Related Experiment Video
Updated: Aug 13, 2026

Real-Time Electrocardiogram Monitoring During Treadmill Training in Mice
Published on: May 5, 2022
Hysteresis of electrocardiographic depolarization-repolarization intervals during dynamic physical exercise and
1Department of Sports Science, University of Wales-Swansea, Singleton Park, Swansea SA2 8PP, UK. m.j.lewis@swansea.ac.uk
Abstract:
The post-exercise electrocardiographic QT interval is shortened relative to that at similar heart rates during exercise or pre-exercise rest. This lag in QT adaptation to the recovering heart rate is described as "hysteresis". No previous studies have quantified the influence of ECG electrode placement on hysteresis following physical exercise. Six males and six females of similar age, mass and aerobic fitness undertook progressive sub-maximal bicycle exercise. A three-channel ECG was recorded continuously during pre-exercise, exercise and recovery. Beat-to-beat NN (cardiac interval) and QT(a) interval (Q wave onset to T wave apex) data were measured for each sinus heart beat. QT(a)-NN hysteresis was calculated as the difference in QT(a) magnitude at identical heart rates during the rest/exercise and post-exercise recovery periods. There were some significant (p < 0.05) between-channel and between-gender differences in calculated hysteresis values. Hysteresis was generally greatest during the second or third minute post-exercise; ranges of means for all channels were 10.9 +/- 11.7 ms to 25.5 +/- 16.8 ms (males) and 19.1 +/- 10.3 ms to 28.4 +/- 3.0 ms (females). For males only, hysteresis values calculated using channel 1 between 1 and 3 min post-exercise were generally significantly (p < 0.05) different to those between 4 and 10 min. Similar trends were observed in females. QT(a)-NN hysteresis is significantly affected by the locations of the ECG electrodes used to record the surface ECG. These results emphasize the need for standardization of ECG electrode placement in future investigations.
More Related Videos
09:23Confirmation of Myocardial Ischemia and Reperfusion Injury in Mice Using Surface Pad Electrocardiography
Published on: November 24, 2016
18:11A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
Published on: December 28, 2012
Related Concept Videos
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Electrocardiogram Fundamentals
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin to...
ECG Interpretation of Rhythms
Components of the Electrocardiogram
The primary components of a normal ECG waveform in Normal sinus rhythm(NSR) include the P wave, PR interval, QRS complex, ST segment, T wave, and occasionally a U wave.
ECG waveforms are divided by vertical and horizontal lines at standard intervals.
The horizontal axis measures time and rate, and the vertical axis measures amplitude or voltage. When...
Electrophysiology of Normal Cardiac Rhythm