No matter what kind of shape you’re in, it’s hard to build muscle when you’re too fatigued to drag your ass to the next exercise. That’s why you can thank a group of Australian researchers from Victoria University, Monash University, Macquarie University, and the Australian Institute of Sport, who joined forces and set out to determine the exact mechanisms that lead to fatigue. It’s a complicated chain of events that take place at a cellular level, but the short answer is serotonin; when this neurotransmitter increases during strenuous exercise, your physical and mental performance decreases along with it. Of course, the researchers then took the next step, which was to figure out how to inhibit serotonin.
The study authors found that branched-chain amino acids (BCAAs) can lower serotonin and consequently delay the onset of fatigue. When athletes drank a formula containing BCAAs—13.5g of leucine, 8g of isoleucine, and 9g of valine— three hours before strenuous exercise, they didn’t just dodge the effects of fatigue, they improved their performance by 10%! The athletes also demonstrated improved mood and vigor throughout their workouts, along with significantly heightened cognitive ability, which was tested using a variety of mental performance tests. This study is just the latest to uncover yet another benefit of supplementing with BCAAs, which are already known to encourage muscle growth, support strength and power, and promote muscle recovery.