Benefits of Physical Exercise

(This article is complementary material for Tutorial 2. All numbered refs plus further research refs are given at the end).

Most people don’t realize that a sedentary lifestyle can reduce their cognitive abilities.

When you engage in exercise your brain benefits because circulation improves, and with it oxygen and nutrient delivery. People who exercise regularly have larger cerebral blood vessels. In June 2009 we saw the first study to compare brain images of elderly subjects who exercise with those who don’t. Physically active elderly people showed healthier cerebral blood vessels. Aerobically active subjects exhibited a vessel pattern similar to younger adults; they had more small-diameter vessels with less tortuosity, or twisting, than the less active group. The researchers identified significant differences in the left and right middle cerebral artery regions confirmed by more than one statistical analysis [17].

The brain uses about 20% of the energy you generate each day. Just like your body, the more you keep it in the healthy zone the better it will perform. If you feel that it is hassle to get through the day, hard to make decisions, and just to juggle all you have to think about, then you need to change some habits. By making sure you eat well and get enough physical exercise you will improve conditions for your brain to function optimally.

Many people’s biggest problem with exercise is starting. Anxiety will talk them out of the task, put it off until the very end of the day or till tomorrow, making one excuse after another. Anxiety is very good at making excuses for not doing things. However, when you do get physical exercise and your anxiety levels drop, things appear in a new light.

Instead of helping you to make excuses and to find ways to avoid exercising, you’ll then remind yourself that you should exercise. You’ll make time for it and to be proud of your efforts and results. Once you get to that point, engaging in physical exercise on a regular basis becomes a lot easier. More neurochemicals that keep you happy will be produced as well so you will have a better attitude than before.

Exercise doesn’t have to mean frantic physical activity! There are enough types of exercises out there to take part in so you never have to waste your time doing those you don’t like. Yoga is one of the best forms of exercise that anyone can take part in at any age. Yoga and Tai Chi can be difficult for people who find it hard to slow down, yet paradoxically they may need it most! The more you practice yoga the easier it gets, so you can move into more advanced forms of yoga as you learn which will offer even more benefits for your mental health.

No matter how old you are or how little you currently exercise, you can make some significant improvements in your life. Starting with ‘little and often’ is the best way, makes the goal more achievable and you won’t be overwhelmed along the way.

Make it a goal to get at least 10 minutes each day of exercise. If you have a very busy lifestyle, presumably you’re getting some exercise already (the average hospital nurse walks 4 miles a day just on the wards). So bear this in mind and choose the type of exercise that helps you relax, not winds you up. It’s not difficult to do yoga stretches sitting on your sofa or in your bed. It really isn’t. There’s nothing wrong with doing Tai Chi while watching Star Trek. Every time you go for a pee, if you spend 10 seconds afterwards bending over to touch your toes (hide on a cubicle) your brain gets a super flush of oxygen and your circulation improves. That’s 10 seconds –hardly difficult to fit in. And even bending down to touch your toes sitting in an office chair a few times a day will do the trick. If you don’t believe this, try it.

Where’s the Proof?

The personal proof is in seeing how much more alert you feel, but there’s plenty of scientific proof as well. Physically active people tend to have better mental health, according to the stats [1].

Compared with inactive people, the physically active had higher scores for positive self-concept, more self-esteem and more positive "moods" and "affects." These findings seem similar in both young people and adults. Physical activity has also been used to treat mental health problems such as depression.

More-active people also score higher on perceived ability to perform activities of daily living, physical well-being and other measures related to quality of life. Studies also suggest that more active lifestyles are linked with higher levels of alertness and mental ability, including the ability to learn.

To do all you can to maintain your mental abilities, you really should be exercising physically in some way.

The Association for Psychological Science recently published a review on prevention of cognitive decline with age [2]

The paper surveys the available research and concludes that cognitive enrichment activities (puzzles, social interaction, etc) may well help you preserve brain function as you age. But they were especially complimentary towards physical activity. "What is most impressive to us," the authors write, "is the evidence demonstrating the benefits of aerobic physical exercise on cognitive functioning in older adults."

Studies in both animals and humans "overwhelmingly" indicate that exercise helps the brain, they write, both generally and also specifically in executive functioning (things like deciding to change behavior or planning ahead), short-term memory, and focusing and maintaining attention. Arthur Kramer [3] (one of the report's authors), said at a news conference that there's enough evidence to launch a public policy campaign that includes an endorsement of exercise to improve brain function.

