Accelerometry as an Estimate of Energy Expenditure in Healthy Children and Children with Cerebral Palsy During Self-Paced Ambulation

Abstract
Oxygen consumption (VO₂) is the criterion standard for determining energy expenditure during activity. Newer technologies have resulted in the development of portable metabolic gas analyzers capable of measuring VO₂ during a wide range of physical activities in the field. Unfortunately, use of these devices is still limited due to the cost, availability and skill level required to utilize this newer technology. However, there is an instrument which may be utilized. Accelerometers are a type of physical activity monitor that provide estimates of energy expenditure and may potentially be of more practical use in the clinical setting. Purpose: This study was designed to compare estimates of energy expenditure using two different accelerometers to VO₂ during self-paced walking speeds in children with spastic diplegia cerebral palsy (CP) and in healthy children (HLT). Methods: Ten HLT children and five children with spastic diplegia CP participated in this pilot study (age range: 7.5-17.5 years). Subjects ambulated at self-paced speeds on a level surface wearing a Caltrac accelerometer and a BioTrainer-Pro accelerometer, while VO₂ was measured simultaneously with an AeroSport KB1-C portable metabolic gas analyzer. Results: Both accelerometers overestimated caloric expenditure in HLT children. In the children with spastic diplegia CP, we found no significant differences in the mean caloric expenditure estimated by the accelerometers and VO₂ (p= 0.62). Conclusions: Preliminary findings suggest accelerometers may have potential as a means of estimating energy expenditure during ambulation in children with spastic diplegia CP, which could be useful to clinicians evaluating therapeutic interventions. Further research is indicated.