Dr.Biol., Professor J.V. Koryagina^1,2
PhD S.V. Nopin¹
PhD V.A. Blinov²
PhD O.A. Blinov^3
1Scientific and Methodological Center Analyst
²Siberian State University of Physical Culture and Sports, Omsk
³Omsk State Agrarian University (OmGAU), Omsk

Keywords: physical working capacity, neurophysiology, proprioception, neuro-muscular system, movement control.

Introduction. A growing number of researchers devote their scientific career to studying the effect of exercise on the brain function. While the behavioral studies showed a strong association between physical exercises, cognitive functions and the psyche, the underlying neurophysiological effects are still unclear.  

The basis for the study was the state contract for R&D № 484 with the Ministry of Sport of the Russian Federation dated September 26^th, 2016.     

Objective of the study was to make an analytical overview of the most promising studies in athletic neurophysiology and psychophysiology for the period since 2010 performed by the leading foreign university laboratories.   

Research method and organization. A number of different methods and approaches including electromyography, magnetic resonance imaging and a deeper analysis of the neurotransmitters have been used recently for better understanding of the neurophysiological predictors for physical working capacity.  

Results and discussion. Sport and brain morphology. Brain-derived neurotrophic factor is a crucial plasticity effector acting as a regulator of survival, growth and differentiation of neurons. Experts from Beckman Institute for Advanced Science and Technology (USA) [9] note that intense exercise and workouts are essential to start the processes by which neurotrophins mediate energy metabolism and neuronal plasticity having a powerful impact on the brain.

Experts of the Emergency Medical Technology center, Kyungil University (Gyeongsan, Republic of Korea) reveled a correlation between the regional cerebellar volume and static balance in female short-track speed skaters [4]. They also found a signification impact of a skater’s qualification and gender: women have a greater volume of the cerebellum than men. 

Scientists from the Ruhr University in Bochum [7] conducted a neuroimaging analysis of the brain of athletes specializing in sports with different energy supply mechanisms (aerobic vs anaerobic). The analysis revealed high grey matter in the supplementary motor area/dorsal premotor cortex in both of the groups of athletes. It was also found that high-level endurance sports affect the structures of the medial temporal lobe, areas that modulate (set the rhythm of) aerobic exercises.   

Scientists of the University of Illinois [1] conducted a neuroimaging investigation of the association between aerobic fitness, hippocampal volume and memory performance in preadolescent children. The findings are the first to indicate that aerobic fitness may relate to the structure and function of the brain.

Neurophysiology of sports states. Scientists of the University of Maryland [7] studied stress, emotion regulation and cognitive performance as predictive contributions of trait into the state of frontal EEG alpha asymmetry. Results implicate state-specific relative left frontal lobe activity as having an adaptive role in the regulation of emotion during cognitive challenge, but only under conditions of sufficient stress.   

Experts of the University of Colorado in Boulder study the neurophysiology of muscle fatigue [5]. Although the nervous system simply needs to provide an activation signal required for a prescribed muscle action, the number and diversity of synaptic inputs that must be integrated by the spinal motor neurons change. The muscle activation by the nervous system can be compromised during fatiguing contractions when significant interactions between the brain and muscles occur, limiting the duration of exercise and stability of the performed action.    

D.M. Smith [16] from the University of Rhode Island (USA) conducted a systematic review of action anticipation studies using functional neuroimaging of a stimulated brain during a sport-specific anticipation task. Expert-novice comparisons were commonly used to investigate differences in action anticipation performance and neurophysiology. Experts tended to outperform novices, and brain structures were reported to be involved differently for experts and novices during action anticipation.    

Expert sport stars reliably execute their skills with remarkable precision and accuracy. To provide an insight into the mechanisms that underpin the superior performance of experts compared to novices, A. Cooke [2] critically reviews in his article experiments that have examined cortical activity (i.e., movement related cortical potentials) and cardiac activity during preparation for action in self-paced aiming sports. According to him, high working capacity of an elite athlete can be explained by a slowing heart rate when performing specific tasks and changes in EEG activity during preparation for action. These responses are interpreted in terms of preparatory information processing and response programming.

