The effects of a single bout of exercise, with energy replacement, on plasma concentrations of TNF-α following consumption of a high-fat, high-carbohydrate mixed meal
Date
2011
Authors
Warro, Daniel, author
Melby, Christopher, advisor
Hickey, Matthew, advisor
Nelson, Tracy, committee member
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Abstract
Background: Cardiovascular disease (CVD) is a major contributor to all-cause mortality in the United States and is a major cause of long-term disability. The risk for CHD typically includes a panel of fasting blood lipids including total, LDL-, and HDL-cholesterol. However, in recent years, the lipemic response to a meal and the accompanying pro-inflammatory molecules are recognized as independent risk factors for the development of CVD. Attention has focused on the vascular endothelium, where an increase in low-grade inflammatory processes leads to the development and progression of vascular insults ultimately contributing to an advanced, complicated atherosclerotic lesion. A large body of evidence suggests that improvements in postprandial lipemia, such as decreased triglycerides (TG) and improved insulin sensitivity can be achieved following an individual exercise session. However, limited data exists elucidating the effects of a prior acute bout of moderate intensity exercise on possible pro-inflammatory changes during the postprandial period. Research consistently shows that an important determinant of the acute metabolic changes associated with a single session of exercise are energy-expenditure dependent. It is of clinical importance to understand the postprandial metabolic response after an acute bout of exercise in which the caloric cost of exercise has been balanced with additional energy intake, i.e. with energy replacement. Purpose: Therefore, the purpose of this study was to determine the effects of a single bout of moderate intensity exercise, with energy replacement, on plasma tumor necrosis factor alpha (TNF-α) concentrations, measured before and after consumption of a high-fat, high-carbohydrate meal in young, non-obese, sedentary females. Methods: Eight, non-obese, sedentary women participated in two separate high-fat, high-carbohydrate meal tests after undergoing different treatments the following day. For the non-exercise condition (NoEx), the day prior to the postprandial challenge subjects refrained from exercise and consumed a prescribed diet. For the exercise condition (Ex) subjects consumed the same prescribed diet, and completed a cycle ergometer exercise bout at 65% peak heart rate, eliciting a net exercise energy expenditure of ~285 kcalories. Subjects then consumed an additional mixed-meal snack to account for the additional energy cost of the exercise. The following morning subjects reported to the laboratory in a fasted state at which time a venous blood sample was obtained. They were then fed a high-fat, high-carbohydrate meal (0.75g fat, 1.1g CHO, and 0.35 g protein/kg body weight), and postprandial venous blood samples were obtained 2, 4, and 6 hours after consumption meal for determination of plasma TNF-α concentrations. Results: Plasma TNF-α concentrations were low in all subjects at baseline and dropped further by the second hour of the postprandial period returning toward baseline in both the Ex and NoEx conditions (time effect, p<0.05). There was not a condition by time interaction on TNF-α concentration, nor a main effect of condition. Conclusions: The results suggest that a single session of moderate intensity exercise, without an energy deficit, results in no significant effect on fasting or postprandial TNF-α plasma concentrations in young, non-obese, sedentary females. However, discretion is advised while interpreting the findings due to the very low concentrations of TNF-α measured in the plasma of these young women.
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Subject
exercise
acute exercise
meal replacement
nutrition
TNF alpha
tumor necrosis factor alpha