The Effect of Beetroot Juice on Repeated Sprint Performance and Muscle Force Production
Year: 2014
Type: article
Abstract: IntroductionThe importance of nitric oxide (NO) for the physiology of mammals, including humans, has now been extensively studied and established, with a large number of studies supporting its role in signal transduction (Murad, 1996; Martin et al., 2000; Hanafy et al., 2001; Murad, 2004) and a range of body processes like vasodilation (Higashi & Yoshizumi, 2003) and vessel homeostasis (Palmer, 2003), liver regeneration (Carnovale & Ronco, 2012), immune response by the macrophages (Bogdan, 2001; Wink et al., 2011), neurotransmission (Oh, 1995; Kiss, 2000). Nitric oxide becomes available in the body through oxidation of L- arginine by the nitric oxide synthetases (NOS) (Alderton et al., 2001), but an additional pathway was recently unveiled, where NO becomes available through the sequential reduction of nitrate to nitrite and of nitrite to NO (Lundberg et al., 2008). As a result, inorganic nitrate from dietary sources emerges as a substrate for the in vivo generation of NO; indeed, dietary intake of nitrate produces the same effect as NO, namely vasoprotective activity, blood pressure reduction and additionally, decreases the whole body oxygen cost during exercise or enhanced maximal performance (Ferreira B Lansley et al., 2011). The effects of nitrate can be achieved through consumption of large amount of vegetables which are nitrate-rich.Beetroot juice (BR) is a nitrate-rich dietary source, containing approximately 5-8 mmol and has therefore been used as a dietary supplement of inorganic nitrate (NO3-) in order to provide benefits to the body through the mechanisms as described above. Given the impact of a range of physiological functions by dietary nitrate supplementation, a number of studies addressed the question of the impact of beetroot juice (as a nitrate-rich food) on physiological responses to exercise, with the prospect of using it as a supplement to enhance performance. One study showed that three days of sodium nitrate supplementation at 0.1 mmol/kg/day resulted in reduction of resting blood pressure and the O2 cost of sub-maximal cycle exercise (Larsen et al. 2007), while reduction of O2 cost of low intensity exercise with an enhanced tolerance to high intensity exercise in humans was observed in a later study, after a six-consecutive day nitrate supplementation (Bailey et al. 2009). The same research group concluded that the same supplements enhance muscle contractile efficiency during knee-extensor exercise (Bailey et al., 2010), while a recent study showed that six days of nitrate supplementation in the form of beetroot juice (~0.5 L/d with~8 mmol/d nitrate) reduced VO2 during submaximal exercise, improved time-trial performance in trained cyclists, thus increasing tolerance of high-intensity work rates and presenting nitrate as a potent ergogenic aid (Cermak et al., 2012a). A follow-up study testing the effect of a single dose of beetroot juice (500 ml, approx. 6.2 mmol NO3) indicated that this dose improved subsequent time-trial performance. Recently, one study showed that dietary nitrate supplementation improved team sport-specific intense intermittent exercise performance after intake of 490 mL of concentrated, nitrate-rich BR by 4.2% when compared to performance after intake of placebo juice (Wylie et al., 2013). In this study 14 male team-sport players were assigned in a double blind, randomized, crossover design performing 30 hours before the completion of a Yo-yo intermittent recovery level 1 test. The most significant improvement was the 4.2% greater performance of the Yo-yo test consuming Beetroot Juice compared to placebo as well as the 400% greater resting plasma nitrite concentration.A number of studies have also tested the effect of BR on force production using the isokinetic dynamometer by completing a series of high intensity exercises and demonstrating that it can improve time-to-exhaustion. In one of these studies 8 men (19-38 years old) consumed a single dose of beetroot juice or placebo for 6 consecutive days and completed series of step moderate-intensity and severe-intensity exercise tests on the last three days resulting a reduction to the O2 uptake and extension to the time-to-exhaustion (Bailey et al. …
Authors: Konstantinos Kokkinoplitis, Neil Chester
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W1775872353