Transcutaneous spinal direct current stimulation induces lasting fatigue resistance and enhances explosive vertical jump performance

Abstract

Transcutaneous spinal direct current stimulation (tsDCS) is a non-invasive neuromodulatory intervention that has been shown to modify excitability in spinal and supraspinal circuits in animals and humans. Our objective in this study was to explore the functional neuromodulatory potential of tsDCS by examining its immediate and lasting effects over the repeated performance of a whole body maximal exercise in healthy volunteers. Using a double-blind, randomized, crossover, sham-controlled design we investigated the effects of 15 min of anodal tsDCS on repeated vertical countermovement jump (VCJ) performance at 0, 20, 60, and 180 minutes post-stimulation. Measurements of peak and take-off velocity, vertical displacement, peak power and work done during countermovement and push-off VCJ phases were derived from changes in vertical ground reaction force (12 performance parameters) in 12 healthy participants. The magnitude and direction of change in VCJ performance from pre- to post-stimulation differed significantly between sham and active tsDCS for 7 of the 12 VCJ performance measures (P < 0.05). These differences comprised of a post-sham fatigue in VCJ displacement/work done, peak to peak power and take-off velocity, and a resilience to this fatigue effect post-active tsDCS. In addition there was also an enhancement of countermovement performance and total work done (P < 0.05). These changes did not vary across repeated VCJ performances over time post-tsDCS (P > 0.05). Our original findings demonstrate that one single session of anodal tsDCS in healthy subjects can prevent fatigue and maintain or enhance different aspects of whole body explosive motor power over repeated sets of VCJs performed over a period of three hours. The observed effects are discussed in relation to alterations in central fatigue mechanisms, muscle contraction mode during jump execution and changes in spinal cord excitability. These findings have important implications for power endurance sport performance and for neuromotor rehabilitation.

Long‐lasting modifications of motoneuron firing properties by trans‐spinal direct current stimulation in rats

“…A metal clip placed on the abdominal skin flap ventral to the lumbar spinal cord served as a reference electrode. The dorsoventral polarization arrangement was similar to those previously described in studies on mice (Ahmed, ) rats (Aguilar et al, ) and humans (Berry et al, ) and provided higher current densities than a previously used dorso‐shoulder arrangement (Parazzini et al, ).…”

“…For example, in sports, this could enable an athlete to produce higher contractile forces with less effort for one hour after DC stimulation, which would provide the athlete with an advantage in numerous disciplines. The application of anodal transcutaneous spinal DC stimulation in humans has been demonstrated to enhance explosive jump performances for up to 1.5 hr following a single 15‐min polarization session (Berry et al, ). However, the practical significance of tsDCS applications may not be limited to increasing muscle activation.…”

“…The purpose of this study was to determine whether modifications to motoneuron electrophysiological properties can be sustained over a long period of time, up to a few hours. An answer to this question will help explain some of the observed functional effects reported for tsDCS in earlier investigations (Berry et al, ; Lamy, Ho, Badel, Arrigo, & Boakye, ). Because stable intracellular recordings from individual motoneurons can last for only minutes, rather than hours, and their reliability substantially decreases with time, an appropriate experimental protocol must be proposed.…”

“…Trans‐spinal direct current stimulation (tsDCS) is emerging as a promising neuromodulative technique that can be used to treat neurological disorders or to facilitate sport performance (Angius, Hopker, & Mauger, ; Ardolino et al , ; Berry, Tate, & Conway, ; Estes, Iddings, & Field‐Fote, ; Lefaucheur et al, ). However, despite the broad application of tsDCS, the physiological mechanisms underlying the observed effects remain unclear, although some significant advances have been made towards our understanding of DC‐evoked neuronal plasticity.…”

Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans

“…For clinical purposes, it would be desirable if the stimulation could be applied non-invasively and at intensities that are not painful. Lately, considerable interest has therefore been devoted to the possibility of modulating spinal neural transmission by transcutaneous application of a constant electrical direct current (DC) over the spinal cord; tsDCS (Berry, Tate, & Conway, 2017;Jankowska, 2017;Murray, Tahayori, & Knikou, 2018;Song & Martin, 2017). This has been spurred on by the demonstration that cortical DC stimulation may modulate cortical excitability and induce lasting plastic changes in cortical circuitry raising prospects of a clinical role in neurorehabilitation following brain lesion (Lefaucheur et al, 2017;Nitsche et al, 2008;Nitsche & Paulus, 2000).…”