This study was designed to investigate the effect of eight weeks of adaptive variable-resistance training (Adaptive-VRT) on chemotherapy-induced sarcopenia, fatigue, and functional restrictions in a convenience sample of pediatric survivors of acute lymphoblastic leukemia (ALL). Sixty-two pediatric survivors of ALL were randomly allocated to the experimental group (n = 31, received the adaptive variable-resistance training) or the Control group (n = 31, received standard physical therapy care). Both groups were assessed for muscle mass, strength, fatigue, and functional capacity before and after treatment.

Sixty-two pediatric survivors of ALL participated in the study. They were recruited from the Pediatric Oncology/Hematology departments of three referral hospitals in Riyadh region, Saudi Arabia. They were between 12 and 18 years old, completed chemotherapy, had secondary sarcopenia, had normal cardiac structure and function, had no lower limb deformities, and did not engage in regular exercise regimens. They were excluded if they had secondary cancers, neurodegenerative impairments affecting memory, attention, or executive functioning, or neuro-musculoskeletal conditions likely to impede the training like recurrent intensive cramps or impaired proprioceptive functions.

Outcome measures

1. Muscle thickness: the thigh muscle thickness was assessed using a standard high-resolution ultrasound imaging system.
2. Muscle strength: The peak concentric torque of the right and left quadriceps was measured through an isokinetic dynamometer.
3. Fatigue: the general fatigue perception was evaluated using the Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale.
4. Functional capacity: Three tests were used; the 6-minute walk test, the timed up and down stairs test, and the 4x10 meter Shuttle Run test.

The experimental group received an adaptive-VRT program, three times a week, for six consecutive weeks, in conformity with the National Strength and Conditioning Association guidelines and American Academy of Pediatrics safety standards. The training protocol included maximum voluntary concentric knee flexor/extensor actions through a motion range between 10 and 90 degrees. Three sets of five to 10 repetitions at angular speeds of 240, 180, and 120 degrees/second were performed. The training started with a warm-up for 10 minutes and ended with a cool-down for 5 minutes.

The control group received the standard exercise program, 45 minutes per session, three times a week, for eight consecutive weeks. The program consisted of flexibility exercise, manual/mechanical strength training, and moderate-intensity aerobic exercises on a treadmill or bicycle ergometer.

Inclusion Criteria:

• Age between 12 and 18 years old
• Complete maintenance chemotherapy
• Secondary sarcopenia
• 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.

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