International Journal of Applied Exercise Physiology 2322-3537 www.ijaep.com
Vol.8 No.1
Received: September 2018 , Accepted: November 2018 , Available online: March 2019
DOI: 10. 30472 /ijaep.v8i1.353
Effects of Exercise on Visual Evoked Potentials
Dr Anjali N Shete1 *, Dr K D Garkal2, Dr Sayeda Afroz3
Associate Professor,Government medical college, Aurangabad 1 , Associate Professor,Government medical college, Aurangabad 2, Professor and HOD,Government medical college, Aurangabad 3
ABSTRACT:
The objective of this study was to investigate the effects of habitual exercise on visual evoked potentials (VEP) in Indian volleyball players. Visual evoked potentials (VEP) are used to assess the central visual pathway. Some physiological factors are known to affect the VEPs . The attention has been drawn to the correlation between the physical activity and evoked potential responses of the athletes. Very few studies have been done on Indian sports persons. Hence the study was conducted on Indian volleyball players. The study group consisted of 20 male volleyball players playing since last 2 years and the control group has 20 male subjects who were not involved in any sports activity. The N75, P100, and N145 latencies were measured before and after exercise. Significant differences were noted in terms of right and left P100 wave latencies between volleyball players and the sedentary subjects. No significant changes were observed in N75 & N145 latencies. The results suggest that habitual exercise affects the VEP . Small sized P100 amplitudes in the volleyball players can be attributed to the effect of rapid visual-activity-demanding sports on the central nervous system.
KEY WORDS: Visual evoked potential, exercise, , volleyball players, visual pathway.
Introduction:
Visual evoked potentials ( VEP) are used to assess the central visual pathways [1]Some studies have shown that the main waves of VEPs are affected by physiological factors such as age, head circumference, gender, color motion and temperature [2,3] Exercise is one of most important factors that affects the latencies of VEPs . There are studies reporting that exercisedecreases VEP latencies in relation to type, duration and intensity of exercise. [4,5]
19
this game , which requires the players reaction for many specific stimuli such as the position of the ball or other players ; the objects in visual space move very quickly and the players decision making proceeds in short time [6]
Many visual skills like visual resolution ability, dynamic visual activity, contrast sensitivity, oculomotor function, visual reaction time and visual coincidence anticipation are significant for volleyball players performance[7] There are some proofs that the participation in dynamic reactive training can improve visual reaction processing[8] and visual abilities [9]
However ;very few studies are done on Indian players to observe the effects of exercise on VEP. Hence ,the study was undertaken to observe the changes in young players who participated in 2 years of training in volleyball. We hypothesized that extensive participation in systemic long term training in volleyball improves early visual processing in young players. This study will determine the contribution of sports training practice to the modulation of visual sensory processing.
Materials and method:
Ethical approval from Institutional Ethics committee was taken prior to the study. Our study involved 20 male volleyball players of age 18-23 years with minimum 2 years of volleyball training experience. Daily minimum 2 hours of volleyball training were followed by all cases. The control group included 20 male volunteers of same age group not involved in any sports activity or exercise schedule. The basic data was recorded and thorough clinical examination was done to exclude any diseases. The subjects selected were healthy with no systemic or ocular disease.
Prior to the test , the subjects were informed about the details of the study to eliminate their fear and were comfortably settled in a quiet and dark room at least for 5 minutes.
The VEPs are recorded by 4 channel antishock neural electrophysiological system ( RMS, India) which is safe and reliable and can be used for clinical investigations. The VEP recordings were done as per protocol established by International society for clinical electrophysiology of vision[10] The range of filters was 1-100 Hz, the sensitivity was 10 μv . VEPs were elicited by mono-ocularly presented checkerboard pattern reversal stimuli with an identical stimuli having (1) large 10 4’ checks and (2) small 0’16’ checks. The VEP was recorded with surface electrodes according to International 10-20 system of EEG electrode placement Jasper 1958 [11] The reference electrode was placed on the vertex. The subjects were instructed to look at a central fixation point. The checkerboard stimulus with an alternating phase change of 1.89 Hz generated a response to the stimulus which is completed before the start of another stimulus . The analysis of such responses were summed and averaged. ( Fig 1) VEPs are three phase composite waves. The first is a smaller negative wave at 75ms, the second is large and stable positive wave peaked at 100ms and the last is a negative wave peaking at 145ms which is unstable and influenced by many other factors. This whole complex of wave is known as NPN complex ( N75, P100, N145) . P 100 latency is the most stable with little variation and hence commonly used index.
