Pre-exercise Ingestion of a Low Glycaemic Index Rice-based Mixed Meal Increases Fat Oxidation and Endurance Running in a Hot-humid Environment

The objective of this research is to determine the influence of low and high glycemic index Malaysian pre-exercise mixed meals on endurance exercise performance in a hot-humid environment. Glycemic index (GI) is a method used to classify CHO-containing foods based on their influence on postprandial blood glucose when compared to the response on blood glucose after ingesting the same amount of CHO from a reference food (glucose or bread). Low GI (LGI) foods are digested and absorbed more slowly as compared to high GI (HGI) foods, resulting in a stable rise in blood glucose levels.

The participants were trained male endurance long-distance runners. On the day of experimental trials, they consumed pre-exercise rice-based mixed meal, either LGI or HGI 3 hours before endurance running exercise. After that, they ran for 45 minutes at constant running speed equivalent to 70% VO2peak, followed by 10km time-trial. The respiratory gases, blood measures, rectal and skin temperature were measured throughout the running test.

Study Overview

• Status: Completed
• Conditions: Healthy; Trained Athletes

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• healthy
• age 18-35 years old
• trained (peak oxygen consumption (V̇O2peak): ≥ 55 mL.kg-1.min-1)
• training volume (>150 min, ≥ three times per week)
• competing at the national level
• >2-year of running experience
• tier 2 (trained) or tier 3 (highly trained) runners (McKay et al. 2022)
• no allergies to any test foods

Exclusion Criteria:

• diagnosis of chronic diseases (i.e. diabetes mellitus, hypertension, cardiovascular disease)
• bone, muscle or joint impairments
• on medication
• currently smoking
• use of illicit drugs
• use of dietary supplements
• on any particular diet

Study Plan

How is the study designed?

Design Details

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to complete 10 km time-trial	The participant was clearly instructed to complete the 10 km time-trial as quickly as possible. The 10 km time-trial commenced with a 30-s rolling start to the participant's 70% V̇O2peak speed, after which the participant could freely adjust the speed. Throughout the 10 km time-trial, the prevailing running velocity and time-lapse were blinded to the participant, and only information on the distance covered at 1 km intervals was verbally provided to the participant.	Up to 1 hour

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fat and carbohydrate oxidation	A portable gas analyser (K5, COSMED, Italy) was used to measure the respiratory gas exchange. Prior to each experimental session, the device was calibrated according to the procedures outlined in the manufacturer's instructions. The mixing chamber measurements were performed for V̇O2, V̇CO2, and respiratory exchange ratio (RER) and were measured continuously throughout exercise trials. The average values for V̇O2 (L.min-1) and V̇CO2 (L.min-1) were calculated over the last 30-s of each 15-min interval during SS running and each 1 km of 10 km time-trial. Whole-body rates of CHO and fat oxidation (g.min-1) were calculated using intensity-dependent equations for moderate to high-intensity exercise (50 - 75% V̇O2max) that assume negligible protein contribution to energy expenditure (Jeukendrup and Wallis 2005): CHO oxidation (g.min-1): (4.210 x V̇CO2) - (2.962 x V̇O2) Fat oxidation (g.min-1): (1.695 x V̇O2) - (1.701 x V̇CO2)	Up to 2 hours
Capillary blood glucose	The capillary blood was sampled for blood glucose via a finger prick using a sterile, single-use lancet (Accu-Check Safe-T-Pro Plus; Roche Diagnostics) during fasting state (before meal consumption), postprandial period (at 15, 30, 60, 90, 120, 180-min intervals), steady-state running (at 10, 30, 45-min intervals), time-trial 10km running performance (at 5, 10km marks).	Up to 5 hours
Serum insulin	The venous blood was sampled for insulin using 22G IV catheter insertion (Surflo IV Catheter, Terumo Med Corporation, Eklton, MD., USA) during fasting state (before meal consumption), postprandial period (at 30, 90, 180-min intervals), steady-state running (at 10, 30, 45-min intervals), time-trial 10km running performance (at 10 km marks).	Up to 5 hours
Serum cortisol	The venous blood was sampled for cortisol using 22G IV catheter insertion (Surflo IV Catheter, Terumo Med Corporation, Eklton, MD., USA) during fasting state (before meal consumption), postprandial period (at 180-min interval), steady-state running (at 45-min interval), time-trial 10km running performance (at 10 km marks).	Up to 5 hours
Serum lactate	The venous blood was sampled for lactate using 22G IV catheter insertion (Surflo IV Catheter, Terumo Med Corporation, Eklton, MD., USA) at postprandial period (at 180-min interval), steady-state running (at 10, 45-min intervals), time-trial 10 km running performance (at 10 km marks).	Up to 2 hours
Heart rate	Heart rate was recorded using heart rate monitor (Garmin HRM-Run®; Olathe, KS, USA) throughout the running test.	Up to 2 hours
Thermoregulatory measure	Rectal temperature (Tre), and skin temperature (Tsk) were continuously measured throughout the running exercise. Tre was measured by self-inserting a disposable thermistor probe (YSI 400 series, Mallinckrodt Medical, Kansas City, Mo., USA) 12 cm beyond the anal sphincter. Tsk was assessed at four distinct sites (left shoulder, left chest, right mid-thigh, and right mid-shin) using iButton temperature sensors (Maxim Integrated Products,Sunnyvale, CA., USA).	Up to 2 hours

Collaborators and Investigators

• Sponsor: Universiti Sains Malaysia

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2022
• Primary Completion (Actual): January 30, 2023
• Study Completion (Actual): January 30, 2023

Study Registration Dates

• First Submitted: July 25, 2024
• First Submitted That Met QC Criteria: August 5, 2024
• First Posted (Actual): August 9, 2024

Study Record Updates

• Last Update Posted (Actual): August 9, 2024
• Last Update Submitted That Met QC Criteria: August 5, 2024
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: USM/JEPeM/19010083

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Private and confidential

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No