Dynamic body acceleration (
DBA) has been used as a proxy for energy expenditure in logger-equipped animals, with
researchers summing the acceleration (overall dynamic body acceleration -
ODBA) from the three orthogonal axes of devices. The vector of the dynamic body acceleration
(
VeDBA) may be a better proxy so this study compared
ODBA and
VeDBA as proxies for rate of oxygen consumption using humans and 6 other species. Twenty-one
humans on a treadmill ran at different speeds while equipped with two loggers, one
in a straight orientation and the other skewed, while rate of oxygen consumption (
) was recorded. Similar data were obtained from animals but using only one (straight)
logger. In humans, both
ODBA and
VeDBA were good proxies for
with all r
2 values exceeding 0.88, although
ODBA accounted for slightly but significantly more of the variation in
than did
VeDBA (P<0.03). There were no significant differences between
ODBA and
VeDBA in terms of the change in
estimated by the acceleration data in a simulated situation of the logger being mounted
straight but then becoming skewed (P = 0.744). In the animal study,
ODBA and
VeDBA were again good proxies for
with all r
2 values exceeding 0.70 although, again,
ODBA accounted for slightly, but significantly, more of the variation in
than did
VeDBA (P<0.03). The simultaneous contraction of muscles, inserted variously for limb stability,
may produce muscle oxygen use that at least partially equates with summing components
to derive
DBA. Thus, a vectorial summation to derive
DBA cannot be assumed to be the more ‘correct’ calculation. However, although within
the limitations of our simple study,
ODBA appears a marginally better proxy for
. In the unusual situation where researchers are unable to guarantee at least reasonably
consistent device orientation, they should use
VeDBA as a proxy for
.