HEALTH, 20 09, 1, 47-50
Published Online June 2009 in SciRes. http://www.scirp.org/journal/health
Specificity and sensitivity of visual evoked
potentials P100 latency to different events exercise
Jing-Guo Zhao1, Shu-Juan Pang1, Guang-Wei Che2
1Physical Education College, Shandong Normal University, Jinan, 250014, P. R. China; 2Physical Education College, Shandong
University of Traditional Chinese Medicine, Jinan, 250014, P. R. China.
Received 6 April 2009; revised 26 April 2009; accepted 29 April 2009.
ABSTRACT
Visual evoked potentials (VEPs) are a series of
signals about visual occipital cortex in response
to visual stimuli and can be used as one of ob-
jective non-invasive neuro-physiological pa-
rameters to reflect the visual organs and central
visual pathway’s functional integrity. Previous
studies have shown that acute and chronic ex-
ercise could affect VEPs independent from body
temperature and other physiological parameters.
VEPs may well be used as neuro-physiological
criteria in defining the performances of the ath-
letes. Different sports training have different
effects on VEPs, but the results are not consis-
tent. P100 latency is the representative compo-
nent of VEPs and it is of high, steady amplitude
and of slight intra- and inter-individual variabil-
ity so that the index is most commonly used.
The purpose of this study was to investigate the
specificity and sensitivity of P100 latency to dif-
ferent physical activities. The neural electricity
device of NDI-200 was used to measure the
pattern reversal VEPs of all subjects, including
the values of the resting state before and after
different events exercise. Different events exer-
cise contained an aerobic cycloergometric ex-
ercise (7 subjects were conducted to a Bruce
Graded Exercise Test on the Monark Ergomedic
839E cycloergometer, THR (target heart rate) =
85% HRmax, 3 times/week, about 10 minutes
once time, 6 weeks), tennis training (16 volun-
teers, 2 hours/day, 3 days/week, 8 weeks),
aerobic Latin exercise (7 subjects, 1 hour/day, 3
days/week, 6 weeks) and the Baduanjin of
Health Qigong training (6 subjects, 1 hour/day, 3
days/week, 6 weeks). The VEPs recordings of
the control groups obtained synchronized with
the experimental groups. SPSS 11.5 for win-
dows was used for statistical analysis. A level of
P﹤0.05 was accepted as statistically significant.
The VEPs P100 latency of post-exercise of all
experimental groups except Baduanjin group
became shorter significantly compared with
those of pre-exercise (P﹤0.05). No significant
difference was found between pre-and post-
exercise for the control groups. This study
showed that exercise could shorten the P100 la-
tency significantly. Moreover, it also indicated
that VEPs were sensitive to exercise to a certain
extent. We concluded that VEPs might well be
used as neuro-physiological criteria in defining
the performances of the athletes. It was found
that the VEPs P100 latency became shorter after
most training programs; furthermore, it demon-
strated that P100 latency of VEPs had little
specificity to different events.
Keywords: visual evoked potentials; P100 latency;
specificity; sensitivity
1. INTRODUCTION
Visual evoked potentials (VEPs) are a series of signals
representing the responses of the visual occipital cortex
to visual stimuli including flash and pattern stimuli, and
can be used as one of the objective non-invasive neuro-
physiological parameters in the assessment of the func-
tions of visual organs, visual pathways and the optical
central nervous system [1]. Previous studies have shown
that both acute and regular/chronic exercise could affect
VEPs independent from body temperature and other
physiological parameters. But all the results are not con-
sistent [2,3,4,5,6,7]. P100 latency is the representative
component of VEPs and the most commonly used index
for its high, steady amplitude and slight intra- and in-
ter-individual variability. In order to investigate the
specificity and sensitivity of P100 latency to different
physical activities, we recorded the efficacy of an aero-
bic cycloergometric exercise, tennis training, aerobic
Latin exercise and Baduanjin of Health Qigong training
for 6 to 8 weeks [8].

