Studying at Cambridge

DAPA Measurement Toolkit



Energy is expended to create the muscular forces which result in bodily movement. A measure of the movement of the body or one of its segments (e.g. arm) can be therefore used to infer the energy expenditure associated with that movement.

Bodily movement occurs in three dimensions (see Figure P.1.3) and can take many forms. Measuring the change in movement with respect to time (the acceleration) in one or more directions can provide data which can be used to predict posture, step counts, or detailed information about the temporal variation in overall physical activity energy expenditure (the pattern).

For some types of movement such as stair use, load bearing and cycling the energy cost may not be equivalent to movement [1].

Figure P.1.3 The three axes of human movement.


  1. Ekelund U, Yngve A, Brage S, Westerterp K, Sjostrom M. Body movement and physical activity energy expenditure in children and adolescents: how to adjust for differences in body size and age. Am J Clin Nutr. 2004;79(5):851-6.