A few things happen during a workout requiring recovery. First, the body burns through a lot of its energy stores. Once the workout is over, the body needs to replenish these stores. Second, exercising damages muscle tissue. Rest and proper nutrient intake repair this damage leading to “gains.” The anabolic window is the period directly following the workout in which nutrient intake is possibly most beneficial.
Benefits of Properly Using the Anabolic Window
After you eat a meal, the body stores energy in a number of ways. Carbohydrates are stored for later use as glycogen in the liver and muscle tissue while glucose in stored in the blood. After a workout, the body burns through a large portion of its glycogen and glucose stores. A post workout meal which includes carbs replenishes these stores quicker.
Studies show the body replenishes glycogen stores much more efficiently with post workout carb intake. The body reduces glycogen resynthesis by 50% when post workout carb intake is delayed by just two hours. There is also evidence showing the addition of protein to a post workout meal enhances glycogen replenishment. Individuals who workout more than once daily would benefit the most from faster glycogen resynthesis.
Protein Breakdown and Protein Synthesis1
Muscle tissue is made out of protein. The body is constantly breaking down and synthesizing new protein. When we synthesize more than breakdown, we are in an anabolic state. When we are breaking down more than we are synthesizing, we are in a catabolic state. Read more: catabolic versus anabolic states. To improve performance, the goal is maximizing protein synthesis while limiting breakdown. Properly using the anabolic window accomplishes both.
Protein breakdown begins during exercise and peaks once a session is over. Properly using the anabolic window limits protein breakdown after a workout. Including protein in a post workout meal slows breakdown and ends it earlier.
Protein synthesis is the process of repairing damaged muscle. Research indicates post workout carbs increase protein synthesis. Protein intake in the form of free amino acids or whole protein also increases synthesis following a workout.
In one study, 10 participants consumed a post workout supplement with 10 grams of protein, 8g carbs, and 3g fat. Half of the subjects took the supplement immediately following the workout while the other half delayed their consumption. The group that took the supplement immediately saw a threefold increase in protein synthesis. The delayed group only saw a 12% increase.
Hypertrophy is making a muscle bigger. Properly timing post workout nutrient intake enhances muscle hypertrophy. Seven studies looked at the effects of immediate post workout nutrition on muscle size and lean body mass. The results were mixed. Of the seven studies, four found significant [positive] differences in muscle size and lean body mass in those who used immediate post workout meals compared to those who delayed their meals. Three studies found no differences between the two groups.
Post Workout Nutrition Recommendations
Utilizing a mix of protein and carbohydrates immediately following a workout seems to have positive effects. The general recommendation is to consume 0.18-0.23 grams of protein per pound of lean body mass following a workout. For example, an individual who weighs 170 pounds, with a body fat percentage of 10%, and lean body mass of 153 pounds (170 pounds – 10% body fat = 153 pounds) should consume 28-35 grams of protein following a workout1.
Carbohydrate intake following a workout is also important. The general recommendation depends on whether carbs are taken with or without protein. If carbohydrates are taken alone, consume 0.55-0.68 grams per pound of body weight. When taken with protein, post workout carb intake should be 0.36 grams per pound2.
Do not separate pre and post workout meals by more than 3-4 hours. Larger pre meals can act as both a pre and post workout meal. In cases of large pre workout calorie intake, the separation between pre and post workout meals can extend to 5-6 hours.
The Bottom Line – How important is the anabolic window?
Properly using the anabolic window provides important benefits including glycogen replenishment, minimizing protein breakdown, maximizing protein synthesis, and increasing muscle hypertrophy. Post workout consumption should include adequate carbohydrate and protein content to speed up the recovery process. The anabolic window isn’t a miracle concept. The research on its benefits is at best, mixed. Utilizing proper post workout nutrition is another piece of the overall puzzle.
- Aragon, A., & Schoenfeld, B. (2013). Nutrient Timing Revisited. Journal of the International Society of Sports Nutrition, 65-89. doi:10.1201/b16307-5
- Ivy, J. L. (2004). Regulation of Muscle Glycogen Repletion, Muscle Protein Synthesis and Repair Following Exercise. Journal of Sports Science and Medicine, 3(3), 131-138.