Abstract
Background: Exercise intolerance is a common side-effect of treatment
for childhood leukemia and lymphoma and contributes to adverse health
and well-being during survivorship. While central, cardiovascular
contributors to fitness have been shown to be impaired, the peripheral
muscular factors have not been studied in this population. Therefore,
peripheral muscular function in children after leukemia and lymphoma
treatment remains unstudied. Procedure: Eleven leukemia and lymphoma
patients aged 8-18 years old who completed treatment 6-36 months prior
and 11 healthy controls were included in analysis.
31P-MRS was used to characterize muscle bioenergetic
metabolism at rest and after in-magnet knee extension exercise. General
exercise capacity was assessed using a submaximal graded treadmill test
and overall physical activity participation was assessed using the
Habitual Activity Estimation Scale (HAES). Results: The patients treated
for leukemia and lymphoma exhibited lower anaerobic function (d=0.72),
slower metabolic recovery (d=0.93), and lower mechanical muscle power
(d=1.09) during in-magnet knee extension exercise compared with the
healthy control group. Lower estimated VO2peak (41.61 ±
5.97 vs. 47.71 ± 9.99 ml.min-1.kg-1,
d=0.76), lower self-reported minutes of physical activity (58.3 ± 35.3
vs. 114.8 ± 79.3 minutes, d=0.99) and higher minutes of inactivity
(107.3 ± 74.0 vs. 43.5 ± 48.3 minutes, d=1.04, p<0.05) were
also observed in the patient group. Conclusions: Children treated for
leukemia and lymphoma exhibit altered peripheral skeletal muscle energy
metabolism in addition to previously reported central cardiovascular
limitations during exercise. It is likely that both deconditioning and
direct effects of chemotherapy treatment contribute to exercise
intolerance in this population.