What is the real impact of upper limb cast immobilisation on activity-related energy expenditure in children?

BACKGROUND: Upper limb fractures and subsequent cast immobilisation constitute a potential cause of reduction in childhood levels of physical activity (PA), with subsequent decrease of energy consumption. The main objective of this study was thus to quantify the decrease of activity-related energy expenditure (AEE) due to upper limb cast immobilisation. METHODS: We conducted a longitudinal matched case-control study that included 35 children and teenagers with a first episode of upper limb fracture and 35 healthy cases. PA was assessed during cast immobilisation by accelerometer. AEE was the calculated using an equation based on the total counts per day measured by accelerometers. RESULTS: AEE in children and teenagers with upper limb fractures was estimated to be 7.4 % lower than healthy controls. The mean difference corresponded to 1.35 kcal/kg per mean valid recorded time (750 min), that is, the waking hours. When converted in kcal per mean subjects’ weight, the difference in AEE amounted 63.5 kcal/day, which corresponds approximately to 26 min of walking at a speed of 4 km/hours. In comparison with the mean AEE in healthy controls (18.2 kcal/kg), the noted decrease (1.35 kcal/kg) represents only 7.4 % of AEE. CONCLUSION: Reduction of AEE in children and teenagers with upper limb fractures may lead to a slight positive energy balance, as there is usually no compensatory reduction of energy intake. An increase of light PA has to be counselled in this situation or patients should be advised to reduce their energy intake during the immobilisation period. LEVEL OF EVIDENCE: Level I: high-quality prospective study (all patients were enrolled at the same point in their disease with ≥80 % follow-up of enrolled patients).