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The Effects of a Dietary Supplement on Exercise Performance in Healthy Older Adults"

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT01073332
Recruitment Status : Completed
First Posted : February 23, 2010
Last Update Posted : May 8, 2015
Information provided by (Responsible Party):

Study Description
Brief Summary:
Human exercise capacity decreases with aging. One explanation may be that blood vessels stiffen with age and release less of a compound called nitric oxide (NO). This compound normally relaxes blood vessels and increases blood flow to muscles, but damaging compounds called free radicals can interfere with this process. Antioxidants may help prevent free radicals from inactivating nitric oxide. The purpose of this study was to investigate the effects of an antioxidant supplement that supports NO production on exercise performance in elderly male cyclists.

Condition or disease Intervention/treatment
Excessive Physical Exercise, Unspecified Dietary Supplement: Arginine antioxidant supplements Dietary Supplement: Placebo

Detailed Description:
Since the discovery of the vascular smooth muscle relaxant properties of nitric oxide (NO) over 25 years ago, studies have implicated this molecule in modulating such processes as atherosclerosis, impotence, angina, platelet function, and blood pressure, among others. Through vascular smooth muscle relaxation in both coronary and skeletal muscle arteries, as well as via independent mechanisms, nitric oxide has also been implicated in improvement of exercise capacity. In addition, NO may be involved in the immune system, assist in memory function and sleep regulation, and act as a cellular signaling messenger. Youthful, healthy and athletic individuals generally have a healthier NO system, compared to sedentary, unhealthy and aging individuals. NiteworksTM is a dietary supplement that includes L-arginine, an amino acid that acts as a nitric oxide donor and has been shown to increase levels of this molecule in the body. NiteworksTM has been formulated as a composite mixture along with other supplements, including antioxidants, that may act synergistically with L-arginine in enhancing exercise capacity.

Study Design

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 16 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary Purpose: Basic Science
Official Title: Arginine and Antioxidant Supplement on Performance in Elderly Male Cyclists: A Randomized Controlled Trial
Study Start Date : October 2004
Primary Completion Date : February 2005
Study Completion Date : February 2005

Resource links provided by the National Library of Medicine

U.S. FDA Resources

Arms and Interventions

Arm Intervention/treatment
Placebo Comparator: Placebo
The placebo group received a powder with all active ingredients replaced with M-100 maltodextrin.
Dietary Supplement: Placebo
The placebo group received a powder with all active ingredients replaced with M-100 maltodextrin.
Experimental: Arginine antioxidant supplements
Dietary Supplement: Niteworks
Dietary Supplement: Arginine antioxidant supplements
The proprietary supplement Niteworks® was manufactured by Herbalife International Inc. (Century City, California, USA). Each serving contained 5.2g L-arginine in a proprietary blend with L-citrulline, 500mg ascorbic acid, 400IU vitamin E, 400ug folic acid, 300mg L-taurine, and 10mg alpha lipoic acid in a lemon-flavored powder form. One serving of supplement powder was mixed with 8 oz of water, administered at bedtime based on the rationale that nitric oxide levels are lowest during sleep due to inactivity, lack of food and low blood pressure.

Outcome Measures

Primary Outcome Measures :
  1. Arginine and antioxidant supplements, as compared with placebo will improve exercise performance [ Time Frame: 3 weeks ]

Secondary Outcome Measures :
  1. Arginine and antioxidant Supplements improve maximal oxygen uptake and anaerobic threshold [ Time Frame: 3 weeks ]

Eligibility Criteria

Information from the National Library of Medicine

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Ages Eligible for Study:   50 Years to 75 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Males and females
  • Age 50-75 years, inclusive
  • Ability to perform pulmonary function and exercise tests
  • Willingness to take supplement powder for 3 weeks
  • Ethical: Subject must sign the Institutional Review Board-approved written informed consent prior to he initiation of any study specific procedures or randomization. A subject will be excluded for any condition that might compromise the ability to give truly informed consent for participation in the study.

Exclusion Criteria:

  • Existing pulmonary or cardiovascular disease
  • Previous cardiac surgery
  • Not able to tolerate breathing through mouthpiece for up to 20 minutes
  • Musculoskeletal disease that would limit exercise
Contacts and Locations

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01073332

United States, California
University of California, Los Angeles
Los Angeles, California, United States, 90095
Sponsors and Collaborators
University of California, Los Angeles
Principal Investigator: Zhaoping Li, MD, PhD University of California, Los Angeles
More Information

Responsible Party: Zhaoping Li, Professor of Medicine, University of California, Los Angeles
ClinicalTrials.gov Identifier: NCT01073332     History of Changes
Other Study ID Numbers: UCLA_IRB_03-08-087-01
First Posted: February 23, 2010    Key Record Dates
Last Update Posted: May 8, 2015
Last Verified: February 2010

Additional relevant MeSH terms:
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs