title: Does exercise duration affect Fatmax in overweight boys?
abstract: To compare the assessment of Fat(max) using a single graded exercise test with 3 min stages against 30 min prolonged exercise bouts in overweight boys. Ten overweight boys (8-12 years) attended the laboratory on seven separate occasions. On the first visit, body anthropometrics and peak aerobic capacity ([Formula: see text]O(2peak)) were assessed. Following this, each participant attended the laboratory after an overnight fast for six morning cycling sessions. During the first session, participants completed a continuous, submaximal graded exercise protocol with seven 3 min stages (GRAD) at 35, 40, 45, 50, 55, 60 and 65% [Formula: see text]O(2peak). The final five visits consisted of a 30 min bout of prolonged exercise (PROL) performed in a counterbalanced order at 40, 45, 50, 55 and 60% [Formula: see text]O(2peak). There was no effect of exercise duration on Fat(max) or the absolute rate of fat oxidation during PROL (p > 0.05). At the group level, GRAD and PROL provided similar estimates of Fat(max) (GRAD: 53 ± 10% [Formula: see text]O(2peak); PROL: 53 ± 10% [Formula: see text]O(2peak); p = 0.995); however, individual variation between the two protocols is shown by a systematic bias and residual error of 0 ± 11% [Formula: see text]O(2peak). Fat oxidation rates remained stable across 30 min of steady-state exercise in overweight boys. Furthermore, Fat(max) was similar at 3, 10, 20 and 30 min of exercise, suggesting that for exercise lasting ≤ 30 min, exercise duration does not affect Fat(max). However, Fat(max) determined with GRAD may need to be interpreted with caution at the individual level given the variation in Fat(max) between protocols.
authors.affiliation: School of Sport Science, Exercise and Health, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia. 10418305@student.uwa.edu.au
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Crisp
authors.forename: Kym J
authors.initials: KJ
authors.lastname: Guelfi
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Licari
authors.forename: Rebecca
authors.initials: R
authors.lastname: Braham
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fournier
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002648:Child; D015444:Exercise; D006801:Humans; D008297:Male; D050177:Overweight / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D005082:Physical Exertion; D013997:Time Factors
chemical_list: D010100:Oxygen
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