48 August / September 2019
Despite these findings, the effectiveness of tDCS has been questioned by a number of scientists who expressed their concern on the limited population size involved in the research [14] and whether the enhancement on endurance exercise performance [15], exercise tolerance or perception [16] is significant. However, as highlighted by Alix-Fages et al., a non-uniform approach has been used to directly compare such studies based on (i) tDCS protocols applied, (ii) stimulated brain area and (iii) evaluated skill, thus results appeared even more controversial.
5. Conclusions
The recent findings from the UK’s WADA accredited Anti-Doping Laboratory pointed out that anabolic agents, stimulants and narcotics were the most frequently detected prohibited substances. This showed a different profile with respect to the overall percentage of AAFs reported by all WADA-accredited laboratories, highlighting the diversity of doping profiling across the world. Future directions in Anti-Doping Testing will look at enhancing the development of new analytical methodologies for keeping up with the evolving nature of doping and at evaluating the suitability of alternative biological matrices.
Nevertheless the potential use of tDCS remains a concern and the Anti-Doping community must consider methods that would facilitate its detection. One area which may be adapted to address this problem is the ABP. A key difference between an ABP adverse finding compared to a “traditional” AAF is that it is no longer a requirement to prove a specific substance has been taken. Instead it is established that the athletes biological markers are outside
their individual specific limits (as defined through the long term monitoring of their own markers), thus resulting from the use of a banned substance or method. It may be therefore that the detection of tDCS could be performed by monitoring markers which would be known to increase through.
6. References
1. WADA Report. 2017 Anti-Doping Testing Figures. 2018 [cited 2019 05/07/19].
2. Thevis, M., et al., Mass spectrometry of stanozolol and its analogues using electrospray ionization and collision induced dissociation with quadrupole linear ion trap and linear ion trap orbitrap hybrid mass analyzers. 2005. 19(22): p. 3369-3378.
3. Cawley, A.T. and U. Flenker, The application of carbon isotope ratio mass spectrometry to doping control. J Mass Spectrom, 2008. 43(7): p. 854-64.
4. De La Torre, X.D.L., Application of GC- C-IRMS in the ABP, in Athlete Biological Passport Symposium. 2018: Rome, Italy.
5. Narduzzi L., D.-p.G., Marchand A, Audran M, Le Bizec B, Buisson C. GH-Omics: a metabolomics approach to detect growth hormone administration. in Manfred Donike Workshop 2019. 2019. Cologne.
6. Brunelin, J., et al., Examining transcranial direct-current stimulation (tDCS) as a treatment for hallucinations in schizophrenia. Am J Psychiatry, 2012. 169(7): p. 719-24.
7. Alix-Fages, C., et al., Short-Term Effects of Anodal Transcranial Direct Current Stimulation on Endurance and Maximal Force Production. A Systematic Review and Meta-Analysis. J Clin Med, 2019. 8(4).
8. Nitsche, M.A. and W. Paulus, Excitability changes induced in the human motor
cortex by weak transcranial direct current stimulation. J Physiol, 2000. 527 Pt 3: p. 633-9.
9. Nitsche, M.A. and W. Paulus, Sustained excitability elevations induced by transcranial DC motor cortex stimulation in humans. Neurology, 2001. 57(10): p. 1899-901.
10. Cogiamanian, F., et al., Improved isometric force endurance after transcranial direct current stimulation over the human motor cortical areas. Eur J Neurosci, 2007. 26(1): p. 242-9.
11. Okano, A.H., et al., Brain stimulation modulates the autonomic nervous system, rating of perceived exertion and performance during maximal exercise. Br J Sports Med, 2015. 49(18): p. 1213-8.
12. Hazime, F.A., et al., Anodal Transcranial Direct Current Stimulation (TDCS) Increases Isometric Strength of Shoulder Rotators Muscles in Handball Players. Int J Sports Phys Ther, 2017. 12(3): p. 402-407.
13. Vargas, V.Z., et al., Modulation of Isometric Quadriceps Strength in Soccer Players With Transcranial Direct Current Stimulation: A Crossover Study. J Strength Cond Res, 2018. 32(5): p. 1336-1341.
14. Reardon, S., ‘Brain doping’ may improve athletes’ performance. Nature, 2016. 531(7594): p. 283-4.
15. Flood, A., et al., The effects of elevated pain inhibition on endurance exercise performance. PeerJ, 2017. 5: p. e3028.
16. Barwood, M.J., et al., The Effects of Direct Current Stimulation on Exercise Performance, Pacing and Perception in Temperate and Hot Environments. Brain Stimul, 2016. 9(6): p. 842-849.
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