Fat oxidation over a range of exercise intensities: fitness versus fatness

Croci, Ilaria, Hickman, Ingrid J., Wood, Rachel E., Borrani, Fabio, Macdonald, Graeme A. and Byrne, Nuala M. (2014) Fat oxidation over a range of exercise intensities: fitness versus fatness. Applied Physiology, Nutrition, and Metabolism, 39 12: 1352-1359. doi:10.1139/apnm-2014-0144


Author Croci, Ilaria
Hickman, Ingrid J.
Wood, Rachel E.
Borrani, Fabio
Macdonald, Graeme A.
Byrne, Nuala M.
Title Fat oxidation over a range of exercise intensities: fitness versus fatness
Journal name Applied Physiology, Nutrition, and Metabolism   Check publisher's open access policy
ISSN 1715-5320
1715-5312
Publication date 2014-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1139/apnm-2014-0144
Open Access Status Not yet assessed
Volume 39
Issue 12
Start page 1352
End page 1359
Total pages 8
Place of publication Ottawa, ON, Canada
Publisher N R C Research Press
Language eng
Abstract Maximal fat oxidation (MFO), as well as the exercise intensity at which it occurs (Fat(max)), have been reported as lower in sedentary overweight individuals but have not been studied in trained overweight individuals. The aim of this study was to compare Fat(max) and MFO in lean and overweight recreationally trained males matched for cardiorespiratory fitness (CRF) and to study the relationships between these variables, anthropometric characteristics, and CRF. Twelve recreationally trained overweight (high fatness (HiFat) group, 30.0%+/- 5.3% body fat) and 12 lean males (low fatness (LoFat), 17.2%+/- 5.7% body fat) matched for CRF (maximal oxygen consumption (((V)over dotO(2max)) 39.0 +/- 5.5 vs. 41.4 +/- 7.6 mL.kg(-1).min(-1), p = 0.31) and age (p = 0.93) performed a graded exercise test on a cycle ergometer. (V)over dotO(2max) and fat and carbohydrate oxidation rates were determined using indirect calorimetry; Fat(max) and MFO were determined with a mathematical model (SIN); and % body fat was assessed by air displacement plethysmography. MFO (0.38 +/- 0.19 vs. 0.42 +/- 0.16 g.min(-1), p = 0.58), Fat(max) (46.7%+/- 8.6% vs. 45.4%+/- 7.2% (V)over dotO(2max), p = 0.71), and fat oxidation rates over a wide range of exercise intensities were not significantly different (p > 0.05) between HiFat and LoFat groups. In the overall cohort (n = 24), MFO and Fat(max) were correlated with (V)over dotO(2max) (r = 0.46, p = 0.02; r = 0.61, p = 0.002) but not with % body fat or body mass index (p > 0.05). Fat oxidation during exercise was similar in recreationally trained overweight and lean males matched for CRF. Consistently, substrate oxidation rates during exercise were not related to adiposity (% body fat) but were related to CRF. The benefits of high CRF independent of body weight and % body fat should be further highlighted in the management of obesity.
Formatted abstract
Maximal fat oxidation (MFO), as well as the exercise intensity at which it occurs (Fatmax), have been reported as lower in sedentary overweight individuals but have not been studied in trained overweight individuals. The aim of this study was to compare Fatmax and MFO in lean and overweight recreationally trained males matched for cardiorespiratory fitness (CRF) and to study the relationships between these variables, anthropometric characteristics, and CRF. Twelve recreationally trained overweight (high fatness (HiFat) group, 30.0% ± 5.3% body fat) and 12 lean males (low fatness (LoFat), 17.2% ± 5.7% body fat) matched for CRF (maximal oxygen consumption (O2max) 39.0 ± 5.5 vs. 41.4 ± 7.6 mL·kg–1·min–1, p = 0.31) and age (p = 0.93) performed a graded exercise test on a cycle ergometer. O2max and fat and carbohydrate oxidation rates were determined using indirect calorimetry; Fatmax and MFO were determined with a mathematical model (SIN); and % body fat was assessed by air displacement plethysmography. MFO (0.38 ± 0.19 vs. 0.42 ± 0.16 g·min–1, p = 0.58), Fatmax (46.7% ± 8.6% vs. 45.4% ± 7.2% O2max, p = 0.71), and fat oxidation rates over a wide range of exercise intensities were not significantly different (p > 0.05) between HiFat and LoFat groups. In the overall cohort (n = 24), MFO and Fatmax were correlated with O2max (r = 0.46, p = 0.02; r = 0.61, p = 0.002) but not with % body fat or body mass index (p > 0.05). Fat oxidation during exercise was similar in recreationally trained overweight and lean males matched for CRF. Consistently, substrate oxidation rates during exercise were not related to adiposity (% body fat) but were related to CRF. The benefits of high CRF independent of body weight and % body fat should be further highlighted in the management of obesity.
Keyword Maximal fat oxidation
Substrate oxidation
Lipid metabolism
Obesity
Fatness
Active overweight
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published on the web 1 August 2014.

 
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Created: Thu, 30 Oct 2014, 01:49:16 EST by Sandrine Ducrot on behalf of School of Human Movement and Nutrition Sciences