Cardiovascular disease (CVD) is considered the primary cause of death in the developed world.
Large scale epidemiological studies indicate that prevalence of hypertension along with
adverse cardiovascular events peak during the winter months. Moreover, during the winter
months outdoor activities and physical stressors such as exercise have been associated with
higher cardiovascular mortality when compared to other periods of the year. Although low
environmental temperatures have been implicated as the triggering factor for cardiovascular
complications, the mechanisms on how cold exposure increase cardiovascular morbidity and
mortality remain to be elucidated. However, new research suggests that cold exposure may
induce increases in cardiac sympathetic activity, endothelial damage and increased arterial
stiffness of central arteries. Cardiovascular drugs including antihypertensive
pharmacological agents seem to be inefficient to provide appropriate therapeutic effects
during cold exposure. Therefore, it is imperative to propose alternative non-pharmacological
therapies intended to prevent the detrimental effects of low environmental temperatures on
cardiovascular function. Recently, oral supplementation of the amino acid L-citrulline has
been proposed as an effective therapeutic adjuvant for the treatment of hypertension.
L-citrulline is known to enhance the bioavailability of L-arginine levels and increase
endothelial nitric oxide (NO) production, one of the main modulators of vascular tone and
blood pressure (BP). L-citrulline supplementation has been shown to increase endothelial
function, reduce BP, and ameliorate endothelial oxidative damage without any adverse effects.
Our group has demonstrated that L-citrulline supplementation attenuates the BP response to
cold exposure (the cold pressor test, CPT). These studies suggest that L-citrulline
supplementation may be a feasible therapeutic aid in order to prevent cardiovascular
complications associated with cold exposure. However the potential cardioprotective effects
of L-citrulline supplementation during cold exposure with exercise have yet to be evaluated.
It is hypothesized that L-citrulline supplementation would reduce arterial stiffness and
blood pressure (BP) responses to physiological stress (cold exposure). This study may lead to
the development of an adjunct therapy for the prevention and management of cardiovascular
adverse events that are particularly increased during the winter months.