If sufficient amounts of carbohydrates are consumed for a long enough period of time,
glycogen levels can reach greater than normal levels, a process called glycogen
supercompensation. The process of glycogen depletion and supercompensation has been used for
years by endurance athletes to improve performance (2). Only recently has it been applied to
bodybuilders and other strength athletes. The carb-load can be classified by three distinct
variables: duration and amount, type, and timing of carbohydrate intake. Each is discussed in
detail below. Other factors which can affect the carb-load are also discussed in this chapter.
Duration and amount of the carb-load
The rate limiting step in glycogen resynthesis appears to be activity of the enzymes
involved in glycogen synthesis (1). Regardless of carbohydrate intake, there is a maximal
amount of glycogen which can be synthesized in a given amount of time, meaning that
consuming all the necessary carbohydrates in a 4 hour time span, with the goal of returning to
ketogenic eating that much sooner, will not work. Only when the proper amount of
carbohydrates is consumed over a sufficient period of time, can glycogen compensation and/or
supercompensation occur.
Following exhaustive exercise and full glycogen depletion, glycogen can be resynthesized to
100% of normal levels (roughly 100-110 mmol/kg) within 24 hours as long as sufficient amounts
of carbohydrate are consumed (1,3). Assuming full depletion of the involved muscles, the amount
of carbohydrate needed during this time period is 8-10 grams of carbohydrate per kilogram of lean
body mass (LBM).
With 36 hours of carb-loading, roughly 150% compensation can occur, reaching levels of
150-160 mmol/kg of muscle glycogen. To achieve greater levels of muscle glycogen (175 mmol/kg
or more) generally requires 3-4 days of high carbohydrate eating following exhaustive exercise (2).
The first 6 hours after training appear to be the most critical as enzyme activity and
resynthesis rates are the highest, around 12 mmol/kg/hour (4). Following weight training, with a
carbohydrate intake of 1.5 grams carbohydrate/kg LBM taken immediately after training and
again 2 hours later, a total of 44 mmol/kg can be resynthesized (17).
Over the the first 24 hours, the average rate of glycogen resynthesis ranges from 5-12
mmol/kg/hour depending on the type of exercise performed (5). In general, aerobic exercise shows
the lowest rate of glycogen resynthesis (2-8 mmol/kg/hour), weight training the second highest
(1.3-11 mmol/kg/hour), and interval training the highest (15 to 33.6 mmol/kg/hour) (5,6). The
reason that glycogen resynthesis is lower after weight training than after interval training may
be related to the amount of lactic acid generated as well as the muscle damage that typically
occurs during weight training (6).
At an average rate of 5 mmol/kg /hour, approximately 120 mmol/kg of glycogen can be
synthesized over 24 hours. This can be achieved by the consumption of 50 grams or more of
carbohydrate every 2 hours during the first 24 hours after training. Intake of greater than 50
grams of carbohydrate does not appear to increase the rate of glycogen synthesis.
Over 24 hours, at 50 grams every 2 hours, this yields 600 grams of carbohydrates total to
maximize glycogen resynthesis. These values are for a 154 pound (70 kilogram) person.