Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: This study aimed to clarify the effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during exercise. METHODS: Twelve young males randomly completed two trials (rest and exercise [leg cycling at 40% peak oxygen uptake] trials) on separate days. In each trial, the internal carotid artery (ICA), an index of cerebral circulation, was measured using Doppler ultrasound 2min after inspiratory loading breathing (IL condition) or non-loading breathing (control condition). During ICA assessments, participants engaged in 3min of spontaneous breathing (SB), followed by 3min of isocapnic hyperventilation (IHV). RESULTS: ICA conductance was lower in the IL condition than in the control condition in both rest and exercise trials. Inspiratory mucle metaboreflex did not reduce ICA blood flow during SB but decreased it during IHV in both trials. CONCLUSION: Our findings suggest that inspiratory muscle metaboreflex could decrease cerebrovascular conductance from rest to light-intensity exercise and attenuates cerebral blood flow with increased respiratory muscle work.

DOI： 10.1016/j.resp.2025.104422

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Exercise-induced increases in shear rate (SR) acutely improve peripheral endothelial function, but the presence of this mechanism in cerebral arteries remains unclear. Thus, we evaluated shear-mediated dilation of the internal carotid artery (ICA), which is an index of cerebrovascular endothelial function, before and after exercise. Shear-mediated dilation was measured with 30 s of hypercapnia in 16 young adults before and 10 min after 30 min of sitting rest (CON) or three cycling exercises on four separate days. The target exercise intensity was 80% of oxygen uptake at the ventilatory threshold. To manipulate the ICA SR during exercise, participants breathed spontaneously (ExSB, SR increase) or hyperventilated without (ExHV, no increase in SR) or with ([Formula: see text], restoration of SR increase) addition of CO2 to inspiratory air. Shear-mediated dilation was calculated as a percent increase in diameter from baseline. Doppler ultrasound measures ICA velocity and diameter. The CON trial revealed that 30 min of sitting did not alter shear-mediated dilation (4.34 ± 1.37% to 3.44 ± 1.23%, P = 0.052). ICA dilation after exercise compared with preexercise levels increased in the ExSB trial (3.32 ± 1.37% to 4.74 ± 1.84%, P < 0.01), remained unchanged in the ExHV trial (4.07 ± 1.55% to 3.21 ± 1.48%, P = 0.07), but was elevated in the [Formula: see text] trial (3.35 ± 1.15% to 4.33 ± 2.12%, P = 0.04). Our results indicate that exercise-induced increases in cerebral shear may play a crucial role in improving cerebrovascular endothelial function after acute exercise in young adults.NEW & NOTEWORTHY We found that 30-min cycling (target intensity was 80% of the ventilatory threshold) with increasing shear of the internal carotid artery (ICA) enhanced transient hypercapnia-induced shear-mediated dilation of the ICA, reflecting improved cerebrovascular endothelial function. This enhancement of ICA dilation was diminished by suppressing the exercise-induced increase in ICA shear via hyperventilation. Our results indicate that increases in cerebral shear may be a key stimulus for improving cerebrovascular endothelial function after exercise in young adults.

DOI： 10.1152/japplphysiol.00543.2023

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PURPOSE: Postprandial hyperglycemia is assumed to have a negative impact on flow-mediated dilation (FMD), an index of endothelial function, and blood flow of the peripheral conduit arteries. This study aimed to determine whether the enhancement of postprandial hyperglycemia by skipping breakfast accelerates endothelial dysfunction and reduces the blood flow in the brachial artery in young men. METHODS: Using a randomized cross-over design, ten healthy men completed two trials: with and without breakfast (Eating and Fasting trials, respectively). Venous blood sampling and brachial FMD tests were conducted before, 30, 60, 90, and 120 min after a 75-g oral glucose tolerance test (OGTT). RESULTS: Skipping breakfast boosted post-OGTT glucose levels than having breakfast (P = 0.01). The magnitude of the decrease in FMD via OGTT did not vary between trials (main effect of trial P = 0.55). Although brachial blood flow tended to decrease after OGTT in both trials (interaction and main effect of time P = 0.61 and P = 0.054, respectively), the decrease in blood flow following OGTT was greater in the Fasting trial than in the Eating trial (main effect of trial, mean difference =  - 15.8 mL/min [95%CI =  - 25.6 to - 6.0 mL/min], P < 0.01). CONCLUSION: Skipping breakfast did not enhance the magnitude of the decrease in FMD following glucose loading, but did accelerate hyperglycemia-induced reduction in brachial blood flow. Current findings suggest that even missing one breakfast has negative impacts on the blood flow regulation of the peripheral conduit arteries in young men who habitually eat breakfast.

