Department of Physiology and Biochemistry, University School of Physical Education, Cracow, Poland;
Institute of Pharmacology, Polish Academy of Science, Cracow, and Faculty of Health Sciences, Jagiellonian University School of Medicine, Cracow, Poland
It is well documented that physical activity can induce a number of various stimuli which are able to enhance the strength and endurance performance of muscles. Moreover, regular physical activity can preserve or delay the appearance of several metabolic disorders in the human body. Physical exercise is also known to enhance the mood and cognitive functions of active people, although the physiological backgrounds of these effects remain unclear. In recent years, since the pioneering study in the past showed that physical activity increases the expression of the brain derived neurothophic factor (BDNF) in the rat brain, a number of studies were undertaken in order to establish the link between that neurothrophin and post-exercise enhancement of mood and cognitive functions in humans. It was recently demonstrated that physical exercise can increase plasma and/or serum BDNF concentration in humans. It was also reported that physical exercise or electrical stimulation can increase the BDNF expression in the skeletal muscles. In the present review, we report the current state of research concerning the effect of a single bout of exercise and training on the BDNF expression in the brain, in both the working muscles as well as on its concentrations in the blood. We have concluded that there may be potential benefits of the exercise-induced enhancement of the BDNF expression and release in the brain as well as in the peripheral tissues, resulting in the improvement of the functioning of the body, although this effect, especially in humans, requires more research.
It is well known that physical activity provides a number of various stimuli which are able to enhance both the metabolic and functional status of the human body. Physical training within a relatively short period of time (weeks or months) is able to increase the expression of a number of genes involved in any enhancement of a physical capacity (1). Perhaps the most spectacular discovery concerning the adaptation of the body to physical training was presented by John Holloszy, who has shown that regular physical activity/training can induce mitochondria biogenesis in skeletal muscles, leading to an improvement of physical performance (2-4). An increase in muscle mitochondria density enhances the metabolic stability of the muscle during exercise and increases muscle performance (5-7).
For a long period of time physical training was almost exclusively associated with athletes and their preparation for top sports events. However, during the last few decades the amount of studies concerning the effect of physical activity/training and its effects on the health status of healthy yet untrained people as well as of patients has substantially increased (8). They were mainly focused on the effect of training on the adaptation of the cardiovascular, hormonal and muscle systems. The new vision of the benefits of regular physical activity has been presented in a series of experiments showing the anti-inflammatory action of physical exercise (for review see (9, 10)). It was demonstrated that the moderate intensity of physical exercise can be an important factor in the prevention as well as in the healing of several metabolic disturbances of the human body (1, 8, 11).
Physical exercise is also known to enhance the mood and cognitive functions in humans (12-15), although the physiological backgrounds of those effects remain unclear. In recent years there has been a growing interest in research concerning the effect of physical exercise and training on the functioning of the brain, with a special focus on its effect on the brain derived neurotrophic factor (BDNF). Several of these studies showed that exercise induced an up-regulation of the BDNF in the hippocampus and might therefore play an important role in the enhancement of cognitive functions in humans.