NCT03682861

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

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 15 (estimated)
• Sponsor: Western University, Canada · Academic / Other
• Sex: All
• Age: 18 Years – 40 Years
• Healthy volunteers: Accepted

Summary

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.

Detailed 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.

Conditions

• Carbohydrate Metabolism

Interventions

Type	Name	Description
BEHAVIORAL	20 km time trial performance	20 km time trial cycling test will be conducted to measure the effect of different drinks on time
BEHAVIORAL	Glycogen lowering exercise	Glycogen will be lowered using a 10-min warm-up period at a workload of 50% max wattage power output (Wmax). Thereafter, participants will be instructed to cycle 2-min block periods at alternating workloads of 90% and 50% of Wmax, respectively. This will be continued until the participants are no longer able to complete the 2 min at 90% Wmax. That moment will be defined as the time at which the individual is unable to maintain cycling speed at 60 revolutions/min. At that moment the high-intensity block will be reduced to 80% Wmax. Again, athletes will cycle until they are unable to complete a 2-min block at 80% Wmax, after which the high-intensity block will be reduced to 70% Wmax. Finally, participants will be allowed to stop when pedalling speed could not be maintained at 70% Wmax.

Timeline

• Start date: 2018-09-30
• Primary completion: 2019-09-30
• Completion: 2019-09-30
• First posted: 2018-09-25
• Last updated: 2018-12-05

Locations

1 site across 1 country: Canada