Neuroscience of Exercise: Perspectives for Exercise Adherence

Abstract

It is well established that physical inactivity may increase the risk for the development of chronic diseases [1]. Also, physical inactivity is related to high costs with public health [2] therefore, regular exercise seems to be critical for individual and public health. In this context, it has been hypothesized that the affective response (pleasure and displeasure) may be a determinant of behavior [3], based on this premise, several original studies were performed during the last years as an attempt to establish a relationship between aerobic exercise and affective responses [4][5][6][7]. In general, the scientific literature demonstrates that aerobic exercise performed at high intensities is related to negative affective responses [8,9]. Moreover, a review published in 2015 showed that the affective response during aerobic exercise at a moderate intensity may predict future physical activity behavior [10]. However, despite the advancement of scientific literature in understanding the relationship between exercise and affective responses, the cerebral mechanisms that underlie this relationship are not well understood.Different theories are used to explain how the brain processes the affective responses. Davidson, proposed that the asymmetric electrical activity of right and left prefrontal cortex (PFC) may explain the pattern of affective response [11]. Specifically, Davidson proposed that the higher activation of left PFC is linked to positive affective response by inhibiting the amygdala whereas the higher activation of right PFC is linked to negative affective response [12]. However, it should be considered that the amygdala and the PFC are not the only structures involved in the affect modulation. The hippocampus, insula and anterior cingulate cortex are also involved in the affect modulation [12]. For example, ventral hippocampus is linked to the reward circuitry and stress response (controlling the hypothalamic-pituitary-adrenal axis) [13] which may influence the affective responses [14].In addition to the electrical and anatomical factors, metabolism is also an important factor to understanding the pattern of affective responses. Several substances such as cortisol [14], epinephrine and norepinephrine [14] and dopamine [15] may influence the affective responses. Another hypothesis used to explain the relationship between exercise and pleasure is the endocannabinoid hypothesis [16] which is based on the premise that an interaction between endocannabinoids and dopamine may influence the reward system increasing the sense of well being. Although research in this area has advanced, one of the main challenges is to understand how the brain interprets sensory inputs to generate an effective response.In summary, the advancement of technology brings new perspectives for neuroscience of exercise. Different instruments may be used to assess cerebral responses to exercise such as electroencephalography, near-infrared spectroscopy or magnetic resonance. However, due to the problems associated with the use of these i...