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Protein Timing Post-workout—How crucial is it?

  • January 16, 2019

You’re sitting in the gym change room after crushing your workout, you feel more sick than you are hungry (thanks leg day!), you still have to pick up groceries, and you still have to pick up your kids from soccer practice. In the midst of it all, you realize you’d rather put off eating for another hour rather than shovel down your post-workout meal. But at the back of mind, you’re wondering: will I be sacrificing my hard earned muscle and effort in the gym if I delay eating? 

A commonly held belief in the fitness industry is that consuming protein immediately post-workout, or within 30-60 minutes, is required for maximum muscle growth. This has been dubbed the “anabolic window”, and many believe that any protein consumed after this hour threshold is no longer used effectively. 

Previous studies looking at the long-term effects of protein timing on muscle growth and strength after a resistance workout did find some positive effects after the immediate consumption of protein. However, it should be noted that these studies were performed on untrained individuals and did not account for participants’ total daily protein intake(an important factor when considering muscle growth). This is a big study limitation because it means that some people may not have been eating enough protein for their body needs to begin with, so anyincrease in protein and resistance training would trigger muscle growth. This resulted in large variations in protein intake between individuals making it very difficult to compare the true effects of post-workout nutrition timing. 

It was not until recently that researchers compared the post-workout protein timing of individuals consuming the same amounts of protein at a level sufficient to support training. These studies suggestedthattotal daily protein intake, rather than the timing of protein, was the stronger predictor of muscle growth.In other words, there were no differences in muscle growth or strength between those consuming their protein immediately following the workout or for those consuming their protein more than 1 hour following the workout. 

Meal and protein timing is also highly dependent on the characteristics of your last meal, including: when your last meal was consumed, what, and how much you ate. As such, researchers suggest a 4-6 hour window(rather than a 30-60 minute window) of opportunity. 

So, what does this mean?For example, if you are training in the morning fasted, maybe try to consume your protein rich meal within 1-hour post-workout in order to provide a fresh supply of amino acids to refuel and rebuild muscle given that you have not eaten since the evening before. But if you were to eat a well-balanced meal 2 hours prior to training, waiting an additional 2 hours until your next meal may not be as detrimental to muscle growth as you may think. This is because there will still be circulating amino acids in your blood. In fact, weight training in itself has been shown to prime the muscles for growth for as long as up to 48 hours after a resistance training session. 

Based on a review of these studies, and until further studies can prove otherwise, it appears that protein timing before or after your resistance training workout is only secondary to total protein intake when trying to maximize muscle growth. The most important factor is that you are consuming an adequate amount of total protein dispersed throughout the day. Therefore, consuming protein as soon as you canmay be the better recommendation. Given the mixed scientific evidence and due to the fact that individual needs vary, there is no need to overstress about not being able to shovel down your post-workout meal in the gym change room. 

References

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, 53-53. doi:10.1186/1550-2783-10-53

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, 54-54. doi:10.1186/1550-2783-9-54

Author: Kelly Chen