Physical fitness throughout chemotherapy in children with acute lymphoblastic leukaemia and lymphoma

Acute lymphoblastic leukaemia/lymphoma (ALL/LBL) and its treatment interfere with normal physical functioning. However, it remains unclear how physical fitness (PF) is affected throughout treatment for ALL/LBL. Sixty-two patients (2.1 to 18.3 years) treated for ALL/LBL underwent four physical tests at nine timepoints from baseline up to 6 months post-treatment. We assessed muscle strength of the quadriceps and tibialis anterior, standing broad jump test (SBJ) for functional mobility and six-minute walk test (6MWT) for endurance. One-sample t-tests were used to compare our results to the norm at each timepoint. Norm-referenced Z-scores were predicted based on time, risk group and age at diagnosis, using linear mixed models. Quadriceps strength, SBJ and 6MWT scores were significantly lower than norm values at all timepoints from diagnosis up to 6 months after maintenance therapy. Significant decreases over time were encountered for quadriceps strength and SBJ, mainly occurring after induction therapy (F = 3.568, p < 0.001 and F = 2.699, p = 0.008, respectively). Age at diagnosis was a significant predictor for tibialis anterior strength (F = 5.266, p = 0.025), SBJ (F = 70.422, p < 0.001) and 6MWT (F = 15.890, p < 0.001) performances, with lower results in adolescents at all timepoints. Six months after treatment, quadriceps strength, 6MWT and SBJ scores remained below expected levels. Conclusion: The decreased quadriceps strength, functional mobility and endurance at all timepoints, with a large deterioration following induction therapy, suggest the need for early interventions, specifically in the adolescent population. The continued low results 6 months after therapy emphasise the importance of long-term rehabilitation