title: Effect of acute dietary nitrate intake on maximal knee extensor speed and power in healthy men and women.
abstract: Nitric oxide (NO) has been demonstrated to enhance the maximal shortening velocity and maximal power of rodent muscle. Dietary nitrate (NO3(-)) intake has been demonstrated to increase NO bioavailability in humans. We therefore hypothesized that acute dietary NO3(-) intake (in the form of a concentrated beetroot juice (BRJ) supplement) would improve muscle speed and power in humans. To test this hypothesis, healthy men and women (n = 12; age = 22-50 y) were studied using a randomized, double-blind, placebo-controlled crossover design. After an overnight fast, subjects ingested 140 mL of BRJ either containing or devoid of 11.2 mmol of NO3(-). After 2 h, knee extensor contractile function was assessed using a Biodex 4 isokinetic dynamometer. Breath NO levels were also measured periodically using a Niox Mino analyzer as a biomarker of whole-body NO production. No significant changes in breath NO were observed in the placebo trial, whereas breath NO rose by 61% (P < 0.001; effect size = 1.19) after dietary NO3(-) intake. This was accompanied by a 4% (P < 0.01; effect size = 0.74) increase in peak knee extensor power at the highest angular velocity tested (i.e., 6.28 rad/s). Calculated maximal knee extensor power was therefore greater (i.e., 7.90 ± 0.59 vs. 7.44 ± 0.53 W/kg; P < 0.05; effect size = 0.63) after dietary NO3(-) intake, as was the calculated maximal velocity (i.e., 14.5 ± 0.9 vs. 13.1 ± 0.8 rad/s; P < 0.05; effect size = 0.67). No differences in muscle function were observed during 50 consecutive knee extensions performed at 3.14 rad/s. We conclude that acute dietary NO3(-) intake increases whole-body NO production and muscle speed and power in healthy men and women.
authors.affiliation: Cardiovascular Imaging Laboratory, Division of Radiological Sciences, Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address: coggana@mir.wustl.edu.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Coggan
authors.affiliation: Cardiovascular Imaging Laboratory, Division of Radiological Sciences, Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Leibowitz
authors.affiliation: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Kadkhodayan
authors.affiliation: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Deepak P
authors.initials: DP
authors.lastname: Thomas
authors.affiliation: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Sujata
authors.initials: S
authors.lastname: Ramamurthy
authors.affiliation: Center for Applied Research Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Catherine Anderson
authors.initials: CA
authors.lastname: Spearie
authors.affiliation: Center for Applied Research Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Waller
authors.affiliation: Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Marsha
authors.initials: M
authors.lastname: Farmer
authors.affiliation: Cardiovascular Imaging Laboratory, Division of Radiological Sciences, Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Linda R
authors.initials: LR
authors.lastname: Peterson
mesh_terms: D000328:Adult; D001682:Biological Availability; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects; D018763:Muscle Fatigue / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009566:Nitrates / Q000008:administration & dosage / Q000494:pharmacology*; D009569:Nitric Oxide / Q000493:pharmacokinetics; D019415:Torque; D055815:Young Adult
chemical_list: D009566:Nitrates; D009569:Nitric Oxide
keywords: Dietary nitrate; Humans; Isokinetic; Muscle power; Nitric oxide