Fig 1 NORMAL VEP
Observations and Results:
Table 1 : Demographic data of Groups ( mean ± s.d.)
Parameters Control Group
n=20
Study Group
n =20
Age ( years) 19.05 ±
0.89
19.60 ± 1.14
Height (cm) 172.15 ±
6.52
172.21 ± 8.10
Weight (kg) 59.01 ±
7.38 63.32 ± 7.32
Head
Circumference (cm)
54.99 ± 1.83
55.65 ± 1.49
Training duration (years)
nil 2.34 ± 0.69
Table 2 : VEP responses of Groups ( mean ± s.d.)
Control Group
n=20
Study Group n =20
Right Eye
latency
N 75 ms P 100 ms
N 145 ms
70.05 ± 3.22
101.8 ± 7.92 140.81 ± 7.89
68.61 ± 3.55ns
96.29 ±
6.11**
136.31
±11.22 ns
Left Eye
latency
N 75 ms P 100 ms N 145 ms
69.77 ± 4.68 101.7 ± 8.70 141.11 ± 6,83
68.56 ±
3.24ns
95.65 ±
6.60**
138.55 ±10.23 ns
NS = not significant
21
Discussion:
Athletic training is often accompanied by high activation of the visual system, especially in sports that require the processing of dynamic visual information. Ball sports players must possess and integrate complex visual information including the flight of a ball and movement of opponents. Detection and determination of visual stimuli is crucial factor in executing successful motor responses. The good performance in elite athletes might be supported by neuroplastic changes in early sensory processing.[12]
One of the method to examine the early sensory processing is the use of VEPs. The mechanism of VEP changes induced by exercise may be due to changes that taking place in the increased rate of neuro transmission [13]
In our study, we have studied the effects of exercise on visual evoked potentials. We tried to see that systemic long term training in volleyball will improve early visual processing in young players. The interaction was observed for VEP wave latencies . Our study showed the significant changes in P100 wave . There was no significant change in other waves ; N75 and N145. ( Table 2)
Our results were similar to previous studies . A shorter P100 latency in Tennis and Squash players. The cause of the shorter latency was related to a greater development of abilities to process visual information rapidly. Zwierko et al [12] assessed the effects of exercise on neural activity in visual pathway in volleyball players which showed shorter P100 latency in players. Jin et al [14] in their study suggested that early visual sensory processing can be modulated by extensive physical exercise.
Ozmer divenli et al [15] also reported significant differences in P100 latency in female and male volleyball players and non athletes.
Our study revealed significant differences in P100 latency in volleyball players. In ball sports the visual system needs to provide the information very rapidly. In the case of volleyball, for proper response selection and action , players must process and integrate a large amount of dynamic visual information which includes ball flight movement and kinetic movements of opponents. The modulation of early sensory processing is evident due to this reason in ball sports. Such modulation was not observed in rowers and cyclists which do not require rapid visual stimuli [16] Volleyball training in our study also showed faster conduction time through the visual pathway. But, the changes observed are not clearly understood still as it may be due to plasticity or feedback mechanisms exerted on primary visual cortex by influences from visual processing [17]
Karni and Sagi[18] put forward the idea that the perceptual learning effect, increasing the speed of visual discrimination can be interpreted in terms of local plasticity induced by retinal input in early visual processing. This may be the reason for faster conduction in our study also.
The changes in VEPs might be related to attentional mechanisms. Volleyball is a dynamic sports which requires high attentional skills because many stimuli are acting simultaneously. Experimental data showed that attention increases the perceptual sensitivity for the discrimination of target stimuli [19] increases the contrast sensitivity [20] and improves visual activity [21]
the attended condition had shorter latency than the unattended condition.
