Acute ingestion of dietary nitrate increases muscle blood flow via local vasodilation during handgrip exercise in young adults

Figures

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  Figure 1. Study Timeline. Following venous catheter insertion and 30 min of quiet rest, participants performed graded handgrip exercise (5%, 15%, 25% maximal voluntary contraction [MVC]) for 4 min at each intensity. During 25% MVC, participants continued performing handgrip exercise for an additional 3 min while they underwent systemic hypoxia (80% SpO2). The blood flow response to graded exercise and hypoxic exercise was assesses in control conditions and following ingestion of 210 or 280 mL of concentrated BR (12.6 mmol nitrate (n = 5) or 16.8 mmol nitrate (n = 6). Participants performed their second bout (beetroot [BR] juice) of exercise either 2 h (12.6 mmol) or 3 h (16.8 mmol) postconsumption. On a separate day and with separate individuals (n = 7), the experimental protocol was repeated with nitrate‐free concentrated BR juice. Venous blood was obtained for NO3− and NO2− at rest prior to the onset of each exercise trial, and for blood gasses at rest and the end of each exercise intensity during normoxia and hypoxia.

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  Figure 2. (A) Plasma Nitrate (NO3−) and (B) Nitrite (NO2−) concentrations in control trial and 2–3 h after ingestion of BR (BEET). *P < 0.05 versus control trial.

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  Figure 3. (A) Forearm blood flow and (B) vascular conductance during graded handgrip exercise and hypoxic exercise prior to and following ingestion of concentrated BR (BEET). *P < 0.05 versus control trial within respective condition (BEET or Placebo). % MVC, % of maximal voluntary contraction.

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  Figure 4. (A) Forearm VO2 and (B) a‐vO2 at rest and during graded handgrip exercise and hypoxic exercise prior to and following BR ingestion (BEET). *P < 0.05 versus control trial. % MVC, % of maximal voluntary contraction.