2009 Studies & Research Blog

This was one of the first human studies to compare the effects of whey protein hydrolysate to the effects of casein protein when combined with a resistance training protocol and is quite relevant to any gym rat. Nineteen recreational bodybuilders in a double blind procedure were given either hydrolyzed whey or casein protein. They were instructed to take 1.5g/kg of either supplement over the course of the 10 weeks of resistance training.  They logged their nutritional intake prior to the nutritional/training program, as well as the first and final week to reduce the chances of skewing the results by altered energy intake.  Strengths tests consisted of 1RM for the barbell bench press, cable pull-down and squat. Body composition was measured using the DEXA, which is considered the gold standard at this point.

Results: After 10 weeks of training and supplementation, the hydrolyzed whey group showed a significant increase in lean body mass(LBM) when compared to the casein group. A significant decrease on body fat was additionally seen in the hydrolyzed whey group with none being seen in the casein group. For the strength tests, again the hydrolyzed whey showed significantly greater increases than the casein group.

Conclusion: This was a interesting study, that is very applicable to how exercise enthusiasts train and supplement with protein. Like most studies, it did have its limitations, with a relatively small number of subjects, nineteen. Another possible variable that could have skewed the results was the fact that the hydrolyzed whey group on a kg basis ingested 250 more calories a day. Additional possibilities for the outcome of this study:Whey is higher in the essential amino acids that are needed for protein synthesis than casein is. Hydrolyzed whey also causes faster and larger spikes of amino-acids in the blood. High concentrations of extracellular essential amino acids, has been shown to be a stimulator of protein synthesis as well. Again this is not a nail in the casein coffin by any means, but it is a good study that will hopefully lead to larger, better controlled studies in the future.

Cribb PJ, Williams AD, Carey MF, Hayes A. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int J Sport Nutr Exerc Metab. 2006 Oct;16(5):494-509.