Strength Training Exercises to Minimize Late Effects of Childhood Leukemia or Lymphoma Among Adolescents: A Multicenter Randomized Controlled Trial

Purpose: Adolescent cancer survivors (ACS) often have persistent impairments in muscle strength, physical function, and quality of life (QoL). This study investigates the efficacy of strength training compared with low-load circuit training in increasing muscle strength over 16 weeks among ACS. Methods: In this superiority randomized controlled trial (NCT06299722), 46 ACS aged 10-19 years were randomized 1:1 to (1) high-load progressive strength training (STEEL) targeting major muscle groups, or (2) circuit training with aerobic and strength components. Primary outcomes were changes in maximal voluntary isometric contraction (MVIC) in elbow flexion/extension and knee flexion/extension measured by handheld dynamometry from baseline to 16 weeks. Secondary outcomes included a one-repetition maximum (1RM) in the leg press and chest press, quality of life assessed with the PedsQL Core 4.0, and fatigue assessed with the PedsQL Multidimensional Fatigue. Assessments were at baseline, 8, and 16 weeks. Results: There were no statistically significant between-group differences in MVIC at 16 weeks. Increases were observed in both groups. Compared with circuit training, STEEL was associated with greater improvements in leg press 1RM (adjusted mean difference 9.9 kg, 95% CI 0.7 to 19.1, P= 0.036) but not chest press 1RM. STEEL was also associated with better physical functioning (adjusted mean difference 7.4 points, 95% CI 0.7 to 14.0, P=0.030) and fewer sleep/rest challenges (adjusted mean difference: 11.4 points, 95% CI 3.1 to 19.6, P=0.007). No other between-group differences in quality of life were observed. Conclusions: High-load progressive strength training was not superior to circuit training for improving isometric muscle strength among ACS. Both groups demonstrated increased muscle strength over time, underscoring the capacity of structured exercise interventions to mitigate strength deficits in this population.