Strength Training Exercises to minimise late Effects of childhood Leukaemia or lymphoma among adolescents – The STEEL study – protocol for a national multicentre randomised controlled trial

Background Adolescent cancer survivors (ACS) often experience long-term impairments in muscle strength, physical function, and quality of life. Strength training may help address these deficits, but there is limited evidence from randomised trials. This study investigates the efficacy of progressive strength training compared to low-load circuit training in increasing muscle strength over 16 weeks among ACS.

In this multicentre randomised controlled trial, we will recruit 60 ACS successfully treated for acute lymphoblastic leukaemia or lymphoma. Participants aged 10–19 years are recruited from paediatric oncology departments across Denmark. They are randomised stratified by sex to either: 1. a 16-week partly supervised progressive strength training programme (STEEL) with individually tailored exercises targeting major muscle groups, progressing in load and volume over time; or 2. a 16-week partly supervised circuit training programme involving aerobic and low-load strength exercises. The primary outcomes are the change in isometric muscle strength in elbow flexion and extension, and knee flexion and extension from baseline to the 16-week follow-up. Secondary outcomes include physical function (dynamic strength, rate of force development, grip strength, and walking endurance), health-related quality of life, metabolic markers, bone mineral density, movement-evoked pain, exercise compliance and fidelity, physical activity level, and participant satisfaction.

This trial addresses the need for evidence-based rehabilitation strategies in ACS. It is designed to detect short-term effects of supervised strength training on key physical health outcomes using a robust, blinded, and clinically relevant comparison. Results may inform future survivorship care and guidelines. Trial Registration ClinicalTrials.gov identifier: NCT05673152. Registered January 4, 2023. Competing Interest Statement The authors have declared no competing interest. Clinical Trial NCT06299722 Funding Statement This study was funded by The Independent Research Fund Denmark and the Danish Childhood Cancer Foundation Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Ethics Committee of North Denmark Region gave ethical approval for this work (N-20230055). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data produced in the present study will be available upon reasonable request to the authors