Effect of Glycemic Index on Physical Capacity in Runners

Effects of Low and Versus Moderate Glycemic Index Diets on Physical Capacity and Body Composition in Endurance- Trained Runners

The purpose of the present study was to assess the influence of low vs moderate glycemic index of a 3-week diet on aerobic capacity, endurance performance and body mass and composition in endurance-trained athletes in a randomized, controlled crossover trial.

Study Overview

• Status: Completed
• Conditions: Glycemic Index; Nutrition; Sport; Physical Capacity
• Intervention / Treatment: Other: Dietary Intervention: Low vs. moderate glycemic index

Detailed Description

The effect of glycemic index of pre-exercise meal on endurance capacity and performance has been widely investigated. However, little is known about the adaptations to longer dietary interventions with different glycemic index and their influence on aerobic capacity and body composition in runners. Therefore, the purpose of this study was the assessment of the influence of low GI vs moderate GI of a 3-week diet on aerobic capacity, endurance performance and body mass and composition in endurance-trained athletes in a randomised, controlled crossover trial.

• Study Type: Interventional
• Enrollment (Actual): 36
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Poland
  • Wielkopolska
    • Poznan, Wielkopolska, Poland, 60-624
      • Poznan University of Life Sciences, ul.Wojska Polskiego 31

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 17 years to 37 years (Child, Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• written consent to participate,
• male and female,
• a current medical clearance to practice sports,
• training experience: at least 3 years,
• minimum of 4 workout sessions a week lasting at least 1.5-2 hours/day,
• age: 17 - 37 years.

Exclusion Criteria:

• current injury,
• any health-related contraindication,
• declared general feeling of being unwell,
• unwilling to follow the study protocol,
• smoking, illicit drug use, alcohol consumption greater than 1-2 drinks/week, dietary supplements use less than 3 weeks before the study,
• females- being pregnant or planning to become pregnant during the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Low Glycemic Index Diet; Group consuming low glycemic index diet. Calculated glycemic index of daily diet was lower than 40. Carbohydrate- containing foods included whole rye bread, pumpernickel bread, whole oats, wheat brans, brown rice, buckwheat, vegetables (besides corn, cooked carrots, potatoes and pumpkin) and fruit such as apples, pears, grapefruits, tangerines, prunes, dried apricots and unripe bananas. Interventions: The experimental procedure for each participant included a 3-week low glycemic index diet. Between the 3-week low and moderate glycemic index diets or a moderate and low glycemic index treatment, a 14-day washout period was introduced.	Other: Dietary Intervention: Low vs. moderate glycemic index
Experimental: Moderate Glycemic Index Diet; Group consuming moderate glycemic index diet. Calculated glycemic index of diet was higher than 60. Carbohydrate- containing foods included wheat bread, wheat rolls, potatoes, instant oats, cornflakes, white rice, millet, boiled carrots and fruit (ripe bananas, grapes, raisins, dates, cranberry, honey and high sugar jams) Interventions: The experimental procedure for each participant included a 3-week moderate glycemic index diet. Between the 3-week low and moderate glycemic index diets or a moderate and low glycemic index treatment, a 14-day washout period was introduced.	Other: Dietary Intervention: Low vs. moderate glycemic index

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in aerobic capacity following low glycemic index diet		Baseline and after 3 weeks
Changes in aerobic capacity following moderate glycemic index diet		Baseline and after 3 weeks
Changes in performance in 12-min running test following low glycemic index diet		Baseline and after 3 weeks
Changes in performance in 12-min running test following moderate glycemic index diet		Baseline and after 3 weeks
Changes in fat mass and fat free mass following low glycemic index diet	Fat mass (kg) and fat free mass (kg) analysis	Baseline and after 3 weeks
Changes in fat mass and fat free mass following moderate glycemic index diet	Fat mass (kg) and fat free mass (kg) analysis	Baseline and after 3 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Statistical evaluation of the significance of differences between the changes in aerobic capacity indices		1 year
Statistical evaluation of the significance of differences between the changes in performance in 12-min running test		1 year
Statistical evaluation of the significance of differences between the changes in fat mass and fat free mass	Fat mass (kg) and fat free mass (kg)	1 year

Collaborators and Investigators

• Sponsor: Poznan University of Life Sciences
• Investigators: Study Chair: Jan Jeszka, Professor, Department of Hygiene and Human Nutrition, Poznan University of Life Sciences, Poznan, Poland

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2015
• Primary Completion (Actual): February 6, 2015
• Study Completion (Actual): May 1, 2015

Study Registration Dates

• First Submitted: February 14, 2017
• First Submitted That Met QC Criteria: February 20, 2017
• First Posted (Actual): February 23, 2017

Study Record Updates

• Last Update Posted (Actual): February 23, 2017
• Last Update Submitted That Met QC Criteria: February 20, 2017
• Last Verified: February 1, 2017

More Information

Terms related to this study

• Keywords: Nutrition; Endurance; Running; Training support; Low Glycemic Index; Moderate Glycemic Index
• Other Study ID Numbers: ULS00001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided
• IPD Plan Description: Shared data will be exclusively related to the level recorded indicators (body composition, aerobic capacity, performance in 12-min running test), without personal data. Depending on the requirements of the journal, the data obtained will be attached to scientific publications, deposited in a public repository or provided by principal investigator when requested.

Drug and device information, study documents

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