Your brain on exercise: Life and longevity, part 9

A systematic review indicated that older adults involved in exercise training derive general benefits to brain health, such as changes in brain structure and function.¹

The big concept to keep in mind is that the brain is very sensitive and responds in a neuroplastic way, depending on the signals it is exposed to. Physical exercise is a powerful signal to the brain, as studies have shown that a large network of brain areas, equal to 82% of the total grey matter volume, were associated with physical activity.² As an example, a meta-analysis study showed that mentally passive sedentary behaviours, such as watching television, could increase the risk of depression.³ A review study found that exercise has shown promise as an effective treatment for depression and causes positive structural changes in the brain areas related to depression.⁴ More good news is that the brain remains plastic throughout life and most age-related declines in cognition can be slowed by various methods such as physical exercise, cognitive training, or non-invasive brain stimulation.⁵A simple balance training exercise for 12 weeks increases brain-derived neurotrophic factor – BDNF – reverse age -related cortical function and appear to be a factor causing neuroplasticity in older adults.⁶ A review summarized that “Physical activity influences cognitive function, vascular health and brain metabolism, which taken together offers benefits for the aging population.”⁷

However, what is lacking in the above studies is the inclusion of the FITT-VP principle (i.e., Frequency, Intensity, Time, Type, Volume, and Progression) to describe the exercise exposure. Exercise advice that is circulating states that one should exercise for at least 150 minutes per week, and should include moderate aerobic exercise and resistance training to support brain health in people.⁸ There is no information regarding all aspects of the FITT-VP principle above. As an example, just manipulating the amount of time the exercise is been executed, will affect the results obtained. Moderate-to-vigorous intensity acute exercise lasting 20 minutes facilitated multiple cognitive function domains in general, whereas the exercise sessions of shorter and longer duration had negligible effects on executive function in late middle-aged adults.⁹ Or that 12 months of aerobic/coordination training improve the volume of the basal ganglia.¹⁰ Great to see this, but what type of aerobic training was applied, time and intensity along with the same information for coordination training. What happened at six months? Because good research methods are lacking regarding exercise and brain function, I’ll present and try to make sense of the information that is presently available.

Exercise effects
To identify if there are differences in the brains of various populations, researchers use a concept called functional connectivity strength (FCS), to assess how the networks of the brain function. A recent study successfully distinguishes the young group, middle-aged group, and elderly group through the FCS parameter, indicating that in the functional pattern of the network, there exists a difference between the three groups.¹¹This means that certain parameters change as aging occurs. Along with the fact that the brain size decreases as aging occurs. This will affect the structures and the functionality within the brain.¹² There are also racial differences regarding the aging of the brain. This study found that eighty-year-olds living in the community, blacks appeared to have higher microstructural integrity of gray matter as compared to whites. Because of the higher microstructural integrity, diffusion is decreased which contributes to more brain damage.¹³

Peripheral muscles and the brain are intimately related. When you exercise muscles, they affect the brain. Physical exercise is crucial for muscle and brain to function optimally.¹⁴ Also, different intensities of exercise affect different areas, the motor cortex is activated during all intensities, while the cerebellum is activated by low intensity exercises.¹⁵

Different types of exercise such as eccentric and concentric muscle contractions induced different patterns of cortical activity respectively. This may be due to a higher level of cognitive demand for motor tasks of a higher degree of difficulty such as that required of eccentric contractions versus concentric contractions.¹⁶ Aging subjects exercising for 12 weeks/3/week on a stationary bike, compared to standard physical activity causes changes to occur in the motor cortex related to the leg muscle area of the bikers. This shows that structural decline in the aging can be reversed.¹⁷  Acute vigorous aerobic exercise improves pre-cortex and cognition and can last up to 2 hours.¹⁸ Any regular exercise you do will positively affect the aging brain. There is strong evidence to support that physical exercise benefits cognitive function during aging.¹⁹

A 12-week program of moderate intensity, progressive treadmill walking, four times per week for 30 minutes, improved both cerebral blood flow and cognitive performance in older adults with and without cognitive impairment.^{20, 21} 

Aging affects gait and interlimb coordination and an aspect of this is related to the motor cortex. However, the motor and sensory cortex areas are the most plastic, hence movement-rich activities such as dancing, gymnastics, walking and singing, or dual-task activities would be the preferred ways to positively activate gait and interlimb coordination.^{22, 23} The corticospinal tract is the main gateway from the cortex, through the brain, into the spinal cord and to muscles. In its passage through the brain, there are inter neural signals to all parts of the brain. The signals to brain areas initiate coordination, strength, balance, posture and gait. Some aspects of plasticity also occur along the corticospinal tract during strength training, but the strength gains are related to motor learning skills.²⁴

Walking on uneven and unaccustomed routes will also activate the primary sensorimotor area, prefrontal area, temporal lobe, and especially the hippocampus in the aging female.²⁵ Physical exercise/movement activates the hippocampus and this repeated activation causes neuromodulation which is critical for the beneficial effects of exercise on the brain,²⁶ and aerobic exercise causes neurogenesis in the hippocampus.²⁷ 

As the brain ages, there is a decrease of approximately 30% in global cerebral blood flow from midlife to older age and weight gain effectively causes more of a decrease of blood flow. With decreased blood flow to the brain, limited nutrients will be available, the brain will shrink and more degenerative changes will occur. Add to this scenario, lack of exercise or activity and you are heading down the wrong road. Therefore, one should take responsibility for your health and lifestyle choices.

Don’t think it’s too late for seniors to benefit from physical activity/exercise. Physical activity can help people with mental/physical health, medical and  neurodegenerative diseases.²⁸ 

The longer you exercise for, the better, and be sure to engage in exercise of different modes, intensities, aerobic, strength or dancing. These factors will lead to the greatest benefits on brain health.²⁹

Diet
Better diets which include vegetables, fruit, whole grains, nuts, dairy, and fish, caused larger brain volumes.³⁰ Good diets help muscles to regenerate with exercise and the muscles then stimulate the brain to improve its’ function. Dietary supplements such as omega 3, B vitamins and antioxidants will all benefit the muscles and the brain.³¹ Blood flow restriction training can assist to strengthen the muscles, and thus the brain. A natural supplement to keep an eye on is Taurine. Taurine is a sulphur-containing amino acid and demonstrates extensive physiological activities within the body, including beneficial effects against different neurological disorders such as neurodegenerative diseases, stroke, epilepsy, diabetic neuropathy, protection against muscle injuries and inflammation.^32,33

Summary
Exercise is life. Exercise contributes to the stimulation of over 80% of the cortex. Think of physical activity or exercise as using the neurons in the brain as scaffoldings. The more exercise we do, the more used, stronger, and flexible the scaffoldings, and therefore the more functional the brain becomes. Because exercise should target all areas of the brain, your program should include aerobic, resisted/power exercises, balance, agility, and plyometrics and should be always progressing with moderate-challenging intensity. Exercise should be a lifestyle activity and done a minimum of four times per week. Additionally, a good diet and supplements will benefit the body and brain and enhance the effects of exercise.

DR. DON FITZ-RITSON is a chiropractor and a rehab specialist. He was an Assistant Professor at CMCC. He published 17 papers and 3 chapters on chiropractic.He co-invented a laser and it received 7 Health Canada Approvals. He is focused on helping the aging population live better lives.