Simple reaction time and obesity in children: whether there is a relationship?
Moradi and Esmaeilzadeh Environmental Health
and Preventive Medicine
Simple reaction time and obesity in children: whether there is a relationship?
Akbar Moradi 0 2
Samad Esmaeilzadeh 0 1
0 Department of Education , Ardabil , Iran
1 University of Mohaghegh Ardabili , 153 Nasim 1, part III of Sabalan, 5619888457 Ardabil , Iran
2 Islamic Azad University science and research Branch , Tehran , Iran
Objective: Reaction time (RT) testing is one of the oldest diagnostic methods used in modern psychology, and is known as simple and sensitive cognitive test. It has been recently reported that RT is related to obesity in young, adult and elderly individuals. However, most of the studies included small sample of participants, used just body mass index (BMI) as body obesity index, and did not consider some potential confounders such as age, socioeconomic status and physical activity in their studies. Furthermore, there is little and contradictory results for children. Therefore, the present study aimed to examine the relationship between RT and weight status in a sample of children. Methods: Three hundred and fifty four 9-12 year old schoolboys underwent standard anthropometry, and various simple RT tests. Results: After controlling for potential confounders no significant relationship was observed between audio-RT (RTA) and clinical RT (RTclin) with BMI, %fat, waist circumference (WC) and waist to height ratio (WHtR) (P > 0.05). But, significant relationship (β = 0.18; P = 0.02) was observed between visual-RT (RTV) and %fat (but not BMI, WC and WHtR). Conclusions: Among the various simple RT tasks and central and total body obesity indices, just significant relationship was observed between %fat and RTV in the schoolboys. According to the results, it is concluded that RT impairment due to obesity may less be observed, or may not be observed for some types of RT tasks and obesity indices during childhood.
Audio-visual reaction time; Body mass index; Clinical reaction time; Cognitive function; Fat percentage; Waist circumference; Waist to height ratio
Environmental Health and Preventive Medicine
Reaction time (RT) testing is one of the oldest diagnostic
methods used in modern psychology, and the first
examinations of this parameter dates back to the nineteenth
century . RT tests are known as simple and sensitive
cognitive test in both healthy individuals and patients
. It is the time interval between the using of a
stimulus and the appearance of quick voluntary response by
an individual. It involves three phases as follows: a)
processing of the stimulus, b) making decision about it
and c) programming a response. Therefore, RT
measurement includes: 1- The sensory neural code latency
traversing both in central and peripheral pathways, 2- Both
cognitive and Perceptive processing, 3- A motor signal
traversing both peripheral and central neuronal
structures 4- And eventually the latency in the end effectors
activation such as muscle activation . Speed of
human’s information processing and its quality can be
evaluated by using one (simple RT) or more (Choice
RT) stimuli, and from an executive functions perspective
both tasks are a measure of sustained attention; however,
choice RT task put greater stress on the decision making
and leads prolonged RT than simple RT .
It has been shown that some factors such as age [5–7],
caffeine and some drugs [8, 9], illnesses ,
socioeconomic status (SES) [6, 7, 11], and physical activity (PA)
lifestyle patterns [6, 7, 12, 13] are associated with RT.
There is also some evidence has recently been reported
by researches underlying relationship between obesity
and RT in young, adult and elderly individuals [14–20].
The evidence suggests that overweight/obese individuals
© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
are inferior while performing RT compared with their
healthy weight peers [14–20]. But, contradictory results
underlying the relationship between obesity and RT have
been reported for children [5, 6].
Regarding the relationship between obesity and RT
that have been reported recently some points should be
noted. For instance, most of the previous studies
underlying the relationship between RT and obesity included
small sample of participants and/or used just body mass
index (BMI) as the obesity index [15–20], while BMI can
be influenced by a number of factors and indices, such
as central obesity, which is more closely linked to some
adverse health outcomes than BMI , and therefore
obesity indices may differentially relate to changes in
cognitive function over time. In addition some previous
similar studies did not consider some potential
confounders such as age, socioeconomic status (SES) and
PA lifestyle patterns [15–20], whereas it has been
reported that SES is strongly correlated with cognitive
ability and achievement during childhood and beyond
; and it has been shown that more physically active
individuals are better able to respond quickly to a
stimulus presented to [6, 7, 12] and are capable of allocating
more attentional resources toward the environment and
process information more quickly .
In this context the purpose of the present study was to
examine whether there is significant relationship
between various RT tasks and obesity indices among a
relatively large numbers of children after controlling for
some potential confounders such as age, SES and PA.
