoactivity. Providing a better understanding of the biological determinants involved in the regulation of activity has important implications for the development of strategies for the prevention of weight gain leading to obesity and subsequent morbidity and mortality in the human population.
Lockheed Martin Engineering and Sciences, and National Aeronautics and Space Administration (NASA) Ames Research Center, Life Sciences Division, NASA Ames Research Center, Moffett Field, California 94035, USA.
Janet C L
JC
Tou
Charles E
CE
Wade
D000273:Adipose Tissue / Q000378:metabolism; D000375:Aging / Q000502:physiology; D000818:Animals; D001066:Appetite / Q000502:physiology; D001835:Body Weight; D004032:Diet; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology; D006801:Humans; D007031:Hypothalamus / Q000293:injuries / Q000502:physiology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D023421:Models, Animal; D009043:Motor Activity / Q000235:genetics / Q000502:physiology; D009765:Obesity / Q000503:physiopathology; D051381:Rats; D012727:Sex Characteristics; D013045:Species Specificity; D013312:Stress, Physiological / Q000503:physiopathology
D012739:Gonadal Steroid Hormones
NASA Center ARC; NASA Discipline Regulatory Physiology