Mechanical Synchrony in Long-Distance Runners: Importance of Previous Exposure to Endurance Races
Prolonged exercise has been shown to lead to elevated levels of cardiac troponin and altered cardiac function on echocardiography. It is not known if cardiac synchrony is altered by prolonged exercise. The aims of this study were to assess changes in intra-left ventricular mechanical synchrony and circulating levels of cardiac troponin following prolonged exercise and to evaluate the importance of prior exposure to endurance racing.
Forty-three male participants in a 30-km cross-country race (20 new participants at this event [median, 3 previous endurance races] age matched against 23 repeat participants [median, 31 previous endurance events]) were assessed prospectively 1 to 2 days before and 24 hours after the race using troponin T and Doppler tissue imaging analyzing the standard deviation of time to peak myocardial systolic velocity (T(s)-SD) in a six-basal, six-midventricular segment model measuring myocardial synchrony. The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene was also analyzed, as I allele carriers reportedly have superior endurance performance, while the D allele predisposes to renin-angiotensin system-induced cardiac remodeling.
Prerace troponin T was undetectable in all runners, and postrace levels were higher in new runners (median, 0.03 microg/L; interquartile range [IQR], 0.01-0.04 microg/L) than in repeat runners (median, 0.01 microg/L; IQR, 0.01-0.02 microg/L) (P = .03). Although new and repeat runners had similar T(s)-SD at baseline (32 msec [IQR, 22-43 msec] vs 34 msec [IQR, 29-45 msec], P = .13), dyssynchrony increased only in new runners (40 msec [IQR, 31-47 msec], P < .001; in repeat runners, median, 38 msec [IQR, 29-43 msec], P = .30; median relative difference, +13% vs +5%, P = .02). ACE genotype distribution was similar in both groups. Multivariate analysis showed that (1) a lack of prior endurance exposure; (2) more copies of the ACE D allele; and (3) lower peak systolic velocity were independent predictors of postrace dyssynchrony (P < .05 for all).
Prolonged exertion increased ventricular mechanical dyssynchrony in new endurance participants and in ACE D allele carriers. The long-term impact of such changes warrants future study.
Available from: David Oxborough
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ABSTRACT: Prolonged endurance exercise in humans has been associated with an acute impairment in diastolic and systolic cardiac function and the release of cardiac troponin. In this chapter, we review recent evidence from studies using novel echocardiographic parameters and highly sensitive cardiac troponin assays. We demonstrate that the mechanics of left and right ventricular functions are acutely impaired after completion of prolonged exercise and that this reduction in function is likely multifactorial in etiology. However, we highlight that exercise-induced cardiac troponin release is not a marker of exercise-induced pathology but likely a physiologic response to exercise. Finally, we discuss the potential link between prolonged exercise and the increased incidence of cardiac pathology in veteran athletes.
Progress in cardiovascular diseases 03/2012; 54(5):407-15. DOI:10.1016/j.pcad.2012.01.007 · 4.25 Impact Factor
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ABSTRACT: Exercise can lead to release of biomarkers such as cardiac troponin T (cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP), a poorly understood phenomenon proposed to especially occur with high-intensity exercise in less trained subjects. We hypothesised that haemodynamic perturbations during exercise are larger in athletes with cTnT release, and studied athletes with detectable cTnT levels after an endurance event (HIGH; n = 16; 46 ± 9 years) against matched controls whose levels were undetectable (LOW; n = 11; 44 ± 7 years). Echocardiography was performed at rest and at peak supine bicycle exercise stress. Left ventricular (LV) end-systolic elastance (E (LV) a load-independent measure of LV contractility), effective arterial elastance (E (A) a lumped index of arterial load) and end-systolic meridional wall stress were calculated from cardiac dimensions and brachial blood pressure. Efficiency of cardiac work was judged from the ventriculo-arterial coupling ratio (E (A)/E (LV): optimal range 0.5-1.0). While subgroups had similar values at rest, we found ventriculo-arterial mismatch during exercise in HIGH subjects [0.47 (0.39-0.58) vs. LOW: 0.73 (0.62-0.83); p < 0.01] due to unopposed increase in E (LV) (p < 0.05). In LOW subjects, a greater increase occurred in E (A) during exercise (+81 ± 67 % vs. HIGH: +39 ± 32 %; p = 0.02) which contributed to a maintained coupling ratio. Subjects with higher baseline NT-proBNP had greater systolic wall stress during exercise (R (2) = 0.39; p < 0.01) despite no correlation at rest (p = ns). In conclusion, athletes with exercise-induced biomarker release exhibit ventriculo-arterial mismatch during exercise, suggesting non-optimal cardiac work may contribute to this phenomenon.
Arbeitsphysiologie 04/2012; 112(12). DOI:10.1007/s00421-012-2396-7 · 2.19 Impact Factor
Available from: Young Joo Kim
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The aim of this study was to observe the changes in endothelial and inflammatory markers in middle-aged male runners with exercise-induced hypertension (EIH) at baseline and at 100-km, 200-km, and 308-km checkpoints during a prolonged endurance ultramarathon.
Among a total of 62 ultramarathon volunteers, 8 with systolic blood pressure higher than 210 mm Hg and 8 with normal systolic blood pressure were selected for this study. The subjects were designated to EIH and control (CON) groups. Blood was collected for the analysis of soluble vascular cell adhesion molecule-1, soluble E-selectin, leukocytes, creatine kinase, and high-sensitivity C-reactive protein.
Soluble vascular cell adhesion molecule-1 showed a significantly greater increase in the EIH group than in the CON group at 100 km and 200 km. Soluble E-selectin also showed a significantly greater increase in the EIH group than in the CON group at 100 km. Leukocytes significantly increased in the EIH group than in the CON group at 308 km. Creatine kinase and high-sensitivity C-reactive protein showed no group differences.
Leukocytes, creatine kinase, and high-sensitivity C-reactive protein showed delayed-onset increases in both groups. Increased exercise intensity may stimulate greater endothelial responses independent of the inflammatory markers in EIH. The loss of a protective effect may be greater in those with EIH than in CONs. Acknowledging and prescribing proper exercise intensity may be critical in preventing possible vascular-related complications in runners with EIH.
American journal of physical medicine & rehabilitation / Association of Academic Physiatrists 06/2013; 92(6):513-522. DOI:10.1097/PHM.0b013e31829232db · 2.20 Impact Factor
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