The carbohydrate (anabolic) window is the half hour following a sports activity, during which it is believed that it is necessary to eat food rich in proteins or carbohydrates for the most effective gain of muscle mass. We checked whether this is supported by scientific evidence.
They write about the carbohydrate window publications for marathon runners, sites about running and in general fitness, sports portals, sites sporting goods retailers. It is discussed by users and users on forums women's and specialized magazines about skiing. In a number of publications, for example in “Komsomolskaya Pravda" and on the website "Pravda.ru“, it is argued that not everyone needs to “close” this window, but only those who play sports professionally.
Carbohydrate window, which is talked about in the context of strength training and sports nutrition, is a conditional period after physical training when the body is most receptive to the absorption of nutrients, especially proteins and carbohydrates. It is believed that at this time, the energy from the foods eaten is primarily used for the restoration and growth of muscle tissue, rather than for the accumulation of fat mass.
The essence ideas The anabolic window is that after intense physical activity, muscles deplete glycogen reserves, the main source of energy. During this conditional period, increased glycogen synthesis occurs, and for accelerated recovery, food rich in carbohydrates and proteins is required. The mechanism of action is as follows: the activity of glycogen synthesis enzymes and insulin sensitivity of muscles is enhanced, and this contributes to the effective delivery of glucose and amino acids to muscle cells. Thus, consuming carbohydrates and protein after exercise should help not only restore energy reserves, but also increase muscle mass, while reducing fat accumulation.
Many specialists in the field of sports medicine and physiology have studied metabolism and recovery of the body after exercise. The key was probably Job John Evey and Robert Portman's "Nutrition Time: The Future of Sports Nutrition", published in 2004. The authors identified three phases of the nutritional system in time and described the effect of various nutrients on the body during a certain period.
In this theory, the first stage is the energy phase, which begins in 10 minutes. before training and lasts throughout the exercise. At this time, the muscles are actively working and consuming energy. The second stage is the anabolic phase, also known as the anabolic window, or the protein-carbohydrate window. It, according to the authors, lasts about 45 minutes. after finishing the workout (and not 30, as most modern sources write). Eating the right foods during this phase, the study found, can double or triple protein synthesis. Finally, the last stage is the growth phase, which lasts 18–20 hours, during which muscle strengthening occurs. Later, other specialists, for example from the University of Regina (Canada), claimed: “The timing of nutrient intake may be more important than absolute daily intake.”
In 2013, the concept of the carbohydrate window subjected criticized by two American specialists: Alan Albert Aragon from the University of California and Brad John Schoenfeld from Lehman College (New York). The authors studied works devoted to replenishing glycogen stores, slowing down breakdown and accelerating protein synthesis. After analyzing data from these works, scientists came to the conclusion that the concept of the anabolic window is not universal. Firstly, if the last meal was one to two hours before training, then the energy received is quite enough for recovery and there is no need to eat after exercise. Second, immediate protein replenishment is critical for only two workouts per day, less than eight hours apart. That is, “closing” the carbohydrate window will benefit professional athletes rather than ordinary fitness club visitors. With one workout per day, the urgency of replenishing glycogen stores is not so important, the study authors believe, the optimal time to eat is the next 24 hours. In addition to athletes, the greatest benefit from the urgent “closing” of the protein-carbohydrate window was received by older people (over 70 years old) and those who were not accustomed to sports activities, that is, beginners.
Schonfeld and colleagues also spent meta-analysis of 20 randomized controlled trials involving 478 subjects. They initially noted that timely protein intake had an effect on muscle hypertrophy, but not on strength. However, when taking into account variables such as total daily protein intake, training frequency and exercise intensity, no significant differences were found between the groups. The authors concluded that the total amount of protein consumed is much more important than the timing of meals.
In 2020, Brazilian scientists shared results of a randomized clinical trial. 34 postmenopausal women followed the same morning strength training program for eight weeks. One group received 30 grams of whey protein immediately after training, followed by carbohydrates in the afternoon. The second received carbohydrates after training, and protein in the afternoon. Both groups increased muscle mass, strength, and functional performance, but there were no significant differences between them. The authors concluded that the timing of protein intake did not influence gains in muscle mass and strength in this group of subjects.
2007 study compared the effect of protein intake before and after exercise using a group of healthy young volunteers who were not professional athletes. Scientists did not find any difference - therefore, no benefits were found from “closing” the anabolic window. Similar in design experiment The 2017 study also found no difference between the group that ate before exercise and those who ate protein and carbohydrates afterward. However, all studies noted that there is no reason to consider the practice of eating after exercise to be in any way harmful.
Thus, you should not “close” the carbohydrate window and expect a radical increase in the effect of training. To restore the body after training, adequate daily intake of proteins and carbohydrates is paramount. It's likely that only older adults and professional athletes who exercise at least twice a day will benefit significantly from immediately eating protein and carbohydrates; others don't need to drink protein shakes or eat high-carbohydrate foods after the gym.
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