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Related Experiment Video

Updated: Dec 18, 2025

Determining the Contribution of the Energy Systems During Exercise

Determining the Contribution of the Energy Systems During Exercise

Published on: March 20, 2012

Comparable Exogenous Carbohydrate Oxidation from Lactose or Sucrose during Exercise.

Oliver J Odell¹, Tim Podlogar, Gareth A Wallis

¹School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UNITED KINGDOM.

Medicine and Science in Sports and Exercise

|June 11, 2020

Summary

Lactose and sucrose provide similar fuel during exercise. Lactose ingestion during exercise increases fat burning and reduces carbohydrate utilization compared to sucrose.

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Area of Science:

Exercise Metabolism
Nutritional Biochemistry
Sports Science

Background:

Carbohydrate (CHO) ingestion enhances endurance performance.
The role of lactose as an exercise fuel source remains unclear.

Purpose of the Study:

To investigate the metabolic response to lactose ingestion during exercise.
Compare lactose utilization with sucrose and water as control.

Main Methods:

Eleven participants cycled at 50% Wmax for 150 minutes.
Ingested beverages containing lactose, sucrose, or water.
Measured substrate and exogenous CHO oxidation using indirect calorimetry and stable isotopes.
Analyzed plasma glucose, lactate, and nonesterified fatty acid concentrations.

Main Results:

Exogenous carbohydrate oxidation rates were similar for lactose and sucrose.
Lactose ingestion led to lower endogenous CHO oxidation compared to water and sucrose.
Fat oxidation was higher with lactose compared to sucrose.
Plasma glucose was elevated with both lactose and sucrose compared to water.

Conclusions:

Lactose and sucrose demonstrate comparable exogenous carbohydrate oxidation rates during moderate-intensity exercise.
Lactose ingestion promotes higher fat oxidation and lower endogenous carbohydrate utilization than sucrose.
Lactose is a viable fuel source during prolonged exercise.