Participating in systemic exercise demanding a high level of visual attention , the athletes make more use of visual information, encode and retrieve relevant information more efficiently , visually locate objects and patterns in the visual field faster and more accurately , use situational probability information better , make more rapid and appropriate decisions and perform better on measures of processing speed and a category of varied attentional paradigms [23,24,25,26]
There is correlation between the reduction of the neural signal transmission time in visual pathway and intensity of exercise . Zheo, Pang and Che[27] indicated that P100 latency is affected by low or high exercise intensity.
Exercise can influence neural activity in the visual path as a result of increase in blood flow and increased O2 and Glucose delivery to the tissues.[28] Probably it leads to release of neurotransmitters that enhance visual processing [29]
The P100 wave is generated from the foveal and extra-foveal retina. Extra foveal retina is responsible for peripheral vision. In volleyball the time to react to environmental demands is very short , directing attention to peripheral events increases readiness to detect a particular stimulus. Anzeneder ans Bosel [30] suggested that volleyball players have a better ability to modulate the distribution of attentional resources within and around peripherally cued areas. Volleyball training can improve attention. Consequently, quick stimulus discrimination and decision making can be improved.
Recently some researchers have suggested that one of the reason for improvement in visual sensory processing may be attributed to mirror neurons. The mirror neurons are special visio motor neurons which discharge action potentials when executing an action as well as during the observation of an action. The observational motor learning in volleyball may improve action
perception and motor execution. Mirror neurons have been proposed as neuro physiological basis of visio-motor and motor-visual transformation processes, and may play a role in the perceptual and motor improvements More studies in this context are needed to support the view.
Conclusion:
The shorter latency of P100 wave of VEP is observed in our study in volleyball players. The findings of our study demonstrated that exercise can affect early sensory processing in volleyball players . The exercise also reduces the signal conduction time in players .The application of VEPs may be used as neurophysiological criteria in defining the visual processing status in subsequent stages of recruitment and selection process of volleyball.
Limitations:
The sample size was very small. The study was done in only one gender so no comparison could be done in male female volleyball players . The small reduction in P100 latency is may be due to inclusion of players with 2 years of training. Future studies can be planned in players with long duration of exercise training.ACKNOWLEDGEMENT:
I would like to acknowledge the volleyball players and the volunteers for participating in the study.
References:
1.Thomas, N. G., Harden, L. M., & Rogers, G. G. (2005).
Visual evoked potentials, reaction times and eye dominance in cricketers. The J of Sp Med and Phys Fitness, 45, 428–433.
2.Allison, T., Wood, C. C., & Goff, W. R. (1983). Brain-stem auditory, pattern reversal visual, and short-latency somatosensory evoked potentials: Latencies in relation to age, sex, brain and body size. Electroencephal and Clinic Neurophysiol,55, 619–-636.
3. Sokol, S., Moskowitz, A., & Towle, V. L. (1981). Age-related changes in the latency of the visual evoked potentials: Influence of check size. Electroencephal and Clinic Neurophysiol, 51, 559–562.
23
related to physical activity. Intern j of Sp Med, 12, 293-298.
5. Dustman RE, Emmerson Rİ Ruhling Ro, shearer DE. steinhaus tA. Johnson sc, Bonekat HW shigeoka Jw. Age. and fitness effects on EEG. ERPS, visual sensitivity and cognition. Neurobiology of Aging 1990; 11: l93 – 200 6. Liviotti G., Lobietti R., Fantozzi S., Merni F. Reaction times in volleyball block: a biomechanical analysis.www.sportkinetics2007.com, 2007.
7. Erickson GB (2007) Sports Vision: Vision Care for the Enhancement of Sports Performance: Butterworth-Heinemann.
8. Ando S., Kida N., Oda S. Central and peripheral visual reaction time of soccer players and nonathletes. Percept Mot Skills, 2001. 92 (3): 786‐794
9. Land M F ,Mcleod P. From eye movements to actions: how batsmen hits the ball .Nat Neurosci. 2000;3:1340-1345.
10.Marmor M.F., Holder G.E., Seeliger M.W., Yamamoto S. Standard for clinical electroretinography. Doc Ophthalmol, 2004. 108: 107–114
11. Jasper 1958 Jasper, H. (1958). The ten twenty electrode system of the international federation. Electroencephal and Clinic Neurophysiol, 10, 370–375
12. Zwierko, T., Lubiński, W., Lubkowska, A., Niechwiej-Szwedo, E.,& Czepita, D. (2011).The effect of progressively increased physical efforts on visual evoked potentials in volleyball player and non-athletes. J of Sports Sci, 29, 1563–1572.
