The effects of exercise intensity vs. metabolic state on the variability and magnitude of left ventricular twist mechanics during exercise

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Author
Armstrong, Craig
Samuel, Jake
Yarlett, Andrew
Cooper, Stephen-Mark
Stembridge, Mike
Stöhr, Eric J.
Date
2016-04-21Type
Article
Publisher
Public Library of Science
ISSN
1932-6203
Metadata
Show full item recordAbstract
Increased left ventricular (LV) twist and untwisting rate (LV twist mechanics) are essential responses of the heart to exercise. However, previously a large variability in LV twist mechanics during exercise has been observed, which complicates the interpretation of results. This study aimed to determine some of the physiological sources of variability in LV twist mechanics during exercise. Sixteen healthy males (age: 22 ± 4 years, O2peak: 45.5 ± 6.9 ml∙kg-1∙min-1, range of individual anaerobic threshold (IAT): 32–69% of O2peak) were assessed at rest and during exercise at: i) the same relative exercise intensity, 40%peak, ii) at 2% above IAT, and, iii) at 40%peak with hypoxia (40%peak+HYP). LV volumes were not significantly different between exercise conditions (P > 0.05). However, the mean margin of error of LV twist was significantly lower (F2,47 = 2.08, P < 0.05) during 40%peak compared with IAT (3.0 vs. 4.1 degrees). Despite the same workload and similar LV volumes, hypoxia increased LV twist and untwisting rate (P < 0.05), but the mean margin of error remained similar to that during 40%peak (3.2 degrees, P > 0.05). Overall, LV twist mechanics were linearly related to rate pressure product. During exercise, the intra-individual variability of LV twist mechanics is smaller at the same relative exercise intensity compared with IAT. However, the absolute magnitude (degrees) of LV twist mechanics appears to be associated with the prevailing rate pressure product. Exercise tests that evaluate LV twist mechanics should be standardised by relative exercise intensity and rate pressure product be taken into account when interpreting results.
Journal/conference proceeding
PLoS ONE;
Citation
Armstrong, C., Samuel, J., Yarlett, A., Cooper, S-M, Stembridge, M., Stöhr, E.J. (2016) 'The effects of exercise intensity vs. metabolic state on the variability and magnitude of left ventricular twist mechanics during exercise', PLoS ONE 11(4): e0154065. doi:10.1371/journal.pone.0154065
Description
This article was published open access in PLoS ONE on 21 April 2016 (online), available at http://dx.doi.org/10.1371/journal.pone.0154065
Rights
Creative Commons Attribution Licensehttps://creativecommons.org/licenses/by/4.0/Sponsorship
Cardiff Metropolitan University (Grant ID: Cardiff Metropolian (Internal))
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- Sport Research Groups [1083]
Except where otherwise noted, this item's license is described as Creative Commons Attribution License
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