Physical Activity, Fitness and the Energy Cost of Activities: Implications for Obesity in Children and Adolescents in the Tropics - Advances in Food and Nutrition Research - page 74

method of direct measurement of oxygen uptake, while the Kofranyi-
Michaelis (KM) respirometer was developed for energy exchange studies
in the field. All of these techniques have their own strengths and limitations
for estimating EE.
Most studies on the energy costs of activities in the tropics ( Table 2.2 )
used either the DB technique, the KM respirometer, or a HR monitor
(together with diary). Under trained hands, the DB technique is considered
to be the gold standard ( Carter & Jeukendrup, 2002 ); however, potential air
leakage is one of the limitations of this method. Hopker, Jobson, Gregson,
Coleman, and Passfield (2012) tested the reliability of the DB technique and
found that the gas sampling attained a low coefficient of variation (CV),
which was less than 0.5% for both oxygen and carbon dioxide. However,
the CV for the bag residual volume was approximately 15%, which is con-
sidered high. This high variation could lead to errors; however, a large gas
sample volume may help to minimize the error.
The KM respirometer, developed as an alternative technique for measur-
ing EE, has generally shown good agreement with the DB technique
( Louhevaara, Ilmarinen, & Oja, 1985 ) , despite a minor overestimation of
VO 2 . Hence, the KM respirometer is still considered reliable for VO 2 mea-
surements in field settings ( Louhevaara et al., 1985 ) . Other than the DB
technique and the KM respirometer, Louie et al. (1998) and Eston,
Ingledew, Fu, and Rowlands (1998) suggested that triaxial accelerometry
provides the best assessment of EE.
In addition to the techniques discussed earlier, the HR method has often
been used to estimate EE due to its ability to record readings over time, its
ease of administration, and its reflection of the relative stress on the cardio-
pulmonary system from PA ( Welsman & Armstrong, 1992 ) . However, HR
can be impacted by the subject's emotional status and Nieman (1999)
suggested that HR is approximately 10% higher for upper-body dynamic
exercises than lower-body dynamic exercises. The level of PF may also affect
the relationship between HR and VO 2 . Physically fit individuals will have a
lower HR due to a greater stroke volume compared to those who are less fit
( Saris, Binkhorst, Cramwinckel, Van Waesberghe, & Van der Veen-
Hezemans, 1980 ). Consequently, HR is higher during static exercise
( Klausen, Rasmussen, Glensgaard, & Jensen, 1985 ) , as it is associated with
the active muscle mass and the percentage of maximum pulmonary venti-
latory response rather than VO 2 .
Despite these limitations, studies in children and adults have shown that
when HR monitor is used together with motion sensors, less error is