Numerous studies in recent years have investigated the effects of dietary nitrate (NO3-) on the physiological responses to, and/or performance during, exercise. This interest stems from the fact that dietary NO3- is an important source of nitric oxide (NO) via the "reverse" NO3- nitrite (NO2-) NO enterosalivary pathway (Kharti et al., 2017). NO3- induced increases in NO bioavailability have been found to enhance both endurance exercise performance (Jones et al., 2018; Van De Walle & Vukovich, 2018) as a result of alterations in oxygen supply, demand, and/or cellular energetics (Bailey et al., 2010), and sprint performance (Rimer et al., 2016) as a result of improvements in muscle contractile properties, that is, in maximal muscle speed and power (Coggan et al., 2015b, 2018b). For example, Lansley et al. (2011a) observed a 2.7-2.8% improvement in mean power during simulated 4- and 16.1-km cycling time trials, whereas Rimer et al. (2016) reported a 6.5% increase in maximal power during an inertial load sprint cycling test. Positive effects of BRJ seem to be most apparent in untrained or moderately trained individuals (Van De Walle & Vukovich, 2018) or patient groups, (Coggan et al., 2015a, 2018a) and less evident or even absent in highly trained athletes (e.g., Bescós et al., 2012). Notably, however, some studies (Hoon et al., 2015; Oskarsson & McGawley, 2018) have yielded negative results for reasons that do not seem to be related to differences in subject selection or other aspects of the experimental design.
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