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Date of Graduation

4-2005

Degree Type

Capstone Project (On-Campus Access Only)

Degree Name

Master of Science in Physician Assistant Studies

First Advisor

Judy Ortiz PA-C

Second Advisor

Jonathon W. Gietzen MS PA-C

Abstract

Problem: 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. Niteworks™ 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. Niteworks™ has been formulated as a composite mixture along with other supplements, including antioxidants, that may act synergistically with L-arginine in enhancing exercise capacity.

Significance: Human exercise capacity declines with advancing age and many individuals lose the inclination to participate in regular physical activity. These changes often result in loss of physical fitness and more rapid senescence. A dietary supplement that energizes the body and increases exercise capacity might preserve physical fitness and improve general health and well being in older humans. Such an effect would have considerable impact in terms of independence of older individuals, decreased loss· of physical function and associated health care costs.

Specific Aims: We examined the hypotheses that Niteworks™, as compared with placebo (a) would lead to improved gas exchange parameters as measured by breath-to-breath measurements, including maximal oxygen uptake and anaerobic threshold, (b) would lead to an earlier lactate peak time and a more rapid lactate recovery after exercise (thereby decreasing muscle fatigue), and (c) maintain a healthy blood pressure and pulse.

Experimental Approach: We recruited apparently healthy human subjects that were cyclists between age 46-73 years from the UCLA campus and local community. They were randomized to receive Niteworks or identical placebo powder for a period of three weeks. Maximum oxygen uptake was measured by incremental exercise testing on a cycle ergometer during the screening visit, during which time we ensured that the patients are able to tolerate exercise testing. At the baseline and final visits, submaximal endurance times were determined for a constant work rate equal to 60% of the maximal work rate attained at baseline. A capillary tube sample of blood was obtained by finger prick at the end of the exercise test and at three minutes intervals (up to twelve minutes post exercise) during the cool-down period, in order to measure peak lactate levels and lactate clearance. Perception of effort was assessed for each exercise task using Borg rate of perceived exertion (RPE) scales. Quality of life measures such as health perception and vitality were assessed using the Medical Outcomes Trust Short Form 36. A blood draw at the screening visit assisted in determining study inclusion.

Results: Based on the results from this study Niteworks ™ was beneficial in older adult cyclists in that their exercise capacity increased. The results showed that the group that received Niteworks ™ had a statistically significant improvement in their anaerobic threshold (week 0-1 p=0.0005 and week 0-3 p=0.045) and ventilatory threshold (week 0-1 p=0.0365 and week 0-3 p=O.0132) as compared to the placebo group. There was no difference in the lactate peak time or a more rapid recovery rate. The subject's maintained a healthy blood pressure and pulse during exercise testing.

Comments

The digital version of this project is currently unavailable to off-campus users; however, it may be requested via interlibrary loan by eligible borrowers from Pacific University Library. Pacific University Library is a free lender. (Library Use: NL)

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