If your idea of cardio day is an hour-long jog or bike ride, a study published in The American Journal of Clinical Nutrition suggests supplementing with the Branched Chain Amino Acid (BCAA) leucine and other Essential Amino Acids (EAAs) can increase your body’s protein synthesis response during the recovery phase.

Researchers had 8 healthy adults cycle on a stationary bike for an hour at 60% of maximum capacity. All received a drink containing 10 grams of EAAs. Some contained 3.5 grams of leucine while others had only 1.87 grams of leucine. The increased concentration helped subjects realize a greater degree of protein synthesis during recovery.

True Strength Moment: Protein synthesis is one of the key mechanisms involved in building muscle size and strength. While all of the EAAs have a role in fueling this process, this study puts the BCAA leucine in the spotlight. A number of ON products offer BCAAs in a 2:1:1 ratio of leucine to isoleucine and valine.