At bedtime, whey did the same job as casein
Thirty-six men took 45 g of casein, 45 g of whey or nothing after evening exercise. Both raised overnight muscle protein synthesis, with nothing to choose between them.
What the study found
Casein's bedtime advantage over whey did not show up
Thirty-six men took 45 g of casein, 45 g of whey, or nothing after evening endurance exercise. Both raised overnight synthesis of contractile muscle protein and, for the first time recorded, of mitochondrial protein. Between the two, nothing to choose, and whey was numerically ahead.
The caveat · Too few to rule out a modest gap
Twelve men per group is not enough to rule out a modest real difference between the two proteins; the comparisons came out at p = 0.69 and p = 0.44. One night, no training outcome, no women. The exercise was endurance rather than resistance training, so the mitochondrial finding does not carry straight over to lifting. Both proteins were measured against a non-caloric placebo, so part of what is captured is protein against nothing.