Author(s): HASSANEIN, Y., KHARBECH, M., TESO, M., DE POLI, R., SOARES, R., AL HAJ ZEN, A., MURIAS, J.M., Institution: WESTERN UNIVERSITY, Country: CANADA, Abstract-ID: 2538

INTRODUCTION:
Vascular occlusion testing (VOT) is widely used in combination with near-infrared spectroscopy (NIRS) and Doppler ultrasound for assessing microvascular (NIRS-VOT) and macrovascular (flow-mediated dilation, or %FMD) function. Few studies, with mixed results, have examined fitness- and sex-related differences at both microvascular and macrovascular levels in untrained and chronically endurance-trained males and females. Whereas NIRS-VOT can differentiate training status and sex-related differences in the response, FMD has shown less sensitivity to detect potential differences (1). Simultaneous assessment of FMD and NIRS-VOT may enable a more integrated evaluation of vascular health. Thus, this study aimed to examine how sex and training status influence vascular response, thereby providing insight into the mechanisms through which endurance training improves vascular health.
METHODS:
Thirteen trained (5 females) and 13 untrained (5 females) participants underwent a cycling incremental test to assess maximal oxygen uptake (V̇O₂max). On a second visit, a 5-minute cuff occlusion was applied to the upper arm to induce post-occlusion reactive hyperemia. Two vascular assessments were conducted simultaneously on the forearm. NIRS-derived flexor digitorum muscle reperfusion slope and brachial artery %FMD were assessed during a VOT. Microvascular function was evaluated by analyzing the reperfusion slope and area under the curve of the tissue oxygen saturation (StO₂) signal in the flexor digitorum muscle after the occlusion, and the brachial artery %FMD was assessed simultaneously. Resting artery diameters were also evaluated.
RESULTS:
Males and trained participants exhibited a steeper reperfusion slope compared to females (1.20±0.53 vs 0.85±0.44 StO₂/s, p<0.05) and untrained (1.36±0.55 vs 0.77±0.25 StO₂/s, p<0.01) participants, respectively. Neither fitness level nor sex differences (p>0.05) were observed in %FMD: untrained: males 7.4±2.3% and females 7.6±3.5%; trained: males 8.5±2.8% and females 8.1±3.8 %FMD. Trained females displayed a higher basal diameter (0.41±0.03 cm) compared to their untrained counterparts (0.27±0.06 cm) (p<0.05), while trained and untrained males displayed similar values (0.37±0.06 vs 0.37±0.05 cm, respectively; p>0.05). Sex differences were observed in the untrained (p<0.05) but not the trained (p>0.05) participants.
CONCLUSION:
Although no differences were observed using %FMD, training and sex differences were detected by the NIRS-VOT. Together, these findings highlight the importance of integrating macrovascular and microvascular assessments to achieve a more comprehensive evaluation of vascular function.
REFERENCE:
1- Rasica, L., Inglis, E. C., Iannetta, D., Soares, R. N., & Murias, J. M. (2022). Fitness Level- and Sex-Related Differences in Macrovascular and Microvascular Responses during Reactive Hyperemia. Medicine and science in sports and exercise, 54(3), 497–506. https://doi.org/10.1249/MSS.0000000000002806