13. Hatfield B D , Landers DM (1987) Psychophysiology in exercise and sports research: an overview. Exerc.Sport.Sci.Rev., 15,351-387.
14. Jin et al 2010 Jin, H., Xu, G., Zhang, J. X., Ye, Z., Wang, S., Zhao, L., … Mo, L. (2010). Athletic training in badminton players modulates the early C1 component of visual evoked potentials: A preliminary investigation.
Intern J Psychophysiol, 78, 308–314.
15.Ozmer divenli et al 2005 Özmerdivenli, R., Bulut, S., Bayar, H., Karacabey, K., Ciloglu, F.,Peker, I., & Tan, U. (2005). Effects of exercise on visual evoked potentials. Intern J of Neuroscience, 115, 1043–1050.
16. Magnie et al 1998 Magnie, M. N., Bermon, S., Martin, F., Madany-Lounis, M., Gastaud, M., & Dolisi,C. (1998).
Visual and brainstem auditory evoked potentials and maximalAerobic exercise: Does the influence of exercise persist after body temperature recovery? Intern J of Sp Med, 19, 255–259.
17. Mehta,Ulbert,Schroeder 2000 Mehta, A. D., Ulbert, I., & Schroeder, C. E. (2000). Intermodal selective attention
in monkeys. I: Distribution and timing of effects across visualareas. Cerebral Cortex, 10, 343–358.
18. Karni and Sagi 1991 Karni, A., & Sagi, D. (1991).
Where practice makes perfect in texture discrimination: Evidence for primary visual cortex plasticity. Proceedings of the NAcad of Sci USA, 88, 4966–4970.
19. Lu and Dosher 1998 Lu, Z. L., & Dosher, B. A. (1998).
External noise distinguishes attention mechanisms. Vision Research, 38, 1183–1198.
20.Cameron, Tai , Carrasco 2002 Cameron, E. L., Tai, J. C., & Carrasco, M. (2002). Covert attention affects the psychometric function of contrast sensitivity. Vision Research,42, 949–967.
21.Carasco and Yesharun 1998 Carrasco, M., & Yeshurun, Y. (1998). Attention improves or impairs visual performance by enhancing spatial resolution. Nature, 396, 72–75.
22.Di Russo and Spinelli 1992,2002 Di Russo, F., & Spinelli, D. (2002). Effects of sustained, voluntary attention on amplitude and latency of steady-state visual evoked potential: A costs and benefits analysis. Clin Neurophysiol, 113, 1771–1777
23. Alves, H., Voss, M. W., Boot, W. R., Deslandes, A., Cossich, V., Salles, J. I., & Kramer, A.F. (2013).
Perceptual-cognitive expertise in elite volleyball players. Frontiers in Psychol, 4, 1–9.
24. Mann, D. T. Y., Williams, A. M., Ward, P., & Janelle, C. M. (2007). Perceptual-cognitive expertise in sport: A meta-analysis. J of Sp & Exer Psychol, 29, 457–478. 25.Starkes, J. L., & Ericsson, K. A. (2003). Expert performance in sports: Advances in research on sport expertise. Champaign, IL: Human Kinetics.
26. Voss, M. W., Kramer, A. F., Basak, C., Prakash, R. S., & Roberts, B. (2010). Are expert athletes ‘expert’ in the cognitive laboratory? A meta-analytic review of cognition and sport expertise. App Cog Psychol, 24, 812–826. 27. Zhao, J. G., Pang, S. J., & Che, G. W. (2009).
Specificity and sensitivity of visual evoked potentials P100 latency to different events exercise. Health, 1, 47–50. 28. Okuno, T., Sugiyama, T., Kohyama, M., Kojima, S., Oku, H., & Ikeda, T. (2006). Ocular blood flow changes after dynamic exercise in humans. Eye, 20, 796–800.
29. Basmak, H., Yildirim, N., Erdinç, O., Yurdakul, S., & Özdemır, G. (1999). Der effekt derlevodopatherapie auf das visuell evozierte potential und die sehschärfe in der amblyopie. Ophthalmologica, 213, 110–113.
