Everyone knows that regular exercise is important for physical and mental health. But very few of us know how much exercise is required to reap the benefits. Many of us walk three or four times a week, and we think that we are getting adequate exercise. But are we really?
According to the existing Canadian physical activity guidelines for older adults, the ideal dosage of exercise is 150 minutes of moderate intensity physical activity or 75 minutes of vigorous-intensity activity per week or an equivalent combination. Examples of moderate intensity physical activity are brisk walking, jogging, biking etc.
A report on Albertans released last year mentioned that only 42% of Albertans over the age of 50 are adequately active.
Among seniors between the ages of 65-74, only 20% of men and 17% of women were found to get adequate activity, and among seniors aged 75 years and above, only 9% of men and 6% of women met the recommended guidelines.
Doing moderate-intensity exercise for 150 minutes per week can significantly reduce our risk of premature death from coronary heart disease, type 2 diabetes, high blood pressure, stroke, and colon cancer, and improve mental health by reducing depression and anxiety. Though this level of exercise was at that considered sufficient for reducing the risk of developing Alzheimer’s disease and other types of dementia, a new research paper published in the Journal of Alzheimer’s Disease says otherwise.
People at risk for Alzheimer’s disease who spend more time doing moderate-intensity exercise have a healthier level of glucose metabolism in the brain — considered a reflection of how healthy and active the brain really is. In contrast, low-intensity physical activity, such as a slow walk, was not related to brain metabolism.
The study, “Moderate Physical Activity is Associated with Cerebral Glucose Metabolism in Adults at Risk for Alzheimer’s Disease,” turned to the Wisconsin Registry for Alzheimer’s Prevention (WRAP) to obtain data about exercise levels and brain health.
WRAP recruits cognitively healthy people in their older middle ages who have one or both parents affected by Alzheimer’s disease. The registry also recruits people with no family history of the disease to use as controls.
Equipping 93 of these patients with accelerometers — a device that measures exercise by analyzing acceleration — the research team at the University of Wisconsin-Madison School of Medicine and Public Health were able to calculate how much the participants exercised.
They then measured their brain glucose metabolism using a brain imaging technique called Positron Emission Tomography (PET).
Moderate-intensity physical activity was related to brain glucose metabolism in all brain areas analyzed — areas that researchers know have abnormal glucose metabolism in people with Alzheimer’s disease. People who spent at least 68 minutes per day in moderate physical activity had better glucose metabolism readings than those who exercised less.
This is the first study that has shown a quantifiable connection between moderate physical activity and brain health. This study has implications for guiding exercise ‘prescriptions’ that could help protect the brain from Alzheimer’s disease, according to Ryan Dougherty, first study author and a graduate student at the University of Wisconsin-Madison.
Previous studies have shown that being physically active also increases the size and function of critical areas of the brain associated with memory, learning, information processing, problem solving and executive functions. It increases blood flow to the brain, delivering more oxygen to the brain and promotes the formation of new nerve cells and new connections, all of which help to mitigate the age-related changes in the brain.
The conclusion is 150 minutes of moderate intensity exercise is beneficial for general health. If we have a family history of dementia, or have multiple health conditions such as high blood pressure, diabetes, high cholesterol, depression, or history of a stroke in the past, we need 68 minutes of moderate intensity exercise every day to delay or slow down dementia.
Many people become discouraged about Alzheimer’s disease because they feel there’s little they can do to protect against it. But these results suggest that engaging in moderate physical activity can reduce our risk, and even slow down the progression of the disease. This should be an additional incentive for us to lace up and explore our beautiful trails and parks.
Padmaja Genesh, who holds a bachelor degree in medicine and surgery as well as a bachelor degree in Gerontology, has spent several years teaching and working with health-care agencies.