Browsing by Subject "Endurance exercise"
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Item The effects of carbohydrate-protein supplementation on endurance exercise performance, recovery, and training adaptation(2010-12) Stegall, Lisa Ferguson; Ivy, John, 1945-; Nunez, Nomeli P.; Tanaka, Hirofumi; Griffin, Lisa; Jolly, ChristopherRecent research suggests that adding protein (PRO) to a carbohydrate (CHO) supplement can have substantial benefits for endurance exercise performance and recovery beyond that of CHO alone. CHO+PRO supplements are often commercially available formulations consisting of carbohydrates (dextrose, maltodextrin) and whey protein. The effects of a supplement containing moderate protein and a low-CHO mixture on endurance performance has not been investigated. Also, the effects of CHO+PRO supplementation in the form of a natural food, flavored milk, on measures of recovery from acute endurance exercise, as well as on chronic aerobic exercise training adaptations, have not been characterized. Therefore, in this series of four studies, the effects of CHO+PRO supplementation on the following areas of endurance exercise performance, recovery, and adaptation are investigated: acute endurance exercise performance, inflammatory and muscle damage markers, muscle glycogen resynthesis, activation of signaling proteins involved in the initiation of protein synthesis and degradation, subsequent endurance exercise performance, and chronic aerobic training adaptations (maximal oxygen consumption, oxidative enzyme activity, body composition, immune cell levels, and inflammatory markers). Study 1 demonstrated that a supplement containing a low-CHO mixture plus moderate protein significantly improved aerobic endurance when cycling at or below the ventilatory threshold, despite containing 50% less CHO and 30% fewer calories relative to a higher CHO beverage. Study 2 demonstrated that CHO+PRO supplementation in the form of chocolate milk (CM) is an effective post-exercise supplement that can improve subsequent performance and provide a greater intracellular signaling stimulus for protein synthesis compared to CHO and placebo. Study 3 found that post-exercise CM supplementation during 4.5 wks of aerobic exercise training improves the magnitude of cardiovascular adaptations more effectively than isocaloric CHO or placebo, while the fourth study demonstrated that post-exercise CM supplementation during 4.5 wks of aerobic training improves body composition more effectively than isocaloric CHO or placebo. The fourth study also demonstrated that 4.5 wks of training does not appear to perturb resting immune cell concentrations or markers of inflammation and muscle damage. Taken together, the results of this research series suggest that CHO+PRO supplementation extends endurance performance, improves recovery, and increases training adaptations more effectively than CHO or placebo.Item Genetic Regulation of Intrinsic Endurance Exercise Capacity in Mice(2013-07-26) Courtney, Sean M.Endurance exercise capacity is a powerful predictor of health status. Having low levels of endurance exercise capacity has been linked with cardiovascular disease. Variation in endurance exercise capacity, measured during a graded exercise test, has been reported across cross-section, twin, and family studies. This variation is evidence of a genetic component to the phenotype of endurance exercise capacity: however, the genetic factors responsible for explaining this variation are undefined, in part because previous research has been performed on a limited scale. Therefore, three sets of experiments were designed to identify: 1) Novel quantitative trait loci (QTL) for endurance exercise capacity in 34 strains of inbred mice using genome-wide association mapping. 2) The effect of chromosome substitution on endurance exercise capacity using linkage analysis in F2 mice. 3) The effect of chromosome substitution on endurance exercise capacity using wild-derived mice. The main findings of this dissertation are: 1) There are strain-specific differences in endurance exercise capacity across 34 strains of male inbred mice. Genome-wide association mapping identified novel putative QTL on chromosomes 2, 7, 11, and 13. 2) Linkage analysis identified a novel QTL on chromosome 14 at the 56 cM position for run time and work. Linkage analysis also identified a potential sex-specific QTL, with the identified QTL significant for male mice only. 3) Novel putative QTL were identified on chromosomes 3 and 14 in chromosome substitution mice from wild-derived mice. These data suggest that chromosome 14 is an important contributor to the genetic regulation of intrinsic endurance exercise capacity. These studies support a genetic component to endurance exercise capacity by identifying strain-specific differences and novel, putative QTL.