In a parallel group design , 40 men ( 21 1 y ) completed unilateral knee-extensor resistance exercise before the ingestion of 25 g whey protein ( W25 ) ( 3.0 g leucine ) , 6.25 g whey protein ( W6 ) ( 0.75 g leucine ) , 6.25 g whey protein supplemented with leucine to 3.0 g total leucine ( W6 + Low-Leu ) , 6.25 g whey protein supplemented with leucine to 5.0 g total leucine ( W6 + High-Leu ) , or 6.25 g whey protein supplemented with leucine , isoleucine , and valine to 5.0 g total leucine .