Since antiquity sages and philosophers have claimed that exercise is good for the body and the brain. Yogasastras and Chinese health writings have, since the days of yore, extolled the virtue of exercise on the mind, not just on the body. Cicero of Greece wrote in 65 BC: “ it is exercise alone that supports the spirits and keeps the mind in vigour”. Note how they connect physical exercise to mental agility. Is there any truth in this connection? What does modern science have to say about it? A remarkable review has just appeared in the journal Neuroscience and Biobehavioral Reviews by Drs. Kirsten Hotting and Brigitte Roeder of the University of Hamburg, Germany with the title “Beneficial effects of physical exercise on neuroplasticity and cognition”, which says it all.
Neuroplasticity refers to the ability of the nervous system (remember, the brain is just that) to modify its organisation in response to conditions imposed on it. And physical exercise is defined as a subcategory of physical activity that is planned, structured, repetitive and purposeful so as to improve or maintain physical fitness (physical activity is of course any bodily movement produced by skeletal muscles that requires energy expenditure).
There has been a spate of research papers during the last 15 years attempting to understand the effects of exercise not on the physique alone but on cognitive function as well; to put it inelegantly, not on brawn alone but brain too. An excellent review on exercise, cognition and the ageing brain has been published by Kramer and colleagues from the University of Illinois (accessible free at < jap.physiol.org/content/101/4/1237.long>).
They point out, after analysing the result of several publications that regular physical exercise reduces the risk of dementia and Alzheimer’s disease in later years; in other words physical activity has a neuroprotective effect is later-life cognition. These results led to actual intervention studies, conducted by researchers on volunteers who are put on a regimen of physical exercise (for example 45 min exercise thrice a week for a six month period). One such experiment involved asking the volunteers to do a focus attention task, requiring them to focus on a single central object while ignoring distracting objects surrounding it. And as they were doing it, they were monitored using functional magnetic resonance imaging, which lets you know which parts of the brain are involved in the task. Volunteers who went through the exercise protocol did far better than those who did not. And the imaging analysis showed increasing activity in the front of the brain.
A few other points came out as important. There are exercises and exercises. Aerobic exercises (which require greater oxygen intake or more extensive breathing) are more efficacious than stretching exercises alone (reminiscent of Pranayama exercises in Yoga?). Secondly while beneficial effects of physical exercises seem more useful for certain aspects of the brain functions such as memory, visual attention, motor control and speed (all involving the frontal region of the brain), we still need to know which other areas of the brain are kindled by exercise. Third, there are different types of physical exercises — aerobic and anerobic, active and sedentary. Here, Hotting and Roeder observe: “first evidence suggests that different types of physical training affect different neuro-cognitive networks”. There is much to be done on this score, perhaps involving yogic experts and karate scholars.
What does modern biology have to say on this? Analysis using animals (rats in particular) suggests that physical exercises increase the grey matter in the brain (which is rich in neurons and connections). Experiments show that (a) aerobic exercises improve behavioural performance on activity, learning and memory (b) that the effect lasts for months years, (c) exercise promotes the formation of new nerve cells, blood vessels and connections (synapses) between neurons (d) two important growth promoting molecules are triggered to higher levels. These are called brain – derived neurotrophic factor (BDNF) and insulin like growth factor 1 (IGFI), both of which promote the production of neurons and neurotransmitters. But it is not clear whether these are temporary increases, though that the increased levels might last a few months, and (e) exercise appears to reduce the risk of chronic diseases such as such as type 2 diabetes, stroke and hypertension.
Can we start exercise any time and at any age? The answer is yes, but consult your doctor (who knows your condition) on what all you can do, how much and how often. Can children start? The answer is a resounding yes — not only because the effect lasts not for now but for later years as well. And physical exercise helps in learning and learning well, since exercise is identified to increase the number of nerve cells, inter-nerve connections, blood supply, and the release of molecules that help positive neural mechanisms.
Lastly should one combine physical exercise with cognitive challenges? In other words, should I exercise, plus do crosswords, sudoku, practice or listen to music? Again the resounding answer is yes; physical and cognitive stimulation contribute additively for improving brain function.