Ramsook Andrew H, Peters Carli M, Leahy Michael G, Archiza Bruno, Mitchell Reid A, Jasinovic Tin, Koehle Michael S, Guenette Jordan A, Sheel A William
Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
Centre for Heart Lung Innovation, University of British Columbia and St Paul's Hospital, Vancouver, British Columbia, Canada.
Exp Physiol. 2020 Dec;105(12):2226-2237. doi: 10.1113/EP089045. Epub 2020 Nov 18.
What is the central question of this study? How does sternocleidomastoid blood flow change in response to increasing ventilation and whole-body exercise intensity? What is the main finding and its importance? Sternocleidomastoid blood flow increased with increasing ventilation. For a given ventilation, sternocleidomastoid blood flow was lower during whole-body exercise compared to resting hyperpnoea. These findings suggest that locomotor muscle work exerts an effect on respiratory muscle blood flow that can be observed in the sternocleidomastoid.
Respiratory muscle work influences the distribution of blood flow during exercise. Most studies have focused on blood flow to the locomotor musculature rather than the respiratory muscles, owing to the complex anatomical arrangement of respiratory muscles. The purpose of this study was to examine how accessory respiratory (i.e. sternocleidomastoid, and muscles in the intercostal space) muscle blood flow changes in response to locomotor muscle work. Seven men performed 5 min bouts of constant load cycling exercise trials at 30%, 60% and 90% of peak work rate in a randomized order, followed by 5 min bouts of voluntary hyperpnoea (VH) matching the ventilation achieved during each exercise (EX) trial. Blood-flow index (BFI) of the vastus lateralis, sternocleidomastoid (SCM) and seventh intercostal space (IC) were estimated using near-infrared spectroscopy and indocyanine green and expressed relative to resting levels. BFI was greater during VH compared to EX (P = 0.002) and increased with increasing exercise intensity (P = 0.036). BFI reached 493 ± 219% and 301 ± 215% rest during VH and EX at 90% peak work rate, respectively. BFI increased to 242 ± 178% and 210 ± 117% rest at 30% peak work rate during VH and EX, respectively. No statistically significant differences in BFI were observed with increased work rate during VH or EX (both P > 0.05). Moreover, there was no observed difference in BFI between conditions (P > 0.05). BFI was lower for a given minute ventilation during EX compared to VH, suggesting that accessory respiratory muscle blood flow is influenced by whole-body exercise.
本研究的核心问题是什么？胸锁乳突肌血流量如何随通气量增加和全身运动强度增加而变化？主要发现及其重要性是什么？胸锁乳突肌血流量随通气量增加而增加。在给定通气量下，与静息性通气过度相比，全身运动时胸锁乳突肌血流量较低。这些发现表明，运动肌肉的工作对呼吸肌血流量有影响，这在胸锁乳突肌中可以观察到。
呼吸肌工作会影响运动过程中的血流分布。由于呼吸肌复杂的解剖结构，大多数研究都集中在流向运动肌肉组织的血流，而非呼吸肌。本研究的目的是研究辅助呼吸肌（即胸锁乳突肌和肋间肌）血流量如何随运动肌肉工作而变化。7名男性以随机顺序进行了3次持续5分钟的恒定负荷骑行运动试验，运动强度分别为峰值工作率的30%、60%和90%，随后进行5分钟的自主通气过度（VH），通气量与每次运动（EX）试验中的通气量匹配。使用近红外光谱和吲哚菁绿估计股外侧肌、胸锁乳突肌（SCM）和第七肋间间隙（IC）的血流指数（BFI），并相对于静息水平表示。与EX相比，VH期间BFI更高（P = 0.002），且随运动强度增加而增加（P = 0.036）。在峰值工作率90%时，VH和EX期间BFI分别达到静息时的493±219%和301±215%。在峰值工作率30%时，VH和EX期间BFI分别增加到静息时的242±178%和210±117%。在VH或EX期间，随着工作率增加，BFI未观察到统计学上的显著差异（均P>0.05）。此外，不同条件下BFI未观察到差异（P>0.05）。与VH相比，EX期间在给定分钟通气量下BFI较低，表明辅助呼吸肌血流量受全身运动影响。
