This study seeks to determine the feasibility of an exercise training progression with the consumption of beetroot juice prior to exercise in postmenopausal women. Results from this investigation will be used to determine preliminary effect sizes for exercise training only (control) and exercise training + beetroot juice (EX+BR) to inform the direction of larger randomized clinical trials on pre-post changes in measures of cardiovascular health and endothelial function.
An increasing body of evidence has supported acute benefits of beetroot juice including lowered blood pressure and greater muscle oxygenation during exercise. Thus, consumption of beetroot juice prior to exercise may alter the perceptual difficulty for a given exercise bout -- possibly resulting in an individual exercising at a greater intensity (without the commensurate increase in discomfort). The investigators propose that repeated exposure to a relatively greater exercise stimulus (via beetroot juice) may elicit more robust cardio-metabolic adaptations compared to exercise training alone (i.e., without beetroot juice). Possible findings could inform a larger randomized clinical trial to determine if pre-exercise beetroot juice supplementation is an effective strategy to promote health related benefits. The investigators will examine the effects of pre-exercise beetroot juice coupled with 8 weeks of supervised exercise training among post-menopausal (75 and younger) women. Qualified individuals will be required to complete an initial screening visit as well as three baseline visits (Visits 1-2). Participants will undergo a series of tests including: dual-energy X-ray absorptiometry scan, bioelectrical impedance analysis, exhaled fraction of nitric oxide, health-related questionnaires, and pulse wave velocity. Participants will also be asked to perform leg muscle function and walking tests. Following the completion of Visits 1-2, participants will attend supervised exercise training sessions 3x/week for 8 weeks. Within 2-6 days from the last exercise training session, participants will repeat the same measurement procedures. The primary objective involves elements of feasibility (e.g., recruitment, retention, adherence, and adverse event) and to generate preliminary effect sizes for 8 weeks of exercise training for two groups: control and EX+BR. Secondary objectives involve preliminary effect sizes for pre-post changes in distance covered during the 6-minute walk test, changes in endothelial-dependent vasodilation, and biomarkers of cardiovascular health.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
30
Participants randomly assigned to the EX + BR group will consume 140 mL beetroot juice containing approximately 12 mmol of nitrate 3 hours prior to the supervised exercise training component.
Participants will perform 8 weeks of supervised exercise training at a frequency of 3x per week.
Indiana University
Bloomington, Indiana, United States
Recruitment rate
The number of eligible participants randomized per months of recruitment time.
Time frame: 24 months
Retention rate
The number of randomized participants who complete at least 17 (out of 24 possible) exercise training sessions.
Time frame: 8 weeks
Adherence to exercise training intervention
The percent of exercise sessions attended out of the 24 possible sessions.
Time frame: 8 weeks
Adherence to dietary nitrate intervention
Breath analysis of fractional exhaled nitric oxide concentrations.
Time frame: 8 weeks
Perceived difficulty of training sessions
Participants will report the perceived exertion at the end of exercise sessions using the Borg category ratio-10 scale that ranges from 0 "no exertion" to 10 "maximal exertion".
Time frame: 8 weeks
Distance covered during a six-minute walk test
Participants will be asked to walk as far as possible at a preferred speed for six minutes according to ATS standards. Distance covered will be measured in meters.
Time frame: Baseline, post-intervention
Soluble endothelial microparticles
Blood samples will be analyzed for adhesion molecules (sICAM-1, sVCAM-1, sE-selectin).
Time frame: Baseline, post-intervention
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