A lot of changes happen when you exercise. Importantly, improved circulation makes it easier to produce new brain cells in the hippocampus (particularly important for memory). Some researchers are now studying the slowing of neurodegenerative diseases like Alzheimers with exercise [4].

A study of 165 older adults (59-81) has found a significant association between physical fitness and performance on spatial memory tests. Fitness was also strongly correlated with hippocampus size [7].

There's a strong association between aerobic fitness and brain performance. Aerobic exercise (as well as BMI) is related to achievement in reading and math [5].

Chemicals influenced by exercise, including neurotransmitters and growth factors, are being investigated for their role in mood and brain function and these links are becoming clearer. One study used PET scans to look at the brains of 10 athletes following a two-hour run. The scans confirmed that during the run, endorphins, norepinephrine, serotonin, dopamine, and brain-derived neurotrophic factor (BDNF) all increased in parts of the brain known to be involved with the processing of emotions [6].

A single 10-minute bout of physical activity boosts attention and problem-solving skills.

A study published online earlier this month in the British Journal of Sports Medicine found that Mental health benefits are observed after 20 minutes of physical activity, though with 20 or 30 minutes the affect is increased (but improvement with increase doesn’t continue to be true –too much exercise is as bad as none at all). Doing the recommended 30 minutes a day of aerobic activity is plenty for your brain as well as your heart [6].

Physical exercise, like mental stimulation, provides a "challenge" to the brain. "The brain needs to get the message that we need it to keep functioning," says Ratey (chief researcher). A lot of different mechanisms are responsible for the exercise-brain connection, including a growth factor called FGF-2 that is produced by exercise and is involved in the generation of new neurons.

Moderate exercise is the best course. While walking distance is related to cognitive ability (the more you walk, the better), walking speed is not. There might be additional benefits gained by interval training—short bursts of intense activity followed by rest periods.

You should check your fitness levels before starting any intense exercise program, particularly if you're new to exercise or have health problems. Here’s a quick easy fitness test:

Stand at the bottom of your stairs, or find a sturdy step about 8” (20cm) high. Take your pulse with a stopwatch. For the next three minutes, step up and down the step twice every five seconds. Then sit and rest for exactly one minute. Then take your pulse.

If you are fit, it should have returned to the rate it was before you started. The further apart the two measurements are, the more unfit you are.

Don’t let ‘unfitness’ put you off exercise though. Even elderly heart failure patients, under medical supervision, benefit from interval training. If you are unfit or recovering from illness, yoga can help a lot too.

A study involving 138 older adults (50 years and over) with mild cognitive impairment found that those who undertook 2 ½ hours of physical activity each week (three 50 minute sessions), ranging from walking, ballroom dancing to swimming, for a six month period, continually out-scored the control group on cognitive tests during the 18 month testing period — showing that memory improvement was still evident a year after the supervised exercise period [8].

There is a correlation between certain brain network functions and physical fitness. (If you want to know more about brain networks, read: “Anatomy, physiology and brain networks: the basics”, in the basics section of the library). Those with strong network 2 will find it easier to exercise. Those with strong front nets are more likely to research health facts (but may have difficulty bridging the gap between ‘knowing the path’ and ‘walking the path’.)

Our input needs also change with age. In youth, exercise improves mental function just by itself, but mental stimulation doesn’t improve brain function without physical exercise. In middle age, improvement comes with either exercise alone or both exercise and mental stimulation (but not just mental stimulation on its own). As we age, mental stimulation on its own becomes more effective on its own, but further improvements still occur with exercise [9].

A review of the research on the effects of exercise on brain functioning supports the view that physical exercise helps people maintain cognitive abilities well into older age [10].

Some of us deal better with lifestyle changes if we make them big, obvious and in our faces. Others do better if very small changes are made a step at a time. Both are equally effective. A study involving 17 people (35–69 years) with mild self-reported memory complaints but normal baseline memory performance scores, has found that just 2 weeks on a program combining a brain healthy low GI diet plan (5 small meals a day; diet rich in omega-3 fats, antioxidants and low-glycemic carbohydrates like fruit and veg), anxiety reduction, relaxation exercises, cardiovascular conditioning (short daily walks and yoga stretching), and mental exercise (such as crosswords and jigsaws) resulted in greatly increased efficiency in working memory regions. Compared to the control group, participants also performed better in verbal fluency [11]. (If you want to know more about low GI diets, read: “Nutrition: the basics” and “Optimal nutrition for beginners”, in the nutrition section of the library.)

