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

Arginine and Antioxidant Supplement on Performance in Elderly Male Cyclists: A Randomized Controlled Trial

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.

Study Overview

• Status: Completed
• Conditions: Excessive Physical Exercise, Unspecified
• Intervention / Treatment: Dietary supplement: Placebo; Dietary supplement: Arginine antioxidant supplements

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 Type: Interventional
• Enrollment (Actual): 16
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90095
      • University of California, Los Angeles

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Arginine and antioxidant supplements, as compared with placebo will improve exercise performance	3 weeks

Secondary Outcome Measures

Outcome Measure	Time Frame
Arginine and antioxidant Supplements improve maximal oxygen uptake and anaerobic threshold	3 weeks

Collaborators and Investigators

• Sponsor: University of California, Los Angeles

Study record dates

Study Major Dates

• Study Start: October 1, 2004
• Primary Completion (Actual): February 1, 2005
• Study Completion (Actual): February 1, 2005

Study Registration Dates

• First Submitted: February 22, 2010
• First Submitted That Met QC Criteria: February 22, 2010
• First Posted (Estimate): February 23, 2010

Study Record Updates

• Last Update Posted (Estimate): May 8, 2015
• Last Update Submitted That Met QC Criteria: May 6, 2015
• Last Verified: February 1, 2010

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Protective Agents; Antioxidants
• Other Study ID Numbers: UCLA_IRB_03-08-087-01