Arginine and creatine are both compounds that have been investigated for cardiovascular health, including conditions commonly referred to as "heart weakness" (such as heart failure or cardiac insufficiency). Arginine is a precursor to nitric oxide, a molecule that helps dilate blood vessels and improve blood flow. Some small studies have explored its use in heart failure, with mixed outcomes; while arginine supplementation may improve endothelial function and exercise capacity in some patients, larger and more rigorous trials are lacking, and there are concerns about safety in severe heart failure, as some studies suggest possible harm.

Creatine is involved in cellular energy production and has been studied for its role in improving muscle strength and endurance, including in skeletal and, to a lesser extent, cardiac muscle. Limited research indicates that creatine supplementation may improve muscle strength and functional capacity in patients with chronic heart failure, but evidence is not robust, and data on direct effects on cardiac function are sparse.

The use of a combined "arginine creatine" supplement specifically for heart weakness is grounded in biological plausibility and some preliminary studies, but the quality and quantity of evidence are limited. Major cardiology guidelines do not currently recommend these supplements as standard therapy for heart failure. Therefore, while there is some scientific rationale and early-stage evidence, it is not strong or definitive.