{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,9]],"date-time":"2026-10-09T05:23:03Z","timestamp":1791523383117,"version":"4.3.4"},"reference-count":43,"publisher":"American Physiological Society","issue":"2","funder":[{"DOI":"10.13039\/501100000038","name":"Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada (Conseil de Recherches en Sciences Naturelles et en G\u00e9nie du Canada)","doi-asserted-by":"publisher","award":["250367-11"],"award-info":[{"award-number":["250367-11"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2018,2,1]]},"abstract":"<jats:p> Compromising oxygen delivery (O<jats:sub>2<\/jats:sub>D) during exercise requires compensatory vasodilatory and\/or pressor responses to protect O<jats:sub>2<\/jats:sub>D:demand matching. The purpose of the study was to determine whether compensatory vasodilation is absent in some healthy young individuals in the face of a sudden reduction in exercising forearm perfusion pressure and whether this affects the exercise pressor response. Twenty-one healthy young men (21.6\u2009\u00b1\u20092.0 yr) completed rhythmic forearm exercise at a work rate equivalent to 70% of their own maximal exercise vasodilation. During steady-state exercise, the exercising arm was rapidly adjusted from below to above heart level, resulting in a reduction in forearm perfusion pressure of \u221230.7\u2009\u00b1\u20090.9 mmHg. Forearm blood flow (ml\/min; brachial artery Doppler and echo ultrasound), mean arterial blood pressure (mmHg; finger photoplethysmography), and exercising forearm venous effluent (antecubital vein catheter) measurements revealed distinct compensatory vasodilatory differences. Thirteen individuals responded with compensatory vasodilation (509\u2009\u00b1\u2009128 vs. 632\u2009\u00b1\u2009136 ml\u00b7min<jats:sup>\u22121<\/jats:sup>\u00b7100 mmHg<jats:sup>\u22121<\/jats:sup>; P &lt; 0.001), while eight individuals did not (663\u2009\u00b1\u2009165 vs. 667\u2009\u00b1\u2009167 ml\u00b7min<jats:sup>\u22121<\/jats:sup>\u00b7100 mmHg<jats:sup>\u22121<\/jats:sup>; P = 0.6). Compensatory pressor responses between groups were not different (5.5\u2009\u00b1\u20095.5 and 9.7\u2009\u00b1\u20099.5 mmHg; P = 0.2). Forearm blood flow, O<jats:sub>2<\/jats:sub>D, and oxygen consumption were all protected in compensators (all P &gt; 0.05) but not in noncompensators, who therefore suffered compromises to exercise performance (6\u2009\u00b1\u200914 vs. \u221236\u2009\u00b1\u200929 N; P = 0.004). Phenotypic differences were not explained by potassium or nitric oxide bioavailability. In conclusion, both compensator and noncompensator vasodilator phenotype responses to a sudden compromise to exercising muscle blood flow are evident. Interindividual differences in the mechanisms governing O<jats:sub>2<\/jats:sub>D:demand matching should be considered as factors influencing exercise tolerance. <\/jats:p><jats:p> NEW &amp; NOTEWORTHY In healthy young individuals, compromising submaximally exercising muscle perfusion appears to evoke compensatory vasodilation to defend oxygen delivery. Here we report the absence of compensatory vasodilation in 8 of 21 such individuals, despite their vasodilatory capacity and increases in perfusion with increasing exercise intensity being indistinguishable from compensators. The absence of compensation impaired exercise tolerance. These findings suggest that interindividual differences in oxygen delivery:demand matching efficacy affect exercise tolerance and depend on the nature of a delivery:demand matching challenge. <\/jats:p>","DOI":"10.1152\/japplphysiol.00952.2016","type":"journal-article","created":{"date-parts":[[2017,7,13]],"date-time":"2017-07-13T20:25:25Z","timestamp":1499977525000},"page":"374-387","source":"Crossref","is-referenced-by-count":12,"title":["Absence of compensatory vasodilation with perfusion pressure challenge in exercise: evidence for and implications of the noncompensator phenotype"],"prefix":"10.1152","volume":"124","author":[{"given":"Robert F.","family":"Bentley","sequence":"first","affiliation":[{"name":"School of Kinesiology and Health Studies, Queen\u2019s University, Kingston, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeremy J.","family":"Walsh","sequence":"additional","affiliation":[{"name":"School of Kinesiology and Health Studies, 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