Int J Sports Med 2003; 24(8): 603-608
DOI: 10.1055/s-2003-43265
© Georg Thieme Verlag Stuttgart · New York

Maximal Fat Oxidation During Exercise in Trained Men

J.  Achten1 , A.  E.  Jeukendrup1
  • 1School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
Further Information

Publication History

Accepted after revision: February 24, 2003

Publication Date:
04 November 2003 (online)


Fat oxidation increases from low to moderate exercise intensities and decreases from moderate to high exercise intensities. Recently, a protocol has been developed to determine the exercise intensity, which elicits maximal fat oxidation rates (Fatmax). The main aim of the present study was to establish the reliability of the estimation of Fatmax using this protocol (n = 10). An additional aim was to determine Fatmax in a large group of endurance-trained individuals (n = 55). For the assessment of reliability, subjects performed three graded exercise tests to exhaustion on a cycle ergometer. Tests were performed after an overnight fast and diet and exercise regime on the day before all tests were similar. Fifty-five male subjects performed the graded exercise test on one occasion. The typical error (root mean square error and CV) for Fatmax and Fatmin was 0.23 and 0.33 l O2 × min-1 and 9.6 and 9.4 % respectively. Maximal fat oxidation rates of 0.52 ± 0.15 g × min-1 were reached at 62.5 ± 9.8 % V·O2max, while Fatmin was located at 86.1 ± 6.8 % V·O2max. When the subjects were divided in two groups according to their V·O2max, the large spread in Fatmax and maximal fat oxidation rates remained present. The CV of the estimation of Fatmax and Fatmin is 9.0 - 9.5 %. In the present study the average intensity of maximal fat oxidation was located at 63 % V·O2max. Even within a homogenous group of subjects, there was a relatively large inter-individual variation in Fatmax and the rate of maximal fat oxidation.


A. Jeukendrup

School of Sport and Exercise Sciences · University of Birmingham

Edgbaston Birmingham B15 2TT · United Kingdom

Phone: +44 121 414 4124

Fax: +44 121 414 4121