All cyclists are looking for a competitive edge on race day. Whether you’re a high level athlete trying to shave a few seconds off your time or a casual rider just hoping to improve your general performance, what you put into your body makes a big difference.

Sports science has recently turned its attention to finding new ways of improving endurance through a process known as “legal doping.” As the name suggests, legal doping for cyclists focuses on gaining performance benefits out of your diet and the mixture of compounds that are naturally found in food.

When it comes to endurance sports like cycling, there are two well-established methods of legal doping – supplementation with dietary nitrate and with caffeine. While caffeine can be obtained in coffee, tea or even in a pill, nitrates are found at a high concentration in beets, root vegetables and leafy greens.

There is a growing body of scientific research which demonstrates that legal doping can improve sport performance. Perhaps more importantly, researchers are uncovering how these legal doping agents work on a physiological level.


Nitrate Supplementation: From Beets to Blood Vessels

Much of the research relating to nitrate supplementation has focused on the consumption of beetroot juice. This is because beetroots are one of the richest sources of dietary nitrate. The majority of nitrate obtained from beetroot juice is converted into nitric oxide as it passes through your digestive system. Once in the bloodstream, nitric oxide functions as a vasodilator (it widens blood vessels), which increases blood flow to muscles and the delivery of oxygen to muscle cells.

Not all nitrate is converted into nitric oxide though. Some nitrate enters the bloodstream in a different chemical form – nitrite. Circulating nitrite has an added advantage for endurance athletes. Nitrite is rapidly converted into nitric oxide (the vasodilator) in the bloodstream wherever there is a shortage of oxygen. This means that additional nitric oxide is produced in the blood vessels that surround hard working muscles fibres (because they rapidly use oxygen from the blood). In turn, this leads to local vasodilation as well as increased blood flow and oxygen delivery to the muscle fibres that need it the most.

Consuming beetroot juice prior to cycling can lead to an improvement in both general circulation and local delivery of oxygen to the muscles that are engaged during the power phase of the pedal stroke (if you think of cycling like a clock face, the power phase occurs between 11 o’clock and 5 o’clock).


Nitrate Supplementation: How Much of a Difference Can Beetroot Juice Make to Your Performance?

By enhancing blood flow to exercising muscles, nitrate supplementation has been shown to improve many aspects of cycling performance, including:
• Improved economy (the relationship between power generated and oxygen consumed)
• Increased time to exhaustion (greater endurance)
• Faster time trials

While the beneficial effects of legal doping with beetroot juice will vary according to your exercise demands, researchers have shown that time to exhaustion can be increased by approximately 4-25%.* In general, this has translated into about a 1-3% improvement in time trial performance.** On the surface, this might seem like a small difference, but shaving a full minute off an hour of race time is a remarkable achievement for a simple dietary choice.


Nitrate Supplementation: How to Legally Dope With Nitrates

Considering that the benefits of dietary nitrate supplementation have been extensively studied, the question is how to best obtain them. Researchers have determined that performance benefits are seen 2-3 hours after consuming beetroot juice. So, it’s important to time your consumption accordingly (at least two hours before an endurance event).

How much beetroot juice do you need to drink? Research suggests that 310-560 mg of dietary nitrate is sufficient. This can usually be found in 500mL of beetroot juice. However, since the concentration of nitrates in food is variable, you’d probably be best served by drinking a little extra.


Caffeine Supplementation: Cycling Benefits & Physiological Effects

The performance enhancing effects of caffeine on endurance exercise have been appreciated by athletes for quite some time. Yet, surprisingly, even though caffeine is a known stimulant for our nervous system, the underlying physiology that explains its effect on cycling performance is still under investigation.

Researchers have recently suggested that caffeine increases ventilation in the lungs (the volume of air exchanged per minute), blood glucose levels and blood lactate levels. It also appears to produce a psychological effect by reducing your perceived level of exertion during exercise. Although it is still a topic of debate, caffeine can increase your maximal voluntary muscle strength by recruiting additional motor units (groups of muscle fibres that are all stimulated by the same motor neuron). It’s likely that a combination of the above factors explains the beneficial effects of caffeine for cyclists.

Depending on the demands of your cycling event, caffeine supplementation will benefit your performance to varying degrees. A recent meta-analysis found that caffeine can increase time to exhaustion by about 24% and can improve time trial performance by approximately 3%. Other studies, however, have found less substantial (but nevertheless beneficial) effects of caffeine on cycling performance.


Caffeine Supplementation: How Much is Too Much?

According to the latest guidelines, consuming 3-6 mg of caffeine per kg of body weight (an hour before exercise) will lead to performance benefits. However, lower doses of caffeine have also been shown to enhance endurance. Several other studies have pointed out that consuming caffeine during exercise appears to improve performance too.

In general, a cup of coffee has about 100mg of caffeine, while caffeine pills are produced at 100-200mg doses. Although you do have a great deal of flexibility, a person who weighs 70kg, for example, should be aiming to consume 210-420 mg of caffeine (the equivalent of 2-4 cups of coffee).

All this being said, you probably need to do some trial and error with your caffeine consumption before exercise. There are several genetic factors that are known to influence how caffeine affects your physical performance. On top of this, too much caffeine can have negative side effects such as nausea and anxiousness, which would likely result in poorer performance.



* Time to exhaustion experiments require individuals to maintain a fixed exercise intensity for as long as possible. The beneficial effects of nitrate supplementation are greater at lower exercise intensities than they are at higher exercise intensities, which more closely reflect “race speed.” This explains the wide effect range of 4-25%.
** Time trial experiments are a better reflection on improvements in exercise performance because they are completed as fast as possible. It is also worth noting that the beneficial effects of nitrate supplementation are generally smaller in elite athletes than in other individuals.



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About the Author

Jeremy is a health and fitness writer with a PhD in molecular sciences. He explores the evolutionary biology of making better lifestyle choices and optimising exercise performance. You can find more of his work on The Industrial Evolution.

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