Related Experiment Video
Updated: Jul 13, 2026

07:26
Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans
Published on: October 17, 2018
Chronotropic incompetence in clinical exercise testing.
The American Journal of Cardiology
|July 1, 1984
Summary
Chronotropic incompetence, an impaired heart rate response during exercise, is a specific indicator of obstructive coronary artery disease (CAD). This finding can help identify patients with CAD, especially those with unclear exercise test results.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Chronotropic incompetence (CI) is a known predictor of obstructive coronary artery disease (CAD).
- A clear definition of normal heart rate response to exercise is lacking, hindering CI diagnosis.
- This study aimed to define normal heart rate responses and evaluate CI in patients undergoing exercise stress tests.
Purpose of the Study:
- To establish normal heart rate responses to progressive exercise.
- To define chronotropic incompetence based on these normal responses.
- To assess the prevalence and specificity of chronotropic incompetence in patients with and without coronary artery disease.
Main Methods:
- Evaluated 312 patients undergoing exercise stress tests and coronary angiography.
- Defined normal heart rate response using data from 140 healthy subjects (mean +/- 2 standard deviations).
- Analyzed exercise heart rates in 172 patients with CAD to identify those with CI.
Main Results:
- Chronotropic incompetence was identified in 16 of 172 patients (9.3%) with CAD.
- Among patients without significant ST-segment changes and not reaching 85% of predicted heart rate, 13 of 65 (20%) exhibited CI.
- Patients with CI and CAD exercised longer (9.4 METs) than those without CI (7.0 METs), p < 0.01.
Conclusions:
- Chronotropic incompetence is infrequent but specific for coronary artery disease.
- CI can aid in detecting CAD in patients with indeterminate exercise stress tests.
- Establishing normal heart rate response parameters is crucial for accurate CI diagnosis.
Related Concept Videos
Decreased pulse rate
Bradycardia is a medical condition in which the heart rate is slower than normal. It occurs when the heart's natural pacemaker, the sinus node, generates slower electrical impulses than the standard rhythm. In adults, bradycardia is diagnosed when the pulse rate falls below 60 beats per minute, indicating a deviation from the normal heart rate range.
There are specific risk factors that can elevate the likelihood of developing bradycardia. Advanced age is a significant factor, with bradycardia...
There are specific risk factors that can elevate the likelihood of developing bradycardia. Advanced age is a significant factor, with bradycardia...
Exercise and Cardiac Output
Regular physical activity is essential for maintaining cardiovascular health, with aerobic exercises being particularly effective. According to the American Heart Association, 150 minutes of moderate to intense aerobic exercise per week is recommended for a healthy heart. Aerobic activities may include brisk walking, running, bicycling, cross-country skiing, and swimming, ideally performed three to five times per week.
Sustained exercise increases the muscles' oxygen demand, which can be met...
Sustained exercise increases the muscles' oxygen demand, which can be met...
Imbalances in Cardiac Output
The heart's primary function is to pump blood throughout the body, maintaining a balance between blood sent out (cardiac output) and blood returning (venous return). If this balance is disrupted, it can result in congestive heart failure (CHF), a severe condition where the heart becomes an inefficient pump, leading to inadequate blood circulation.
CHF can occur due to the failure of either side of the heart. Left-side failure leads to pulmonary congestion—the right side continues to send blood...
CHF can occur due to the failure of either side of the heart. Left-side failure leads to pulmonary congestion—the right side continues to send blood...
Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...
ECG Interpretation of Arrhythmias I: Sinus Arrhythmias
Arrhythmias are disturbances in the heart's rhythm that lead to abnormal heartbeats. These irregularities can originate from different parts of the heart and are classified based on their origin and nature.
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism, and...
Exercise Stress Test
Introduction
Exercise stress testing, commonly known as a treadmill test, is a noninvasive procedure used to evaluate cardiovascular function and diagnose heart conditions.
Definition
An exercise stress test measures the heart's response to exertion using a treadmill or stationary bicycle. Chest electrodes record the heart's electrical activity through an ECG, and blood pressure is monitored regularly.
Purposes
Exercise stress testing, commonly known as a treadmill test, is a noninvasive procedure used to evaluate cardiovascular function and diagnose heart conditions.
Definition
An exercise stress test measures the heart's response to exertion using a treadmill or stationary bicycle. Chest electrodes record the heart's electrical activity through an ECG, and blood pressure is monitored regularly.
Purposes

