Early studies on protein synthesis and post-workout
Original studies suggested that because weight-training damages muscles, we need to consume protein immediately post-workout to help aid in muscle protein synthesis.
As such, 8 – 16 hour experiments were conducted by ultimately looking at how much protein was being synthesized in the body. This was done to figure out:
1) If these amino acids were elevated.
2) For how long the amino acids were elevated.
They also did studies based on two groups, in which one group consumed protein immediately post-workout and the other did not. A as result, they saw an efficient increase in growth size in the group who consumed protein immediately post-workout.
Why is this recommendation no longer true?
These studies do not accurately show whether or not someone’s lean mass is growing over time. Studies by Alan Aargon and Schoenfeld (2013, 2017) found that it isn’t actually timing that influenced muscle protein synthesis, but rather the overall amount of total protein that a person is consuming.
Consider a simple example: person A consumes a protein shake post-workout with about 25g of protein, while person B doesn’t. Both keep all other meals similar in amounts of macro nutrients. Hence, person A consumes 25g more protein than person B.
Many of the studies advocating post-workout protein neglected the fact that the total amount of protein may be larger in those groups who consumed protein immediately post-workout. A study by Mitchell CJ (2014) saw that those initial increases in muscle protein synthesis do not predict long-term growth.
My recommendation for an athlete
Schoenfeld (2017) stated that there is roughly 4-6 hours to consume protein post-workout. So, as long as that person did not train fasted. I recommend that athletes dieting down to prepare for a show, or training hard for a competition at least try and consume protein post-workout within at least 1-4 hours. This depends on whether that person can stomach eating the protein quickly. However, if that person is in a fasted state, then it may be more important to consume protein immediately. Following a workout due to the catabolic nature of training on the body.
My general recommendation for a person to stay in shape?
For the general person trying to just eat well and stay in shape, I would suggest consuming about 0.2g/lb of protein (according to studies) within 4-6 hours post-workout. However, overall total daily protein intake should be more of a concern than timing of that protein. Again, if that person is in a fasted state, I would recommend consuming protein immediately post-workout.
Aragon, A., & Schoenfeld, B. (2013). Nutrient Timing Revisited. Nutrient timing revisited: is there a post-exercise anabolic window?, 65-89. doi:10.1201/b16307-5
Atherton, P. J., & Smith, K. (2012). Muscle protein synthesis in response to nutrition and exercise. The Journal of Physiology, 590(Pt 5), 1049–1057. http://doi.org/10.1113/jphysiol.2011.225003
Kerksick, Chad, et al. “International Society of Sports Nutrition position stand: Nutrient timing.” Journal of the International Society of Sports Nutrition, vol. 5, no. 1, 2008, p. 17., doi:10.1186/1550-2783-5-17.
Lemon, P. W., Berardi, J. M., & Noreen, E. E. (2002). The Role of Protein and Amino Acid Supplements in the Athleteʼs Diet. Current Sports Medicine Reports, 1(4), 214-221. doi:10.1249/00149619-200208000-00005
Mitchell, C. J. (2014). Correction: Acute Post-Exercise Myofibrillar Protein Synthesis Is Not Correlated with Resistance Training-Induced Muscle Hypertrophy in Young Men. Acute Post-Exercise Myofibrillar Protein Synthesis Is Not Correlated with Resistance Training-Induced Muscle Hypertrophy in Young Men, 9(5). doi:10.1371/journal.pone.0098731
Phillips, S. M. (2014). A Brief Review of Critical Processes in Exercise-Induced Muscular Hypertrophy. Sports Medicine, 44(S1), 71-77. doi:10.1007/s40279-014-0152-3
Schoenfeld, B. J., Aragon, A., Wilborn, C., Urbina, S. L., Hayward, S. E., & Krieger, J. (2017). Pre- versus post-exercise protein intake has similar effects on muscular adaptations. PeerJ, 5. doi:10.7717/peerj.2825
Schoenfeld, B. J., Aragon, A. A., & Krieger, J. W. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Journal of the International Society of Sports Nutrition, 10, 53. http://doi.org/10.1186/1550-2783-10-53