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Measuring Energy Expenditure in Manual Wheelchair Users with ActiGraph Monitor

Due to the lack of accurate and reliable commercial activity monitors for manual wheelchair users (MWUs), many researchers have been developing custom energy expenditure (EE) models that can be applied to this population. Nightingale et al. (2014) have recently developed two models that are tailored to MWUs based on a commercial monitor, ActiGraph GT3X (1) worn at the wrist and upper arm, respectively. In this study, we evaluated these models in eight MWUs during resting, wheelchair propulsion and arm ergometry exercises. The accuracy of the models was compared against the gold standard measured by a portable metabolic cart. Results showed that both wrist (Mean signed error (MSE): 5.16±94.8, Mean absolute error (MAE): 70.6±63.4%) and upper arm (MSE: 18.3±72.7%, MAE: 58.8±46.4%) models performed better than the manufacturer’s default model when applied to the wrist (MSE: -15.1±104.3%, MAE: 74.1±74.9%) and the upper arm (MSE: -34.5±133.9%, MAE: 103.8±91.2%). However, the custom models still yielded significant errors in estimating EE in MWUs. The estimated EE by the wrist and the upper arm models showed high correlations with the criterion EE (r=0.77 and 0.81 respectively), as well as high agreement (ICC (3, 1) = 0.79 and 0.86 respectively). A more accurate custom EE prediction model for a more diverse set of physical activities (PA) is needed to allow MWUs and clinicians to use ActiGraph for assessing the PA levels on a daily basis.