One of the most recent, popular supplements for athletes looking to boost performance comes in the form of a naturally-occurring amino acid called L-arginine.
The reason for its popularity is twofold says Scott Forbes, a doctoral student in exercise physiology. "First, L-arginine is a precursor for nitric oxide that is known to improve blood flow, which in turn may aid the delivery of important nutrients to working muscles and assist with metabolic waste product removal. Secondly, L-arginine has been shown to increase growth hormone levels in the blood."
The benefits of growth hormone are diverse, including increasing the use of fat as a fuel as well as insulin and insulin-growth factor-1 (IGF-1) levels. However, most of the research conducted on L-arginine has been in a clinical setting and the benefits for physically active individuals are not as established. In some cases they are conflicting.
"One of the reasons for this is that the amount an individual has to consume has not been clearly established and this information is rarely provided by the manufacturers of such products," explains Forbes, a doctoral student in exercise physiology.
For Forbes it was a theory worth testing and he wanted to test two different L-arginine doses on healthy, athletic men the group most likely to purchase this readily-available supplement.
"L-arginine is interesting for a few reasons," says Forbes. "It can increase growth hormone response, and so can increase muscle mass. Also it has an impact on insulin, which is another anabolic hormone. A recent hot topic has been about nitric oxide as a vasodilator. The theory is that if you can vasodilate your arteries you can potentially enhance blood flow to the muscles and enhance nutrient delivery and waste product removal."
L-arginine is also often prescribed for older adults with cardiovascular disease, endothelial dysfunction or hypertension for its vasodilation proper
|Contact: Jane Hurly|
University of Alberta - Faculty of Physical Education and Recreation