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Characterization of electrocardiogram changes throughout a marathon
Vanessa Franco1, Clifton Callaway, David Salcido
1Department of Emergency Medicine, University of Pittsburgh, Iroquois 400A, 3600 Meyran Avenue, Pittsburgh, PA, 15261, US, vfranco@mednet.ucla.edu.
Insights
Cardiovascular physiology during marathons shows increased heart rate variability and T-wave alternans (TWA) as the race progresses. These changes appear to be physiological, with no cardiac events observed in runners.
Area of Science:
- Cardiovascular physiology
- Exercise science
- Sports medicine
Background:
- Limited data exists on cardiovascular physiological changes during marathon running.
- Continuous electrocardiographic monitoring provides insights into cardiac function during endurance events.
Purpose of the Study:
- To continuously characterize electrocardiographic activity throughout a marathon.
- To investigate changes in heart rate, heart rate variability, and T-wave characteristics during marathon running.
Main Methods:
- 19 marathon runners (14 men, 5 women; age 39 ± 16 years) were monitored using Holter devices.
- Continuous evaluation of heart rate (HR), heart rate variability (HRV), T-wave amplitude, T-wave amplitude variability, and T-wave alternans (TWA) throughout the race.
- Data analyzed for changes occurring during the marathon and immediately post-race.
Main Results:
- Heart rate variability (HRV), T-wave amplitude variability, and T-wave alternans (TWA) increased progressively throughout the marathon.
- Complex oscillatory patterns and TWA were observed in 86% of subjects, indicating increased T-wave amplitude variability.
- Post-marathon, heart rate (HR) was elevated and HRV was suppressed compared to pre-marathon levels.
Conclusions:
- Both HRV and T-wave amplitude variability, particularly TWA, increase during marathon running.
- The observed increase in TWA is likely a physiological adaptation to prolonged exertion, as no arrhythmias or cardiac events were detected.
- Continuous ECG monitoring reveals dynamic cardiovascular adaptations during endurance events.
Purpose:
There are few data examining cardiovascular physiology throughout a marathon. This study was devised to characterize electrocardiographic activity continuously throughout a marathon.
Methods:
Cardiac activity was recorded from 19 subjects wearing a Holter monitor during a marathon. The 19 subjects (14 men and 5 women) were aged 39 ± 16 years (mean ± SD) and completed a marathon in 4:32:16 ± 1:23:35. Heart rate (HR), heart rate variability (HRV), T-wave amplitude, T-wave amplitude variability, and T-wave alternans (TWA) were evaluated continuously throughout the marathon.
Results:
Averaged across all subjects, HRV, T-wave amplitude variability, and TWA increased throughout the marathon. Increased variability in T-wave amplitude occurred in 86 % of subjects, characterized by complex oscillatory patterns and TWA. Three min after the marathon, HR was elevated and HRV was suppressed relative to the pre-marathon state.
Conclusion:
HRV and T-wave amplitude variability, especially in the form of TWA, increase throughout a marathon. Increasing TWA as a marathon progresses likely represents a physiologic process as no arrhythmias or cardiac events were observed.
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