ACUTE DIETARY NITRATE SUPPLEMENTATION FAILS TO IMPROVE EXERCISE ECONOMY IN ELDERLY

Abstract

Objective: Improvements in exercise economy following dietary nitrate (NO3-) supplementation in young, athletic populations has been well documented, but little research has focused on whether these same benefits translate to elderly populations. Design: Participants completed two experimental trials in a double-blind, randomized, crossover design. Setting: University laboratory. Participants: Twenty-one elderly participants >65 yr (10 male/11 female, mean ± SD; age: 72 ± 6 yr). Intervention: Each trial consisted of participants ingesting a 70ml dose of either NO3- rich (NIT; 5.0mmol.L-1) or NO3- depleted (PLA; 0.003mmol.L-1) beetroot juice two hours prior to reporting to the laboratory. Measurements: On arrival at the laboratory, blood pressure was assessed followed by a five minute walking economy test on a treadmill (3km.h-1 and 1% gradient). VO2, heart rate and RPE were monitored during the walking test. Results: There were no significant differences (p > 0.05) between NIT and PLA trials for any of the measured variables during the walking test. Furthermore, no differences were found for blood pressure between trials. All results were associated with trivial or unclear effect sizes. Conclusion: Despite recent reports of improved exercise economy in young, athletic populations following NO3- supplementation, the current study did not find any benefit to sub-maximal VO2, heart rate, perceived exertion or blood pressure in elderly participants when performing a 5-minute walk following NO3- supplementation.