PURPOSE: We investigated the feasibility of the Actiheart monitor to determine total daily energy expenditure and the validity of the Actiheart step test as an accurate estimate of peak oxygen uptake.

METHODS: (Equation is included in full-text article.)O2 peak was estimated with the Actiheart step test and compared with a cardiopulmonary exercise test. Total daily energy expenditure was measured using the Actiheart monitor on days with and without classmate coadmission.

RESULTS: Of 26 eligible measurement periods (15 children), 89% participated and 91% could participate safely; however, 35% fulfilled demands for valid monitoring. The percentage of children not completing the monitoring period was 10% (attrition) and adherence to classmate visits was 84%. Forty-eight percent of the measurement periods provided data, and only 27% was calibrated data. Actiheart step test significantly overestimated (Equation is included in full-text article.)O2 peak compared with the Cardio Pulmonary Exercise Test.

CONCLUSION: Measuring total daily energy expenditure using Actiheart is not feasible, nor implementable in children with cancer. Furthermore, the Actiheart step test is not a valid test to estimate (Equation is included in full-text article.)O2 peak in children with cancer.