Cardiorespiratory fitness and physical activity in children with cancer

PURPOSE: This study assessed cardiorespiratory fitness (CRF), physical activity (PA), and sedentary behavior (SB), as well as factors associated with these outcomes in children during or shortly after cancer treatment. METHODS: Cross-sectionally, CRF data, obtained by the cardiopulmonary exercise test, and PA and SB data, obtained by an accelerometer, were assessed in children with cancer (8-18 years old). Linear regression models were used to determine associations between CRF, PA, or SB and patient characteristics. RESULTS: Among 60 children with cancer, mean age 12.6 years, 35 boys, 28 % were during cancer treatment. CRF, reported as the z score of VO2peak, showed that 32 children had a VO2peak z score which was -2 below the predicted value. CRF was significantly associated with PA and SB: each additional activity count per minute resulted in 0.05 ml/kg/min VO2peak increase and each additional minute sedentary reduced VO2peak by 0.06 ml/kg/min. Multiple linear regression models of PA and SB showed that decreased activity was significantly associated with higher age, being fatigued, being during childhood cancer treatment (p < 0.001), or having a higher percentage of fat mass. The multiple linear regression model showed that lower CRF was significantly associated with increased fatigue, being during cancer treatment, having a higher percentage of fat mass, and lower belief of own athletic competence (p < 0.001). CONCLUSION: This study revealed that children during or shortly after cancer treatment have low CRF scores. The most inactive children had a higher fat mass, were fatigued, older, and during childhood cancer treatment. Unexpectedly, treatment-related factors showed no significant association with activity behavior