DOI： 10.1007/s00421-023-05273-6

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Language：Japanese   Publisher：(一社)日本基礎理学療法学会  

Ichushi

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Excessive arterial pressure elevation induced by resistance exercise (RE) attenuates peripheral vasodilatory function, but its effect on cerebrovascular function is unknown. We aimed to evaluate the effect of different pressor responses to RE on hypercapnia-induced vasodilation of the internal carotid artery (ICA), an index of cerebrovascular function. To manipulate pressor responses to RE, 15 healthy young adults (11M/4F) performed two RE: high intensity with low repetitions (HL) and low intensity with high repetitions (LH) dynamic knee extension. ICA dilation, induced by 3 min of hypercapnia, was measured before and 10 min after RE using Doppler ultrasound. HL exercise elicited a greater pressor response than LH exercise. In relaxation phases of RE, ICA blood velocity increased in both HL and LH trials. However, ICA shear rate did not significantly increase in either trial (P = 0.06). Consequently, neither exercise altered post-exercise hypercapnia-induced ICA dilation (HL, 3.9 ± 1.9% to 5.1 ± 1.7%; LH, 4.6 ± 1.4% to 4.8 ± 1.8%; P > 0.05 for all). When viewed individually, the changes in ICA shear rate were positively correlated with changes in end-tidal partial pressure of carbon dioxide (PETCO2) (r = 0.46, P < 0.01) than with mean arterial pressure (r = 0.32, P = 0.02). These findings suggest that the effects of RE-induced pressor response on cerebrovascular function may be different from peripheral arteries. An increase in PETCO2 during the relaxation phase may play a more crucial role than elevated pressure in increasing cerebral shear during dynamic RE.

DOI： 10.1007/s00421-022-05096-x

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Language：English   Publishing type：Research paper, summary (international conference)  

Web of Science

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Language：Japanese   Publisher：理学療法科学学会  

[Purpose] The aim of the present study was to investigate the effects of acute electric stimulation on flow-mediated vasomotor function. [Subjects and Methods] Eight young healthy men participated in this study. Electrical stimulation was applied to the right forearm for 30 minutes. Before and after electrical stimulation, flow-mediated dilation (FMD) and low flow-mediated constriction (L-FMC) were measured at the right brachial artery. [Results] FMD and L-FMC tended to increase after electrical stimulation, but no significant differences were observed between pre- and post-stimulation. In contrast, FMD+L-FMC significantly increased after electrical stimulation compared to before stimulation. [Conclusion] These results suggest that acute electric stimulation affects flow-mediated vasoconstrictor and dilator functions. Further studies are needed to elucidate the effect of electrical parameter settings on the vascular function.

DOI： 10.1589/rika.32.249

Ichushi

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Language：Japanese   Publisher：日本基礎理学療法学会学術誌局  

健常成人男性21名(22.4±1.9歳)を対象とした。漸増運動負荷試験により換気性作業閾値(VT)の80%の負荷量(80%VT)を算出し、80%VT強度での定常負荷運動にて弾性胸帯を使用しない条件(N条件)と、弾性胸帯を用いた胸部圧迫による胸郭制限を加えた条件(C条件)の2条件で、呼吸循環諸量の測定を行った。定常負荷運動前の胸郭制限前後において、肺活量は、胸郭制限前に対して胸郭制限後が有意に低値であった。胸郭制限前後での肺活量の低下率は16.3±7.7%であった。自覚的運動強度を両条件間で比較し、安静時から定常負荷運動9分にかけてC条件がN条件よりも高い値を示した。心拍数は、定常負荷運動開始から両条件ともに増加し、定常負荷運動終了にかけてC条件がN条件に対して有意に高かった。LF/HFは、C条件で定常負荷運動開始から増加し、定常負荷運動終了にかけてN条件に対して有意に高値を示した。

Ichushi

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Language：English   Publishing type：Research paper, summary (international conference)  

DOI： 10.1249/01.mss.0000485587.76585.f6

PubMed

Web of Science

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Language：Japanese   Publisher：日本基礎理学療法学会学術誌局  

Ichushi

J-GLOBAL

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