Effects of a single dose of a betalain-rich concentrate on determinants of running performance and recovery muscle blood flow: a randomized, triple-blind, placebo-controlled, crossover trial

Purpose This study aimed to examine the effects of a single dose of a betalain-rich concentrate (BRC) on determinants of running performance and recovery lactate clearance. Methods In this a randomized, triple-blind, placebo-controlled, crossover trial, 17 male recreational runners (Age: 19.0 +/- 1.0 years; Height: 176.8 +/- 6.2 cm; Weight: 70.62 +/- 8.1 kg; Body fat: 12.8 +/- 0.03%; VO2max: 58.9 +/- 8.6 ml/kg/min) consumed an acute dose of a BRC (100 mg) or a placebo (100 mg of dextrose; CON) and performed a running economy protocol (RE) at velocities corresponding to 60% and 80% of maximal oxygen consumption (VO2max) followed by a VO2max test. Both exercise and recovery skeletal muscle oxygenation (SmO2) were assessed via near-infrared spectroscopy (NIRS), and recovery lactate was obtained. Results BRC resulted in lower heart rate (HR) at velocities corresponding to 80% of VO2max (p = 0.05) and maximum HR (HRmax; p = 0.01), and a lower rating of perceived exertion (RPE) at velocities corresponding to 60% of VO2max (p = 0.02) when compared to CON. BRC also improved post-exercise SmO2 at 3 (p = 0.05), 4 (p = 0.02), and 5 min (p = 0.01) but not lactate clearance (p > 0.05). BRC did not significantly improve RE or VO2max (p > 0.05). Conclusions A single dose of BRC did not enhance RE or VO2max. However, the observed improvements in exercise HR, RPE, and SmO2 suggest that BRC may confer cardiovascular benefits for exercise and recovery.