Heli J. Roy | 3/18/2005 11:10:41 PM
Scientists are learning about the role of genetic and non-genetic factors in cardiovascular, metabolic and hormonal responses to aerobic exercise through a three-part investigation begun 12 years ago, according to LSU AgCenter nutritionist Dr. Heli Roy.
"Results from the HERITAGE Family Study have important implications for understanding variation from one person to the next in a variety of physiological responses and risk factors for common chronic diseases," Roy says.
"Because of the large number of subjects who completed the same standardized training program, the study will give information on gender, race, age or initial level of fitness response to exercise or a response of any combination of them," the nutritionist adds.
Launched in 1992 by a consortium of five institutions, the study, which constructs its acronym from HEalth, RIsk factors, exercise Training And GEnetics, began examining three areas:
"The main goal of the multi-center project was to study the role of one’s genes in influencing the cardiovascular and metabolic responses to aerobic exercise training," Roy explains, adding, "Genes also may be involved in the varied response in the individual’s risk factors to exercise, such as lowered cholesterol level or improvement in lung capacity."
Phase 1 was conducted from 1992 to 1997. During this phase, 742 healthy, sedentary subjects (483 whites and 259 blacks), 17-65 years old, were recruited, tested, exercise-trained in the laboratory under supervision with the same program for 20 weeks and re-tested.
These subjects came from families of white descent with both parents and biological adult offspring and from families or pairs of first-degree relatives of black ancestry. Various metabolic parameters such as blood pressure, glucose and insulin levels, hormones and dietary intakes were determined during this phase.
Phase 2 of the study was conducted from 1997 to 2001. During this phase, the data from the previous phase were analyzed, including molecular and genetic studies. These analyses provided information about diabetes and heart disease risk factor response to exercise and possible genetic involvement in response to exercise.
Phase 3 of the study is still on-going (from 2001 to 2004). The main focus of Phase 3 is to expand and refine the search for genes and mutations that affect cardio-respiratory response to endurance exercise and cardiovascular disease and type 2 diabetes risk factor response to regular exercise.
"Individuals respond quite differently to drugs, diet or exercise," Roy says, explaining, "For instance, there are considerable individual differences in improvement in aerobic capacity with aerobic training."
She notes that people can improve from almost 0 percent to 50 percent, even though all the subjects may complete exactly the same training program. Scientists had previously assumed that these variations resulted from differing degrees of compliance with the training program, that is, good compliers improve the most and poor compliers show little or no improvement.
"It is now clear, however, that even when there is full compliance with the program, there is substantial variation in the percentage improvements in different people," Roy says.
The research is funded by grants from the National Heart, Lung and Blood Institute of the National Institutes of Health of the U.S. government.
The consortium is composed of research teams from the following five institutions: Indiana University, directed by James S. Skinner, Ph.D.; University of Minnesota, directed by Arthur S. Leon, M.D.; Texas A&M University, directed by Jack H. Wilmore, Ph.D.; Washington University directed by D.C. Rao, Ph.D.; and the LSU Pennington Biomedical Research Center, directed by Claude Bouchard, Ph.D. The consortium was put together by Dr. Bouchard. The project director at the LSU Pennington Biomedical Research Center, Baton Rouge, La., is Tuomo Rankinen, Ph.D.