Employing a tri-axial accelerometer for estimating energy expenditure during simulated load carrying

  • S.E.H. Davies
  • S.N. Mackinnon


The Tritrac-R3D, a portable tri-axial accelerometer, was assessed for its ability to estimate energy expenditure during simulated load carrying activities. The Tritrac data were compared to metabolic data collected simultaneously by a MetaMax ergospirometry system while ten, healthy male subjects (aged 20.7 ±1.4 years) walked on a motorised treadmill. The subjects were measured under three conditions: no load (0%), carrying a load equivalent to 15% body mass and carrying a load equivalent to 30% body mass. When statistically compared with the MetaMax data, a significant difference of 2.105 kcal.min -1 was observed for the 30% load condition (p<0.001). This significant difference was eliminated when the data used to initialise the Tritrac was corrected to include the magnitude of the mass carried, as well as the subject's mass. Pearson Product Moment Correlations between the Tritrac and MetaMax data were calculated for each experimental condition. Correlation strength between these variables improved as the load carried increased from 0% to 30% (r=.406, .494, .818 respectively). The strongest correlation was found when all conditions were combined (r=.628) and the association was further improved when corrected Tritrac data were used (r=.857). Evidence from this study suggests that the Tritrac provides a reasonable estimate of energy expenditure gradients during load carrying activities.

(S. African J. for Research in Sport, Physical Ed. and Recreation: 2001 23 (2): 23-34)

Journal Identifiers

print ISSN: 0379-9069