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

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.

Study Overview

• Status: Unknown
• Conditions: Carbohydrate Metabolism
• Intervention / Treatment: Behavioral: Glycogen lowering exercise; Behavioral: 20 km time trial 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.

• Study Type: Interventional
• Enrollment (Anticipated): 15
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Arash Bandegan, PhD; Phone Number: 88139 519 6612111; Email: abandeg@uwo.ca

Study Locations

• Canada
  • Ontario
    • London, Ontario, Canada, N6A 3K7
      • Recruiting
      • Exercise Nutrition Laboratory (Western University)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo; 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	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.; Behavioral: 20 km time trial performance; 20 km time trial cycling test will be conducted to measure the effect of different drinks on time
Experimental: Carbohydrate drinks; 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	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.; Behavioral: 20 km time trial performance; 20 km time trial cycling test will be conducted to measure the effect of different drinks on time

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
20 km time trial	participants will ride for 20 km on a stationary bike and time to finish will be measured	40 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
VO2	VO2 will be measured using a metabolic cart	2 hours
Blood glucose	glucose will be measured using glucometer	2 hours
VCO2	VCO2 will be measured using a metabolic cart	2 hours
Serum insulin	Insulin will be measured using an immumoassay kit	2 hours
Blood lactate	blood lactate will be measured using lactate meter	2 hours

Collaborators and Investigators

• Sponsor: Western University, Canada

Publications and helpful links

General Publications

• 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.
• 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.

Study record dates

Study Major Dates

• Study Start (Actual): September 30, 2018
• Primary Completion (Anticipated): September 30, 2019
• Study Completion (Anticipated): September 30, 2019

Study Registration Dates

• First Submitted: September 21, 2018
• First Submitted That Met QC Criteria: September 21, 2018
• First Posted (Actual): September 25, 2018

Study Record Updates

• Last Update Posted (Actual): December 5, 2018
• Last Update Submitted That Met QC Criteria: December 3, 2018
• Last Verified: December 1, 2018

More Information

Terms related to this study

• Other Study ID Numbers: 112747

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No