Effects Of An Acute Dose Of A Betalain-rich Concentrate On Determinants Of Running Performance

Beetroot juice has been shown to enhance exercise performance due to its high nitrate content, but the role of other compounds such as betalains, remains unclear. Betalain dosing has shown improvement in running performance following a seven-day loading scheme; however, the effects of a single dose of betalains on predictors of running performance remain unknown. PURPOSE: To examine the acute effects of a betalain-rich concentrate (BRC) on running performance and economy. METHODS: Seventeen college-age males (19.00 ± 1.75 yrs) consumed 100 mg of BRC containing 25% betalains and 100 mg of dextrose (placebo, [PLA]) in a randomized, counterbalanced, double-blinded, placebo-controlled trial. Participants were instructed to consume BRC or PLA 2 hr prior to completing a running economy protocol, in which participants ran at submaximal speeds corresponding to 60% and 80% of their VO2max for 5 min, before proceeding with a VO2max test. Heart rate (HR), skeletal muscle oxygen saturation (SMO2), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were recorded during the last 30 seconds of each velocity of the running economy test and at the end of each stage of the VO2max test. SMO2 was recorded at the end of every min for 5 min following the VO2max test. Lactate (LAC) was measured at 3-, 6-, 9-, and 12-min post-exercise. Repeated measures analyses of variance were performed to assess differences between BRC and PLA. Alphas were set a priori to p <.05. RESULTS: Peak HR (BRC: 188.00 + 5.65 vs. PLA: 191.00 + 5.43 bpm) and RPE (BRC: 8.59 + 1.62 vs. PLA: 9.59 + 1.70) were significantly lower after BRC supplementation compared to PLA (p = .010 and p = .019, respectively) at 60% VO2max. A trend toward significance was observed for HR at 80% VO2max (p = .051). SMO2 was statistically significant between BET and PLA between min 4 (p = .017) and min 5 (p = .014) post-exercise. No statistically significant differences in SMO2 RER, or VO2 were observed between treatments during exercise, nor were there observed differences between treatments for VO2max or LAC (p > .05). CONCLUSION: BRC reduced HRmax and RPE during submaximal running exercise and increased post-exercise skeletal muscle oxygen saturation compared to PLA. However, BRC did not improve running economy or VO2max compared to PLA.