ABSTRACT
Fatmax is the exercise intensity (% peak VO2) that elicits the maximal fat oxidation (MFO) rate (Jeukendrup and Achten, 2001). Higher fat oxidation during treadmill compared with cycling exercise has been found consistently in adults (e.g., Capostagno and Bosch, 2010). However, similar findings in children are sparse (Lafortuna et al., 2010). Exercise mode comparisons of fat oxidation have used a small number of intensities corresponding to the exercise mode-specific peak (Mácek et al., 1976). However, peak VO2 is typically 7 to 10 % higher for treadmill (TM) compared with cycling exercise (CE) in untrained individuals (Mácek et al., 1976). The higher absolute VO2 during treadmill exercise may explain differences in fat oxidation between exercise modes. Therefore, a comparision of fat oxidation over a wide range of both relative and absolute exercise intensities is warranted. Cycling regularly at Fatmax might improve exercise fat oxidation and other health markers in young people (Ben Ounis et al., 2009). Walking or jogging may help to further optimise these effects through the recruitment of a larger active muscle mass and subsequent elevation of fat oxidation. However, we are not aware of studies that have compared Fatmax between treadmill and cycling exercise in children. To our knowledge, only one study has compared fat oxidation over a range of exercise intensities between treadmill and cycling in young people, but this study was limited to obese adolescent boys and Fatmax was not estimated (Lafortuna et al., 2010). Moreover, similar studies involving girls and non-obese children appear to be unavailable and the influence of puberty on fat oxidation must be considered (Riddell, 2008). Therefore, the aim of the present study was to compare fat oxidation and Fatmax over a range of intensities during treadmill and cycling exercise in pre- to early pubertal girls and boys.
