Physiological and Placebo Effects of Beetroot Juice in Virtual Cycling Using the Balanced Placebo Design.

The physiological and placebo effects of beetroot juice remain unclear in settings outside traditional laboratory environments. Using a randomized, between-participant balanced placebo design, we asked 67 trained cyclists to complete 20-min time-trials on a virtual cycling platform with the ingestion of either beetroot juice or placebo (~552 or ~0.2 mg nitrate, respectively). After completing baseline trials, participants were randomized to one of four experimental groups: 1) informed beetroot juice/given beetroot juice (BRJ/BRJ), 2) informed beetroot juice/given placebo (BRJ/PLA), 3) informed placebo/given beetroot juice (PLA/BRJ), and 4) informed placebo/given placebo (PLA/PLA). Mean (± standard deviation) changes in power output (W) between baseline and experimental trials for each group were: BRJ/BRJ = 2.06 ± 2.81, BRJ/PLA = 4.29 ± 2.81, PLA/BRJ =  -0.12 ± 2.81, PLA/PLA = 3.06 ± 2.90. Linear mixed-effects models revealed that neither the expectation, actual supplementation, or the interaction between expectation and supplement changed between baseline and experimental trials for all groups (χ2 ≤5.15, all p ≥.05). Similar results were found for relative power, speed, distance, heart rate and cadence (χ2 ≤5.15, all p ≥.05). Our results suggest that in comparison to baseline, cycling performance over 20‑min virtual time‑trials did not change when participants received an acute dose of beetroot juice both openly and deceptively. Similarly, the expectation that beetroot juice had been received did not change any outcomes. In short, physiological and placebo effects of an acute dose of beetroot juice did not change 20-min time-trial performance during a virtual cycling platform.