Does postexercise modelled capillary blood flow accurately reflect cardiovascular effects by different exercise intensities?

作者：Stoecker F^*; Von Oldershausen C; Paternoster F K; Schulz T; Oberhoffer R

来源：Clinical Physiology and Functional Imaging, 2018, 38(3): 431-438.

DOI：10.1111/cpf.12434

• cycling exercise
• interval exercise
• local haemodynamic
• muscle oxygenation
• NIRS
• oxygen extraction

Blood flow (BF) in exercising muscles is an important factor for exercise capacity. Recently, a non-invasive method to estimate capillary BF (Q(cap)) was introduced. Using this method, the Fick principle is re-arranged by using relative differences in deoxygenated haemoglobin (HHb) as a surrogate for arteriovenous O-2 difference and pulmonary oxygen uptake (VO2) instead of muscular oxygen uptake. The aim of this study was to examine (I) the relationship between Q(cap) and exercise intensity during and following exercise, and (II) to critically reflect the Q(cap) approach. Seventeen male subjects completed six bouts of cycling exercise with different exercise intensities (40-90% peak oxygen uptake, VO2peak) in randomized order. VO2 and HHb were monitored continuously during the trail. Q(cap) was modelled bi-exponentially, and mean response time (MRT) was calculated during recovery as well as the dissociation of modelled VO2 and Q(cap) recovery kinetics (MRT/VO2). End-exercise Q(cap) increased continuously with exercise intensity. This also applied to MRT. Postexercise MRT/VO2 increased from 40 to 60% VO2peak but remained stable thereafter. The results show that Q(cap) response to exercise is linearly related to exercise intensity. This is presumably due to vasoactive factors like shear-stress or endothelial-mediated vasodilation. MRT/VO2 shows that postexercise Q(cap) is elevated for a longer period than VO2, which is representative for metabolic demand following exercise 70% VO2peak. This is a hint for prolonged local vasodilation. According to previous studies, Q(cap) could not be modelled properly in some cases, which is a limitation to the method and therefore has to be interpreted with caution.

• 出版日期2018-5