Carbohydrate-rich meals with sucrose for complete muscle and liver glycogen recovery within 12 hours after intense exercise

Glycogen is another word for sugar storage within the human body. Hence, sugars
are stored within the muscles and liver in the form of glycogen. During
exhaustive exercise, the body will use these stored sugars to deliver energy to
enable exercise performance. As a result, these sugar stores will be empty
after prolonged moderate- to high-intensity exercise. By ingesting sufficient
carbohydrates after exercise, these stores can be replenished again in both the
muscle as well as the liver.
We have recently demonstrated that with sucrose (table sugar) ingestion, the
recovery of these sugar stores in the liver can be doubled compared with
glucose ingestion.

Given that (elite) athletes often need to recover fast after exercise because
they need to optimally perform several days in a row (think about the Tour de
France, for example), it is important to accelerate the recovery of these sugar
stores (glycogen) within the body. Therefore, we want to investigate whether
the ingestion of large amounts of carbohydrates (mainly in the form of sucrose)
can fully replenish liver and muscle glycogen stores within 12 hours.

The goal of this study is to assess the recovery of muscle and liver glycogen
stores (by ingesting carbohydrates) within 12 hours after exhaustive exercise.

Randomized cross-over design.

The group of males will receive either nothing (only water/thee) or 10g/kg body
mass of carbohydrates during 12 hours of recovery of exhaustive endurance
exercise. The carbohydrate-rich meals will contain primarily sucrose.
During 1 test day the participants will receive a carbohydrate-rich breakfast
to determine (maximal) liver and muscle glycogen levels in rest. This is
necessary to assess whether full recovery of liver and muscle glycogen can
occur within 12 hours.

The burden and risks associated with participation are low. Participants will
come to the university four times: 1 screening (2 hours), 2 experimental trials
(each 17 hours) and 1 experimental trial (6 hours). During the screening visit,
we will perform a DEXA and determine their VO2max with a cycling test. For 2
days prior to the experimental trials, participants will be asked to keep their
diets as consistent as possible and to refrain from consuming alcohol or
performing any type of intense physical exercise. We will ask the participants
to fill out a medical questionnaire and record their food intake and physical
activity for the last 2 days prior to the experimental trials. For the
experimental trial, participants will be fasted and will need to refrain from
eating or drinking (except for water) from 22h00 the evening before. During 2
experimental trials, participants will complete an exercise session,
additionally participants will receive either nothing (only water/tea) or large
amounts of a carbohydrate-rich diet (primarily containing sucrose). During 1
experimental trial a carbohydrate-rich breakfast will be provided. The
researchers involved will collect muscle and blood samples en perform MRI
procedures (10x in total). For blood collection, insertion of the catheters is
comparable to a blood draw and could result in a small hematoma. We will take
52 blood samples (8 mL) during the experimental trial. The total amount of
blood drawn (416 mL) is less than the amount of a blood donation (500 mL) and
will be completely restored in approximately 1 month. We will collect in total
8 muscle biopsies from the vastus lateralis during two experimental trials.
Muscle biopsies will be taken under local anaesthesia by an experienced
physician, but may cause some minor discomfort up to 24 h after completion. The
discomfort is comparable to muscle soreness or the pain one has after bumping
into a table. There is no direct benefit for the participants except for their
contribution to the scientific knowledge and this will provide the basis for
novel nutritional interventions to accelerate post-exercise recovery for elite
and recreational athletes, which will be obtained from this study and used in
the future.