Author(s): TESO, M., DE POLI, R., ÇABUK, R., ALMURIKHI, S., KHARBECH, M., SOARES, R.N., TOWNSEND, N., MURIAS, J.M., Institution: HAMAD BIN KHALIFA UNIVERSITY, Country: QATAR, Abstract-ID: 2094

INTRODUCTION:
Flow-mediated dilation (FMD) and NIRS-derived oxygen saturation (StO2) reperfusion slope are widely interpreted as markers of conduit artery endothelial function and vascular responsiveness at the macro- and microvascular levels, respectively. Integration of both techniques is useful to improve the detection of vascular adaptations to exercise training, especially when considering the potential influence of the exercise intensity domain. Thus, this study aimed to explore whether changes in FMD and NIRS-Reperfusion slope hemodynamic vascular adaptations occurred in response to intensity domain-specific endurance training.
METHODS:
39 healthy, sedentary adults (17 females) were randomly assigned to three age-, sex-, and V̇O2max-matched groups. Groups were assigned to continuous cycling training groups in the moderate (MOD) and heavy (HVY) intensity domains 3 times per week for 10 weeks, or to a no-exercise control group (CTRL). Aerobic fitness (V̇O2max) was assessed during a ramp-incremental test to volitional exhaustion. %FMD, and StO2 reperfusion slope were measured during a vascular occlusion test investigating the brachial artery and the flexor-digitorum muscle, respectively. All measures were performed before (pre) and after 10 weeks of training (post).
RESULTS:
CTRL showed no significant differences between pre and post for V̇O2max (38.5 ± 7.3 vs 36.7 ± 8.7 mL·kg-1·min-1; p = 0.15), %FMD (8.42 ± 3.07 vs 7.89 ± 4.44 %), and StO2 reperfusion slope (0.90 ± 0.38 vs 0.88 ± 0.40 StO2⋅s-1) (p > 0.05 for all variables). MOD and HVY groups showed similar increases in V̇O2max (mL·kg-1·min-1, MOD, pre = 33.5 ± 5.0 vs post = 36.5 ± 6.8; HVY, pre = 30.3 ± 7.6 vs post = 34.8 ± 7.9), %FMD (%, MOD, pre= 6.28 ± 2.10 vs post = 8.27 ± 3.23; HVY, pre = 5.73 ± 1.94 vs post= 7.32 ± 4.33), and StO2 reperfusion slope (StO2⋅s-1, MOD, pre = 0.96 ± 0.48 vs post = 1.23 ± 0.50; HVY, pre = 0.78 ± 0.34 vs post = 1.14 ± 0.40) (p < 0.05 for all variables) with no difference between groups and no interaction groups x time (p > 0.05 for all variables). Whereas at post, StO2 reperfusion slope showed a moderate correlation with V̇O2max (r = 0.66, p < 0.05), %FMD did not (r = 0.09, p = 0.19).
CONCLUSION:
Both %FMD, a marker of conduit artery endothelial function, and StO2 reperfusion slope, a marker of microvascular responsiveness, detected vascular adaptations following 10 weeks of endurance training, regardless of the training intensity domain. However, only the StO2 reperfusion slope showed a significant correlation with V̇O2max after training. These findings reinforce the importance of evaluating changes in vascular function through combined assessments of micro- and macrovascular responses to better characterize vascular adaptations associated with improvements in cardiorespiratory fitness in healthy individuals.