Exercise helps the brain to recover movements after a stroke. Here is how it happens!
Exercise brings new neurons and new connections.
This is exciting news;
First, exercise stimulates neurons to release a special protein; the ” Brain-Derived Neurotrophic Factor” (in short, BDNF)1. This protein appears in the blood only as a response to exercise. Keep in mind researchers have shown its presence as a response to aerobic exercise1; however, they believe resistance type of exercise too may also stimulate neurons to release this protein.
What does this protein (BDNF) do?
Second, this protein triggers a series of changes in multiple areas of the brain. These changes include the sprouting of new dendrites and synapses1 (see Figure 1). With these structural adaptations, the repair work begins. This is a sort of remodelling. These new neurons and connections are essential to take over the jobs earlier carried out by dead neurons.
This remarkable ability of the brain to undergo structural changes to face changing realities is commonly called “neuroplasticity”.
Aerobic exercise triggers the growth of new neurons and new connections (synapses) among neurons.Mang et al. 2013; Physical therapy and Rehab. journal
However, there is a catch!
The exercise intensity level should cross a minimum threshold to release this protein.
The BDNF protein does not appear if the exercise attempts do not reach the required intensity threshold level. We have another important fact to remember: The intensity level and the BDNF level go hand-in-hand – the higher the intensity level more the release of BDNF level!
What is the minimum threshold?
It should be moderate-to-high intensity. Treadmill high-intensity interval training resulted in significantly high blood levels of the BDNF at least 20 minutes when compared to treadmill moderate-intensity continuous exercise; that is what researchers have found out2.
What is the minimum threshold?
Other benefits of exercise
Mang et al. (2013)1 describe other types of assistance aerobic exercises provide to the brain’s recovery attempts.
Releasing messenger proteins
Researchers have uncovered that exercises stimulate neighbouring neurons to release messenger proteins such as dopamine and serotonin. Neurons require these proteins to communicate with each other fast and efficiently.
These are urgent requirements! Because the brain has to adapt to face new challenges after the stroke attack.
How do we know this?
New technologies such as Functional MRI (fMRI) help researchers to view the changes while someone is carrying out activities or exercises.
Increasing the brain’s blood flow
Exercises increase the blood flow to the brain; This is necessary because the neurons require food and more oxygen for their extra-duty work at present.
Increasing muscle strength
This is again really necessary to restart activities of daily living as early as possible. More importantly, muscle non-use results in irreversible muscle wasting.
Types of exercises and activities we should promote?
Certain rules apply here in promoting post-stroke exercises and activities; this post outlines what those rules are; Following posts discuss what those rules are;
- Six rules to regain movements after a stroke
- Regaining arm movement after stroke
- Best practices to regain walking after stroke
- Cameron S. Mang, Kristin L. Campbell, Colin J.D. Ross, Lara A. Boyd, Promoting Neuroplasticity for Motor Rehabilitation After Stroke: Considering the Effects of Aerobic Exercise and Genetic Variation on Brain-Derived Neurotrophic Factor, Physical Therapy, Volume 93, Issue 12, 1 December 2013, Pages 1707–1716, https://doi.org/10.2522/ptj.20130053
- Boyne, P., Meyrose, C., Westover, J., Whitesel, D., Hatter, K., Reisman, D. S., Cunningham, D., Carl, D., Jansen, C., Khoury, J. C., Gerson, M., Kissela, B., & Dunning, K. (2019). Exercise intensity affects acute neurotrophic and neurophysiological responses poststroke. Journal of applied physiology (Bethesda, Md. : 1985), 126(2), 431–443. https://doi.org/10.1152/japplphysiol.00594.2018