Listening and Speaking III

Although conventional wisdom is reflected in the old

Roman dictum, "Mens sana in corpore sano" already

acknowledged the obvious connection between

physical and mental health, the scientific community

only recently has been given to the relationship

between exercise and brain function. Initially it was

thought that the positive effects of exercise were due

primarily to the cerebral blood flow increases

significantly, so that brain cells are better oxygenated

and nourished, which helps to make them healthier.

Even being this an important, exercise produces a

variety of effects on the brain, which are only now

beginning to know, and cannot be explained solely

by a higher supply of nutrients. For example, not

only intellectual activity is important for maintaining

the intellectual capacity as you grow older, exercise

is too, and still do not understand how.

The exercise has proved an excellent method of

protection against neurodegenerative diseases, and

may even help reduce the impact of these diseases.

Basically, the exercise seems to

activate a series of processes

responsible for maintaining and

protecting the nerve cells, which we

call neuron-physiological systems.

If exercise protects the brain from

both internal and external attacks

to which it is subjected throughout

life, it is clear that a sedentary

lifestyle, very marked in modern

societies is a risk factor for

neurodegenerative diseases, such

devastating in today's society.

Human physiology has developed, therefore, to meet these physicalneeds, and indeed, requires it. Tounderstand the human body needsphysical activity to maintain a set of basic functions.

We can summarize by saying thatthe functional capacity of neuronsdepends on the use made of themis a continuous optimization of resources, are engaged in a taskas many neurons as it takes, and ifthe task increasingly requires more dedication, number or functionalcapacity of neurons increases.

How physical exercise

stimulates the brain? When performing a physical activity, apart from coordinating

the movement of the muscles involved in the movement that is

taking place, the brain coordinates all bodily functions

necessary for these muscles to function properly in a situation

that basically requires a higher energy consumption. The

metabolic pathways activated and controlled by the brain

reasonably well known for years, and are described in detail in

textbooks of physiology. However, there are changes in the

brain, which are not related to control of metabolic functions

associated with the implementation of the exercise, such as

breathing, heart rate or glucose uptake, but the functional

properties of neurons themselves.

Two independent lines of work have made recently

are paying more attention to the connection between

exercise and brain function. The first concerns the

observation of a few decades ago that the

environment influences in unexpected ways in the

development and maintenance of learning ability and

memory. And former experiments show that

environments that provide the greatest amount and

quality of stimuli favor greater brain development,

both from the standpoint of anatomical and

functional.

The endocrine axis of

pituitary growth hormone

(GH) and hepatic IGF-I

controls the growth of

many tissues and their

proper functioning.

Recent observations

also indicate that the

brain would be a target

organ of the trophic

actions of IGF-I liver,

including a protective

effect against internal

and external

aggressions.

There is already enough evidence to suggest that

this trophic substance stimulated by exercise is one

of those responsible for the beneficial effects of

exercise on the brain (see Figure 2). On reaching the

brain, IGF-I stimulates the production of other trophic

substances, which incidentally are the same that

encourages exercise, also increases the activity of

neurons, enhances the brain's ability to receive

information from the body, stimulates blood flow to

the brain, increases glucose uptake by neurons and

protects neurons from all types of conditions that can

cause malfunction or even death.

Figure 2: The performance of moderate physical activityin laboratory rodents who had varying degrees of motor impairment before starting exercise produced substantialimprovements in their motor skills. In one group of mice, "moderately disabled" (left panel), animals are unable tohold onto a roller in constant motion for over 200 seconds. This task is very simple to do for normal healthyanimals capable of walking on the roll for an indefiniteperiod, although they have more than 360 seconds toavoid motivation.

After a week of moderate exercise (running 1 km / hour / day) of sick animals have a normal motor skillscontinue to be maintained while exercising. In a second group of animals, "severely disabled" (rightpanel), the exercise not only significantly increasesthe motor ability (although not reaching normal levels), but more important is the fact that animalswho exercise survive much longer and in bettercondition. This can be interpreted as that exercisekeeps alive neuronal groups that are essential forlife.

Knowing the mechanisms by which physical exercise

is beneficial to the brain is not of purely academic

interest. For example, we may allow the

development of therapeutic strategies based on

better knowledge of these mechanisms.

Of course the best option is to exercise as a

preventive measure and maintenance. It is in the

case of pathological conditions that preclude

exercise training when the alternatives are important.