During 2013–2014, a cross-sectional data were drawn
from a sample of three hundred and fifty four, 9–12
year old schoolboys of three schools, in the center of
Ardabil Province, North West of Iran. Three schools
were selected randomly from a list of boys’ urban
public schools (N = 130). The nature and purpose of
the study were explained to all schoolboys (n = 964)
before invitation for participating in the present study.
Children were excluded of the study if they were
identified with known presence of chronic disease or
using any medication which could affect RT [9, 10].
Children who were invited and passed the exclusion
criteria of the study and gave their consent verbally
(n = 605) were given written consent forms for their
parents approval. Total of four hundred fifty three
signed consent forms were collected and the owners
of the forms were recruited into the study.
Nonetheless, at the end of the study, complete data were
collected from 354 participants [dropped data because of
illness, absence and withdrawal for some personal
reasons etc.] (Fig. 1). Age of the boys was determined
from their date of birth in their school register. The
anthropometric variables and RT tests were
measured in the empty room. The measurements took
place when a participant was at rest. For this mean,
during the physical education lessons selected boys
were requested to undergo the measurements. All
measurements were performed during the winter and
spring of the year 2013. General characteristics of
the participants are indicated in Table 1. The present
study was approved by the Human Ethics Committee
of the Ardabil Department of Education, and the
experiment was performed in accordance with the
ethical standards of the committee and with the
Anthropometric variables and obesity indices
Height of the participants was measured barefoot in the
Frankfurt horizontal plane with a telescopic height
measuring instrument (Type SECA 225) to the nearest
one mm. Weight of the participants was measured in
without shoes and underwear with an electronic scale
(Type SECA 861) to the nearest 0.1 kg.
BMI and %fat were measured as the total body obesity
indices and waist circumference (WC) and waist to
height ratio (WHtR) were measured as the central body
obesity indices. BMI was calculated as body weight in
kilograms divided by the square of height in meters. WC
was measured midway between the superior border of
the iliac crest and the lowest rib with an inelastic
measuring tape at the end of normal expiration to the nearest
0.1 mm. WC was divided by the height to determine the
waist to height ratio (WHtR). Lange skinfold caliper was
used to assess triceps and calf skinfold thickness  on
the right side of the body for all the subjects. The
average of three measures was calculated for each site and
then %fat was calculated according to the equations .
Boys %fat ¼ 0:735 ðsum of average skinfoldsÞ
Reaction time (RT) tests
All participants were made familiar with procedure of
the RT tests and were requested to avoid using caffeine
containing drinks  and any acute PA . The boys
were made to sit comfortably in a chair and were
motivated to better their results as much as possible, using
the dominant hand, with a protocol of 5 practice trials
for each RT tests followed by data acquisition trials. Data
from practice trials were not included to analyses. In our
experiments we used rest break times (5 min) between
each RT test to prevent fatigue .
Fig. 1 Flow diagram demonstrating the study methodology
Audio Reaction Time (RTA) and Visual Reaction time (RTV)
RT software which was installed on a laptop was used
for obtaining both RTA and RTV which had an
interstimulus interval from1000 to 3000ms, response range
from 150 to 1500 ms, and a display accuracy of 0.001 s.
By starting each RT test each subject completed 40 RTV
and 40 RTA executions. For performing RTV the subject
was requested to press a default key (spacebar) as soon
as possible, using the index finger, which was in contact
Table 1 General characteristics of the boys (n = 354)
BMI body mass index, PA physical activity, RTclin clinical reaction time, RTA
audio reaction time, RTV visual reaction time, WC waist circumference, WHtR
waist to height ratio
with the key, when a large dot (highlighting green circles
against a yellow background) appeared on the monitor.
For executing RTA the subject was requested to press
the key every time he heard a “beep” sound. Headphone
was provided for clarity of sound. After completing each
test, average of performances for each test were recorded
for each subject.
Clinical Reaction Time (RTclin)
In addition to the above computerized simple RT tests
we measured a new clinical measure of RT (RTclin)
which has been recently developed and validated [24,
25]. Each boy participated in simple RTclin testing, using
the RTclin apparatus, which has been described elsewhere
[5–7, 24, 25] but is repeated here for convenience of the
reader. The apparatus for measuring RTclin is a
measuring 0.8 m long stick, marked in 5 mm increments
embedded in a weighted rubber disk. Each boy sat with the
dominant forearm resting on a horizontal desk surface,
such that the proximal edge of the hypothenar eminence
was positioned at the edge of the desk. The apparatus
was held by the examiner vertically, with the weighted
disk put inside the boy’s open hand, such that the
superior surface of the weighted disk was aligned with the
plane of the boy’s first 2 digits and no part of his hand
was in contact with the weighted disk. The apparatus
was dropped by the examiner at predetermined,
randomly assigned time intervals of between two and five
seconds to prevent the boy from anticipating the time
of drop. Then, the boy tried to catch the apparatus as
quickly as possible after it began to drop. In the
event of an anticipatory catch before the apparatus
was dropped, the examiner restarted the
randomdelay interval count before dropping the apparatus. If
the device was dropped by a boy that trial did not
include in the calculation of mean RTclin. The boys
were tested using the dominant hand with a protocol
of 10 data acquisition trials. The distance the device
fell before being caught by the boy was recorded in
meters (m), and used to calculate RTclin in seconds
(s) for each trial using the formula for a body falling
under the influence of gravity (t = 0.45 × √d); where
“d” is distance (m) and “t” is time (s) [24, 25]. Mean
baseline RTclin values were calculated for each boy.
