Did I Just Waste a Workout? The Big Theory Behind Post-Workout Nutrition
A couple years ago I remember overhearing a group of high-school aged kids saying : “Dude, I forgot my protein at home. I just wasted this whole workout”. I honestly couldn’t help but let out a little chuckle (c’mon, this just seems absurd) but immediately after I remembered thinking, is that true?
Much like how children develop their personalities and characteristic traits from their parents; young lifters often absorb their knowledge from whom they deem to be credible, such as YouTube, Instagram and other social media platforms. In High School and college, I looked up to the seniors on my football teams because they were bigger, stronger, faster and I believed if it worked for them, it would work for me.. This mentality is very common and you can see why people grab on to others ideas and routines but, this can also sometimes lead to a long vicious cycle of misinformation.
If you go into any gym across the world you will most likely see someone gulping down a protein shake post-workout. It is very likely because they have been told about the “Anabolic Window”. This term refers to a theory that there is a short period of time after a workout where the body is primed for MPS (Muscle Protein Synthesis)where the body is fed an adequate amount of protein in conjunction with carbohydrates. Now this isn’t just BroScience, there have been numerous credible studies that have backed this claim . However, there have been just as many that disprove this theory as well .
The primary means of support behind the theory of the “Anabolic Window” are based on this fact: local glycogen levels are depleted post workout resulting in increased protein breakdown which in turn place the body in a catabolic state (when you are trying to build muscle this isn’t optimal). While this is true to a certain degree, here’s a brief breakdown to help explain why this isn’t the case for every person or every workout.
ATP (Adenosine Tri-Phosphate) is responsible for all muscle contractions and 80% of its production during a training session is derived from the breakdown of glucose. During a typical high volume bodybuilding workout most of the local glycogen stores of the muscle being trained will be depleted. (explain briefly what high volume workouts are). It is very important to replenish this depleted glycogen before the next training session for optimal performance and muscle building benefits for a competitive bodybuilder or an endurance/performance athlete. However, this may not be as important as we once thought for the average gym goer who isn’t training with such intensity and as frequently. The urgency of glycogen repletion greatly diminishes as the rest intervals between glycogen depleting events (i.e. a workout) exceeds 8 hours [3,4]. For the average person that only workouts once per day, Glycogen stores should be completely replenished before their next workout, given that proper nutrition and adequate nutrient intake throughout the day is in place.
Now that we know the average person can replenish the glycogen depleted during a workout with proper nutrition and hydration throughout the day after a workout. As for an increase in Muscle Protein Synthesis, Resistance Training by itself is shown to promote protein synthesis but this also influences the breakdown of proteins. . With this being said it is logical to assume that if protein is being broken down and the goal is to build muscle, why not supplement with more protein post-workout? The potential benefits of consuming protein soon after a workout does not have much evidence based support. A study conducted by Tipton et al.  found no significant difference in MPS between subject groups in which they consumed 20 grams of Whey protein post exercise. An additional study by Willoughby et al.  supplemented their subjects with 20 grams of protein 1 hour both pre and post workout. The result was that they did find an increase in total body mass, more specifically fat-free mass. Although it is unclear whether the findings of this study were because of nutrient timing or because of the addition of 40 grams of protein to their diet.
In conclusion, if you are an athlete planning to workout twice a day or if you have long and strenuous workouts planned on consecutive days you may want to replenish immediately after your workouts. If someone has trained fasted, they may also see potential benefits in supplementing with protein/carbohydrates post workout. To be clear, consuming a protein shake post workout certainly won’t hurt you, but lack of doing so is not likely to erase the workout's results! So, the next time you forget your protein shaker at home, take a deep breath, your muscles will be okay.
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B.S. Health Education
Personal Trainer @ The GYM Milford
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Aragon, A.A., Schoenfeld, B.J. Nutrient timing revisited: is there a post-exercise anabolic window?. J Int Soc Sports Nutr 10, 5 (2013). https://doi.org/10.1186/1550-2783-10-5