In young men who exercise regularly, consuming beetroot juice or citrulline malate does not make their leg muscles stronger during maximum effort cycling or leg extensions, even though beetroot juice raises certain compounds in the blood.

Taking beetroot juice and citrulline malate supplements does not change how much energy the body uses or how it balances oxygen and carbon dioxide during intense leg exercise in young, active men.

Drinking beetroot juice with 400 mg of nitrate raises levels of nitrate and nitrite in the blood of young, active men during leg exercise, but does not improve how well they perform, how much blood flows to their muscles, how efficiently they use energy, or their hormone levels during the exercise.

Consuming beetroot juice before intense leg exercise does not lead to increased blood flow in the main artery of the thigh or swelling in the large thigh muscle during the exercise.

Taking 8 grams of citrulline malate does not change blood nitrate/nitrite levels, leg strength during high-intensity exercise, blood flow, or how efficiently the body uses energy in young men who exercise recreationally.

Drinking beetroot juice with a specific amount of nitrate doesn’t make the body use less oxygen when older adults with a certain type of heart failure exercise lightly — so if they feel less tired, it’s probably because their blood flows better or their heart doesn’t have to work as hard, not because their muscles are using energy more efficiently.