An evaluation of data processing when using the ActiGraph GT3X accelerometer in non‐ambulant children and adolescents with cerebral palsy

PURPOSE: To evaluate vertical acceleration, vector magnitude, non‐wear time, valid day classifications, and valid period classifications in the data processing phase when using the ActiGraph GT3X accelerometer in non‐ambulant children and adolescents with cerebral palsy (CP). MATERIAL AND METHODS: Accelerometer data retrieved from 33 non‐ambulant children and adolescents (4–17 years) with CP were analysed. Comparisons of (i) vertical acceleration versus vector magnitude, (ii) two different non‐wear times, (iii) three different settings to classify a day as valid and (iv) two different settings to classify a period as valid were made. RESULTS AND CONCLUSIONS: Vector magnitude and a non‐wear time of at least 90 consecutive minutes statistically significantly increased minutes recorded per day, especially for sedentary time. There was a statistically significant difference in numbers of valid days depending on time criteria set to determine a valid day, whereas there was no statistically significant difference in valid periods using 3 compared to 4 days. This study suggests using the pre‐settings in ActiLife; vector magnitude, non‐wear time of 90 consecutive minutes, 500 min recorded per day with periods of at least 3 valid days when assessing physical activity objectively by the ActiGraph GT3X accelerometer in non‐ambulant children and adolescents with CP.