Soy and whey protein have different concentrations of leucine, an amino acid known to be a particularly potent simulator of muscle protein synthesis. The purpose of this study is to determine whether matching soy and whey protein supplements for leucine content instead of by total protein content would contribute to differences in strength increases and muscle growth in response to 12 wk of resistance training.

Inclusion Criteria:

• non-smoking
• body mass index (BMI) 18.5-24.9
• recreationally active

Exclusion Criteria:

• participated in structured weight training during the previous 12 month
• vegetarian or vegan
• presence of chronic disease
• pregnant, postpartum up to six months, lactating, or intention to become pregnant
• allergy to whey or soy
• changes in body weight more than 10 pounds in the past three months

12 weeks

1. No non-protein control (ex: placebo, maltodextrin)
2. No objective measurement of physical activity outside of the exercise intervention
3. No objective verification if the participants consumed protein powder on non-training days