Exercise Protocols to Estimate Fatmax and Maximal Fat Oxidation in Children

Abstract

Consensus on the exercise protocol used to measure Fatmax (exercise intensity corresponding to maximum fat oxidation (MFO)) in children has not been reached. The present study compared Fatmax estimated using the 3 min incremental cycling protocol (3-INC) and a protocol consisting of several 10 min constant work rate exercise bouts (10-CWR) in 26 prepubertal children. Group Fatmax values were the same for 3-INC and 10-CWR (55% VO2peak) and 95% limits of agreement (LoA) were ± 7% VO2peak. Group MFO values were similar between protocols, although 95% LoA were -94 to 113 mg·min-1. While 3-INC provides a valid estimation of Fatmax compared with 10-CWR, caution should be exercised when estimating MFO in prepubertal children.

Does exercise duration affect Fatmax in overweight boys?

“…However, only one study has attempted to validate the use of a single, incremental protocol to determine Fat max in children. Zakrzewski and Tolfrey (2011) compared Fat max estimated from 3 min incremental stages to that estimated from six 10 min constant load bouts and found comparable results between the two protocols in healthy prepubertal children. Based on these results, the authors recommended that a 3 min incremental protocol could be used to provide an estimation of Fat max in this population, but acknowledged that it might not be appropriate for obese children (Zakrzewski and Tolfrey 2011).…”

“…Zakrzewski and Tolfrey (2011) compared Fat max estimated from 3 min incremental stages to that estimated from six 10 min constant load bouts and found comparable results between the two protocols in healthy prepubertal children. Based on these results, the authors recommended that a 3 min incremental protocol could be used to provide an estimation of Fat max in this population, but acknowledged that it might not be appropriate for obese children (Zakrzewski and Tolfrey 2011). Furthermore, the exercise duration of 10 min utilised in the constant load bouts may not have been long enough to observe any potential increase in fat oxidation rate over time (Cheneviére et al 2009;Meyer et al 2007;Pillard et al 2007).…”

“…The few studies that have determined Fat max in children and adolescents have also utilised incremental protocols with 3-6 min stages, adapted from Achten et al (2002), and report Fat max to occur between 40-56% _ VO 2peak (Aucouturier et al 2009;Lazzer et al 2007Lazzer et al , 2010Riddell et al 2008;Zakrzewski and Tolfrey 2011;Zunquin et al 2009). However, only one study has attempted to validate the use of a single, incremental protocol to determine Fat max in children.…”

“…The intensity at which fat oxidation is the greatest has been termed Fat max (Achten et al 2002) and is commonly expressed as a percentage of maximal or peak oxygen uptake (% _ VO 2max/peak ). Some researchers suggest that the identification of Fat max may allow for the development of more appropriate exercise interventions aimed at reducing fat mass and other medical consequences associated with obesity (Ben Ounis et al 2008;Brandou et al 2003;Dumortier et al 2003;Venables and Jeukendrup 2008;Zakrzewski and Tolfrey 2011). As it is important to intervene in the early onset of obesity, before any long-term consequences have a chance to develop (e.g., diabetes, musculoskeletal abnormalities, poor self-esteem), it may be particularly beneficial to be able to determine Fat max in a pediatric population.…”

Effect of breakfast glycemic index on metabolic responses during rest and exercise in overweight and non-overweight adolescent girls

“…Breath-bybreath data were displayed online using a portable metabolic cart (K4 b 2 , Cosmed, Rome, Italy) and interpolated into 1-s intervals for subsequent analyses. Calibration procedures were carried out before each experimental test, as described previously (Zakrzewski and Tolfrey, 2011). Fat oxidation rates were calculated using stoichiometric equations, with the assumption that the urinary nitrogen excretion rate was negligible and a physiological steady-state had been attained (Frayn, 1983).…”