48 J. G. Zhao et al. / HEALTH 1 (2009) 47-50
SciRes Copyright © 2009 HEALTH
2. MATERIALS AND METHODS
2.1 Subjects
All subjects filled out the PARQ (Physical Activity
Readiness Questionnaire) & YOU questionnaire and
they have no optic or other systematic disease or other
history of neurological disease or exercise taboos. Writ-
ten consent was obtained from all subjects. The experi-
ment was approved by the local ethics committee.
3. EXPERIMENTAL DESIGN
3.1 The Aerobic Cycloergometric Exercise
11 healthy volunteers [(average age, (24±1) years)] from
Shandong Normal University were selected for this
study from October to December, 2007. Of these, 8 stu-
dents participated in the exercise including 4 boys and 4
girls. Meanwhile the 1st control group was consisted of
3 girls. This exercise was completed using the Monark
Ergomedic 839E cycloergometer with Bruce Graded
Exercise Test, THR (target heart rate) at 85% HRmax,
and 10 min a time, 3 times/week, for 6 weeks. The 1st
control group was measured synchronized with the ex-
perimental group.
3.2 The Tennis Training
45 healthy volunteers from Shandong Normal University
were selected for this study from April to June, 2007. 31
of them were majored in physical education. There were
21 male students [average age, (26±3) years; height,
(177±6) cm; weight, (74±8) kg; sports life, (8±4) years]
and 10 female students [average age, (24±1) years,
height, (165±6) cm, weight, (59±10) kg; sports life, (5±3)
years]. Of these, 11 males and 5 females participated in
the tennis training for 8 weeks. The remained 14 stu-
dents of them were studying as usual and had no profes-
sional sports history. There were 9 males [average age,
(23±1) years; height, (170±3) cm; weight, (65±8) kg]
and 5 females [average age (23±1) years; height, (157±3)
cm; weight, (50±5) kg]. According to that whether they
were majored in physical education or not, and whether
they took part in tennis training, the students were di-
vided into 3 groups: a tennis group of physical education
students (n =16), the 2nd control group (a non-tennis
group of physical education students, n =15), the 3rd
control group (a non-tennis group of non-physical edu-
cation students, n =14). Although there were differences
in age among the three groups, it could be overlooked,
because some previous studies have reported that the
latencies and amplitudes of VEPs are stable from the age
of 18 to 49.
3.3 The Aerobic Latin Exercise and Baduan-
jin of Health Qigong Training
27 healthy girls from Shandong Normal University were
selected to perform this experimental protocol. They
were randomly divided into three groups. The aerobic
Latin group contained 7 girls, the Baduanjin Health
Qigong group included 6 volunteers and the 4th control
group was consisted of 7 students. Both the aerobic
Latin and Baduanjin Health Qigong group took exercise
1 hour/day, 3 days/week, for 6 weeks, respectively. In
the experimental duration, the 4th control group was
examined synchronized with the two exercise groups.
3.4 Instrument
VEPs in response to middle check stimuli were recorded
and analyzed using an NDI-200 neural electricity tester,
which was produced by Shanghai Haishen Medical
Electronic Instrument Co., Ltd. This instrument is a kind
of 4-channel, anti-shock-type neural electrophysiological
system, which is safe and reliable, and which can be
used for clinical application to record electromyograms
and visual-, brainstem auditory-, and somatosensory-
evoked potentials.
3.5 Measurement of VEPs
Prior to the study, all subjects were thoroughly informed
about the details of the study to eliminate their fears, and
they were comfortably settled in a quiet and dark room
waiting for testing for 5 minutes.
3.5.1 Recording Conditions
The sites where the electrodes were to be placed were
cleaned with 75% alcohol, and then the electrodes were
smeared with conductive paste and placed on the skin.
The VEPs recordings were performed using bipolar
electrodes on the head; the recording electrode was posi-
tioned 1.5 cm above the occipital bone, the reference
electrode was placed on the middle forehead and the
ground electrode was placed on the vertex. After the
electrode impedance test, the electrode impedance was
kept below 5kΩ.