These are the kinds of changes we recommend in the tutorials –one step at a time towards improvement, without any big hassle. Moderate exercise together with improved lifestyle habits is much more effective than exercise alone. A review of 96 papers involving 36 very large, ongoing epidemiological studies in North America and Europe looking at factors involved in maintaining cognitive and emotional health in adults as they age has concluded that controlling cardiovascular risk factors, such as reducing blood pressure, reducing weight, reducing cholesterol, treating (or preferably avoiding) metabolic syndrome and diabetes is important for maintaining brain health as we age. The link between anxiety, hypertension and cognitive decline was the most robust across studies [12].

They also found protective factors most consistently reported for cognitive health included emotional support, better initial performance on cognitive tests, better lung capacity, more physical exercise, moderate alcohol use, and use of vitamin supplements. Psychosocial factors, such as social disengagement and depressed mood, are associated with both poorer cognitive and emotional health. Increased mental activity throughout life, such as learning new things, also benefits brain health.

One study takes an important step in explaining cognitive impairment in diabetics, and suggests a possible path of causation from anxiety to age-related memory impairment. The study assessed non-diabetic middle-aged and elderly people. Those with impaired glucose tolerance (a metabolic syndrome condition) had a smaller hippocampus and scored worse on tests for recent memory. These results were independent of age or overall cognitive performance. The brain uses glucose almost exclusively as a fuel source, and the ability to get glucose from the blood is reduced in diabetes [14]. One of the primary reasons exercise works to lower your cancer risk is because it drives your insulin levels down.

Regular, light exercise reduces cellular aging in the brain. Fewer byproducts of oxidative stress are produced, and genetic changes are observed in DNA [13]. There are actual anatomical differences in the brains of physically fit versus less fit older adults (over 55). Specifically, they found very distinct differences in the gray and white matter in the frontal, temporal, and parietal cortexes. With lack of blood supply, these tissues shrink, a reduction closely matched by declines in cognitive performance. Fitness, it appears, slows that decline [15].

A team of researchers [16] who demonstrated in late 1999 that aerobic exercise is just as effective as medication in treating major depression has now reported that the same exercise program also appears to improve the cognitive abilities of these patients. The researchers found significant improvements in the higher mental processes of memory and the executive functions (network 6), which include planning, organization and the ability to mentally juggle different intellectual tasks at the same time.

Exercise also increases self esteem. Regular practice results in fewer anxious thoughts and less anxiety about ourselves and the future. The experience of mastering a new situation and changing established habits increases our motivation to seek new challenges. This openness and self-confidence is also partly responsible for participants staying physically, socially and mentally active and being self-reliant, all of which are prerequisites for optimal cognitive functioning.

