Dileucine and Resistance Training Adaptations

This study seeks to compare the observed changes in resistance training adaptations after supplementation of isomolar amounts of leucine or dileucine in healthy resistance-trained men. This will provide a better understanding of supplementation with leucine versus dileucine over a 10-week period in regards to increasing muscular performance.

The study will be conducted using a randomized, double-blind approach with individuals being provided daily 2-gram doses of leucine, 2-gram doses of dileucine, or a placebo. Daily blinded supplementation will occur each day for a 10-week period of time while completing a heavy resistance training program. Participants follow the resistance training program for a total of 10 weeks. To compare the efficacy of leucine in form of amino acid or dipeptide supplementation on resistance training adaptations, changes in fat-free, lean, and fat mass will be determined using a 4-compartment body composition model. Skeletal muscle cross-sectional area will be assessed using ultrasound. Maximal strength, muscular endurance, and power will also be assessed. Participants will be required to provide weekly compliance and complete one supervised workout per week. After 2, 6, and 10 weeks of following the supplementation and resistance training regimens, participants will return to the laboratory to complete testing bouts consisting of identical assessments of body composition, muscular strength, muscular endurance, lower-body power, and anaerobic capacity. Adverse events related to each supplementation group will be recorded and assessed.

Eligibility Criteria:
Inclusion Criteria:

* Male
* Between the ages of 18-39 years of age
* Currently participating in resistance training exercise

Exclusion Criteria:

* Female
* Participants who are determined to not be weight stable defined as week 0 and week 2 body mass levels deviating by 3% or more.
* Any individual who is currently being treated for or diagnosed with a cardiac, respiratory, circulatory, musculoskeletal, metabolic, immune, autoimmune, psychiatric, hematological, neurological or endocrinological disorder or disease.
* Body mass index \> 25 kg/m2. Individuals with a body mass index greater than 25 kg/m2, but a body fat percentage less than 25% fat will be accepted into the study
* Individuals who present with any previous injury or illness that would prevent them from appropriately completing all exercise lifts.
* Participants who are not able to fit onto the DEXA table will not be able to participate in the research due to size restrictions of the equipment. This typically includes individuals exceeding 400 pounds or those greater than 6'4".
* Those individuals with less than 12 months of structured resistance training experience will be excluded from the study.
* Individuals whose maximal relative upper body strength is below 1.0 will be excluded.
* Individuals whose maximal relative lower body strength is below 1.5 will be excluded.
* All participants who DO NOT abstain from taking any additional forms of nutritional supplementation deemed to be ergogenic or that will impact resistance training adaptations (pre-workouts, creatine, beta-alanine, etc.) for four weeks prior to beginning this study and for the entire duration of the study.
* Individuals who are currently using or have used within the past 12 months anabolic-androgenic steroids.