Effects of graded heat stress on global left ventricular function and twist mechanics at rest and during exercise in healthy humans
Stöhr, Eric J.
MetadataShow full item record
Increased left ventricular (LV) twist and untwisting (LV twist mechanics) contribute to the maintenance of stroke volume during passive heat stress. However, it remains unknown whether changes in LV twist mechanics are related to the magnitude of heat stress and whether performing exercise during heat stress alters this response. We examined global LV function and LV twist mechanics in 10 healthy men at baseline and three progressive levels of heat stress, at rest and during knee-extensor exercise. At rest, heat stress increased cardiac output and reduced end-diastolic volume and end-systolic volume, whilst stroke volume and mean arterial pressure (MAP) were maintained. Left ventricular twist and untwisting velocity also increased from baseline to severe heat stress (from 10.6 ± 3.3 to 15.1 ± 5.2 deg and from −123 ± 55 to −210 ± 49 deg s−1, respectively, both P < 0.01) and correlated significantly with body temperature, heart rate and LV volumes (P < 0.05). Similar to resting conditions, progressive heat stress during exercise increased cardiac output and reduced end-diastolic volume and end-systolic volume with a maintained stroke volume. However, MAP declined (P < 0.01) and there was no significant change in LV twist and untwisting velocity, resulting in non-significant relationships between twist mechanics and systemic responses. In conclusion, LV twist mechanics increase proportionally with the magnitude of heat stress at rest. However, there is no increase in LV twist and untwisting velocity from control exercise to severe heat stress during exercise despite a significant increase in body temperatures and cardiac output. We, therefore, suggest that the maintenance of stroke volume in the combined conditions of heat stress and small muscle mass exercise may be further facilitated by other peripheral factors, such as the continuous decline in MAP.
Stöhr, E.J., González‐Alonso, J., Pearson, J., Low, D.A., Ali, L., Barker, H. and Shave, R. (2011) 'Effects of graded heat stress on global left ventricular function and twist mechanics at rest and during exercise in healthy humans', Experimental physiology, 96(2), pp.114-124.
This article was published in Experimental Physiology on 23 November 2010 (online), available at http://dx.doi.org/10.1113/expphysiol.2010.055137
- Sport Research Groups 
Showing items related by title, author, subject and abstract.
Stöhr, Eric J.; Stembridge, Mike; Shave, Rob; Samuel, Jake; Stone, Keeron J.; Esformes, Joseph I. (Lippincott, Williams & Wilkins, 2017-05-16)PURPOSE: To improve the current understanding of the impact of resistance exercise on the heart, by examining the acute responses of left ventricular (LV) strain, twist and untwisting rate ('LV mechanics'). METHODS: LV ...
Williams, Alexandra; Shave, Rob; Cheyne, William; Eves, Neil (Wiley, 2017-02-11)Background. Sex differences in LV mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV hemodynamics. ...
The effects of exercise intensity vs. metabolic state on the variability and magnitude of left ventricular twist mechanics during exercise Armstrong, Craig; Samuel, Jake; Yarlett, Andrew; Cooper, Stephen-Mark; Stembridge, Mike; Stöhr, Eric J. (Public Library of Science, 2016-04-21)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, ...