Protein shakes after working out? The Post-Workout Anabolic Window of Opportunity

The workout routine norm – warm-up, workout, and post-workout shake. Everyone who seems to know anything about working out always includes a high in protein recovery drink and they tell you to drink as soon as you are done working out and you HAVE to get it down within a strict time limit of 30 minutes. Are they right? Is your workout useless unless you follow this steadfast rule?

The Post-Workout Anabolic Window of Opportunity

When someone talks about ingesting 15-30 g of protein along with other nutrients within a specified time period of working out they are referring to the nutrient timing of protein or a post-workout anabolic window of opportunity. The idea is your muscles respond better to the uptake of nutrients closer to the end of a workout rather than eating during periods farther away from your workout. Early research on nutrient timing showed support for an anabolic window*. Subjects in studies showed increased muscle hypertrophy, or muscle gain when ingesting protein within a 30 minute period after workouts. Test groups who did not eat until 3 hours after their workout had fewer muscle gains than the other test groups.

So there you have it, cut and dry, you must take a post workout shake otherwise you might as well not even workout… not necessarily. Early research did not account for control factors such as overall nutrition, total daily intake of protein, and prior activity level of the subjects. More recent studies took these controls in mind and new findings suggest a much different picture of nutrient timing and the post-workout anabolic window of opportunity.

Nutrition Viewed Through a Long-Term Lens

New studies focusing on resistance trained men, meaning a population of subjects already in shape, showed no difference in muscle gain when given a pre-workout shake with 25 g protein compared to a post workout shake with the same amount of protein*. Because the men in the study were already trained, this potentially shows the older research did not take into account the effect of an anabolic window in the long-term. For the average person, this probably means as you get your body in better shape, ingesting protein right after you workout will not yield you better results than if you just eat healthily and get enough protein in during the day.

What the research says for now…

As of where the scientific sports science community stands right now, this seems to be the most supported stance.

Nutrient timing is important, but the supposed post-workout anabolic window of opportunity is not as small of a time period as previously thought. If a meal with the proper amount of protein, combined with the right amount of other macronutrients, is consumed within 3 or 4 hours after a workout, muscles will be able to intake those nutrients and build muscle*.

So, timing is important, but even more crucial to building muscle is the overall daily intake of protein. In fact, it is the most important. Current findings show a daily intake of 1.6 to 2.2 g per kilogram of body mass to be optimal for muscle growth. For example, a person weighing 150 pounds, or 68 kg should ingest 109-150g of protein per day to maximize their muscle gains*.

Ultimately, nutrition is important but can be tricky. New research is always coming out so it is good to stay in the loop. Physical therapists are often up to date on this information but nutrition isn’t in our scope of practice. So it is best to refer to a nutritionist or proper sports scientist if you really need to get your nutrition under control. But, if you are looking to get back in shape or are already in shape, there are many ways a physical therapist can optimize your training.

Stay safe, have big fitness gains, and be consistent! Happy training!

*Schoenfeld, B. J., & Aragon, A. A. (2018). Is There a Postworkout Anabolic Window of Opportunity for Nutrient Consumption? Clearing up Controversies. Journal of Orthopaedic & Sports Physical Therapy, 48(12), 911-914. doi:10.2519/jospt.2018.0615