Physiology & Biochemistry Montenegro R et al. Prefrontal cortex DC stimulation and oxygen uptake at rest and post-exercise recovery. Int J Sports Med accepted after revision January 07, 2013 Bibliography DOI http://dx.doi.org/ 10.1055/s-0033-1333769 Published online: 2013 Int J Sports Med © Georg Thieme Verlag KG Stuttgart · New York ISSN 0172-4622 Correspondence Dr. Paulo de Tarso Veras Farinatti Institute of Physical Education and Sports Rio de Janeiro State University Rua São Francisco Xavier 524 sala 8133F 20550013 Rio de Janeiro Brazil Tel.: + 55/21/2587 7847 Fax: + 55/21/2587 7862 pfarinatti@gmail.com Key words ● ▶ energy expenditure ● ▶ metabolism ● ▶ isocaloric exercise ● ▶ EPOC ● ▶ central nervous system ● ▶ health Does Prefrontal Cortex Transcranial Direct Current Stimulation Influence the Oxygen Uptake at Rest and Post-exercise? reference electrode would modulate brainstem activity as reflected by the heart rate variability (HRV), respiratory rate, blood pressure, and sym- patho-vagal balance in healthy subjects. The results showed that tDCS did not significantly change the activity of brainstem autonomic cent- ers. However, more recent studies showed that anodal tDCS may influence the autonomic nerv- ous system modulation [23, 42]. Thus, more studies are needed to verify the possible influ- ence of tDCS on the modulation of cardiorespira- tory control and autonomic nervous system. Furthermore, anodal tDCS has been shown to modulate the neuronal activation and increase regional cerebral blood flow (rCBF) at rest in the prefrontal (and motor) cortex of healthy subjects [21, 43]. However, no studies investigating the magnitude of such improved cerebral oxygena- tion on oxygen uptake (V ˙ O 2 ) were found. There is evidence that aerobic submaximal exer- cise increases the oxygenation of the prefrontal cortex (PFC), as suggested by changes in oxyhe- moglobin (O 2 Hb), total Hb, and O 2 saturation [10, 16, 34]. Thus, the PFC activation seems to be related to V ˙ O 2 and energy expenditure (EE), as reflected by higher values of V ˙ O 2 during exercise and post-exercise recovery, when compared to baseline period [18]. Nonetheless, the tDCS influ- Introduction ▼ Transcranial direct current stimulation (tDCS) is a non-invasive technique widely used in neuro- logical disorders treatment [4, 6, 31]. It is a tech- nically simple tool in which a continuous weak electric current is applied to the brain via 2 elec- trodes that are placed on the subject’s scalp. The modulator underlying effects of the stimulation seem to be able to reach sub cortical areas [19]. Anodal tDCS has been shown to induce neuro- logical changes in the cell membrane resting potential, favoring depolarization and increasing spontaneous neuronal firing rate. On the other hand, opposite effects seem to be generated by cathodal tDCS [26]. These effects may be influ- enced by electrode montage (i. e., bilateral or uni- lateral and bi-cephalic or extra-cephalic tDCS) [2] or frequency of tDCS sessions [1]. Recently, tDCS has also been applied with other purposes, such as improving physical performance [8], physical rehabilitation [36, 37] or appetite regu- lation [24]. Little is known about the influence of tDCS on the modulation of cardiorespiratory centers and autonomic nervous system [20, 30] and the avail- able evidence is controversial. Vandermeeren et al. [41] investigated if tDCS with an extracephalic Authors R. Montenegro 1 , A. H. Okano 2 , F. A. Cunha 3 , E. B. Fontes 4 , P. Farinatti 5 Abstract ▼ The study evaluated the effect of transcranial direct current stimulation (tDCS) applied over prefrontal cortex on the oxygen uptake (V ˙ O 2 ) at rest and during post-exercise recovery. The V ˙ O 2 was assessed in eleven healthy subjects before, during tDCS (sham or anodal tDCS, 2 mA, 20 min), and 30-min following isocaloric aerobic exer- cise (~200 kcal). During tDCS, no changes were observed on V ˙ O 2 compared to baseline (P = 0.95) and sham condition (P = 0.85). The association between isocaloric exercise and anodal tDCS increased the V ˙ O 2 throughout 30-min recovery compared to sham condition (P < 0.001). There- fore, the energy expenditure within the excess post-exercise oxygen consumption (EPOC) period, after anodal tDCS was approximately 19 % higher compared to the sham condition (P < 0.05). In conclusion, anodal tDCS applied on the prefrontal cortex combined with sub- maximal aerobic exercise increased the EPOC, enhancing the V ˙ O 2 and energy expenditure at least for 30-min of recovery. Affiliations Affiliation addresses are listed at the end of the article Downloaded by: Lenamar Vieira. Copyrighted material.