Association Between Genetic Background and the Response to Exercise Training
Abstract
Cardiorespiratory fitness has been shown to increase with physical activity regardless of intrinsic exercise capacity, age, sex, and race. However, the variation in the response to training is heterogeneous, including individuals who do not respond and even those who respond negatively. Exercise is known to produce a cascade of beneficial physiological adaptations including the modulation of mitochondrial biogenesis, oxidative phosphorylation, and glucose transport in skeletal muscle. However, non-responders fail to gain the benefits that increased exercise capacity provides. Many variables in physical activity are adjustable (including intensity, duration, and volume) thereby providing means to attempt to optimize training to cardiorespiratory fitness in non-responders, if the response to exercise is not genetically set. Therefore, two sets of experiments were designed to: 1) characterize differences in training responses across a large number of inbred mouse strains and identify quantitative trait loci associated with the response to exercise training using genome-wide association mapping; 2) determine the interaction between genetic background and training volume (intensity x duration) on exercise performance and skeletal muscle proteins in four inbred mouse strains.
The main findings of this dissertation are: 1) The response to exercise training was heterogeneous with some strains being non-responders. Genome-wide association mapping identified QTL regions associated with the training response for both time and work with peak SNP residing in candidate genes. Overlap in previously identified genes and QTL within human and rodent studies were confirmed as well; 2) Body weight, delta time and delta work were significant for main effects for strain and intensity. Significant interactions for all three phenotypes include strain x duration, and strain x duration x intensity. Protein content did not follow any specific trends associated with changes in exercise capacity. However, increases in proteins that were expected to increase with exercise capacity did yield higher concentrations more frequently with four-week continuous moderate exercise. In summation, four-week low continuous exercise appears to be the optimal training paradigm for increasing exercise capacity in a mouse model.
Citation
Avila, Joshua J (2016). Association Between Genetic Background and the Response to Exercise Training. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /191960.