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Dietary nitrate (NO3-) has been shown to impact oxygen consumption (VO2) as well as exercise performance in a number of prior studies. To date, previous investigations have observed NO3- effects at moderate to high-intensity (e.g. time to fatigue, time trials) exercise and often in trained athletes. However, less is known in regards to prolonged exercise and the potential impact of NO3- on post-exercise excess oxygen consumption (EPOC), particularly in untrained individuals. Here, we tested the hypothesis that acute dietary nitrate supplementation would attenuate VO2 during and following prolonged cycle ergometry. Six young, moderately active, healthy males (age: 26±2 years, body mass index: 23.5±0.5 kg/m2; VO2max: 37.7±5.1 ml/kg/min) performed step-wise maximal cycle exercise and prolonged submaximal cycle exercise (45 min; 38±2% of max work rate) in control (anti- bacterial mouthwash) and acute NO3- supplementedconditions [70ml concentrated beet root juice (0.4g NO3-), 2 hrs prior to exercise] on separate occasions. Measurements of VO2 (indirectcalorimetry), arterial blood pressure (MAP; sphygmomanometry), and heart rate (HR; ECG) were made for 45 min prior, during, and 60 min following exercise bouts. NO3- reduced MAP at rest ~1-3mmHg and this was accompanied by reflex-mediated HR increases (2-4 bpm). However, NO3- had no impact on VO2 during 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: 0.86±0.3 L vs NO3-: 0.95±.2 L). Thus, while NO3- supplementation may have performance benefits, especially in elite athletes exercising at high intensities, in recreationally active males, there appears to be little impact on changes in VO2 due to submaximal prolonged exercise.

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Honors Thesis

Primary Advisor

Anne Crecelius

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Health and Sport Science


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Effects of single-dose dietary nitrate on oxygen consumption during and after prolonged submaximal exercise in healthy humans