Cardiff Metropolitan University
13 - 1346_1_merged_1489185827.pdf (996.56 kB)

Reduced blood flow through intrapulmonary arteriovenous anastomoses during exercise in lowlanders acclimatizing to high altitude

Download (996.56 kB)
journal contribution
posted on 2022-12-12, 16:39 authored by Lindsey M. Boulet, Andrew T. Lovering, Michael M. Tymko, Trevor A. Day, Michael StembridgeMichael Stembridge, Trang Anh Nguyen, Philip N. Ainslie, Glen E. Foster

 Blood flow through intrapulmonary arteriovenous anastomoses ( is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. After high altitude (HA) acclimatization, resting is similar to that at SL, but it is unknown whether this is true during exercise at HA. We reasoned that exercise at HA (5050 m) would exacerbate as a result of heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL [25, 50 and 75% of SL peak oxygen consumption (] and at HA (25 and 50% of SL Echocardiography was used to determine cardiac output ( and pulmonary artery systolic pressure (PASP), and agitated saline contrast was used to determine (bubble score; 0–5). The principal findings were as follows: (i) was similar at SL rest (3.9 ± 0.47 l min−1) compared with HA rest (4.5 ± 0.49 l min−1; P = 0.382), but increased from rest during both SL and HA exercise (P < 0.001); (ii) PASP increased from SL rest (19.2 ± 0.7 mmHg) to HA rest (33.7 ± 2.8 mmHg; P = 0.001) and, compared with SL, PASP was further elevated during HA exercise (P = 0.003); (iii) was increased from SL rest (0) to HA rest (median = 1; P = 0.04) and increased from resting values during SL exercise (P < 0.05), but was unchanged during HA exercise (P = 0.91), despite significant increases in and PASP. Theoretical modelling of microbubble dissolution suggests that the lack of in response to exercise at HA is unlikely to be caused by saline contrast instability. 


Gouvernement du Canada | Natural Sciences and Engineering ResearchCouncil of Canada (Conseil de Recherches en Sciences Naturelles et en Génie duCanada): Glen E Foster, 2014-05643


Published in

Experimental Physiology




  • AM (Accepted Manuscript)


Boulet, L.M., Lovering, A.T., Tymko, M.M., Day, T.A., Stembridge, M., Nguyen, T.A., Ainslie, P.N. and Foster, G.E. (2017) 'Reduced blood flow through intrapulmonary arteriovenous anastomoses during exercise in lowlanders during acclimatization to high altitude', Experimental Physiology, 102 (6), pp. 670-683

Print ISSN


Electronic ISSN


Cardiff Met Affiliation

  • Cardiff School of Sport and Health Sciences

Cardiff Met Authors

Mike Stembridge

Cardiff Met Research Centre/Group

  • Cardiovascular Physiology

Copyright Holder

  • © The Publisher


  • en

Usage metrics

    Cardiovascular Health & Ageing - Journal Articles


    Ref. manager