Cardiorespiratory fitness and physical activity in children with cancer

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. 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. 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). 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.