High-Dose Nitrate Supplementation Attenuates the Increased Blood Pressure Responses to Isometric Blood Flow Restriction Exercise in Healthy Males

Abstract

The effect of nitrate (NO3−) supplementation on blood pressure (BP) responses during large muscle mass isometric and ischaemic exercise in healthy young adults is unclear. The aim of the present study was to assess the effect of 5-day supplementation of NO3− on BP responses during a short isometric contraction and a sustained ischaemic contraction. In a randomised, double-blinded, crossover design, 14 healthy active young adults underwent BP measurements after 5 days of either NO3− (NIT) or placebo (PLA) supplementation. Beat-by-beat BP was measured at pre- and post-exercise rest, and during a short (20 s) isometric contraction at 25% maximal strength and throughout a sustained ischaemic contraction. Plasma nitrite (NO2−) concentration increased significantly after NO3− supplementation compared to placebo (475 ± 93 nmol·L−1 vs. 198 ± 46 nmol·L−1, p < 0.001, d = 3.37). Systolic BP was significantly lower at pre- (p = 0.051) and post-exercise rest (p = 0.006), during a short isometric contraction (p = 0.030), and throughout a sustained ischaemic contraction (p = 0.040) after NO3− supplementation. Mean arterial pressure was significantly lower at pre- (p = 0.004) and post-exercise rest (p = 0.043), during a short isometric contraction (p = 0.041), and throughout a sustained ischaemic contraction (p = 0.021) after NO3− supplementation. Diastolic BP was lower at pre-exercise rest (p = 0.032), but not at post-exercise rest, during a short isometric contraction, and during a sustained ischaemic contraction (all p > 0.05). Five days of NO3− supplementation elevated plasma NO2− concentration and reduced BP during a short isometric contraction and a sustained ischaemic contraction in healthy adults. These observations indicate that multiple-day nitrate supplementation can decrease BP at rest and attenuate the increased BP response during isometric exercise. These findings support that NO3− supplementation is an effective nutritional intervention in reducing SBP and MAP in healthy young males during submaximal exercise.

Keywords: cardiovascular health; functional food; nitric oxide; nutrition; supplements.

Figure 1

Group mean (SD) and individual plasma nitrite (NO₂⁻) concentration responses after 5-day dietary nitrate (NIT) or placebo (PLA) supplementation are shown in the black and dashed lines, respectively. * p  <  0.05.

Figure 2

Blood pressure at pre-exercise rest (A), and post-exercise rest (B) in NIT and PLA trials. SBP: systolic blood pressure, DBP: diastolic blood pressure, MAP: mean arterial pressure. Data are mean ± SD. * p < 0.05.

Figure 3

Systolic blood pressure (SBP), diastolic blood pressure (DBS), mean arterial pressure (MAP) during short isometric contraction (A) and a sustained ischaemic contraction (B) following nitrate (NIT) and placebo (PLA) supplementation. Data are mean ± SD. * p = 0.030 for SBP and p = 0.041 for MAP. # Main effect of supplementation, p = 0.040 for SBP and p = 0.021 for MAP.