EFFECTS OF BEET JUICE ON OXYGEN CONSUMPTION BETWEEN TRAINED AND UNTRAINED CYCLISTS
INTRODUCTION: Beet juice, due to its high nitrate concentration, has been shown to have many physiological benefits such as decreasing oxygen consumption (VO2) and improving endurance via the nitrate-nitrite-nitric oxide reduction pathway. PURPOSE: The objective of the study was to investigate the effectiveness of beet juice on lowering VO2 during steady-state exercise in trained versus untrained individuals. METHODS: Seventeen subjects; 8 trained and 9 untrained, age 21 ± 2 yr, performed two submaximal graded exercise tests on a cycle ergometer. Work rate was increased every two to three minutes until a target heart rate (65% heart rate reserve (HRR)) was achieved. Once at this rate, subjects continued to bike for 10 min. The same procedure for the first performance trial was repeated for the second performance trial. Prior to each trial, subjects were instructed to drink 70 mL/d of either concentrated beet juice or a cranberry juice placebo in counterbalanced order for 6 d. VO2 was measured using a respiratory mask and Parvo metabolic cart. Resting heart rate (HR) and blood pressure (BP) data were collected at baseline. Heart rate was also measured throughout each trial in the last 10 s of each work rate. Repeated measures analysis of variance was run to detect any differences in VO2 between groups, between the change in VO2 for the experimental conditions, and between beet juice and placebo trials. RESULTS: A significant difference in VO2 was detected between trained (30.1± 4.5 mL·kg-1·min-1) and untrained (23.5 ± 4.2 mL·kg-1·min-1) individuals (p = 0.000) confirming the presence of two distinct levels of training. No significant difference was found in the change in VO2 between the beet juice and placebo conditions on trained (-0.1 ± 3.8 mL·kg-1·min-1) or untrained (0.0 ± 2.5 mL·kg-1·min-1) groups (p = 0.862). When the two training groups were pooled, no difference was found between the beet juice (26.7 ± 5.5 mL·kg-1·min-1) and placebo (26.6 ± 5.5 mL·kg-1·min-1) conditions (p= 0.964). CONCLUSION: Six days of beet juice supplementation did not lower oxygen consumption during steady state exercise regardless of training status.
Reynolds, S; Berkoe, H; Travis, J; Lebon, H; Van Wyck, D; Caudill, K; Lynde, C; and McCann, D
"EFFECTS OF BEET JUICE ON OXYGEN CONSUMPTION BETWEEN TRAINED AND UNTRAINED CYCLISTS,"
International Journal of Exercise Science: Conference Proceedings:
3, Article 44.
Available at: http://digitalcommons.wku.edu/ijesab/vol8/iss3/44
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