The previous blog Time to rethink the protein intake guidelines for athletes? reported on a recently published study from the research group of Professor Kevin Tipton. Kevin and I used to share offices next to each other at the University of Birmingham, so I used this paper as an excuse to ask him some questions about the paper. The stuff you don’t read in the paper…
AJ: First of all, congratulations with a great study that keep challenging our think just when we think we have figured it all out and have optimised our recommendations! Thank you for taking the time to answer some of my questions that remained after reading the paper.
Let’s start with an obvious question. If 40 grams is better than 20 grams, where is the limit? Could greater intake be even better?
KT: I’m not sure 50-60g would provide an even better response. the mean increase from 20g to 40g in our study was about 20%. So, for a 100% increase in intake, there is only a 20% increase in muscle protein synthesis. Also, I reckon it’s worth noting the individual responses. There is quite a bit of variability. So, for some individuals I bet a bit more protein may be beneficial. However, for the vast majority, I don’t believe it would.
AJ: There is a term called the muscle full effect, to describe that above a certain protein intake there are no further effect on muscle protein synthesis?
KT: Do you mean is there a muscle full effect at all or in our study? Actually, I reckon the answer to both is probably yes. There seems to be sufficient evidence for this concept. And the muscle full effect may help explain some of our results.
AJ: With the findings of your recent study in mind, what is your recommendation now for those athletes who want to gain as much muscle as possible as fast as possible?
KT: My recommendation to athletes that want to gain as much muscle as possible is that the optimal amount of protein to consume after exercise likely depends on the exercise performed. At least that is how we are interpreting our results. I should note that we did not test this directly and this comparison must be done. Until then, 20g is likely enough for most doing a split routine. However, I am not ready to discount the notion that many larger individuals may need more if they’re doing a split routine. That notion still has not been directly tested. Our results must be limited to a whole body routine. With a whole body routine, perhaps 40g is better.
AJ: If you need 3 grams of leucine to maximally stimulate protein synthesis as suggested by others and we can ingest a larger amount of protein, does this suggest that the quality of the protein becomes a less important factor? (It is easier to ingest essential amino acids including leucine when you simply eat more protein)?
KT: That is a great question. I really don’t know. We are assuming 3g of leucine is enough, but is that not based, at least in part, on previous results showing 20g of whey (containing roughly 3g leucine) was optimal. If 3g of leucine is ideal, then you’re probably right. Not enough work on other types of proteins has been done. As far as I know the only dose studies on proteins other than whey were done in Stu Phillips lab with soy. There was a greater response with 40g soy than 20g. However, that study was done with old folks and 40g whey was still better. So, clearly more studies in proteins other than whey need to be done.
AJ: Do the results of your study suggest that an athlete would be better off taking 40 grams of protein 5-6 times a day?
KT: I don’t think we can assume you need 40g 5-6 times per day. Our results apply only to the time immediately after exercise. we did not measure the responses to resting or to times later after exercise.
AJ: Is there a risk that increasing the protein intake will go at the cost of carbohydrate intake and could this ultimately affect recovery, performance and/or muscle growth?
KT: I’m sure there is a risk. I’ve always argued, and I know you do too, that athletes must balance the various demands. There is no one size fits all and it is nonsensical to just adopt one particular concept for all situations.
AJ: Taken together your studies seem to show greater protein synthetic rates with smaller muscle groups than larger muscle groups. Could this have implications for training? For example: train smaller muscle groups at a time?
KT: I had not really thought about it in those terms, but I reckon you’re right. Again, I’m not sure how practical it would be to train one muscle at a time given time demands and the necessity for other training. Perhaps split routines are a better suggestion. However, you’re right that that is a good question for future research. Our study seems to have developed a lot of those future questions. Certainly more than we’ve answered. But, is that not usually the case.
AJ: Thanks a lot Kevin, it was a pleasure tapping into your knowledge as always and please keep us posted about the great work that you and your colleagues do at the University of Stirling!