Clinical trial NCT03682861: Effect of Glycogen Replenishment on Time Trial Performance Following a Glycogen Lowering Exercise
Official title: Effect of Glycogen Replenishment on Time Trial Performance Following a Glycogen Lowering Exercise
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Carbohydrate Metabolism
Lead sponsor: Western University, Canada
Sponsor class: OTHER
First posted: 2018-09-25
Enrollment: 15
Sex: ALL
Minimum age (years): 18
Maximum age (years): 40
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: SINGLE_GROUP
Intervention model description: It is a repeated measure design where each participant will undergo all four treatment in a randomized fashion to prevent any order effect. Treatments (recovery drinks) include a placebo which will be similar in taste and flavour to other treatments and three carbohydrate containing drinks mixed in water at different concentrations. Design of the study is composed of three main stages: 1) glycogen lowering exercise, 2) glycogen replenishment and rest and 3) performance based, timed cycling exercise. All participants will arrive fasted to the laboratory, performing an exercise protocol that lowers their glycogen levels, followed by ingestion of different drinks (every 30 min) during 2 hours of a 4 hour rest and finally performing a 20 km stationary bike test for the time to finish to evaluate the effect of recovery drinks ingested.
Primary purpose: OTHER

Brief 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.

Eligibility criteria: 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

Primary outcomes:
measure: 20 km time trial
timeFrame: 40 minutes
Secondary outcomes:
measure: VO2
timeFrame: 2 hours
measure: Blood glucose
timeFrame: 2 hours
measure: VCO2
timeFrame: 2 hours
measure: Serum insulin
timeFrame: 2 hours
measure: Blood lactate
timeFrame: 2 hours
Other outcomes:
Locations:
city: London
country: Canada
facility: Exercise Nutrition Laboratory (Western University)
state: Ontario
Study officials:
affiliation: Western University
name: Peter Lemon, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Ivy JL. Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med. 1998 Jun;19 Suppl 2:S142-5. doi: 10.1055/s-2007-971981.
citation: Upshaw AU, Wong TS, Bandegan A, Lemon PW. Cycling Time Trial Performance 4 Hours After Glycogen-Lowering Exercise Is Similarly Enhanced by Recovery Nondairy Chocolate Beverages Versus Chocolate Milk. Int J Sport Nutr Exerc Metab. 2016 Feb;26(1):65-70. doi: 10.1123/ijsnem.2015-0056. Epub 2015 Aug 27.