Presented this week at Experimental Biology 2012 in San Diego, the clinical study found a blend of 25% isolated soy protein, 25% isolated whey protein and 50% casein boosted overall anabolic performance more than whey protein isolate alone.
"This study confirms that consuming a blend of proteins (soy, whey and casein) versus whey protein alone provides a prolonged delivery of amino acids to the muscles, making it optimal for consumption following resistance exercise," said senior researcher Dr Blake Rasmussen.
“Critical for sports nutrition consumers…”
The professor, who is also the interim chair of the Department of Nutrition & Metabolism at the University of Texas Medical Branch, added: "The results of this study are critical for sports nutrition consumers and regularly active individuals."
Anabolic performance in this context is measured by the capacity to build muscle after exercise.
The blend was first used in a pre-clinical study and presented at Experimental Biology 2011.
Fast, intermediate, slow
Dr Rasmussen and his team suggested the improved performance could be explained by the manner in which the different proteins were typically processed by the body.
Whey is processed the most quickly, casein the slowest, with soy in between, leading to amino acids being delivered later to muscles.
Greg Paul, global marketing director for sports nutrition and weight management at soy supplier, Solae, said the study highlighted muscle functioning misconceptions.
"Your muscles don't recover in 30 minutes,” said Paul. “It takes at least 24-48 hours for your muscles to recover after a resistance exercise."
"This study showed that protein blends can provide amino acid delivery for up to five hours, meaning if you consume a product or protein shake with these blends, the prolonged effect will deliver essential amino acids to feed your muscles until your next meal."
Suzane Leser, nutrition manager for Lifestyle Ingredients at UK supplier, Volac, added: "Slow and fast proteins have their particular benefits, so it's important that consumers should have the choice to find the product that works for them in specific situations, both in terms of performance and taste."
"The protein blend used consisted of 75% dairy proteins so it's great to see dairy again recognised as the leading proteins in post exercise muscle recovery."
The double-blind, randomised clinical trial featured 19 young adults before and after ingestion of 19g of protein from the blend or 17.5g of whey protein.
Experimental Biology 2011 congress, San Diego, California
April 29-May 2, 2012
‘Effect of Protein Blend vs. Whey Protein Ingestion on Muscle Protein Synthesis Following Resistance Exercise’
Author: B. Rasmussen et al