A scientist from the Laboratory of Physical Activity, Performance and Health of the University of Pau and Pays de l’Adour (France) presented a review of the effects of general and local fatigue on postural control [13]. Postural control is a complex function that includes maintenance of the vertical projection of the center of gravity. General exercises have a greater impact on the sensory receptors and balance functions that local ones that cause postural control deterioration. The effects of local fatigue on postural control vary depending on the exercise parameters, the postural control test protocol used, characteristics of the subject and physiological conditions of the test. Fatigue of proximal muscles as well as the extensor muscles of the lower extremities worsens postural control more than fatigue of distal muscles and flexor muscles of the upper extremities.

Ideomotorics and physical working capacity. Scientists of the Waseda University (Japan) [10] analyzed and presented in their review the accumulated research with regard to capabilities for ideomotorics, brain activity during it, its advantages as well as the impact of sensory inputs on ideomotorics. It is found that certain parts of the brain including those of the supplementary motor area, premotor cortex and parietal cortex are activated both while performing movements and while creating images of movements. Although ideomotorics is performed without movement or muscle contraction, sensory signals from the periphery interact with the motor imagery.

To elucidate the neural substrate associated with kinesthetic motor imagery of difficult whole-body movements, a scientist of the Waseda University (Japan) [11] measured brain activity during a trial involving kinesthetic motor imagery and action observation as well as during a trial with action observation alone. The vividness of kinesthetic motor imagery as assessed by questionnaire was the highest for chin-up, less for kip and the lowest for giant swing. The results suggest that activity in the primary visual cortex is dependent upon the capability of kinesthetic motor imagery for difficult whole-body movements. Since the activity in the primary visual cortex is likely related to the creation of a visual image, the authors speculate that visual motor imagery is recruited unintentionally for the less vivid kinesthetic motor imagery of difficult whole-body movements.    

Movement control. Scientists from the University of Mainz (Germany) [17] assessed in their study how a mirror can be used in sport as a visual feedback tool to train specific skills and how these effects relate to skill level. After four training days using only the right hand, the performance of both hands improved. Performance improvement was more pronounced when athletes used only the left hand. 

The article of the scientists from the Queensland University of Technology in Brisbane (Australia) and Sheffield Hallam University (UK) [3] dwells upon the consequences of insufficient contact between biomechanics and theoretical foundations of biology, psychology, behavioral neuroscience and motor control. Studies have shown how people adjust coordination models while performing a task, regardless of their skill level. The research demonstrates how the inherent properties of the dynamic neurobiological systems such as numerous degrees of freedom of the motor system may be used to meet the interacting constraints during exercise and work. 

An Arizona State University expert [4] proposed a novel interpretation of control of human movements that involve multiple joints and called it the leading joint hypothesis. The hypothesis suggests that joints of a multijoint limb play different roles in motion production in accordance with their mechanical subordination in the joint-hinge. There is one (leading) joint that creates a dynamic framework for the movement of the whole limb. Acceleration/deceleration on the front joint is simple, created by a mutual activity of the muscles in the same way as during a single-joint movement, i.e. mainly excluding the effect of other joint movements.  

In locomotion, humans have to deal with road irregularities, adapting their movements by passive/active leg adjustments. Scientists from the Friedrich-Schiller-University of Jena (Germany) [12] investigated the stiffness regulation in the ankle and knee joint and analysed the correlation between EMG, kinematic and dynamic parameters. The authors identified the pre-activation control as a key for altering the leg posture in preparation for altered ground properties. During the stance phase the control of activation plays a minor role since geometry and the initial conditions (e.g., leg length, landing angle and landing velocity) ensure an adequate adjustment of joint stiffness as well as leg stiffness.   

