The Effect of Protein Blend Supplementation and Resistance Exercise on Skeletal Muscle Growth and Adaptation

The goal of this project was to determine the efficacy of a new protein supplement to improve muscle growth and strength when ingested following exercise. The hypothesis is that novel supplementation of mixed dietary proteins (protein “blend”) with different amino acid release profiles will prolong amino acid levels in the blood leading to increased muscle growth during resistance exercise-training (RET) as compared to a commonly used single protein source. I tested this hypothesis in the acute and chronic response to exercise and protein ingestion via two separate randomized double-blinded clinical trials. In the first clinical trial 20 young adults were randomly selected to ingest either the Blend or Whey protein 1 hour following high intensity resistance exercise. By combining a stable isotopic infusion with blood and muscle biopsy sampling I traced the acute post-exercise muscle protein synthesis response. In the second clinical trial I randomized ~60 young men into 3 supplement groups (Blend,Whey,Placebo) to undergo 12 weeks of RET. Outcomes of muscle mass and strength were measured pre/post 12 weeks of RET to determine efficacy and potential treatment differences in gains in muscle size and/or strength. To gain insight into potential mechanisms for these adaptations I assessed muscle protein expression, composition and RNA concentration.
I found that post-exercise protein blend supplementation was effective in stimulating post-exercise muscle growth following a bout of high intensity resistance exercise. This finding indicated that protein blend supplementation has a high potential to enhance muscle growth during resistance exercise training. I examined this further after chronic resistance exercise training and found that protein supplementation enhanced whole body lean mass gain, however this effect was not found in the leg, specifically, vastus lateralis muscle myofibers, indicating that this enhancement occurred in other areas, such as the upper body.