Protein Timing is not that Important
Protein consumption after an intense exercise session is commonly practiced by recreational exercisers and elite athletes. The theory of nutrient timing states that there is a limited period following an exercise session, an anabolic window, to maximize the rebuilding of tissue and restore energy stores in an enhanced manner to improve performance and body composition (Aragon & Schoenfeld, 2013). This is a widely followed theory in the exercise community, but there is conflicting evidence about the efficacy of protein consumption after an exercise session, and it is difficult to separate the effects of protein eaten post exercise and increased protein intake.
After a resistance exercise training session muscle protein synthesis increases 112% from a fasted state, while muscle breakdown rates increase 31% for a three-hour period. This anabolic window is theoretically the best time to consume protein. When protein is consumed after a workout session, it significantly enhances muscle protein synthesis rate and muscle protein accretion compared with when ingestion is delayed for longer period (Hoffman, 2007). However, upon further examination other factors are more important in aiding in recovery, improving hypertrophy, and performance.
There is a major flaw in the methodology of many early studies in protein timing research. Most early studies use subjects in a fasted state and many exercisers eat 1 or 2 hours prior to competition or training. Aragon and Schoenfeld (2013) explain that a small or moderate amount of protein consumed in a meal prior to training can sustain amino acid delivery during the post exercise period, which would make more protein ingestion redundant
Stark, Lukaszuk, Prawitz, and Salacinski (2012) in their review argue that type of amino acid and total amount of protein are more important than timing in maximizing hypertrophy and muscular strength. The amino acid leucine is of chief importance as it stimulates mTOR signaling pathway, which in turn stimulates muscle protein synthesis, and leucine is more effective than all the other branch chain amino acids at stimulating muscle protein synthesis. It is recommended that an athlete or weightlifter consume 3-4 g of leucine per day to enhance muscle protein synthesis and some good sources of leucine include beef, chicken, milk, eggs and cheese (Stark et al., 2012). Total protein recommendations vary by activity level, sport and training goal but it is encouraged for weight lifters to consume between 1.2g/kg-2g/kg of protein to maximize hypertrophy and strength.
In a meta-analysis by Schoenfeld, Aragon, and Krieger (2013), found that although eating protein after exercise can lead to increases in muscle strength and size, it is impossible to separate the effects of an increase in total protein intake. In the studies supporting protein timing, average protein intake was increased from 1.33 g/kg to 1.66g/kg. Increasing dietary protein is far more important than the timing of consumption when trying to maximize muscular adaptations.
For recovery, small protein ingestion mixed with carbohydrates may be helpful. Training recovery can be defined as the time period required between exercise bouts necessary to have an equal or greater performance from the prior one, and typically requires glycogen repletion (Bishop, Jones, & Woods, 2008). Intense, prolonged exercise uses glycogen and is associated with muscle fatigue. Consuming carbohydrates replenishes glycogen stores. When carbohydrate is combined with protein glycogen storage replenishment rate increases due to an increased insulin response (Ivey, 2004). The additional protein also limits muscle damage, therefore shortening recovery periods. Ivey (2004) recommends an ideal meal to enhance recovery following an exercise bout that significantly depletes glycogen to have a carbohydrate to protein ratio of 4:1 and this will reduce both the amount of carbohydrate and frequency of
supplementation required to maximize glycogen storage.
Nutrient timing for just protein seems to do be ineffective, when compared to just increasing total protein intake if the goal is to improve performace and hypertrophy. Ingesting protein post workout may enhance recovery, but only when eaten with carbohydrates, which helps to replenish glycogen stores lost in activity.
Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: Is there a post-exercise anabolic window? Journal
of the International Society of Sports Nutrition, 10(1), 1-11.
Bishop, P. A., Jones, E., & Woods, A. K. (2008). Recovery from training: A brief review. Journal of Strength and Conditioning Research, 22(3), 1015-1024.
Hoffman, J. R. (2007). Protein intake: Effect of timing. Strength and Conditioning Journal, 29(6), 26-34.
Ivey, J. L. (2004). Regulation of muscle glycogen repletion, muscle protein synthesis and repair following exercise. Journal of Sports Science & Medicine, 3(3), 131-138.
Schoenfeld, B., Aragon, 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(1), 53-88.
Stark, M., Lukaszuk, J., Prawitz, A., & Salacinski, A. (2012). Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight-training. Journal of the International Society of Sports Nutrition, 9(1), 54-62.