Increasing the amount of nitrate in the diet has shown promising results for exercise performance over the last few years. The use of beetroot juice to increase nitrate intake has been used successfully and although the mechanisms still need clarifying, the results are positive.
Nearly all studies thus far have focused upon endurance-based exercise much of which has been performed at sub-maximal intensities. This study is the first to look at its use in a sport requiring very high intensity and great force production.
Although the group size was relatively small, the quality and experience of the subjects was high and they undertook a testing session, which formed part of their normal training program. I think this is a huge positive as they were all familiar with the session and it is likely to be hugely competitive amongst the athletes.
The study was a double blind, crossover design that is important. However I am not sure the blinding was particularly good. In the most recent of the studies coming from the group at Exeter University the blinding has been achieved by removing the nitrate (active component) from the juice, therefore not altering the appearance or flavour significantly. This, I can assure you if you haven’t tasted beetroot juice is pretty distinctive! A blackcurrant drink was used as the placebo, so although color may have been similar it most definitely would have tasted very different. Whether the athletes knew what the aim of the study was, and that beetroot juice may have an ergogenic effect is unknown. I would suggest that the use of nitrate depleted beetroot juice should be used in all studies now because the publicity surrounding the potential ergogenic effect may make an obvious placebo useless.
The results of the 6 x 500m ergometer intervals with 90 seconds rest between each are of great interest though. The improvement over the entire six intervals was 0.4%. The most promising results were in the second half of the session, with intervals 4-6 showing a mean improvement of 1.7% in comparison with the placebo trials.
Previous studies have suggested an improvement in mitochondrial efficiency caused by the nitrate supplementation as an explanation for improved performance. There is also the possibility that an improvement in muscle force could also explain the positive results seen here. Unfortunately this study does not provide us with data to uncover whether either of these proposed mechanisms is responsible.
This study suggests another exciting area for research into the effects of nitrate rich beetroot juice on performance. Much further work into high intensity exercise needs to be repeated but it may shed light on the complex mechanisms that cause dietary nitrate to provide an ergogenic effect.
As a follow up it does make me think again about how statistical significance and real life improvements in performance can differ greatly in a sporting arena. Does a 1.7% improvement in the second half of races mean the difference between a medal and watching from the stands? I will have a look and get back to you…