Exercise for the Brain

Exercise Changes the Brain

Exercise is recognized to have a positive impact on almost every health, vision, and mental condition – everything from heart disease to glaucoma to cognitive impairment. For those concerned with weight loss getting adequate exercise is more important than diet. People who are active are less likely to develop certain malignancies including colon and prostate cancer, osteoporosis and dementia, and extend their average life expectancy by three to seven years without doing anything else.1 Even low levels of exercise confer great benefit.

Exercise Extends the Biological Clock

Exercise appears to prevent cell deterioration. Researchers have found that it prevents shorting of DNA at the ends (telomeres) of chromosomes. Such shortening limits cell division, creating a ticking biological clock. When the telomeres get too short the cell dies. In addition, exercise does more than protect telomeres. It protects the cell from deterioration in other ways preventing programmed cell death.2

Your Dose of Exercise

At the same time ‘dosage’ of exercise is important. The 2008 AMA standard recommends 30 minutes of moderate exercise daily (e.g. brisk walk) for good health. But studies have found that even less is beneficial. A large study in Taiwan evaluated the amount of exercise taken by almost 200,000 men and almost 220,000 women. The subjects were placed in one of five categories depending on how vigorous the exercise: inactive, low, medium, high or very high and life expectancy was calculated for each group.3 Even the low activity group, (15 minutes daily) had 14% lower mortality risk than the inactive group.

Extending moderate exercise such as walking briskly to 30 minutes a day is connected to even better health results. Every extra 15 minutes resulted in an extra 4% decrease in mortality risk – the highest levels being 63-88 minutes of exercise every day. The more vigorous the exercise, the greater the reduction. Similarly in European studies more exercise was associated with a lower death rate from all causes.4

Aerobic Exercise: Better Results

Exercise regimes begun after cognitive impairment has progressed have limited effect. Mild exercise is a prevention tool, not a cure.

However, aerobic exercise has a larger positive effect on the brain. One study compared subjects who were performing aerobic exercise compared to controls who were stretching only. The volume of the brain increased, according to MRIs and aerobic exercise groups see a marked improvement in executive brain functioning tests.5 Sixteen subjects (average age 63) with mild cognitive impairment, a risk factor for Alzheimer's disease, participated in an aerobic exercise such as treadmill, elliptical, or stationary bike four times per week. The 19 members of the control group stretched instead.

At the start of the study and after six months, all the study participants had MRI tests. The researchers were surprised to see a significant difference between brain volume growth in the two groups. Both had improvements, but the cardiovascular exercise group had greater preservation of total brain volume and an increase in local gray matter volume. Additionally, the directional stretch of brain tissue was increased more for the aerobic exercise group. On the other hand, the group that only stretched their muscles had local atrophy within the white matter connecting fibers.

While the aerobic exercise group had improvements on executive brain functioning tests, the stretching group did not. Executive brain functioning refers to the mental skills which allow one to get things done – short term memory, taking initiative, keeping track of things mentally, planning, prioritizing, etc.

Interval Aerobic: Best Results

It appears that interval-based aerobic exercise is best. Animal studies suggest that low-intensity exercise is better than high-intensity exercise; that high-intensity exercise abolishes some of the benefits of low-intensity, including improvements in spatial memory, reduced free radical activity in the hippocampus, increased numbers of neurons and dendritic spines, and upregulation of synaptic density in the brain.6

A 2016 meta-analysis of 18 trials with over 800 patients found that combined aerobic and non-aerobic exercise interventions and aerobic-only programs both had a positive effect on cognition.7

A study published in 2020 found that alternating high-intensity with low-intensity walking was extremely beneficial. Sixty-four patients, 60 or older were tested at the beginning of the study for memory ability. A control group did stretching exercises, another group walked moderately and steadily on treadmills three times a week for 50 minutes. The others performed three rounds of interval walking in which they walked at 90% of their capacity for four minutes, followed by three minutes of easy walking. After 12 weeks, "only the interval walkers now showed significant improvements in both physical endurance and memory performance, and their gains were linked. The more fit someone became, the more his or her memory sharpened."8

Another study, 20 weeks in duration, with 68 patients (average age 70) found similar results with five sets of walking intervals of three minutes at 70% capacity followed by three minutes at 40% capacity. Compared to continuous moderate walking, elderly interval walkers showed significant improvements in both physical endurance and memory performance. 9

Walking Briskly Reduces Dementia Risk

A 2016 meta-analysis summarizes these findings. It evaluates 17 studies reporting the risk of cognitive decline (nearly 10,000 participants) and the risk of dementia (nearly 14,000 participants). Researchers reported that a low walking pace has a 89% of cognitive decline compared to a fast walking pace.10

Walking pace is inversely associated with the risk of cognitive decline, so get out and take a brisk walk!


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