Effects of nitrate supplementation in trained and untrained muscle are modest with initial high plasma nitrite levels

TY - JOUR

T1 - Effects of nitrate supplementation in trained and untrained muscle are modest with initial high plasma nitrite levels

AU - Christensen, Peter Møller

AU - Petersen, Nanna K

AU - Friis, Signe N

AU - Weitzberg, Eddie

AU - Nybo, Lars

N1 - CURIS 2017 NEXS 083

PY - 2017/12

Y1 - 2017/12

N2 - Nitrate (NO3 -) supplementation resulting in higher plasma nitrite (NO2 -) is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO2) during submaximal exercise in non-athletic populations, whereas effects in general are absent in endurance-trained individuals. To test whether physiologic effects of (NO3 -) supplementation depend on local muscular training status or cardiovascular fitness, male endurance-trained cyclists (CYC, n=9, VO2-max: 64±3 mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3 mL/min/kg), acutely consumed nitrate-rich beetroot juice (NO3 -) ~9 mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO2-max) and incremental leg cycling (LEG-ex) and arm-cranking exercise (ARM-ex). NIT increased (P<.001) resting plasma by ~1200% relative to PLA. Plasma (NO3 -) increased ~25% (P<.01) with a significant change only in CYC. LEG-ex VO2 (~2.60 L/min), ARM-ex VO2 (~1.14 L/min), and resting MAP (~87 mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG-ex VO2 (~2.03 L/min), ARM-ex VO2 (~1.06 L/min), or resting MAP (~85 mm Hg). VO2-max was not affected by supplementation, but incremental test peak power was higher (P<.05) in LEG-ex for CYC in NIT relative to PLA (418±47 vs 407±46 W). In both CYC and CON, high initial baseline values and small increases in plasma NO2 - after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of (NO3 -) supplementation.

AB - Nitrate (NO3 -) supplementation resulting in higher plasma nitrite (NO2 -) is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO2) during submaximal exercise in non-athletic populations, whereas effects in general are absent in endurance-trained individuals. To test whether physiologic effects of (NO3 -) supplementation depend on local muscular training status or cardiovascular fitness, male endurance-trained cyclists (CYC, n=9, VO2-max: 64±3 mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3 mL/min/kg), acutely consumed nitrate-rich beetroot juice (NO3 -) ~9 mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO2-max) and incremental leg cycling (LEG-ex) and arm-cranking exercise (ARM-ex). NIT increased (P<.001) resting plasma by ~1200% relative to PLA. Plasma (NO3 -) increased ~25% (P<.01) with a significant change only in CYC. LEG-ex VO2 (~2.60 L/min), ARM-ex VO2 (~1.14 L/min), and resting MAP (~87 mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG-ex VO2 (~2.03 L/min), ARM-ex VO2 (~1.06 L/min), or resting MAP (~85 mm Hg). VO2-max was not affected by supplementation, but incremental test peak power was higher (P<.05) in LEG-ex for CYC in NIT relative to PLA (418±47 vs 407±46 W). In both CYC and CON, high initial baseline values and small increases in plasma NO2 - after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of (NO3 -) supplementation.

KW - Cycling economy

KW - VO2 max

KW - NO bioavailability

KW - Blood pressure

U2 - 10.1111/sms.12848

DO - 10.1111/sms.12848

M3 - Journal article

C2 - 28165641

SN - 0905-7188

VL - 27

SP - 1616

EP - 1626

JO - Scandinavian Journal of Medicine & Science in Sports

JF - Scandinavian Journal of Medicine & Science in Sports

IS - 12

ER -