40g is more than 20g? You must be kidding me!
In one of those, at least in my mind, somewhat artificial single-leg exercise studies (Yang. 2012), in which the subjects perform a given number of single legged leg extensions (in the study at hand 3 sets @10RM) Yang et al. tried to elucidate the individual and combined effects of different doses (10g, 20g, 40g) of whey protein alone or in combination with the aforementioned unilateral leg exercise on myofibrillar protein synthesis (FSR) in thirty-seven non-frail older men (~age 71 +/- 4 years, BMI 26 kg/m²).
|Figure 1: Myofibrillar fractional protein synthesis in exercised and non-exercised leg of older men after 3 sets of leg extensions and the ingestion of either control beverage or 10g, 20g or 40g of whey protein (data adapted from Yang. 2012)|
[m]yofibrillar FSR in the non-exercised leg (fed only) was significantly increased with W20 and W40 compared with W0, with no significant difference observed between W20 and W40. [...] in the W20 and W40 exercised legs, myofibrillar FSR was statistically elevated above the W0 and W10 exercised legs. Furthermore, myofibrillar FSR for W40 was approximately 32 % greater than for W20 (p < 0.02).With the increase in FSR from 20g to 40g still being more than just marginally significant (+32%!), I would bet any money (well, sort of ;-) that we would not see significant ceiling effects with 60g of whey... maybe not even with 80g.
So what? Replace your 400ml shaker with a huge barrel to dissolve 1kg of whey post-workout?
The stark contrast to previous findings in younger individuals, as well as the overall somewhat ridicolous "exercise" protocol (I mean, 3 sets à 10 reps with one leg?) does yet raise the question how significant these results actually are. Yang et al. obviously believe that the age of the subjects may be the underlying reason for these discrepancies and state:
Given the evidence that the muscle protein synthetic response following resistance exercise is blunted in aged muscle, our data and that of others suggest that consuming a relatively high amount of dietary protein after resistance exercise may, potentially, increase rates of MPS in the elderly to the same extent as in young adults.And while this obviously could factor in, the trainee in me tells me that you can as well walk in the park to induce the same "protein synthetic response" as with 3 sets of 10 reps (just to make sure: this is not a scientifically validated fact ;-)
|Figure 2: Fractional protein synthesis in the Moore study, where a ceiling effect occurred and the Yang study, where it was absent (data based on Moore. 2008 and Yang. 2012)|
We still miss lots of pieces of the puzzle and search for them in the wrong places
Personally, I feel that these results confirm my gut feeling that the current focus on a) the 2h post-workout window after a single workout, b) the signaling over the substrate function of protein ingestion and c) the narrow-minded focus on whey or even leucine, in isolation, may have helped us to elucidate the important role of mTOR & co, but are of little to no practical relevance for the average gymrat. What, for example, happens if you co-ingest whey + casein? What is the influence of the whole foods meal, I have ~45min after my shake at the gym? What will the insulin spike (3x over baseline for the 40g whey group in the study at hand) do to my blood sugar levels (catecholamins, cortisol, glucagon, ...), if I have a "real" workout under my belt and my liver and muscle glycogen stores are depleted? These are only a few examples of questions, which are in my humble opinion of much greater importance, than the "ideal" amount of whey, let alone leucine, I am supposed to take after my workouts.