Physical activity (PA)
PA for the children was measured using the PA
Questionnaire - Children (PAQ-C) a reliable and valid
measure of PA for children during the school year [26–28]
with some alternations to suit to our society [29, 30].
Children were requested to fill out the questionnaire
under their parents’ supervision.
Socioeconomic status (SES)
SES was computed from parents’ education and
occupational status which is explained previously [6, 7, 30, 31].
Descriptive statistics were run on all variables. Data were
screened for problems of skew, kurtosis, and outliers.
Initial Pearson product–moment correlations were
conducted on relationship between RT tests and age, SES and
PA score. Any variable exhibiting a significant correlation
with the dependent variable (RT) was included as a
covariate/confounder in the analyses. For finding the
relationship between the RT tests and the obesity indices
hierarchical regression analysis was conducted in 2 steps.
In the first step confounding variables (age, SES and PA)
were entered, and in the second step obesity indices were
entered, separately. All calculations were performed using
SPSS v.21.0 software for Windows (SPSS Inc, Chicago, IL,
USA). The significance level was set at p < 0.05.
Pearson correlation (Table 2) indicated significant
negative relationship between age and RTV, RTA and RTclin
(P < 0.01). Significant negative relationship was observed
between SES and RTV, RTA and RTclin (P < 0.01).
Although, negative relationship was observed between
PA and the RT tests, only significant relationship was
observed between PA and RTclin (P < 0.05).
(P = 0.11)
(P = 0.09)
RTclin clinical reaction time, RTA audio reaction time, RTV visual reaction time,
PA physical activity, SES socioeconomic status
Multiple linear regression analysis (Table 3) indicated
significant negative relationship between age and the RT
tests (P < 0.01). Significant negative relationship was
observed between RTclin and SES (P < 0.05). Significant
negative relationship was found between PA and RTclin
and RTV (P > 0.05). Linear regression analysis after
adjustment for the potential confounders (step 2) indicated
significant relationship between RTV and %fat (P < 0.05).
No significant relationship was observed between RTV,
BMI, WHtR and WC (P > 0.05). In addition regression
analysis indicated no significant relationship between
RTA and RTclin with the all obesity indices (P > 0.05).
The results indicated that among the various obesity
indices and simple RT tests, and after controlling for the
possible confounders only significant relationship was
observed between RTV and %fat. No significant
relationship was observed between RTV, BMI and central
obesity indices; and no significant relationship was observed
between RTclin and RTA to the obesity indices.
In the previous studies among schoolboys no
significant relationship was observed between RTclin and
various obesity indices (BMI, %fat, WC and WHtR), which
the present study results replicate the previous study
results [5, 6]. It has been suggested that type of the RT
Table 3 Relationship between the RT tests with possible
confounders (step 1) and the obesity indices (step 2)
−0.17 (P = 0.02)
−0.18 (P = 0.01)
−0.03 (P = 0.69)
−0.09 (P = 0.29)
−0.05 (P = 0.50)
−0.08 (P = 0.29)
−0.03 (P = 0.63)
−0.09 (P = 0.13)
0.04 (P = 0.55)
0.03 (P = 0.70)
−0.01 (P = 0.09)
0.03 (P = 0.61)
0.04 (P = 0.54)
−0.12 (P = 0.04)
0.13 (P = 0.07)
0.18 (P = 0.02)
0.06 (P = 0.41)
0.07 (P = 0.30)
BMI body mass index, PA physical activity, RTclin clinical reaction time, RTA
audio reaction time, RTV visual reaction time, SES socioeconomic status, WC
waist circumference, WHtR waist to hip ratio
Note: In the first step confounding variables (age, SES and PA) were entered,
and in the second step obesity indices were entered, separately
task might play an important role in the relationship
between weight status and RT [5–7]. For instance, some
recent studies reported contradictory results based on
the relationship between type of task performance and
obesity, and discrepancy results have been shown
between healthy weight and obese children for different
types of RT, and it has been concluded that “childhood
obesity is negatively and selectively associated with
prefrontal inhibitory control” [14, 32].
