Biology Reference
In-Depth Information
the role metabolic rate and energy cost of activities play in the development
of obesity in children and adolescents.
Ekelund et al. (2002)
found that accelerometer-measured PA was lower
in obese adolescents even though their EE did not differ significantly from
their normal weight counterparts. The authors hypothesized that this result
was due to the increased energy cost of moving a larger body mass, even
though the obese group was less physically active.
Ekelund et al. (2002)
suggested that the energy costs of activities were not associated with obesity
in children and adolescents, but the duration of PA and the total amount of
PA play an important role. Moreover,
Goran, Hunter, Nagy, and Johnson
(1997)
reported that time spent in PA was negatively associated with fat
mass, and the authors found no association between body fat mass and
the energy cost of PA (using doubly labeled water). On the other hand,
Lazzer et al. (2003)
reported that the EE associated with physical activities
was lower in obese adolescents despite the higher energy cost of the physical
activities. These results suggested that energy imbalance impacts the devel-
opment of overweight and obesity and may result from low PA.
The energy cost of walking adjusted for body mass was not significantly
different between obese and nonobese individuals (
Delextra, Matthew,
Cohen, & Brisswalter, 2011
)
, and our finding is in agreement with previous
studies (
Ekelund et al., 2002; Treuth et al., 1998
). However,
Browning and
Kram (2007)
reported that, at the same speed of exercise, the energy cost was
significantly greater in obese than in normal weight children, in both boys
and girls, especially at high walking speeds (
Katch, Becque, Marks,
Moorehead, & Rocchini, 1988
)
. Moreover, similar findings were also
reported by
Maffeis et al. (1993)
.
Schwartz, Koop, Bourke, and Baker
(2006)
employed a nondimensional normalization scheme in an energy cost
comparison for children that compensated for physiological and anthropo-
metric factors. The net walking metabolic rate was approximately 20%
greater in obese children compared to their normal weight counterparts.
This result may be due to obese children having larger pulmonary ventila-
tory responses to exercise than nonobese children (
Browning & Kram,
2007
), to the greater muscle force required by those who are obese having
to support excess body fat (
Grabowski, Farley, & Kram, 2005
)
, and to the
increased rate of fat oxidation and increased cardiac and respiratory work
(
Bruckner et al., 1991
)
. There are only a few studies that directly compared
the energy costs of activities among obese and nonobese adolescents across a
range of walking speeds (
Beatriz & Oded, 2003; Lazzer et al., 2003
). Nev-
ertheless, available findings suggest that walking and running entails more
