Alterations and Specifications of Excess Post-Exercise Oxygen Consumption: A Review

This review describes oxygen consumption, both in terms of a goal of weight management and aerobic training. It introduces excess postexercise oxygen consumption (EPOC) and the benefits that can come from it. EPOC can aid in weight management as a means to continue to expend energy even after exercise has ceased. This review also discusses the many determinants of EPOC and analyzes the effects of various conditions on the elevated consumption. Such conditions include duration and intensity of exercise, training status, and supplementation. Later discussed are the possible underlying mechanisms and how they are responsible for EPOC. Although they have yet to be well-understood, these mechanisms provide insight into how EPOC is facilitated and why it occurs at all. More research is being conducted in attempts to better understand this concept and how EPOC can be advantageous to our human health. Consistent aerobic exercise leads to many health benefits such as a positive impact on blood lipid levels and blood pressure, as well as increased energy expenditure for healthy weight management. Additionally, regular aerobic exercise can positively affect mental health, such as reducing depression and anxiety (Mersy, 1991). In general, aerobic exercise decreases the risk of the development of cardiovascular disorders, or disorders that affect the heart, blood vessels, or both. Given the significant burden of cardiovascular disease, aerobic exercise is a commonly prescribed lifestyle modification and is therefore important to fully understand. Regular aerobic exercise causes the body to increase its oxygen consumption, otherwise known as its VO2. The consumption of oxygen fuels mitochondrial activity within muscle cells to produce ATP, the primary energy currency of all cells. During exercise, increased ATP is necessary in order to fuel contraction-relaxation cycles of muscles that together allow for body movement. With prolonged activity, the substrate for oxidative metabolism can come from stored energy sources, promoting weight loss. Ultimately it is the mass balance of energy intake versus energy expenditure that determines whether one will gain, lose, or maintain weight

Effects of Single-Dose Dietary Nitrate on Oxygen Consumption During and After Maximal and Submaximal Exercise in Healthy Humans

International Journal of Exercise Science 11(3): 214-225, 2018. Dietary nitrate (NO3-) has been shown to reduce oxygen consumption (VO2) during moderate to high-intensity (e.g. time to fatigue, time trials) exercise and often in trained athletes. However, less is known regarding prolonged exercise and the potential impact of NO3- on post-exercise excess oxygen consumption (EPOC), particularly in untrained individuals, who may have different metabolic goals during exercise than trained individuals. We tested the hypothesis that acute nitrate supplementation in the form of beet root juice will significantly decrease both VO2 during maximal exercise and EPOC in both maximal and submaximal exercise trials. Eight young, moderately active, healthy males (age: 24.8±1.4 years, body mass index: 23.7±0.4 kg/m2; VO2max: 34.2±3.9 ml/kg/min) performed step-wise maximal cycle exercise (n=4) and prolonged submaximal cycle exercise (n=6) (45 min; 38±2% of max work rate) in control (anti-bacterial mouthwash) and acute NO3– supplemented conditions [70ml concentrated beet root juice (0.4g NO3-), 2 hrs prior to exercise] on separate occasions. Measurements of VO2 (indirect calorimetry), arterial blood pressure (MAP; sphygmomanometry), and heart rate (HR; ECG) were made before, during, and following exercise bouts. NO3- reduced MAP at rest ~1-3mmHg. However, NO3- had no impact on VO2 during maximal (VO2max, Ctrl: 34.2±3.9 ml/kg/min vs NO3-: 31.7±4.4 ml/kg/min), submaximal exercise (average of min 25-45, Ctrl: 24.6±2.4 ml/kg/min vs NO3-: 26.8±3.3 ml/kg/min) or EPOC (area under the curve, Ctrl: 0.57±0.24 L vs NO3-: 0.66±0.16 L). Thus, while NO3- supplementation may have performance benefits in elite athletes exercising at high intensities, in recreationally active males, there appears to be little impact on changes in VO2 due to maximal or submaximal prolonged exercise