Although, several recent studies have reported positive
relationship between RT and obesity (measured by BMI)
among young, adult and older people [15–20], however,
we observed that among a relatively larger sample of
participants, using various obesity indices and RT tests
and controlling for potential confounders just RTV was
significantly related to %fat. In this context it should be
stated that subcutaneous fat percentage as an overall
body obesity index has been reported as a better body
obesity predictor than BMI and has been concluded that
BMI as a measure of total body obesity does not account
for varying proportions of fat, muscle mass, and bone or
the distribution of body fat [33, 34]. However, to the best
of our knowledge little studies underlying the
relationship between obesity and RT have used subcutaneous fat
percentage as well as central obesity.
Interestingly, we observed negative (but not significant)
relationship between RTclin and obesity in the children.
Our results are according to some recent studies that have
reported it is not necessarily appropriate to consider body
adiposity as a negative factor influencing neuromuscular
RT performance, and in contrast body lipid reserves are
integral to the development of the nervous system (e.g.,
the development of myelin nerve heath) and thus better
RT, even amongst individuals within the healthy weight
ranges . Therefore, according to the results of the
present study and literature [5–7, 17, 32, 35, 36] it is
plausible that RT impairment due to obesity lees be
observed during childhood, or may not be observed for some
types of RT tasks and obesity indices.
However, since the study has several limitations,
results need to be interpreted with caution. For example,
the cross-sectional nature of the study limits the
possibility to draw conclusions regarding causality of any of
the observed associations in the present study.
Furthermore, the present study did not include subjects of both
sexes. Therefore, for more reliable results about the
relationship between RT and weight status, additional
studies by using larger sample size, various age groups, RT
tests, obesity indices and in both sexes are needed.
SE designed the study, helped for the measurements and data collection,
performed the statistical analyses and wrote the manuscript and submitted
it. AM helped for the measurements and data collection. Both authors read
and approved the final manuscript.
Ethics approval and consent to participate
All procedures performed in studies involving human participants were in
accordance with the ethical standards of the Human Ethics Committee of
the Education Department and with the 1964 Helsinki declaration and its
later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in
1. Merkel J. Die zeitlichen Verhältnisse der Willensthähigkeit . Philos Stud . 1885 ; 2 : 73 - 127 .
2. Jakobsen LH , Sorensen JM , Rask IK , Jensen BS , Kondrup J. Validation of reaction time as a measure of cognitive function and quality of life in healthy subjects and patients . Nutrition . 2011 ; 27 : 561 - 70 .
3. Botwinik J , Thompson LW . Premotor and motor components of reaction time . J Exp Psychol . 1966 ; 71 : 9 - 15 .
4. Magill RA . Motor learning and control: Concepts and applications . 8th ed. New York : McGraw-Hill Companies ; 2011 .
5. Esmaeilzadeh S. Reaction time: does it relate to weight status in children? HOMO-J Compar Hum Biol . 2014 ; 65 : 171 - 8 .
6. Moradi A , Esmaeilzadeh S. Association between reaction time, speed and agility in schoolboys . Sport Sci Health . 2015 ; 11 : 251 - 6 .
7. Esmaeilzadeh S , Farzizadeh R , Kalantari HA , Mahmoudi A. Does obesity cause reaction time impairment in youth? HOMO-J Compar Hum Biol, Under review .
8. Durlach PJ , Edmunds R , Howard L , Tipper SP . A rapid effect of caffeinated beverages on two choice reaction time tasks . Nutr Neurosci . 2002 ; 5 : 433 - 42 .
9. Spencer SV , Hawk-Jr LW , Richards JB , Shiels K , Pelham Jr WE , Waxmonsky JG . Stimulant treatment reduces lapses in attention among children with ADHD: The effects of methylphenidate on intra-individual response time distributions . J Abnorm Child Psychol . 2009 ; 37 : 805 - 16 .
10. Smith A , Brice C , Leach A , Tiley M , Williamson S. Effects of upper respiratory tract illnesses in a working population . Ergonomics . 2004 ; 47 : 363 - 9 .
11. Noble KG , Norman MF , Farah MJ . Neurocognitive correlates of socioeconomic status in kindergarten children . Dev Sci . 2005 ; 8 : 74 - 87 .
12. Murray NP , Russoniello C . Acute Physical Activity on Cognitive Function: A Heart Rate Variability Examination. Appl Psychophysiol Biofeedback . 2012 ; 37 : 219 - 27 .
