Stroke Volume Explained: What It Is and How Exercise Can Help
Stroke volume is an important measure of how the heart functions. It describes how much blood the heart pumps with each beat and can provide useful information about cardiovascular health, exercise capacity and circulation.
Understanding stroke volume can help explain how the heart responds to exercise, why some people experience reduced exercise tolerance, and how tailored exercise can support cardiovascular function.
What is stroke volume?
Stroke volume (SV) is the amount of blood pumped out of the heart’s left ventricle with each heartbeat. It is usually measured in millilitres (mL).
Stroke volume is influenced by several factors, including:
Preload: how much blood fills the heart before it contracts.
Contractility: how strongly the heart muscle contracts.
Afterload: the resistance the heart must pump against.
Stroke volume also contributes to cardiac output — the total volume of blood the heart pumps each minute.
Cardiac output = Heart rate × Stroke volume
Together, these measures help explain how the cardiovascular system delivers oxygen to the body, both at rest and during exercise.
How is stroke volume measured?
Stroke volume can be estimated using an echocardiogram (heart ultrasound) and measured using other imaging techniques, such as cardiac MRI.
It is important to distinguish stroke volume from ejection fraction (EF). Ejection fraction describes the percentage of blood in the ventricle that is pumped out with each beat, whereas stroke volume describes the actual volume of blood ejected.
A person can have a normal ejection fraction but a relatively low stroke volume. Both measurements need to be interpreted in the context of the overall cardiac assessment.
What can cause a low stroke volume?
Stroke volume varies between individuals and can change depending on heart rate, body position, hydration, exercise and other physiological factors. A lower measurement does not automatically indicate a problem, but it may warrant further assessment when considered alongside symptoms or other clinical findings.
Possible causes include:
Heart muscle conditions: Conditions such as heart failure or cardiomyopathy can affect the heart’s ability to fill or pump blood effectively.
Heart valve disease: Conditions such as aortic stenosis can affect blood flow out of the heart.
Reduced circulating blood volume: Dehydration or low blood volume can reduce the amount of blood returning to the heart to be pumped with each beat.
Reduced heart filling: Differences in ventricular size, filling or relaxation can influence stroke volume, even when ejection fraction is preserved.
Circulatory conditions: Some people with postural orthostatic tachycardia syndrome (POTS) have been found to have reduced stroke volume. This is not the case for everyone with POTS.
The significance of a low stroke volume depends on the underlying cause, the measurement conditions and the person’s broader clinical picture.
How does exercise affect stroke volume?
During exercise, the body needs more oxygen, so the heart must pump more blood to the working muscles. It achieves this by increasing heart rate and stroke volume.
Regular exercise can improve cardiovascular fitness, support the heart’s ability to respond to increased demands, and improve the muscles’ ability to use oxygen efficiently.
The type and intensity of exercise will depend on a person’s health, fitness and clinical needs.
Aerobic exercise — such as walking, cycling or swimming — helps improve cardiovascular fitness and the body’s ability to sustain physical activity.
Resistance training helps build muscle strength and supports everyday function. Stronger muscles can also make physical tasks feel more manageable.
Exercise may not increase stroke volume in everyone, and improvements in fitness do not necessarily mean resting stroke volume will increase. The benefits depend on factors such as the person’s starting fitness, underlying health conditions and exercise program.
What if you have a cardiovascular condition?
Exercise can be beneficial for many people living with cardiovascular conditions, but the approach should be appropriate to their individual circumstances.
For example, people recovering from a heart attack, coronary artery bypass surgery or other cardiac procedures may benefit from a structured exercise program that gradually rebuilds fitness and confidence.
For some people with POTS or other conditions affecting circulation, exercise may need to begin in a seated or lying position, with progression guided by symptoms and recovery.
A tailored exercise program considers the person’s diagnosis, symptoms, medications, current capacity and goals. It is not about pushing harder — it is about finding an appropriate starting point and progressing safely.
How long does it take to see improvements?
Cardiovascular fitness can begin to improve over several weeks of consistent exercise, with further adaptations developing over time.
Progress will vary depending on the individual, their health and the type of training they undertake. Improvements may include better exercise tolerance, greater functional capacity and increased confidence with movement, even if resting stroke volume does not change significantly.
How CardioCare Clinic can help
At CardioCare Clinic, we provide individualised exercise physiology for cardiovascular health — from prevention and improving fitness to recovery following a cardiac event or procedure.
Your program is tailored to your health history, current capacity and goals, with the aim of helping you build strength, improve exercise tolerance and feel more confident with movement.
Looking after your heart doesn’t start with a diagnosis.
Learn more about our exercise physiology services.