3.5.2 Recording Methods
All subjects were seated comfortably in a dark room 100
cm away from the monitor. After 5 min of dark adapta-
tion, they were instructed to gaze at a fixed point in the
middle of the screen with one eye (the advantage eye,
that is the better visual acuity one), with natural pupil,
but they couldn’t blink throughout the test, while the
other eye which was not tested was covered. In order to
make the waveform reliable, we measured each subject
two times and took the average of the two measure-
ments.The VEPs recordings were accomplished using
eyeglasses in subjects who were myopic.
3.5.3 Stimulation
A chessboard pattern reversal method in middle check
(25×25) mm2 was displayed on a 12-inch screen. The
stimulation frequency was at a speed of 2 Hz, lightness
of 90 cd/m2, contrast of 80%.

J. G. Zhao et al. / HEALTH 1 (2009) 47-50 49
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3.5.4 Wave Recording
The range of filters was 1-100 Hz, the sensitivity was 10
μV/div. In order to improve the SNR 100 responses were
averaged.
3.5.5 Wave Recognition
Tests were performed strictly according to the require-
ments for recording stable VEPs. VEPs were three-phase
composite waves. The first was a smaller negative wave,
and its peak time was at about 75 ms, the second wave
was a large and stable positive wave, which peaked at
about 100 ms, and the last was a negative wave peaking
at about 145 ms, which was not only unstable, but also
be influenced easily by many other factors. This three-
wave compound is also named the NPN complex, and it
is the main waveform used for clinical observation. The
waves were named separately as N75, P100 and N145,
according to both their peak times and that whether they
were negative or positive waves.
3.5.6 Index Analysis
The latencies of N75, P100 and N145 waves were tested
separately. Measurements of the latencies were made
from the beginning of stimulation to the peak response
time.
3.5.7 Reliability of VEPs Measurements
All the subjects took part in the exercise according to the
coach strictly and completed the examinations actively.
The operator of this study had regular special training
and operated the procedure seriously.
4. STATISTICAL ANALYSIS
The experimental data were analyzed by SPSS for win-
dows 11.5. The Independent-Samples and Paired-Sam-
ples T Test were used for testing the significant differ-
ences of inter-group and intra-group. A level of P<0.05
was accepted as being statistically significant. Meas-
urement data are expressed as Mean±SD.
5. RESULTS
Comparisons of VEP P100 latencies before and after dif-
ferent events are shown in Table 1.
Obviously, P100 latency shortened significantly after
the aerobic cycloergometric exercise for 6 weeks, tennis
training for 8 weeks and aerobic Latin exercise for 6
weeks compared with those of pre-exercise (P<0.05)
except Baduanjin of Health Qigong program for 6 weeks.
However, no significant difference was found in corre-
sponded control group between the first and the second
measurement (P>0.05).
6. DISCUSSION
VEPs are a family of signals induced in response to vis-
ual stimuli (flashed or patterned stimulus) within the
visual occipital cortex; they mainly reflect the conduc-
tive function from retinal nerve cells to the optic central
system. Pattern-reversal VEPs (also named PR-VEPs)
were adopted by this study; they were acquired to use
stimuli with the same brightness, namely a black and
white checkerboard (25mm×25mm), which was reversed
at a certain frequency. In the visual pathway, the retina
makes a rough analysis of stimuli information; while the
lateral geniculate body is the relay station of the central
visual pathway. P100 latency is the typical component of
VEPs NPN complexes and it is the most commonly used
index for its high, steady amplitude and slight intra- and
inter-individual variability. The P100 latency is measured
from the beginning of stimulation to the peak response
time and it could reflect the information processing and
conduction velocity from ganglion cells to optic center
of visual system. Previous studies demonstrated that
VEPs latencies of athletes’ were significantly shorter
than those of non-athletes. Many factors could influence
VEPs, such as stimuli, recording parameters and indi-
vidual differences between subjects [9]. Visual reaction
time has been shown to be much shorter in athletes
training in the types of sports that demand rapid eye ac-
tivity (such as tennis, volleyball and squash) than other
types of sports (for example, cycling) [2]. Recent studies
have shown that both acute and chronic exercise could
affect VEPs independently of body temperature and
other physiological parameters. The capability and level
of visual function are important to athletes so that VEPs
can well be used as neuro-physiological criteria in clas-
sifying the performances of the athletes [2,3,11,12].
