The results of a new study suggest that a protein blend (combination of soy, whey and casein) may be best to consume post-workout for building muscle.
Specifically, the blend of proteins in this study showed an increase in a person's 'anabolic window' (the amount of time it takes for building muscle to occur post exercise).
Dr Rasmussen, professor and interim chair of the department of nutrition & metabolism at the University of Texas Medical Branch and the senior author of this study, said: "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.
"The results of this study are critical for sports nutrition consumers and regularly active individuals."
The protein in the blend used in this study consisted of 25% isolated soy protein, 25% isolated whey protein and 50% casein.
Soy, whey and casein proteins are all absorbed at different rates during digestion. Whey protein is referred to as a 'fast' protein because it is rapidly absorbed whereas casein, a 'slow' protein, requires several hours to be digested.
The ability of soy protein to deliver amino acids is 'intermediate,' meaning concentrations in blood peak somewhat later compared to whey, but its digestion rate is much quicker than casein. Hence, the effect of all three of these proteins combined appears to provide the extended release of amino acid delivery to the muscles.