Within 5-year off-chemotherapy: How the cardio-respiratory response to exercise is related to energy expenditure, fatigue, and adiposity in children with acute lymphoblastic leukaemia?

Objective: To explore the cardio-respiratory response to exercise and examine the relationships among specific measures of cardio-respiratory function, energy expenditure (EE), fatigue and adiposity in children survivors of acute lymphoblastic leukaemia (ALL). Methods: Seventy survivors of ALL (13.31 ± 2.60 years) and 34 controls from the siblings (12.71 ± 2.36 years) participated and were assessed for submaximal and maximal exercise capacity, body composition, EE and fatigue. Results: ALL survivors had significantly lower submaximal (VO₂; p = 0.002) and maximal (VO_2peak; p ˂ 0.001) cardio-respiratory capacity than their controls. At the submaximal exercise test, EE was significantly lower in ALL survivors (p < 0.001), but the heart rate (HR) was significantly higher (p = 0.005). The VO₂ and HR were significantly correlated [r (95%CI) = 0.689 (0.542 to 0.795), p < 0.001]. The VO_2peak negatively associated with adiposity [r (95%CI) = −0.368 (−0.554 to −0.145), p = 0.002]. Fatigue significantly correlated with the VO_2peak [r (95%CI) = 0.581 (0.401 to 0.718), p < 0.001] and adiposity [r (95%CI) = −0.303 (−0.502 to 0.073), p = 0.012]. Conclusion: Children survivors of ALL experience low cardio-respiratory fitness within 5-year off-chemotherapy. Associations exist between measures of cardio-respiratory fitness, EE, fatigue and adiposity. However, it has not yet been proven whether these are cause or effect.