Table 1. Comparisons of VEPs P100 latencies of pre- and post-exercise.
Events N Weeks The P100 latencies (ms)
Pre-exercise Post-exercise P
Aerobic Cycloergometric Group
The 1st Control Group
The tennis Group
The 2nd Control Group
The 3rd Control Group
The Aerobic Latin Group
Baduanjin Group
The 4th Control Group
7
3
16
15
14
7
6
7
6
6
8
8
8
6
6
6
96.0±4.8
94.5±8.8
97.9±3.9
99.3±10.8
99.4±6.1
98.4±5.7
97.9±2.5
99.4±6.1
92.7±7.6
95.4±10.4
96.3±3.7
101.2±11.0
99.7±5.5
97.3±5.7
96.2±2.4
99.7±5.5
＜0.05
＞0.05
＜0.05
＞0.05
＞0.05
＜0.05
＞0.05
＞0.05

50 J. G. Zhao et al. / HEALTH 1 (2009) 47-50
SciRes Copyright © 2009 HEALTH
In order to use VEPs as an index in evaluating physi-
cal training and classifying the performance of athletes,
especially the P100 latency, it is necessary to investigate
both the sensitivity and specificity to different exercise.
Therefore, we observed the efficacy of an aerobic cyclo-
ergometric exercise, tennis training, aerobic Latin exer-
cise and Baduanjin of Health Qigong training for 6 to 8
weeks in the basis of our previous studies [10,11,12].
It is known to all that VEPs P100 latency is sensitive
to physical exercise. Considerable studies have revealed
that an acute exercise could shorten the P100 latency
significantly but the values returned to the basal level
after exercise [3,11,12]. In this study, the VEPs P100
latency shortened significantly compared with those of
pre-exercise (P<0.05) after an aerobic cycloergometric
exercise for 6 weeks, tennis training for 8 weeks and
aerobic Latin exercise for 6 weeks, but no statistical dif-
ference was found between the values measured firstly
and secondly in all the control subjects corresponding to
the experimental groups. These results indicated that not
only an acute exercise but also a period time of exercise
(6 to 8 weeks) could shorten the VEPs P100 latency sig-
nificantly. The results further supported the viewpoint
that VEPs may well be used as neuo-physiological crite-
ria in classifying the performances of the athletes. How-
ever, there were no reports about correlation between
VEPs P100 latency and the athletes’ performances. Fur-
ther studies should be done in the future about feature of
VEPs P100 latency in athletes of different training level.
Some studies have reported that VEPs were different
among different events athletes, but all the findings are
not consistent [2,3,4,5,6,7]. In this study, we mainly
examined the representative component of VEPs NPN
complexes-the P100 latency of inter-and intra-subjects.
Our results showed that the P100 latency was shorter
significantly after an aerobic cycloergometric exercise
for 6 weeks, a tennis training for 8 weeks and an aerobic
Latin exercise for 6 weeks compared with those values
of pre-exercise (P<0.05) except the Baduanjin of Health
Qigong exercise for 6 weeks. We thought that the dif-
ference might be due to its lower intensity of the
Baduanjin of Health Qigong exercise. This demonstrated
that VEPs P100 latency was sensitive to most physical
exercise, which was to say that its specificity to different
training programs was poor. As a result, it was difficult
to reflect the feature of different sports training with a
single VEPs examination. Our findings suggested that
both transversal and longitudinal studies should be done
so as to investigate the VEPs specificity to different
events, including the VEPs P100 waveforms, amplitudes
and latencies.
7. CONCLUSIONS
The present study demonstrated that VEPs P100 latency
became shorter significantly after most physical exercise.
That was to say VEPs P100 latency was sensitive to dif-
ferent events training to a certain extent, but its specific-
ity is very poor.
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