Related Experiment Video
Updated: Jun 5, 2026
A Novel Digital Platform for a Monitored Home-based Cardiac Rehabilitation Program
Published on: April 19, 2019
Heart rate responses during isometric exercises in patients undergoing a phase III cardiac rehabilitation program
Poliana H Leite1, Ruth C Melo, Marcelo F Mello
1Physical Therapy Departament, Laboratory of Cardiovascular Physical Therapy, Nuclear Research in Physical Exercise, São Carlos, São Carlos, SP, Brasil.
Insights
Low-intensity isometric contractions maintained over time elicit similar heart rate responses in cardiac patients as brief, high-intensity exercises. This finding is crucial for optimizing cardiac rehabilitation programs and understanding cardiovascular responses to different exercise types.
Area of Science:
- Cardiology
- Exercise Physiology
- Rehabilitation Medicine
Background:
- Cardiovascular responses to exercise depend on contraction type, intensity, and duration.
- Patients with coronary artery disease (CAD) or risk factors require tailored exercise protocols.
Purpose of the Study:
- To assess heart rate (HR) responses to varying isometric contraction intensities and durations in patients with CAD or risk factors.
- To compare HR variations during maximal (MVC) and submaximal (SMVC) isometric contractions.
Main Methods:
- Evaluated HR variation (ΔHR) during MVC (5 and 10 seconds) and SMVC (30% and 60% of MVC, until exhaustion) using a handgrip dynamometer.
- Measured cardiac vagal modulation (RMSSD index) at rest, during SMVC, and during recovery.
Main Results:
- Higher ΔHR observed with longer MVC (MVC-10 vs. MVC-5) and higher SMVC intensity (SMVC-60 vs. SMVC-30).
- RMSSD index decreased significantly during SMVC but returned to baseline post-contraction.
- No significant difference in ΔHR between prolonged submaximal and brief maximal contractions.
Conclusions:
- Prolonged, low-intensity isometric contractions yield comparable HR responses to brief, high-intensity contractions in CAD patients.
- Findings suggest that exercise duration may be as critical as intensity in modulating cardiovascular responses during isometric contractions in cardiac rehabilitation.
Background:
the magnitude of cardiovascular responses is dependent on the static and dynamic components as well as the duration and intensity of the contraction performed.
Objective:
to evaluate the heart rate responses to different percentages of isometric contractions in 12 patients (63 ± 11.6 years) with coronary artery disease and/or risk factors for coronary artery disease that were participating in a phase III cardiac rehabilitation program.
Methods:
heart rate variation (ΔHR) was evaluated during maximum (MVC, five and ten seconds in duration) and submaximal (SMVC, 30 and 60% of MVC-5, until muscle exhaustion) voluntary contraction, using a handgrip dynamometer. Additionally, the representative index of cardiac vagal modulation (RMSSD index) was calculated at rest (pre-contraction), at the final 30 seconds of SMVC and during recovery (post-contraction).
Results:
ΔHR showed higher values in MVC-10 versus MVC-5 (17 ± 5.5 vs 12 ± 4.2 bpm, p<0.05) and the SMVC-60 vs SMVC-30 (19 ± 5.8 vs 15 ± 5.1 bpm, p<0.05). However, results for CVM-10 showed similar ΔHR compared to results for CVSM (p> 0.05). RICVM at rest decreased (p<0.05) during SMVC-30 (30% = 27.9 ± 17.1 vs 12.9 ± 8.5 ms) and SMVC-60 (60% =25.8 ± 18.2 vs 9.96 ± 4.2 ms), but returned to the baseline values when the contraction was interrupted.
Conclusions:
in patients with coronary artery disease and/or risk factors for coronary heart disease, low intensity isometric contraction, maintained over long periods of time, presents the same effect on the responses of HR, compared to a high intensity or maximal isometric contraction of briefly duration.
More Related Videos
07:44Evaluation of Changes in Hydration and Body Cell Mass with Bioelectrical Impedance Analysis after Exercise Program for Rheumatoid Arthritis Patients
Published on: July 14, 2023
07:40Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training
Published on: October 10, 2019
Related Concept Videos
01:20Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
01:19Cardiac Output I:Effect of Heart Rate on 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...
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
01:26Exercise Stress Test
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
01:26Heart Failure III: Clinical Manifestations
01:17Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...