PhD N.A. Karatygin^{1, 2}
PhD I.I. Korobeynikova²
Y.A. Venerina^1
1I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow
²FSBNI Anokhin Scientific Research Institute of Normal Physiology, Moscow

Keywords: theta rhythm, EEG, sport, competitive progress.

Corresponding author: nikol.karatygin@yandex.ru

Abstract

Objective of the study was to analyze benefits of the EEG theta rhythm tests for competitive performance rating purposes in some sports disciplines, with the EEG theta-activity rates applicable as the competitive progress biomarkers.

Results and conclusion. Subject to the study was a correlation of the EEG theta rhythm amplitude with the individual attention control; plus a clear correlation between the frontal-medial theta rhythm amplitude and competitive progress found by a few studies. Some studies found the theta rhythm amplitudes for the sports professionals and beginners showing expressed differences that may be interpreted as indicative of the skills levels, with the theta rhythm rates applicable for the skill set rating purposes. Of special interest were analyses of the theta rhythm amplitude fluctuation profiles as biomarkers of the skill difficulty levels and state anxiety in sports.

Subject to the studies were also transcranial magnetic stimulation (with the theta packing protocols) methods used to correct the psycho-emotional control, optimize attention and motor memorizing mechanisms for a faster progress in the athletic skills mastering and excellence process. Of special importance in this context was the finding that transcranial magnetic stimulation of motor cortex improves the anaerobic performance. It should be emphasized, however, that the fast progress of the transcranial magnetic stimulation methods is associated with some risks as steps up the pre-competitive mental and physical fitness and, hence, may be interpreted as a sort of "neural doping". The study data and analyses give the grounds to conclude that the theta-rhythm-harmonized frequencies may be beneficial for precompetitive mental conditioning, with the EEG theta rhythm amplitude applicable as promising biomarkers for the training system improvements and competitive progress.

Background. Competitive accomplishments in modern sports require the individual resources being efficiently and completely mobilized for success, with the modern developments in neurophysiology being potentially beneficial for the relevant sports applications. Electroencephalography is ranked among the most informative and accessible non-invasive methods yielding important data on the brain activity in variable functional states. Modern technologies with their artifacts removal algorithms make it possible to obtain the EEG logs in quiescent state and on the move, with special benefits for the training and competitive performance rating and analyzing purposes.

It should be mentioned that all rhythms in the oscillatory activity of neurons are inextricably connected and representing some specific aspects of neurophysiological processes. Nevertheless, modern research classifies them into a few rhythm ranges, with their individual characteristics applicable as prognostic biomarkers of the nervous system activity on the whole and for competitive performance improvement purposes in particular.

One of the most promising prognostic criteria in this context are the EEG theta rhythm amplitude varying in the 4-7Hz range [5]. Thus P.K. Anokhin believes that a theta rhythm amplitude growth may be indicative of an individual fitness for a specific operational stress [1]. The theta rhythm amplitude was demonstrated to grow in response to cognitive stresses including such unspecific factors as the attention control levels [7], task difficulty levels and task solving effectiveness [14]. In addition, a few studies found correlations of the theta rhythm amplitude with the individual typological characteristics including the trait anxiety and stress tolerance [2]. The above individual psycho-physiological qualities ratable, among other things, by the EEG theta-activity tests are rather important for competitive progress in many sport disciplines.

Objective of the study was to analyze benefits of the EEG theta rhythm tests for competitive performance rating purposes in some sports disciplines, with the EEG theta-activity rates applicable as the competitive progress biomarkers.

Results and discussion. Theta rhythm oscillations are fixed in many brain structures including hippocampus, parietal and prefrontal cortex and sensory areas of the cortex. Of special interest for research is the so-called frontal-medial theta rhythm (FM-theta rhythm) commonly associated with the attention controls. For example, a theta rhythm study of a basketball sample found the FM-theta rhythm being more stable prior to successful throws. Moreover, the theta-2 range amplitude was found to grow to 6-8 Hz in aiming phase of a successful throw due to a special attention balancing phase, as believed by the analysts [6].

The FM-theta amplitude with competitive success correlation may be sport- and skill-level specific. For example, a study of the FM-theta amplitudes in golf found them being lower in cases of accurate shots versus the inaccurate ones – indicative, as the authors believe, of the pre-success attention control being optimally focused;  whilst excessive attention (with the related FM-theta amplitude growth) was found detrimental to the shooting accuracy [13]. It is believed that the FM-theta amplitude growth is negatively correlated with success for a wide range of visual-motor skills. This may be explained by the task-specific theta rhythm amplitude being negatively correlated with the skill ‘automation’ level – i.e. the high is the skill level in many cases, the higher is the success expectancy [8].

Correlation of the theta rhythm amplitude with the skill level was supported by a few studies of athletes grouped by the skill levels – to demonstrate the beginners and professionals being rather different in the theta rhythm test rates. Thus, a professional shooting sample was tested with the FM-theta amplitude growth prior to a shot – in contrast to the beginner shooters [10]. It was concluded that a successful competitor must develop a high motor skill level plus special attention control skills to timely concentrate on the key performance aspects, with such special concentration detectable by the FM theta patterns.

It is commonly believed that the theta rhythm amplitude growth is indicative, on the one hand, of the motor task difficulty level and, on the other hand, of the growing fatigue under long physical stress associated with the growing mental efforts to control attention and performance. These correlations were found by a few studies including the competitive performance analyzing ones [3]. Most of them have demonstrated a clear direct correlation of fatigue with the FM-theta rates [17].

Furthermore, the theta activity rates have been found correlated with emotions on the whole and sports-specific anxiety in particular [15]. A few experimental studies have found that stimulation of the anterior cingulate cortex by the theta-rhythm-matching frequencies helps mitigate anxiety [11], and it was assumed that the same effect may be achieved by non-invasive transcranial magnetic stimulation methods applicable, among other things, for the precompetitive state anxiety control purposes.

It may be pertinent to mention in this context that the past decades have seen a growing popularity of different transcranial magnetic stimulation methods including the theta packing transcranial magnetic stimulation ones (Theta Burst Stimulation, TBS). The TBS method has been proved beneficial for the attention control purposes [4]. It was also found that the TBS increases excitability of the cortex thereby improving the motor skills mastering process efficiency [16] and the sports-specific anaerobic performance [12].

The above data demonstrate good prospects for the transcranial magnetic stimulation applications in the sports training and competitive systems, although many in the sports research and athletic communities are somewhat concerned about the ethical aspects of such stimulations. Knowing that some stimulation methods may result in long-term effects on the attention control, motor memory and motor functions in sports, the transcranial magnetic stimulation applications, particularly the precompetitive ones, it is not improbable that they may be considered a sort of “neural doping” [9].

Conclusion. Our analysis of the available study reports on the subject gives reasons to conclude that the EEG theta rhythm test rates as biomarkers of athletic performance and competitive fitness may be rather promising for many purposes, particularly the competitive performance improvement ones. The theta rhythm biomarkers may be used for the training system perfection, attention control and motor skills excellence purposes, with special benefits for the precompetitive mental/ emotional conditioning tools. Good understanding of the theta rhythm oscillation test benefits for the athletic performance control purposes will help develop the relevant transcranial magnetic stimulation application procedures (protocols) to ensure due attention and competitive performance controls for success.

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