The participants (average age of 14) had at least 3 years of experience with judo.

The participants drank either nitrate-rich beetroot juice (794 mg of nitrate) or a placebo beverage 2 hours before undergoing multiple exercise tests, each separated by 10 seconds of rest. There was a one-week washout period between the two conditions.

Compared to the placebo beverage, the nitrate-rich beetroot juice improved the following:

Judo-specific fitness, including more judo throws completed (+2.4%)
Explosive jump height (+3%)
Back strength (+3.2%)
Handgrip strength (+8.4%)

There was no difference in perceived exertion between the groups.

Beets for a beatdown: Beetroot juice improves judo-related exercise performance Original paper