Abstract
The aim of the study was to evaluate skeletal muscle oxygenation and exercise capacity in childhood cancer survivors (CCS), and assess their association, in comparison with healthy controls. Twenty-six CCS (12 male, 6 months-10 yrs after treatment, mean age 17.59 (IQR:5.21 yrs) and 26 matched control subjects were recruited. Subjects performed a maximal incremental cardiopulmonary exercise test (CPET) on a treadmill with measurement of VO(2)peak (peak oxygen uptake). Simultaneously, muscle oxygenation was measured in the gastrocnemius muscle via Near InfraRed Spectroscopy. Changes (µM) in deoxyhemoglobin (ΔHHb), total hemoglobin (ΔtHb), and tissue saturation index (ΔTSI) were calculated as the differences between maximal (ΔHHb/ΔtHb) or minimal (ΔTSI) exercise test- and rest values. CCS had a significantly lower VO(2)peak (-12.05 ml/kg/min, p < .001) compared to controls. CCS also demonstrated a significantly lower fractional O(2) extraction (ΔHHb) during CPET (10.81µM (IQR:10.51) vs. 14.66µM (IQR:14.23), p = .036). In a univariate stepwise linear regression analysis, a significant overall model fit was found with ΔHHb and HRmax explaining 32.6% of the variance in VO(2)peak among CCS. These results indicate that both central and peripheral limiting factors might contribute to lower CRF in CCS, therefore both should be considered when designing exercise interventions aimed to enhance CRF in CCS.