A Bout of High-Intensity Interval Training (HIIT) in Children and Adolescents during Acute Cancer Treatment—A Pilot Feasibility Study

SIMPLE SUMMARY: Exercise can counteract some of the adverse effects of cancer and its treatment. Epidemiological and mechanistic data suggest that exercise can influence cancer hallmarks, survival, and recurrence. Our pilot study aimed to assess the feasibility and safety of a single bout of high-intensity interval training (HIIT) in childhood cancer patients. The predefined feasibility criteria included recruitment rate, acceptability, practicability, and data acquisition. Very strict inclusion criteria and surveillance guaranteed safety, and no severe adverse events occurred. Our HIIT protocol is applicable only in a small number of childhood cancer patients. Blood lactate concentrations and heart rates significantly increased after HIIT, indicating that the patients achieved the targeted high exercise intensity. In conclusion, our preliminary data suggest that HIIT is safe and feasible in a small number of childhood cancer patients who do not suffer from severe side effects of treatment. Additional exercise protocols should be developed for patients with pronounced cancer-related impairments and health restrictions. ABSTRACT: Low- and moderate-intensity exercise is safe and feasible during childhood cancer treatment. The feasibility of a bout of high-intensity interval training (HIIT) in this population has not been analyzed to date. Pediatric cancer patients aged between 6 and 18 years were selected based on clinical conditions to perform ten sets of 15 s HIIT (>90% of estimated maximal heart rate (HR(max))) and 1 min active recovery on a bicycle ergometer within the first three chemotherapy courses. We assessed safety and feasibility criteria and the following parameters: perceived exertion rate, heart rate, and lactate and adrenaline concentrations. Out of 212 eligible patients, 11 patients aged 13.9 ± 3.6 years (n = 7 ♂) with lymphoma, leukemia, rhabdomyosarcoma, nephroblastoma, and synovial sarcoma completed the bout of HIIT without serious adverse events. During exercise, patients reached a BORG value maxima of 16 ± 1.2, and their heart rates rose from 78 ± 17 beats per minute (bpm) at rest to 178 ± 12 bpm after exercise (90 ± 6% estimated HR(max)). The power-to-weight ratio was 2 ± 0.5 W/kg (watt per kilogram). Blood lactate concentrations increased from 1.09 ± 0.50 mmol/L (millimole per liter) at rest to 5.05 ± 1.88 mmol/L post-exercise. Our preliminary data suggest that HIIT is applicable only in a small number of childhood cancer patients. Individually adapted exercise protocols for patients with multiple impairments are needed.