References

1. US Surgeon Generals report on physical activity & health
2. (US) Association for Psychological Science, Jun 2009
3. Arthur Kramer is a neuroscientist at the University of Illinois at Urbana-Champaign, US.
4. Henriette van Praag, a researcher in the neuroplasticity and behavior unit in the laboratory of neurosciences at the (US) National Institute on Aging.
5. Darla Castelli, a researcher in the department of kinesiology and community health at the University of Illinois-Urbana-Champaign, US.
6. John Ratey & Castelli, in Cerebral Cortex, Mar 2009 (Germany). John Ratey is a psychiatrist at Harvard Medical School and author of Spark: The Revolutionary New Science of Exercise and the Brain.
7. Jan 2009 in “Hippocampus”. Full reference http://www.eurekalert.org/pub_releases/2009-02/uoia-pfi022409.php
8. Sep 2008 issue of the Journal of the American Medical Association. Full reference http://www.eurekalert.org/pub_releases/2008-09/ra-wtp090108.php http://www.eurekalert.org/pub_releases/2008-09/uom-aow090108.php http://www.eurekalert.org/pub_releases/2008-09/jaaj-emh082808.php
9. Aug 2007 issue of Behavioral Neuroscience. Full text available at http://www.apa.org/journals/releases/bne1214679.pdf http://www.eurekalert.org/pub_releases/2007-08/apa-eam080107.php
10. Findings from the review were presented Aug 2006 at the 114th Annual Convention of the American Psychological Association (APA). Full reference http://www.eurekalert.org/pub_releases/2006-08/apa-ehs080106.htm
11. The study was published in the June 2006 issue of the American Journal of Geriatric Psychiatry. Full reference http://www.newsroom.ucla.edu/page.asp?RelNum=7062 It was presented at the American College of Neuropsychopharmacology's Annual Meeting on Dec 2006, in Hawaii. http://www.eurekalert.org/pub_releases/2005-12/g-nsf121205.htm
12. The review was published in the Jan 2006 issue of Alzheimer's & Dementia. Full reference http://www.eurekalert.org/pub_releases/2006-02/aa-nss021606.htm
13. The research was presented at the Society for Neuroscience's 35th annual meeting in 2005 in Washington, D.C. http://www.eurekalert.org/pub_releases/2005-11/uof-lea110905.htm
14. Feb 2003 issue of Proceedings of the National Academy of Sciences, US. Full reference http://www.eurekalert.org/pub_releases/2003-02/nyum-hsb013003.htm
15. Feb 2003 issue of the Journal of Gerontology: Medical Sciences. Full reference http://www.eurekalert.org/pub_releases/2003-01/uoia-sif012703.htm
16. Duke University Medical Center, US. The study was published in the Jan 2001 issue of the Journal of Aging and Physical Activity. http://www.eurekalert.org/pub_releases/2001-01/DUMC-Aeic-1401101.htm
17. Researchers led by Elizabeth Bullitt, M.D., Van L. Weatherspoon Distinguished Professor of neurosurgery University of North Carolina at Chapel Hill School of Medicine, US. Published Jun 2009 in Medicine & Health / Health & Jul 2009 in the American Journal of Neuroradiology http://www.physorg.com/news165500423.html

Further Research

January 2005 issue of Neurobiology of Aging. Full reference http://www.eurekalert.org/pub_releases/2005-01/uot-mtc011705.htm http://www.eurekalert.org/pub_releases/2005-01/nioa-des011805.htm

Maintaining physical activity linked to less cognitive decline in older men. This study was published in the Dec 2004 issue of Neurology. Full reference
http://www.eurekalert.org/pub_releases/2004-12/aaon-mpa122104.htm

Walking may protect elderly from dementia. (A study of more than 2,200 men between the ages of 71 and 93).
The study was published in the Sept. 2004 issue of the Journal of the American Medical Association. Full reference
http://www.eurekalert.org/pub_releases/2004-09/uovh-wmp091504.htm

Physical activity associated with better mental functioning in older women. Study of 18,766 women aged 70 to 81 years. The report was published in the Sep. 2004 issue of JAMA http://www.eurekalert.org/pub_releases/2004-09/jaaj-pai0916904.htm

Exercise improves attention and decision-making (An imaging study involving adults ranging in age from 58 to 78.)
The study was reported on Feb 16-20 as part of PNAS Online Early Edition, ahead of regular print publication in the Mar 2004 issue of Proceedings of the National Academy of Sciences. http://www.eurekalert.org/pub_releases/2004-02/uoia-esf021104.htm

Study of the effects of exercise on 124 previously sedentary adults, 60 to 75 years old. Kramer, A.F.,Hahn, S., Cohen, N.J., Banich, M.T., Mcauley, E., Harrison, C.R.,Chason, J., Vakil, E., Bardell, L., Boileau, R.A. & Colcombe, A. 1999. Ageing, fitness and neurocognitive function. Nature, 400, 418 - 419.

Study of 442 people, 65 - 95 years old.

Perrig-Chiello, P. 1998. The effects of resistance training on well-being and memory in elderly volunteers. Age and Ageing, 27

Regularly working out with weights can reduce their risk of cancer by 30-40 percent. Study of 8,500 men for more than two decades: Researchers said it’s possible to reduce cancer mortality rates in men by promoting resistance training involving the major muscle groups at least two days a week. The Telegraph May 26, 2009

Cancer Epidemiology Biomarkers & Prevention 18, 1468, May 1, 2009