Tri-Axial Dynamic Acceleration as a Proxy for Animal Energy Expenditure; Should We Be Summing Values or Calculating the Vector?

Abstract

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 r2 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 r2 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 .

Counting calories in cormorants: dynamic body acceleration predicts daily energy expenditure measured in pelagic cormorants

“…Because of the strong relationship between total ODBA and total VeDBA (R 2 =0.99, t 15 =211.4, P<0.0001), we only considered a single total DBA formulation for AIC analysis. Total ODBA was omitted given its marginally poorer performance and because of the theoretical arguments put forward by Gleiss et al (2011) and Qasem et al (2012). The most parsimonious model identified by AIC analysis for predicting DLW-estimated mass-specific total energy expenditure was a total VeDBA model parameterizing surface swimming separate from all other modes of locomotion (Table 1) Table S1), but time budget models were also highly sensitive to activity parameterization in comparison to the relatively robust total VeDBA models.…”

“…However, Gleiss et al (2011) raised concerns about ODBA, arguing non-independence in the axes of motion and advocating instead for the use of vectorial dynamic body acceleration (VeDBA). In comparing these two interpretations of DBA, Qasem et al (2012) found little difference between the VeDBA and ODBA. However, this study was selfacknowledged as being limited in scope, given its investigation into only a single activity (treadmill walking) in humans and a small number of captive animal species.…”

Can accelerometry be used to distinguish between flight types in soaring birds?

“…VeDBA is a vectorial measure of the total dynamic movement of the animal and has been used as a proxy for energy expenditure [47]. Any movement due to changes in speed by the animal or as a result of turbulence that the animal experiences from the environment will manifest itself in the VeDBA.…”

Accelerometers and simple algorithms identify activity budgets and body orientation in African elephants Loxodonta africana

“…The 2 methods (line interpolation and SD) were computed for each axis of these data se quen ces. For each sequence, dynamic acceleration values were summed across the 3 axes, yielding overall dynamic body acceleration (ODBA; Wilson et al 2006, Qasem et al 2012. In this way, we were able to directly compare the 2 methods used to compute ODBA.…”

“…The most common measure of dynamic acceleration is ODBA, which includes accelerations from all 3 axes in its computation (Qasem et al 2012). However, one could reduce the number of axes measured as a proxy for ODBA (see Gleiss et al 2010).…”