Evaluation of Sports Supplements on Blood Flow
Condition: Determine the Effects of Nitrosigine and Citrulline-malate on Flow-mediated Dilation Among Young Adults
MeSH terms: Dilatation, Pathologic
Study type: Interventional

Summary: 
      Many athletes seek to increase their plasma (blood) nitric oxide content prior to exercise in
      order to augment vasodilation. Increased vasodilation during exercise, especially high
      intensity resistance training, allows for more blood flow to muscle tissues, which may give
      the athlete benefits such as increased work capacity and acute muscle hyperemia, which is
      commonly referred to as muscle pump. Pre-workout supplements are typically taken 30 minutes
      to 1 hour prior to the onset of exercise, so the current investigation seeks to determine if
      citrulline malate or nitrosigine can effect vasodilation within 1 hour of supplementation,
      and if so, which supplement is more effective. Based on previous findings, we hypothesize
      that a certain exercise intensity needs to be present for citrulline malate and nitrosigine
      to have an effect, so a change may not be observable at rest.
    

Detailed description: 
      Data collection will be conducted by qualified research staff and students at the University
      of Arkansas Exercise Science Research Center (ESRC). Upon contact with the research team, a
      medical/health questionnaire will be sent via email to the subject. This will be the initial
      screening tool to determine if the subject qualifies for the project. The subjects must meet
      the inclusion and none of the exclusion criteria in order to qualify for the study.
      Participants will be instructed to do the following the day of data collection: 1. No
      caffeine, stimulants, or blood thinners (such as ibuprofen, advil, aspirin, warfarin,
      clopidogrel, etc.) 24 hours prior to testing. 2. Wear comfortable clothes (short sleeve top).
      3. Take all medication as normal (aside from those mentioned in #1). Participant testing will
      be conducted as follows: participant arrives at ESRC; height, weight, blood pressure, and
      complete questionnaires (electronically): medical history, 24-hour dietary recall,
      International Physical Activity Questionnaire (IPAQ). IPAQ is a standardized questionnaire
      used to evaluate an individual's level of physical activity in their daily life. After
      completing all surveys, the subject will be asked to lie in a supine position for 15 minutes,
      then they will have the diameter of the brachial artery (medial side of upper arm) assessed
      with ultrasound (GE Logiq e). Ultrasound is a non-invasive way of determining the diameter of
      arteries. A total of 10 measurements will be taken of the brachial artery. After the initial
      10 measurements (~3-5 minutes), flow-mediated dilation (FMD) will be performed. Flow mediated
      dilation will be performed with a Hokanson rapid cuff inflator. The cuff (blood pressure
      cuff) will be position on the forearm (just above the wrist) and will be inflated to
      250-300mmHg for a period of 5 minutes to restrict blood flow. After the 5-minute inflation
      period, the cuff will deflate and vessel diameter will be re-assessed (10 additional trails).
      Following the initial FMD assessment, one of three supplements will be consumed:
      citrulline-malate (8 g), Nitrosigine (1.5 g), or placebo (8 g Dextrose). After consumption,
      participants will remain in ESRC for 60 minutes to allow for digestion of the substance.
      Following the 60-minute absorption period, FMD will be re-assessed.
    

Intervention name(s): inositol-stabilized arginine silicate
Intervention type(s): Dietary Supplement
Intervention description(s): Participants were asked to complete the experimental protocol in a 2-hour fasted state. Each participant's brachial artery FMD was assessed twice during each trial, once before supplement ingestion, and again 60 minutes post-ingestion. Male participants were required to wait for a minimum of seven days between trials as a supplement washout period. Female participants reported for supplement trials outside of their follicular phase of the menstrual cycle so that results were not confounded by changes in serum estradiol, which can significantly attenuate flow-mediated dilation. Sixty minutes after supplement consumption, each participant was asked which supplement they thought they had consumed. Participants were also asked whether they experienced any adverse side effects.
Intervention MeSH terms: Inositol
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomized, double-blind, crossover design
Masking: Double (Participant, Investigator)
Primary purpose: Other
Keywords: flow-mediated dilation; vasodilation; Nitrosigine; Citrulline-Malate