Determination of the exercise intensity that elicits maximal fat oxidation in individuals with obesity

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Maximal fat oxidation (MFO) and the exercise intensity that elicits MFO (FatMax) are commonly determined by indirect calorimetry during graded exercise tests in both obese and normal weight individuals. However, no protocol has been validated in individuals with obesity. Thus, the aims were to develop a graded exercise protocol for determination of FatMax in individuals with obesity, and to test validity and inter-method reliability. Fat oxidation was assessed over a range of exercise intensities in 16 individuals (Age: 28 (26-29) years, BMI: 36 (35-38) kg m-2) (95%CI) on a cycle ergometer. The graded exercise protocol was validated against a short continuous exercise (SCE) protocol, in which FatMax was determined from fat oxidation at rest and during 10-min continuous exercise at 35, 50 and 65% of maximal oxygen uptake (VO2max). Intraclass and Pearson correlation coefficients between the protocols were 0.75 and 0.72 and within subject coefficient of variation (CV) was 5 (3-7)%. A Bland Altman plot revealed a bias of -3% points of VO2max (Limits of Agreement: -12 to 7). A tendency towards a systematic difference (p=0.06) was observed, where FatMax occurred at 42 (40-44) and 45 (43-47)% of VO2max with the graded and the SCE protocol, respectively. In conclusion, there was a high-excellent correlation and a low CV between the two protocols, suggesting that the graded exercise protocol has a high inter-method reliability. However, considerable intra-individual variation and a trend towards systematic difference between the protocols reveal that further optimization of the graded exercise protocol is needed to improve validity.

TidsskriftApplied Physiology, Nutrition and Metabolism
Udgave nummer4
Sider (fra-til)405-412
Antal sider8
StatusUdgivet - apr. 2017

ID: 173476270