Kylie N. Sears, Tony R. Montgomery, Colin W. Kipper, Petra Kis, Taylor K. Dinyer-McNeely, Shane M. Hammer
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This study determined if ETT is the highest intensity at which the contraction phase of intermittent exercise does not limit the matching of microvascular oxygen delivery to muscle oxygen demand.</p><h3 data-test=\"abstract-sub-heading\">Methods</h3><p>Microvascular oxygenation characteristics of the biceps brachii muscle were measured in sixteen young, healthy individuals (8M/8F, 22 ± 3 years, 80.9 ± 20.3 kg) by near-infrared spectroscopy during maximal effort elbow flexion under control conditions (CON) and with complete circulatory occlusion (OCC).</p><h3 data-test=\"abstract-sub-heading\">Results</h3><p>Increases in total-[heme] were blunted during OCC compared to CON (225 ± 87 vs. 264 ± 88 μM, <i>p</i> < 0.001) but OCC did not elicit a compensatory increase in deoxygenated-[heme] at any timepoint (108 ± 62 vs. 101 ± 61 μM, <i>p</i> > 0.05). Deoxygenated-[heme] was significantly elevated during contraction, relative to relaxation, above ETT (107 ± 60 vs. 98.8 ± 60.5 μM, <i>p</i> < 0.001), but not at ETT (91.7 ± 54.1 vs. 98.4 ± 62.2 μM, <i>p</i> = 0.174). Total-[heme] was significantly reduced during contraction, relative to relaxation, at all contraction intensities during CON (<i>p</i> < 0.05) and OCC (<i>p</i> < 0.05).</p><h3 data-test=\"abstract-sub-heading\">Conclusion</h3><p>These data suggest that ETT may reflect the highest contraction intensity at which contraction-induced increases in intramuscular pressures do not limit muscle perfusion to a degree that requires further increases in fractional oxygen extraction (i.e., deoxygenated-[heme]) despite limited microvascular diffusive conductance (i.e., total-[heme]).</p>","PeriodicalId":12005,"journal":{"name":"European Journal of Applied Physiology","volume":null,"pages":null},"PeriodicalIF":2.8000,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Muscle microvascular oxygen delivery limitations during the contraction phase of intermittent maximal effort contractions\",\"authors\":\"Kylie N. 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引用次数: 0
摘要
目的间歇最大力量收缩时的终点测试扭矩(ETT)反映了肌肉代谢稳态可达到的最高收缩强度。本研究确定了 ETT 是否是间歇运动收缩阶段不会限制微血管供氧与肌肉需氧量匹配的最高强度。方法对 16 名年轻健康人(8M/8F,22 ± 3 岁,80.9 ± 20.3 kg)的肱二头肌微血管氧合特征进行了测量。结果与控制条件(CON)相比,OCC 期间总[血红素]的增加减弱(225 ± 87 vs. 264 ± 88 μM,p < 0.001),但 OCC 在任何时间点都不会引起脱氧[血红素]的补偿性增加(108 ± 62 vs. 101 ± 61 μM,p > 0.05)。相对于舒张期,脱氧血红素在收缩期显著升高,高于 ETT(107 ± 60 vs. 98.8 ± 60.5 μM,p < 0.001),但在 ETT 期没有显著升高(91.7 ± 54.1 vs. 98.4 ± 62.2 μM,p = 0.174)。这些数据表明,ETT 可能反映了最高的收缩强度,在这种强度下,收缩引起的肌内压增加不会限制肌肉灌注到需要进一步增加部分氧萃取的程度(即......),而不会限制肌肉灌注到需要进一步增加部分氧萃取的程度(即......)、脱氧血红素])。
Muscle microvascular oxygen delivery limitations during the contraction phase of intermittent maximal effort contractions
Purpose
The end-test torque (ETT) during intermittent maximal effort contractions reflects the highest contraction intensity at which a muscle metabolic steady-state can be attained. This study determined if ETT is the highest intensity at which the contraction phase of intermittent exercise does not limit the matching of microvascular oxygen delivery to muscle oxygen demand.
Methods
Microvascular oxygenation characteristics of the biceps brachii muscle were measured in sixteen young, healthy individuals (8M/8F, 22 ± 3 years, 80.9 ± 20.3 kg) by near-infrared spectroscopy during maximal effort elbow flexion under control conditions (CON) and with complete circulatory occlusion (OCC).
Results
Increases in total-[heme] were blunted during OCC compared to CON (225 ± 87 vs. 264 ± 88 μM, p < 0.001) but OCC did not elicit a compensatory increase in deoxygenated-[heme] at any timepoint (108 ± 62 vs. 101 ± 61 μM, p > 0.05). Deoxygenated-[heme] was significantly elevated during contraction, relative to relaxation, above ETT (107 ± 60 vs. 98.8 ± 60.5 μM, p < 0.001), but not at ETT (91.7 ± 54.1 vs. 98.4 ± 62.2 μM, p = 0.174). Total-[heme] was significantly reduced during contraction, relative to relaxation, at all contraction intensities during CON (p < 0.05) and OCC (p < 0.05).
Conclusion
These data suggest that ETT may reflect the highest contraction intensity at which contraction-induced increases in intramuscular pressures do not limit muscle perfusion to a degree that requires further increases in fractional oxygen extraction (i.e., deoxygenated-[heme]) despite limited microvascular diffusive conductance (i.e., total-[heme]).
期刊介绍:
The European Journal of Applied Physiology (EJAP) aims to promote mechanistic advances in human integrative and translational physiology. Physiology is viewed broadly, having overlapping context with related disciplines such as biomechanics, biochemistry, endocrinology, ergonomics, immunology, motor control, and nutrition. EJAP welcomes studies dealing with physical exercise, training and performance. Studies addressing physiological mechanisms are preferred over descriptive studies. Papers dealing with animal models or pathophysiological conditions are not excluded from consideration, but must be clearly relevant to human physiology.