Researchers from the Sport Science Department of the University of Freiburg (Germany) reported the importance of core muscle strength for lower-body stabilization [6]. Based on the biomechanical aspects it is important that the center of stabilization is not limited to stabilization of the body frame only. Functional training on unstable surfaces produces high neuromuscular activation of the trunk muscles and improves functional indicators and physical working capacity. The study presented by the authors focuses on the most basic definitions of functional stabilization, outlines the impact of core stability training, stable and unstable conditions and prepares biomechanical arguments about the context of the trunk and lower limbs stabilization as well as instability training effects.

Sporting achievements and proprioception. Proprioceptive ability specific to the movement challenges of a sport was hypothesized to relate to both years of sport-specific training and the competition level that a sport performer has reached. To test this hypothesis, experts of the Shanghai University of Sport [8] studied proprioceptive sensitivity of the ankle joint. Test scores were higher for athletes than non-sport-specific individuals. Regression analysis demonstrated the importance of good ankle proprioception in athletic success. Ankle proprioception testing is recommended in sports orientation as well as in the identification of athletes who require specifically targeted training to improve their proprioceptive abilities.

Therefore, the modern science has made a notable progress in understanding the neurophysiological predictors of physical working capacity. Strenuous physical loads were found to be of positive effect on the neurotrophic processes in the brain. The study identified a few specific aspects of the regional brain morphology and physiology for the regions in control of certain motor skills and conditional abilities, with neurophysiological characteristics of different athletic conditions being described. Issues of ideomotorics, movement control and proprioception are being considered by scientists from the points of view of neurophysiology and psychophysiology. The study data gives the means to understand the mechanisms underlying the athletic efficiency in different sport activities.

References

1. Chaddock L. et al. A neuroimaging investigation of the association between aerobic fitness, hippocampal volume, and memory performance in preadolescent children. Brain research, 2010, vol. 1358, pp. 172-183.
2. Cooke A. Readying the head and steadying the heart: a review of cortical and cardiac studies of preparation for action in sport. International Review of Sport and Exercise Psychology, 2013, vol. 6, no. 1, pp 122-138.
3. Davids K., Glazier P. Deconstructing neurobiological coordination: the role of the biomechanics-motor control nexus. Exercise and sport sciences reviews, 2010, vol. 38, no. 2, pp. 86-90.
4. Dounskaia N. Control of human limb movements: the leading joint hypothesis and its practical applications. Exercise and sport sciences reviews, 38.4, 2010, 201 p.
5. Enoka R.M. Unraveling the neurophysiology of muscle fatigue. Journal of Electromyography and Kinesiology, 2011, vol. 21, no. 2, pp. 208-219.
6. Gollhofer A., Gehring D., Mornieux G. Importance of core muscle strength for lower limb stabilization. 6  International Congress on Science and Skiing 2013, St. Christoph a. Arlberg, Austria, p.  11.
7. Goodman R.N. Stress, emotion regulation and cognitive performance: The predictive contributions of trait and state relative frontal EEG alpha asymmetry. International Journal of Psychophysiology, 2013, vol. 87, no.2, pp.115-123.
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14. Park I.S., Yoon J.H., Kim N., Rhyu I.J. Regional сerebellar volume reflects static balance in elite female short-track speed skaters. Int J Sports Med. 2012 Nov 9. Available at (Free access): http://www.ncbi.nlm.nih.gov/pubmed/23143696.
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Corresponding author: koru@yandex.ru

Abstract

The article gives an analytical overview of the most promising studies in athletic neurophysiology and psychophysiology for the period of 2010-2016 performed by the leading foreign university laboratories. Analysis of the study reports showed that the modern science has made notable progress in understanding the neurophysiological predictors of physical working capacity. Strenuous physical loads were found to be of positive effect on the neurotrophic processes in brain. The study identified a few specific aspects of the regional brain morphology and physiology for the regions in control of certain motor skills and conditional abilities, with neurophysiological characteristics of different athletic conditions being described. Issues of ideomotorics, movement control and proprioception are being considered by scientists. The study data gives the means to understand the mechanisms behind the athletic efficiency in different sport activities.