After a hard workout, be sure to drink a liter of coffee with sugar!
It is known that the use of carbohydrates and caffeine before and during physical activity improves various athletic performance. Scientists at the Garvan Institute of Medical Research (Sydney), working under the guidance of Dr. John A. Hawley, have demonstrated for the first time that a combination of caffeine and carbohydrates helps restore the energy reserve of muscles after a heavy load.
The work involved 7 well-trained cyclists participating in endurance competitions. The study consisted of 4 stages. At first, the participants practiced on a bicycle ergometer until exhaustion, after which they ate a low-carb dinner. The purpose of this stage was to deplete muscle glycogen reserves before the second stage was held the next day.
Before the start of the second stage (the next morning), the participants did not eat anything. After repeated exhausting training on a bicycle ergometer, they drank a cocktail containing carbohydrates or a complex of carbohydrates and caffeine, and rested in the laboratory for 4 hours. During the rest period, the authors took several muscle tissue biopsies and a large number of blood samples from the participants in order to assess the amount of glycogen contained in the muscles and the concentration of glucose-regulating metabolites and hormones in the blood.
The entire two-day exercise cycle was repeated after 7-10 days. The only difference was that the participants who drank a carbohydrate cocktail for the first time, this time drank a complex of carbohydrates and caffeine, and vice versa.
The drinks had identical appearance, taste and smell and contained the same amount of carbohydrates. The experiment was conducted on the principle of a double-blind method under placebo control, so neither the researchers nor the participants themselves knew which scheme each of them followed.
As a result of processing the results, the following conclusions were made:
– an hour after the workout, the level to which muscle glycogen was restored did not depend on the nature of the cocktail;
– four hours after the workout, participants who drank a cocktail with caffeine had a 66% higher level of muscle glycogen than those who were limited to carbohydrates;
– during the 4-hour recovery period, the caffeinated cocktail caused an increase in blood glucose, insulin, as well as several signaling proteins involved in the transport of glucose into muscle tissue to higher values than the carbohydrate cocktail;
It is not yet clear how caffeine contributes to the flow of glucose into muscle tissue. Apparently, one of the mechanisms is an increase in the levels of glucose and insulin circulating in the blood. In addition, caffeine can increase the activity of a number of signaling enzymes, including calcium-dependent proteicanases and protein kinase B (or Akt), involved in glucose uptake by muscle tissue during and after exercise.
During the work, the scientists used high doses of caffeine, which allowed them to establish its role in accelerating the absorption of glucose by muscle tissue. However, caffeine potentially has negative side effects, such as sleep disturbances and nervous excitement, so the next stage of work is to evaluate the effectiveness of small doses of the stimulant.
Hawley emphasizes that people react differently to caffeine consumption. So during the experiment, some of the participants noted problems with sleeping at night after drinking a cocktail with a large dose of caffeine (8 mg per kg of body weight is the equivalent of 5-6 cups of strong coffee), while others fell asleep well and did not experience negative side effects. Therefore, the authors recommend that athletes who are interested in the results obtained do not start taking caffeine during or shortly before the start of important tests, but find out the individual optimal doses in advance.