The use of beetroot juice as a natural performance enhancing agent grabbed the public’s attention during Leicester City’s amazing English Premier League title triumph last season.
It was widely touted as one of the innovative approaches implemented by the team’s sports scientists as they powered their way to an epic league title.
But the potential performance enhancing effects of beetroot juice have been understood and used by sports scientists for many years.
Beetroot juice has been shown to improve cycling [1] rowing [2] and running [3] performance as well as improving performance at altitude [4].
Supporting Leicester City’s use of beetroot juice is the study of Wylie et al [5] where beetroot juice supplementation was also found to improve team sport performance. However, it does appear that with elite athletes especially endurance athletes, the beneficial effects of beetroot juice supplementation are less pronounced [6,7].
Although beetroot is also an excellent source of antioxidants and micronutrients, it is the nitrates within the beetroot that results in the performance improvement. After eating it, nitrates are absorbed into the bloodstream and returned to the salivary glands in the mouth.
It is there that bacteria reduce the nitrates to nitrites. These nitrites subsequently pass into the stomach and on into the intestines where they are again absorbed into the blood stream.
Within the exercising muscle specifically, where there is low oxygen content and high acidity level, these nitrites are further reduced to nitric oxide. It is this nitric oxide that enhances performance.
Nitric oxide has numerous important functions during exercise. Firstly nitric oxide is responsible for increasing blood flow and therefore the supply of oxygen and substrates (fuel) to the exercising muscles [8].
It does this by increasing blood flow to the exercising muscle while also playing a role in the formation of new vessels to increase blood flow across the length of the muscle [9]. Furthermore nitric oxide appears to preserve energy by reducing the energy demand of the exercising muscle [10] and increasing energy production efficiency [11].
Another interesting twist is that the skin contains a reserve of nitrates, which are mobilised during exposure to sunlight. More and more research is coming out each year to further understand the mechanisms of nitrate induced performance enhancement.
So the question remains over how to supplement beetroot juice.
Supplementation of beetroot juice has been shown to be equally as effective when used immediately prior to exercising and in the days preceding exercise. A large intake of beetroot juice was shown to increase nitrite levels 8-fold, four hours after ingestion [12].
Alternatively, a moderate intake of beetroot juice every day for two weeks increased and then maintained nitrite levels [13].
A word of warning though: consuming beetroot juice may cause some gastric discomfort and therefore you should not attempt the supplementation prior to a competition without practicing your strategy first in training!
