Effect of Glycemic Index on Physical Capacity in Runners

Poznan University of Life Sciences

Status: Completed

Conditions: Glycemic Index; Sport; Physical Capacity; Nutrition

Treatments: Other: Dietary Intervention: Low vs. moderate glycemic index

Study type: Interventional

Funder types: Other

Identifiers

NCT03062527

ULS00001

Details and patient eligibility

About

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.

Full 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.

Enrollment: 36 patients

Sex: All

Ages: 17 to 37 years old

Volunteers: Accepts Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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36 participants in 2 patient groups

Low Glycemic Index Diet

Experimental group

Description:

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.

Treatment:

Other: Dietary Intervention: Low vs. moderate glycemic index

Moderate Glycemic Index Diet

Experimental group

Description:

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.

Treatment:

Other: Dietary Intervention: Low vs. moderate glycemic index