Sci MX GRS5 contains optimum quantities of both. For the periods in between training sessions meal times & during sleep muscles continue to repair themselves & this is when gradually absorbed proteins are best. So in addition to whey protein GRS5 also contains gradually released proteins from milk egg white & soy which together with work in synergy with a complex enzyme package called Opti Zyme which increases the uptake of BCAAs branch chained amino acids & free form amino ac