Ingestion of Casein and Whey Proteins Result in Muscle Anabolism after Resistance Exercise.
Medicine & Science in Sports & Exercise. 36(12):2073-2081, December 2004.
TIPTON, KEVIN D.; ELLIOTT, TABATHA A.; CREE, MELANIE G.; WOLF, STEVEN E.; SANFORD, ARTHUR P.; WOLFE, ROBERT R.
Abstract:
Purpose: Determination of the anabolic response to exercise and nutrition is important for individuals who may benefit from increased muscle mass. Intake of free amino acids after resistance exercise stimulates net muscle protein synthesis. The response of muscle protein balance to intact protein ingestion after exercise has not been studied. This study was designed to examine the acute response of muscle protein balance to ingestion of two different intact proteins after resistance exercise.
Methods: Healthy volunteers were randomly assigned to one of three groups. Each group consumed one of three drinks: placebo (PL; N = 7), 20 g of casein (CS; N = 7), or whey proteins (WH; N = 9). Volunteers consumed the drink 1 h after the conclusion of a leg extension exercise bout. Leucine and phenylalanine concentrations were measured in femoral arteriovenous samples to determine balance across the leg.
Results: Arterial amino acid concentrations were elevated by protein ingestion, but the pattern of appearance was different for CS and WH. Net amino acid balance switched from negative to positive after ingestion of both proteins. Peak leucine net balance over time was greater for WH (347 +/- 50 nmol[middle dot]min-1[middle dot]100 mL-1 leg) than CS (133 +/- 45 nmol[middle dot]min-1[middle dot]100 mL-1 leg), but peak phenylalanine balance was similar for CS and WH. Ingestion of both CS and WH stimulated a significantly larger net phenylalanine uptake after resistance exercise, compared with the PL (PL -5 +/- 15 mg, CS 84 +/- 10 mg, WH 62 +/- 18 mg). Amino acid uptake relative to amount ingested was similar for both CS and WH (~10-15%).
Conclusions: Acute ingestion of both WH and CS after exercise resulted in similar increases in muscle protein net balance, resulting in net muscle protein synthesis despite different patterns of blood amino acid responses.
Interesting, thanks for posting. I wonder if, since each had different routes to protein synthesis, it would be best to have some of both. Too bad they didn't have a fourth test group for possible additive and interactive effects, and possibly a bigger sample.
assuming he meant quantity is more important than quality....
I agree, to a large extent. I think that if you get more protein than you need, the importance of protein quality diminishes. (By "quality" I mean nitrogen-retention measures, such as "Bioavailability." This is the common usage in advertising).
If you're carefully dieting, or esp. crash-dieting, protein quality becomes more important.
The comparison of whey protein vs. casein is not one of bioavailability, but speed of digestion. The common theory is that fast-digesting proteins, such as whey isolates, are 'better' for immediate post-workout feeds. The research Coach Hale posted makes that questionable -- at least under conditions such as those described in the article. As others point out, maybe a larger population, maybe doing other exercises that worked more muscle, maybe taking protein immediately after a workout as opposed to an hour, would make some difference. Then again, maybe speed of digestion is not the limiting factor in protein synthesis in muscle. Maybe it would be if the study subjects didn't eat a lot of protein apart from the supplemental protein in the study. A lot of maybes.
The basic 'general wisdom', -- in case it wasn't obvious -- is that casein is better as a 'night time' protein meal, or any other time there may be time between feedings, since it is slower digesting and in effect more like a time-release supplement.
Again, the study cited calls this into question, but is hardly anything like conclusive on this point.
I agree, the study doesn't test the right factors to make the statement given in the thread title.
Should be 'under very strict set of circumstances, one measure of protein uptake is the same for Whey and Casein' (though I guess that wouldn't fit ;-) )
assuming a a sufficient amount of non limiting protein (not limited in indisensable amino acid profile as it pertains to needs ) is consumed there is little differnece in net protein balance
another thing to keep in mind is absorption rates vary with mixed protein meals
blood aminos from whey spike in about an hour and dont return to baseline until about 4hrs, so most atheltes are eating every 3hrs anyway so abroprtion rates as they pertain to extracellular amino availability not an issue
i will be receving the full study in a couple of days , which will allow me to look more into it