Both professional athletes and everyone who participates in sports to maintain and improve their health want to use nutritional supplements to increase their exercise performance and get more benefits from their training. However, while we want to increase our health and performance, we may not benefit but be harmed by consuming the wrong product in the wrong dose. For this reason, when choosing nutritional supplements, the more natural and quality ones should be preferred. In this article, we will examine beetroot juice, which is one of the most natural nutritional supplements.
How Does Beetroot Juice Have an Ergogenic Effect?
Beetroot (beta vulgaris) juice is used as a nutritional supplement due to its high inorganic nitrate content. Nitrate is found in dark green leafy vegetables and processed meats in addition to beetroot juice. 75% of the nitrate taken orally is excreted in the urine, the part that interests us is the remaining 25%. This portion is converted to nitrite by the enzyme nitrate reductase by anaerobic bacteria in the oral cavity and then to nitric oxide in the stomach.
In addition to nitrate taken from food, the body naturally produces nitric oxide from L-arginine by the enzyme nitric oxide synthase (NOS). Especially in hypoxic environments, this production increases and the parts of the skeletal muscle that need oxygen are adapted to the available oxygen.
Nitric Oxide
Nitric oxide is a vasodilator and its best known physiological function is to relax the smooth muscles of blood vessels. It also affects the mitochondrial enzymes of the electron transport chain, regulating muscle contraction and oxygen uptake. In addition, it takes part in many physiological functions such as the breakdown of pathogens in macrophages and neutrophils, inhibition of platelet aggregation, and neurotransmitter effect.
Increased nitric oxide in the body with consumption of beetroot juice;
- Increases ATP production by increasing the efficiency of oxidative phosphorylation,
- Induces physiological mechanisms that affect oxygen use in skeletal muscle,
- Increases blood flow to the muscles,
- Supports oxygen transfer in the muscle,
- Enhances muscle contraction,
- Increases mitochondrial biogenesis and efficiency,
- Increases muscle glucose uptake,
- Increases gene expression.
Effects of Beetroot Juice on Cardiorespiratory Endurance
Cardiorespiratory endurance or aerobic endurance is an indicator of the capacity of the respiratory and circulatory systems to provide the oxygen needed by the working muscles for energy production and the capacity of the muscles to use this oxygen during physical activity. Studies have shown that beetroot juice increases cardiorespiratory endurance and performance in long/short-term exercises, and prolongs exhaustion time in submaximal high intensity exercises.
- Acute consumption of beetroot juice provides an ergogenic effect by reducing the amount of oxygen consumption during exercises performed at maximal oxygen consumption (VO2max) or slightly lower intensity. Therefore, it prolongs the time to reach fatigue and improve performance.
- Chronic consumption of beetroot juice increases cardiorespiratory performance at exercise intensities of anaerobic threshold and VO2max.
Effect of Beetroot Juice on Cardiorespiratory Endurance in Hypoxic Conditions
In sports performed at high altitudes such as mountain bike races, the amount of oxygen in the inhaled air decreases, and sufficient oxygen cannot be supplied to the muscles. This adversely affects cardiovascular endurance. We mentioned above that nitric oxide production in the body increases as an adaptation response in hypoxic conditions. Beetroot juice can be used to facilitate and improve this adaptation. Kelly et al., in 2014, showed that beetroot juice supplementation for 3 days improved the exhaustion time and efficiency in hypoxic conditions (1).
High-Intensity Interval Training (HIIT) and Beetroot Juice
Beetroot juice supplementation reduces muscle fatigue in intermittent high-intensity training. However, it is not known exactly how it achieves this effect. One of the presumed reasons are as follows; It limits the formation of metabolites such as ADP and inorganic phosphates that cause muscle fatigue. Another reason is; beetroot juice has a positive effect on power production by improving calcium release and reuptake from the sarcoplasmic reticulum.
Interaction with Other Supplements
In a study conducted to investigate the effect of combined use of beetroot juice (8 mmol nitrate) and caffeine (5 mg/kg); It was observed that during exercise at 80% of VO2max, the time to exhaustion increased by 46% compared to placebo, however the magnitude of the effects was similar to those of beetroot juice and caffeine supplements used separately (2). This shows that beetroot juice and caffeine do not contribute positively or negatively to each other.
Not Just for Sports Performance
Beetroot juice is recommended to be a part of treatment in people with chronic obstructive pulmonary disease (COPD), hypertension, heart failure and insulin resistance.
Dosage and Timing
Beetroot juice has an ergogenic effect with a dose of 6 to 8 mmol or 350 to 500 mg of nitrate. An average of 100 ml to 130 ml of beetroot juice contains nitrates at this level, this value can be increased in high levels athletes training intensely. It is known that plasma nitrite concentration reaches its peak in 2 to 3 hours after nitrate consumption. For this reason, it is recommended to consume beetroot juice 90 minutes before the exercise.
References
- Kelly J., Vanhatalo A., Bailey S.J., Wylie L.J., Tucker C., List S., Winyard P.G., Jones A.M. Dietary nitrate supplementation: Effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2014;307:920–930. doi: 10.1152/ajpregu.00068.2014
- Handzlik L., Gleeson M. Likely Additive Ergogenic Effects of Combined Preexercise Dietary Nitrate and Caffeine Ingestion in Trained Cyclists. ISRN Nutr. 2013;2013:396581. doi: 10.5402/2013/396581
- Olsson H, Al-Saadi J, Oehler D, Pergolizzi J Jr, Magnusson P. Physiological Effects of Beetroot in Athletes and Patients. Cureus. 2019;11(12):e6355. Published 2019 Dec 11. doi:10.7759/cureus.6355
- Domínguez R, Cuenca E, Maté-Muñoz JL, et al. Effects of Beetroot Juice Supplementation on Cardiorespiratory Endurance in Athletes. A Systematic Review. Nutrients. 2017;9(1):43. Published 2017 Jan 6. doi:10.3390/nu9010043
- Domínguez R, Maté-Muñoz JL, Cuenca E, et al. Effects of beetroot juice supplementation on intermittent high-intensity exercise efforts. J Int Soc Sports Nutr. 2018;15:2. Published 2018 Jan 5. doi:10.1186/s12970-017-0204-9
