Effect of Glycogen Replenishment on Time Trial Performance Following a Glycogen Lowering Exercise

Western University, Canada

Status: Unknown

Conditions: Carbohydrate Metabolism

Treatments: Behavioral: 20 km time trial performance; Behavioral: Glycogen lowering exercise

Study type: Interventional

Funder types: Other

Identifiers

NCT03682861

112747

Details and patient eligibility

About

Fifteen endurance-trained male/female will be randomly assigned to do four exercise and nutrition trials involving ingestion of four different concentrations of sweet corn derived starch (food component) in water (0, 1, 1.5 and 2 g. kg-1. h-1). Each trial will be separated by at least one week. During these four experimental trials athletes will be subjected to a glycogen-lowering cycling exercise protocol followed by a 4-h post-exercise recovery period (2h feeding then 2 hours of rest). At the end of 4-h period they will do a 20 kilometre time trial test on a stationary bike in a laboratory condition to measure the effect of different glycogen repletion rates on exercise performance.

Full description

Post-exercise glycogen synthesis rate is an important factor in determining the time needed to recover. Glycogen synthesis is affected not only by the extent of glycogen depletion but also in a more direct manner by the type, duration, and intensity of the preceding exercise because these will differentially influence the acute enzymatic changes as well as recovery from the acute changes that are induced by strenuous exercise. To optimize glycogen synthesis rates, adequate amounts of carbohydrate should be ingested. It has been suggested initially that a carbohydrate intake of 0.35 g·kg body wt-1 ·h-1 , provided at 2-h intervals, maximized muscle glycogen synthesis. Others observed no differences in glycogen storage rates after subjects ingested 0.75 or 1.5 g carbohydrate·kg-1 · h-1 provided at 2-h intervals. In a follow-up study, it was reported that an intake of >0.5 g·kg-1 · h-1 is necessary to maximize post-exercise glycogen synthesis if supplements are administered at 2-h intervals. Higher glycogen synthesis rates have been reported in studies in which carbohydrates were ingested more frequently and at higher ingestion rates than in previous studies. Other efforts to increase glycogen synthesis rates by changing the form of administration (ie, as a solution, as a solid, or intravenously) have been unsuccessful. While the above range of intake rates has been suggested to maximize muscle glycogen resynthesis post-exercise, the required dosage with sweet corn derived high glycemic starch and its effect on a subsequent time trial exercise is currently unknown. So, investigators objective in this experiment is to find out optimal sweet corn derived recovery ingestion dose by using a glycogen lowering exercise protocol, followed by glycogen repletion via ingestion and a subsequent 20 km time trial cycling performance.

Enrollment: 15 estimated patients

Sex: All

Ages: 18 to 40 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• are a healthy male or female endurance athlete of 18- 40 years of age
• have ≥2 y endurance training experience; training for ˃1 h/day

Exclusion criteria

• Have symptoms or take medication for respiratory disease
• Have symptoms or take medication for cardiovascular disease
• Have symptoms or take medication for metabolic disease
• Have symptoms or take mediation for neuromuscular disease
• Use heart rate or blood pressure medications
• Use any medications with side effects of dizziness, lack of motor control, or slowed reaction time
• Have any cardiovascular or neuromuscular limitations to exercise
• Are pregnant or find out that you are pregnant during experiment

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Single Group Assignment

Masking: Single Blind

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15 participants in 2 patient groups, including a placebo group

Placebo

Placebo Comparator group

Description:

Placebo flavored drink similar to treatments but with no energy will be ingested post glycogen lowering exercise, followed by a 20 km time trial intervention

Treatment:

Behavioral: Glycogen lowering exercise

Behavioral: 20 km time trial performance

Carbohydrate drinks

Experimental group

Description:

Sweet corn derived starch mixed in water at three different concentrations (6%, 12% and 18%) will be ingested post glycogen lowering exercise, followed by a 20 km time trial intervention

Treatment:

Behavioral: Glycogen lowering exercise

Behavioral: 20 km time trial performance