Ovaltine for endurance, beetroot juice for strength

Beetroot juice as a source of muscle strength? It’d be nice if it were that easy, wouldn’t it? Although it’s not quite as simple as that, recent studies have offered hope that drinking beetroot juice could improve your exercise performance and make strength training more efficient. That being said, you still need to lift the weights. But let’s take it from the top.

Beetroot (latin Beta vulgaris) is a root vegetable belonging to the amaranth family. A relative of the sugar beet and the chard, beetroot was probably brought to Central Europe by the Romans as a cultivated plant. It’s likely, however, that the plant originated from North Africa. During the 19th and 20th centuries, it was further refined as a crop, taking on the even red colour given to it by a high concentration of betalains. In the mid-19th century, beetroot juice was often used to colour wine.

The vegetable’s dark purple roots are usually eaten boiled, fried or raw. A 100-gramme portion of raw beets consists of just under 88 g of water, 9.6 g of carbohydrates, 1.6 g of protein and 0.8 g of fat, and provides 43 kcal of energy. Beetroot also has a high concentration of biologically active substances, including inorganic nitrate (NO3-). An average of 1,275 g/L can be found in commercially available beetroot juices [4].

Nitrate metabolism

After eating foods containing nitrates, the compound finds its way into the stomach. In the small intestine, it’s almost completely absorbed into the blood. This increases the blood’s plasma nitrate concentration. About 60 per cent of the nitrate supplied by food is expelled again through urine. About a quarter of the nitrate, however, is actively absorbed by the salivary glands in the mouth and reduced to nitrite (NO2-) by bacteria on the surface of the tongue. The nitrite now contained in the saliva then enters the stomach, where it’s reduced to nitric oxide (NO) in the acidic environment. Some nitrite, however, does enter the bloodstream, where it’s able to reach various tissues before chemical reactions reduce it to NO [5]. NO is an essential signalling molecule that regulates various physiological functions [6,7]. Among other things, NO plays an important role in vasodilation [8], mitochondrial respiration [9], glucose and calcium homeostasis [10,11], muscle contractility [12] and the development of fatigue [13]. Put simply, it affects your energy levels and muscle function.

NO is really important for our bodies, despite only having a short half-life ranging from a few milliseconds to a few seconds in duration. This means our bodies need to continuously produce NO, which they can do in two different ways [14]. This can either be done with the help of the enzyme nitric oxide synthase (NOS), [15] or without NOS by continuously reducing dietary- or endogenous nitrate to nitrite and finally to NO [16,17].

How an NO increase boosts performance

The body’s energy currency is adenosine triphosphate, or ATP for short. Adenosine consists of the nucleobase adenine and the sugar ribose. This means the complete ATP molecule comprises adenine, ribose and three phosphates. ATP is used to produce energy by breaking down the individual phosphates in a biochemical reaction called hydrolysis.

Our body needs ATP to make muscles contract. Since it has the ability to recycle this energy, it can maintain ATP levels in the muscles over long periods – depending on exercise intensity. During sprint training, ATP turnover increases up to 100-fold compared to resting metabolic rate. This eclipses the metabolism in all other tissues. In turn, however, it places the highest energy demands on the muscles. Since intramuscular ATP stores are relatively low, every metabolic pathway capable of recycling ATP is activated. During a short sprint (30–60 seconds) at maximum speed, the contracting muscles burn through a lot of energy. This energy comes from metabolic pathways able to rapidly provide ATP. ATP can be produced in several ways, both with oxygen and without. Oxidative phosphorylation, which requires oxygen and takes place in our mitochondria, synthesises a lot of ATP. However, the process is relatively slow compared to substrate chain phosphorylation, which can generate ATP without oxygen.

Bailey et al. [18] investigated the effects of beetroot juice on metabolic processes during low- and high-intensity exercise. The experimental group that received beetroot juice was distinguished by the fact they converted less ATP during low- and high-intensity exercise. Oxygen uptake was significantly lower at the end of low-intensity exercise (placebo: 870 ± 42 vs. beetroot juice: 778 ± 38 ml/min; P < 0.05). During high-intensity exercise, on the other hand, this was only the case 360 seconds into the session (placebo: 1692 ± 70 vs. beetroot juice: 1460 ± 54 ml/min; P < 0.05), and not at the end (placebo: 1726 ± 65 ml/minvs. beetroot juice: 1647 ± 100 ml/min, P > 0.05).

The results suggest that nitrate-rich food and drinks (such as beetroots and their juice) improve the interplay between muscle strength and the consumption of ATP. This translates into lower oxygen uptake during exercise. It’s is also worth knowing that high ATP consumption rapidly depletes limited intramuscular energy stores such as phosphocreatine, and significantly impacts muscle fatigue [19]. In a later study, Larsen and his team [20] demonstrated that nitrate-rich diets made ATP production from mitochondrial oxidative phosphorylation more efficient. This makes mitochondria able to produce more ATP per unit of oxygen consumed.

New study results

In a randomised crossover study, Kadach et al. [21] investigated the effect of nitrate on quadricep strength during 60 maximal contractions of the knee joint. They recruited 10 healthy study participants aged 23 ± 4 years. Three hours before the test, each person was given either a nitrate-rich drink or a drink containing no additional nitrate. The test consisted of a series of 60 single-leg maximal voluntary contractions on a dynamometer, with the unexercised leg serving as a control.

A single maximal contraction lasted three seconds and there was a two-second pause between each contraction. As a result, the test lasted around five minutes. In addition, the quadriceps received electrical stimulation during the first, 15th, 30th, 45th, and 60th contractions to assess the role of central and peripheral factors in muscle fatigue. Muscle biopsies were taken, and saliva, blood, and urine were analysed.

Within one hour of ingesting a nitrate-rich drink, the nitrate concentration in the muscles increased. Compared to the group that didn’t receive a nitrate-rich beverage, peak torque and average torque were significantly higher in the first 90 seconds of the five-minute test. The development of central and peripheral fatigue was similar between the two conditions.

Conclusion

This means ingesting nitrate-rich foods such as beetroot juice about an hour before your workout can improve muscle contractile performance – a boost you can take advantage of. Study results show that as little as 5–8.5 mmol or 310–527 mg of nitrate improves intracellular metabolic processes. However, to increase performance, a nitrate dose equalling more than 8.5 mmol or more than 527 mg is necessary [14].

As the commercial goes, Ovaltine keeps you going for longer. Beetroot juice, however, makes you stronger. Want to see for yourself? Give it a go!

Juice + SmoothiesAvailability unknown

Biotta Organic beetroot

1 x 50 cl

14

Juice + SmoothiesAvailability unknown

Biotta Organic beetroot

1 x 50 cl

14

References

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