Fitness and metabolic response to exercise in young adult survivors of childhood lymphoma

PURPOSE

Childhood lymphoma survivors (CLSs) are at high risk of reduced daily activity. This work studied metabolic substrate use and cardiorespiratory function in response to exercise in CLSs.

METHODS

Twenty CLSs and 20 healthy adult controls matched for sex, age, and BMI took an incremental submaximal exercise test to determine fat/carbohydrate oxidation rates. Resting echocardiography and pulmonary functional tests were performed. Physical activity level, and blood metabolic and hormonal levels were measured.

RESULTS

CLSs reported more physical activity than controls (6317 ± 3815 vs. 4268 ± 4354 MET-minutes/week, p = 0.013), had higher resting heart rate (83 ± 14 vs. 71 ± 13 bpm, p = 0.006), and showed altered global longitudinal strain (- 17.5 ± 2.1 vs. - 19.8 ± 1.6%, p = 0.003). We observed no difference in maximal fat oxidation between the groups, but it was reached at lower relative exercise intensities in CLSs (Fatmax 17.4 ± 6.0 vs. 20.1 ± 4.1 mL/kg, p = 0.021). At V̇O₂ peak, CLSs developed lower relative exercise power (3.2 ± 0.9 vs. 4.0 ± 0.7 W/kg, p = 0.012).

CONCLUSION

CLSs reported higher levels of physical activity but they attained maximal fat oxidation at lower relative oxygen uptake and applied lower relative power at V̇O₂ peak. CLSs may thus have lower muscular efficiency, causing greater fatigability in response to exercise, possibly related to chemotherapy exposure during adolescence and childhood. Long-term follow-up is essential and regular physical activity needs to be sustained.