This article was written by Sarah Ashcroft Accredited Exercise Physiologist (AEP), Accredited Exercise Scientist (AES), PhD. 

After a stroke, the brain and body may need to relearn skills such as moving, speaking, remembering, or completing everyday tasks. More than 475,000 Australians are living with the lasting effects of stroke, so finding ways to support recovery is important. Exercise is already recommended after stroke because it can improve strength, fitness, heart health and confidence. It can also help lower the risk of another stroke. Now, researchers are trying to learn more about how exercise may help the brain itself recover.

One reason exercise may help the brain recover after stroke is a process called neuroplasticity. Neuroplasticity is the brain’s ability to change, adapt, and build new connections. Think of it like the brain finding new pathways when old ones have been damaged. After stroke, neuroplasticity can help the brain relearn skills and improve how it works. Exercise may support this process by increasing helpful proteins in the brain and body. One important protein is called Brain-Derived Neurotrophic Factor, or BDNF. Often described as a “fertiliser” for the brain, BDNF helps brain cells survive, grow, and connect to one another.

What type of exercise helps neuroplasticity after stroke?

A review of research on stroke survivors found that high-intensity aerobic exercise appears to be the best type of exercise for increasing BDNF in the blood. This matters because higher BDNF may support neuroplasticity and brain recovery after stroke. For the greatest benefits, the following type of exercise is recommended:

• Aerobic exercise that makes the heart and lungs work harder, such as cycling, walking on a treadmill, or using a stepper.
• “High intensity” exercise that feels challenging. This is usually exercise that makes your breathing feel heavier and talking in full sentences difficult.

One way to do high-intensity aerobic exercise is High Intensity Interval Training, also called HIIT for short. HIIT involves switching between short bursts of harder exercise and easier recovery periods. For example, a person might pedal quickly on a bike for one minute, then pedal slowly for one minute, and repeat this pattern. HIIT can improve fitness and heart health, and it may also help the brain by supporting neuroplasticity. However, HIIT is not the only way to exercise at a higher intensity, and it is not suitable for everyone. The right exercise plan depends on the person’s health, stroke recovery, goals, and safety needs.

What do stroke survivors think about HIIT?

When we spoke with stroke survivors, the top three main reasons they might not want to try HIIT were:

1. They did not know what HIIT was or how it could help them.
2. The words “high intensity” sounded scary, too hard, or unsafe.
3. They felt little support from health professionals, family, friends, or other stroke survivors.

They also explained that the top three strategies that would make HIIT feel more possible were:

1. Clear information about what HIIT involves and how it can be done safely.
2. Support from a trained exercise professional, such as an Accredited Exercise Physiologist (AEP).
3. A program that is personalised, so the harder and easier intervals match the person’s ability.

What do exercise professionals think about HIIT?

Exercise professionals also saw possible benefits of HIIT, but they raised important safety questions. For example, they wanted to know when it is safe to start HIIT after stroke, how fatigue should be managed, and how each person should be screened before beginning. The exercise professionals suggested that screening may include talking with the person’s doctor, checking their health history, and doing exercise testing. This helps make sure the exercise is challenging enough to be useful while still safe.

Should all stroke survivors do HIIT?

HIIT can be helpful for some people, but it is not a “one-size-fits-all” solution. The key message is that high-intensity aerobic exercise may be especially useful for supporting neuroplasticity after stroke. HIIT is one way to reach this higher intensity, but it may not be right for everyone. Some people may need a different type of aerobic exercise, a slower build-up to high intensity exercise, or extra medical guidance. Anyone thinking about HIIT after stroke should speak with an Accredited Exercise Physiologist (AEP). They can design a plan that is safe, personalised, enjoyable, and based on the person’s goals.