Alpha-hydroxyisocaproic acid (HICA) is a metabolite of leucine, a modified amino acid. Unlike leucine, HICA works as a signaling molecule instead of a direct building block for muscle protein synthesis. Small, short-term trials show it may reduce markers of muscle breakdown after exercise and help preserve lean mass during calorie restriction or aging, though findings are not yet robust.
Athletes looking to accelerate recovery from resistance or endurance training often use HICA. While leucine doses reach multiple grams to trigger protein synthesis, HICA doses stay well under 2 grams a day.
You can take a single dose before or after a workout, or split it into two servings across the day. Most people handle it without issue, but mild stomach upset can happen.
Cautious use is wise because human data is still limited to small studies. Pregnant or breastfeeding people should avoid it due to missing safety data. Talk with a healthcare provider before starting, particularly if you have a metabolic condition.