Here’s a brief overview of each compound:

1. Cardarine (GW-501516): Not a SARM, but often included in stacks. Cardarine is known for its potential to enhance endurance and increase fat burning. It activates certain pathways that affect metabolism and endurance capacity.
2. S23: A potent SARM known for its potential to increase muscle mass and strength while aiding fat loss. It’s part of a new generation of SARMs, but comprehensive human studies are limited.
3. SR-9009: Also known as Stenabolic, SR-9009 is not a SARM but a Rev-Erb agonist. It has been researched for its potential effects on metabolism and endurance by increasing mitochondrial activity in cells.
4. MK-2866 (Ostarine): A well-studied SARM that is versatile and used for both bulking and cutting cycles. It’s known for its potential to help maintain and increase lean body mass while aiding fat loss.

Combining these compounds aims to achieve synergistic effects on muscle growth, fat loss, endurance, or overall performance. However, it’s crucial to note that such combinations increase the complexity of potential side effects, interactions, and risks.

Due to the limited comprehensive human studies, potential health risks, and unknown long-term effects associated with combining these compounds, using such stacks should be approached with extreme caution. Consulting with a healthcare professional or a specialist in fitness and supplementation is highly recommended before considering or using these combinations. Understanding potential risks, interactions, and the lack of robust human studies is essential for informed decision-making about supplementation.