This study compared the effects of constant-load aerobic exercise (CL-AEx) and graded aerobic exercise (G-AEx) on cardiopulmonary fitness and functional capacity in pediatric survivors of acute lymphoblastic leukemia (ALL).

A cohort of 72 pediatric ALL survivors was randomly assigned to one of three groups: a CL-AEx group (n=24), a G-AEx group (n=24), or a control group (n=24). All groups participated in a structured exercise regimen. The CL-AEx group performed additional moderate-intensity aerobic training at a fixed load, while the G-AEx group performed additional aerobic training with progressive increases in intensity and duration. The control group performed the structured exercise regimen only. Interventions were administered three times per week for 12 consecutive weeks.

Cardiopulmonary fitness and functional capacity were assessed in all three groups at baseline and following the completion of the 12-week intervention.

Seventy-two pediatric ALL survivors were recruited from the Pediatric Oncology and Hematology departments of three referral hospitals in the Riyadh region, Saudi Arabia. Inclusion criteria required participants to be aged 10-18 years, have completed chemotherapy, present with secondary sarcopenia, and possess normal cardiac structure and function without lower limb deformities. Participants were also required to be non-regular exercisers. Exclusion criteria included a history of secondary cancers, neurodegenerative impairments affecting memory, attention, or executive function, or any neuromusculoskeletal condition likely to impede training compliance (e.g., recurrent intensive cramps or impaired proprioceptive function).

Outcome Measures

Cardiopulmonary Fitness: Peak oxygen uptake (VO₂ peak) was assessed using the McMaster cycle ergometer protocol.

Functional Capacity: This was evaluated via three performance-based tests: the 6-Minute Walk Test (6MWT), the Timed Up and Down Stairs Test (TUDS), and the 4x10 Meter Shuttle Run Test.

Interventions

All interventions were delivered three times per week for 12 consecutive weeks under close supervision by an experienced pediatric physical therapist.

Constant-Load Aerobic Exercise (CL-AEx) Group: This group (n=24) performed a structured exercise regimen plus a moderate-intensity aerobic training program. The aerobic component was maintained at a constant intensity of 65% of the maximum age-predicted heart rate for 45 minutes per session, each preceded by a 5-minute warm-up and followed by a 5-minute cool-down.

Graded Aerobic Exercise (G-AEx) Group: This group (n=24) performed the same structured exercise regimen plus an aerobic program with progressive intensity and duration. Starting at 50% of maximum age-predicted heart rate for 25 minutes, the parameters were increased every two weeks, culminating at 75% for 50 minutes in the final two weeks. Each session also included a 5-minute warm-up and cool-down.

Control Group: This group (n=24) performed only the structured exercise regimen for 45 minutes per session. The regimen included flexibility exercises, progressive resistance training, balance training, and conditioning activities.

Inclusion Criteria:

• Age between 10 and 18 years old
• Complete maintenance chemotherapy
• Normal cardiac structure and function
• Absence of lower limb deformities
• Not engaging in regular exercise regimens

Exclusion Criteria:

• Secondary cancers
• Neurodegenerative impairments affecting memory, attention, or executive functioning
• Neuro-musculoskeletal conditions are likely to impede the training.

A single-blind protocol was adopted. The researcher who collected the data was blind to the allocation of treatment