- Placebo plus 5mg/kg caffeine
- Beetroot juice providing 8mmol of nitrate
- Beetroot juice plus caffeine
Participants cycled at 60% maximal oxygen uptake for 30 minutes, followed by a time to exhaustion (TTE) trial at 80% max. Saliva was collected before supplement ingestion, before exercise, and after the exercise to exhaustion trial for salivary nitrate, nitrite, and cortisol analysis. At the end of the study, in beetroot trials, saliva nitrate and nitrite increased >10-fold before exercise compared with pre-ingestion.
Exercise to exhaustion with beetroot and caffeine was 46% higher than in the placebo and 18% more than with beetroot alone and 27% higher than caffeine alone.
Here’s another example of supplement synergy where combining beetroot and caffeine has additive effects on exercise performance compared with either beetroot or caffeine alone. - FLEX