Can Caffeine or Protein Intake Influence Muscle Glycogen?
Research & Development
By Andrew Oye
By Chad Kerksick, PhD
Apr 26, 2012
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Are you a bodybuilder who resistance trains with high amounts of volume, little rest and high intensity? Are you are an endurance athlete who participates in prolonged bouts of exercise several times per week or participate in events that may last several hours or span more than one day?
If you answered "yes" to either of these scenarios the need for your body to rebuild glycogen is critically important. Limited amounts of glycogen can be stored in our muscles and when you train hard and long, these stores of glycogen can become depleted. Training with depleted muscle glycogen can negatively impact your training intensity leading to overall reductions in the quality of your training. Do this on a regular basis and your ability to achieve the greatest training outcomes may also be limited. Athletes know that the best way to recover your glycogen stores is to eat a diet that contains significant amounts of carbohydrate. Adding nutrients to a diet rich in carbohydrate is also commonly suggested to increase the amount of glycogen recovery that occurs. Caffeine and protein are two nutrients that are regularly used for this purpose, but research is limited. A recent study was completed to compare the impact of consuming carbohydrate with protein or caffeine on the muscle's ability to rebuild lost muscle glycogen (Beelen 2011). Each subject completed three testing sessions where each session was started with an intense exercise bout that depleted muscle glycogen levels. After the exercise bout was completed, the cyclists rested and recovered for six hours while consuming either a beverage that contained just carbohydrate, carbohydrate + protein or carbohydrate + caffeine. Blood and muscle samples were collected before and after each exercise session and insulin levels (one of the most powerful bodybuilding hormones) were increased to a greater extent after consuming the carbohydrate + protein combination. When rates of muscle glycogen synthesis were compared, no significant difference was found for the rate at which muscle glycogen was rebuilt. This outcome indicates that the speed at which glycogen is rebuilt after an exhaustive bout of cycling exercise is not influenced by adding protein or caffeine to carbohydrate.
In addition, analysis of the muscle samples supported this outcome and showed that glycogen levels inside type I or type II muscle fibers were not different between the three different combinations of nutrients. In summary, the results of this study suggest that adding a small dose of caffeine or protein may not provide any additional benefit when trying to stimulate as much muscle glycogen recovery as possible. This study and a number of others have now provided consistent evidence that the most adequate means of increasing muscle glycogen levels after exhaustive exercise is to consume carbohydrates in high amounts at regular intervals over the course of several hours after completion of the exercise bout. (A good source of high-glycemic carbs and protein in correct ratio can be found in advanced post-workout formulas such as MyoZene from BioQuest.) While adding caffeine or protein may have other benefits, adding them to a regular supply of carbohydrates will not lead to further increases in muscle glycogen levels.
1. Beelen, M, Kranenburg, JV, Senden, JM, Kuipers, H and Van Loon, LJ (2011). "Impact of caffeine and protein on post-exercise muscle glycogen synthesis." Medicine and science in sports and exercise.
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