Deer antler velvet is supposed to help you build muscle. It allegedly elevates levels of IGF-1, an important hormone that helps you pack on mass. As “side effects” you also should see improvements in strength and endurance. And some products even claim it speeds recovery, which is why it was linked to Ray Lewis who earlier suffered an apparent season-ending injury, and yet has played and performed at a high level in the playoffs.
Insulin-like Growth Factor 1 (IGF-1) is an anabolic molecule which appears to induce growth of the antlers themselves, although testosterone may be the primary growth factor. Currently, there is no evidence that serum IGF-1 is increased following Velvet Antler ingestion with one study using 1.5g of Velvet Antler for 11 weeks failing to increase serum IGF-1.
A systemic review on human interventions makes note of a study conducted on patients of osteoarthritis (Edelman et al. 2000; cannot be located online) which found improvements in joint pain symptoms relative to baseline in the Velvet Antler group and not placebo, although a lack of information on blinding and randomization precludes results that can be drawn from this study.