Scientists from Australia have confirmed that whey protein isolate is far superior to casein for muscle growth.
In a double-blind, controlled study, two groups of drug-free bodybuilders took part in a 10-week training programme. One group supplemented their diet with whey isolate, the other group used an equal amount of a standard casein supplement (found commonly in many supplements).
The study, presented at the 2002 American College of Sports Medicine’s annual conference, shows that subjects using whey gained an average of 11 pounds of pure muscle in 10 weeks. Those using casein also gained muscle, but the results were less dramatic (1.8 pounds).
Here’s more information about how the study was done.
Abstract #1688
THE EFFECT OF WHEY ISOLATE AND RESISTANCE TRAINING ON STRENGTH, BODY COMPOSITION AND PLASMA GLUTAMINE
P.J. Cribb, A.D. Williams, A. Hayes, M.F. Carey
Center for Rehabilitation in Exercise and Sport Science, Victoria University of Technology, Australia
PURPOSE:
This study examined the effects of these two supplements on strength, body composition and plasma glutamine levels during a 10-week intense resistance training program.
METHODS:
In a randomized, double-blind protocol thirteen resistance-trained males (mean SD age:25.5 6.68yr; height:179.67 7.94cm; weight:83.97 4.98kg.) supplemented their normal diet with either a 100% whey isolate or casein protein supplement (1.5gms/kg body wt/day) for 12 weeks. To ensure normal eating patterns were maintained, written three-day food recordings were completed by the bodybuilders throughout the study. Compliance to the supplement intake and nutrition recordings was 100%. Strength was assessed by 1-RM in the barbell bench press, squat and lat-pull down. Body composition was assed by DEXA QDR 4500. Plasma glutamine levels were determined by the enzymatic method with spectroscopic detection. All assessments occurred in the week before (week 1) and the week after training (week 12).
RESULTS:
The whey isolate group achieved a significantly greater gain (P < 0.01) in lean mass than the casein group (4.99 - 0.25 vs. 0.81 - 0.43 kg for whey and casein groups, respectively). While both groups significantly increased (P < 0.05) strength in the three exercises assessed, the whey isolate group made greater strength increases (P < 0.05) in all three exercises compared to the group supplementing with casein. The whey isolate group also showed a significantly greater (P < 0.05) change in fat mass (-1.46 - 0.52) than the casein group (+0.19 0.27 kg). Plasma glutamine levels, pre- and post-training, did not change in either group.
CONCLUSION:
The major finding of this study was that a 100% whey isolate protein supplement was more effective at increasing muscle mass and strength and decreasing fat mass than a casein protein supplement in resistance trained athletes. Both types of protein appear to prevent a decline in plasma glutamine levels that have previously been reported with intense exercise training
Reference
Cribb, P. J., Williams, A. D., Hayes, A., & Carey, M. F. (2002) The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Medicine and Science in Sports and Exercise, 34, S1688
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