Maximal heart rate does not limit cardiovascular capacity in healthy humans: insight from right atrial pacing during maximal exercise. (2nd December 2013)

• Record Type: Journal Article
• Authors: Munch, G. D. W.; Svendsen, J. H.; Damsgaard, R.; Secher, N. H.; González‐Alonso, J.; Mortensen, S. P.
• Is Part Of: Journal of physiology. Volume 592:Number 2(2014:Jan.)
• Page Start: 377
• Page End: 390
• Publication Date: 2013-12-02
• Subjects: Physiology -- Periodicals; 612.005
• DOI: 10.1113/jphysiol.2013.262246
• Languages: English
• ISSNs: 0022-3751

Abstract

<abstract abstract-type="highlights"> <title>Key points</title> <p> <list id="tjp5968-list-0001" list-type="bullet"> <list-item> <p>During high intensity whole‐body exercise, systemic and contracting skeletal muscle O<sub>2</sub> delivery and uptake (<alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sqs9g4w" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:00223751:tjp5968:equation:tjp5968-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>̇</mml:mo></mml:mover><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:msub></mml:math></alternatives>) are compromised, but the underlying mechanisms remain unclear.</p> </list-item> <list-item> <p>We evaluated the effect of a ∼20 beats min<sup>−1</sup> increase in heart rate (HR) by right atrial pacing during incremental cycling and knee‐extensor exercise on cardiac output (<alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sqs9hj1" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:00223751:tjp5968:equation:tjp5968-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>Q</mml:mi><mml:mo>̇</mml:mo></mml:mover></mml:math></alternatives>) and stroke volume (SV).</p> </list-item> <list-item> <p>An increase in HR during both exercise modalities did not alter <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sqs9hgx" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:00223751:tjp5968:equation:tjp5968-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>Q</mml:mi><mml:mo>̇</mml:mo></mml:mover></mml:math></alternatives> due to a proportional decrease in SV.</p> </list-item> <list-item> <p>The lower SV during atrial pacing in the cycling trial was associated with a diminished cardiac filling pressure, but similar arterial pressure.</p> </list-item> <list-item> <p>The results demonstrate that the human heart can achieve a higher HR than observed during maximal exercise, suggesting that HR<sub>max</sub> and myocardial work capacity do not limit cardiac performance in trained human subjects.</p> </list-item> <list-item> <p>Instead, restrictions in ventricular filling appear to compromise cardiac preload, SV and <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sqs9hdt" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:00223751:tjp5968:equation:tjp5968-math-0004" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mi>Q</mml:mi><mml:mo>̇</mml:mo></mml:mover></mml:math></alternatives> at exercise intensities close to <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg4sqs9hc8" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:00223751:tjp5968:equation:tjp5968-math-0005" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mover accent="true"><mml:mi>V</mml:mi><mml:mo>̇</mml:mo></mml:mover><mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi> max </mml:mi></mml:mrow></mml:msub></mml:math></alternatives>.</p> </list-item> </list> </p> </abstract>