Transcranial Direct Current Stimulation of the Temporal Lobe Does Not Affect High-Intensity Work Capacity

Abstract

Stimulation of the left insular cortex may affect heart rate variability (HRV) and exercise effort perception. These studies investigated the effects transcranial direct current stimulation (tDCS) and electrode orientation on HRV and repeated maximal knee extensions. In study 1, following sham stimulation, anodal left temporal lobe stimulation, or anodal right temporal lobe stimulation, 10 male and 10 female subjects (age=21.0±1.5 yr) completed 50 maximum isokinetic extensions at 180°s. There was a significant effect of stimulation condition on HRV for only one (SD2; p=.037; η=.159) of five HRV metrics. There was no significant effect on isokinetic fatigue percent, or isokinetic work (all p≥.278; all η≤.065). It has been proposed that placing the cathode electrode on the shoulder, may differentially affect tDCS. Therefore, in study 2, the effects of electrode orientation on tDCS-induced changes in HRV was assessed in ten healthy females and eight healthy males (21.6±2.5 yr) who completed cephalic, extracephalic, and sham trials. In the cephalic montage, the anode was placed over the left temporal lobe and the cathode was placed over right prefrontal cortex. In the extracephalic montage, the cathode was placed on the shoulder on the same side of the body as the anode. Neither cephalic nor extracephalic montages affected HRV (all p≥.152; all η≤.105). These data suggest that anodal tDCS of the insular cortex has little effect on HRV, and does not improve high-intensity exercise performance in the current population. Therefore, anodal tDCS applied over the left temporal lobe is not recommended for high intensity performance enhancement.

Effect of transcranial direct current stimulation on supramaximal intermittent exercise performance

“…The left IC seems to have its activity diminished when high-intensity exercises are done, whereas exercises with higher sympathetic activity, characteristic in supramaximal exercises, increase the activity of right IC 34 . Furthermore, there is evidence that anodal tDCS applied over the left temporal cortex is not effective for high-intensity performance enhancement 35 . Accordingly, stimulating the left IC before a supramaximal intermittent cycling exercise does not modulate the pleasure and displeasure sensations, and consequently does not decrease the RPE response and performance improvement.…”

“…The IC is located below the temporal cortex and it is deeper than other cortical areas, such as the motor cortex. Although the subcortical areas are affected by tDCS 2,5 , stimulation of temporal lobe targeting IC is questionable 35 . However, other areas of the brain, i.e.…”

“…The cathodal electrode placed over the contralateral prefrontal area (i.e., Fp2 area) in a cephalic montage may negatively affect the effects of anodal stimulation by decreasing excitability in the brain area 9 . Indeed, this could affect the perceived exertion and performance in exercise 35 . Thus, an extracephalic stimulation where the reference electrode is placed on the shoulder would annul out this negative effect 38 .…”

Transcranial Direct Current Stimulation at 4 mA Induces Greater Leg Muscle Fatigability in Women Compared to Men

“…The FT commenced with the same submaximal warm-up as the strength test (15 reps, concentric/concentric, 60 • /s) and consisted of 40 continuous concentric/concentric maximal contractions of the knee extensors and flexors at 120 • /s [25]. This FT protocol has been well established in both healthy people and people with neurological disorders [14,15,[26][27][28][29][30]. At minute 15 of the tDCS protocol (see "tDCS sessions" below), the R-FT was performed, followed by the L-FT.…”

Effects of Transcranial Direct Current Stimulation (tDCS) and Exercises Treadmill on Autonomic Modulation of Hemiparetic Patients Due To Stroke—Clinic Test, Controlled, Randomized, Double-Blind

“…(9) and CICCONE et al(34) that observed the increase of performance in healthy individuals when compared to Group sham.The literature has demonstrated that tDCS may modify the autonomic responses in healthy individuals Vandermeeren et al(35) and Clancy et al (36), in healthy athletes Montenegro et al (6) and Okano et al (9). This is the first study that has as purpose to assess the effects of tDCS over the left temporal lobe, in HRV in individuals with stroke sequel.…”