13. Sibley BA , Etnier JL . The relationship between physical activity and cognition in children: A meta-analysis . Pediatr Exer Sci . 2003 ; 15 : 243 - 56 .
14. Kamijo K , Pontifex MB , Khan NA , Raine LB , Scudder MR , Drollette ES , et al. The negative association of childhood obesity to cognitive control of action monitoring . Cere Cortex . 2014 ; 24 : 654 - 62 .
15. Skurvydas A , Gutnik B , Zuoza AK , Nash D , Zuoziene IJ , Mickeviciene D. Relationship between simple reaction time and body mass index . Homo-J compar Hum boil . 2009 ; 60 : 77 - 85 .
16. Deore DN , Surwase SP , Masroor S , Khan ST , Kathore V. A cross sectional study on the relationship between the body mass index (BMI) and the audiovisual reaction time (ART) . J Clin Diag Res . 2012 ; 6 : 1466 - 8 .
17. Gunstad J , Paul RH , Cohaen RA , Tate DF , Gordon E. Obesity is associated with memory deficits in young and middle aged adults . J Eat Weight Disord . 2006 ; 11 : 15 - 9 .
18. Nene AS , Pazare PA , Sharma KD . A study of relation between body mass index and simple reaction time in healthy young females . Indian J Physiol Pharmacol . 2011 ; 55 : 288 - 91 .
19. Nikam LH , Gadkari JV . Effect of age, gender and body mass index on visual and auditory reaction times in Indian population . Indian J Physiol Pharmacol . 2012 ; 56 : 94 - 9 .
20. Gentier I , Augustijn M , Deforche B , Tanghe A , De Bourdeaudhuij I , Lenoir M , D'Hondt E. A comparative study of performance in simple and choice reaction time tasks between obese and healthy-weight children . Res Dev Disabil . 2013 ; 34 : 2635 - 41 .
21. Lindqvist P , Andersson K , Sundh V , Lissner L , Björkelund C , Bengtsson C. Concurrent and separate effects of body mass index and waist-to-hip ratio on 24-year mortality in the Population Study of Women in Gothenburg: evidence of age-dependency . Eur J Epidemiol . 2006 ; 21 : 789 - 94 .
22. Roche A , Heymsfield SB , Lohman TE . Body Composition. Champaign: Human Kinetics ; 1996 .
23. Welford AT . Choice reaction time: basic concepts . In: Welford AT, editor. Reaction Times . New York : Academic ; 1980 . p. 73 - 128 .
24. Eckner JT , Kutcher JS , Richardson JK . Pilot evaluation of a novel clinical test of reaction time in National Collegiate Athletic Association Division I football players . J Athl Train . 2010 ; 45 : 327 - 32 .
25. Eckner JT , Whitacre RD , Kirsch N , Richardson JK . Evaluating a clinical measure of reaction time . Arch Physcal Med Rehab . 2006 ; 87 : 10 .
26. Kowalski KC , Crocker PRE , Faulkner RA . Validation of the physical activity questionnaire for older children . Pediatr Exerc Sci . 1997 ; 9 : 174 - 86 .
27. Kowalski KC , Crocker PRE , Donen RMD . The physical activity questionnaire for older children (PAQ-C) and adolescents (PAQ-A) manual . Retrieved on 2007 ; from http://www.hkin.educ.ubc.ca/behavioural/PAQ%20manual.pdf.
28. Crocker PRE , Bailey DA , Faukner RA , Kowalski KC , McGrath R. Measuring general levels of physical activity: Preliminary evidence for the physical activity questionnaire for older children . Med Sci Sports Exerc . 1997 ; 29 : 1344 - 9 .
29. Esmaeilzadeh S. Relationship between depressive symptoms with physical activity and physical fitness among children . Ment Health Prev . 2014 ; 2 : 11 - 7 .
30. Esmaeilzadeh S. The association between depressive symptoms and physical status including physical activity, aerobic and muscular fitness tests in children . Environ Health Prev Med . 2015 ; 20 : 434 - 40 .
31. Kalantari HA , Esmaeilzadeh S. Association between academic achievement and physical status including physical activity, aerobic and muscular fitness tests in adolescent boys . Environ Health Prev Med . 2016 ; 21 : 27 - 33 .
32. Kamijo K , Pontifex MB , Khan NA , Raine LB , Scudder MR , Drollette ES , et al. The association of childhood obesity to neuroelectric indices of inhibition . Psychophysiology . 2012 ; 49 : 1361 - 71 .
33. Nooyens AC , Koppes LL , Visscher TL , Twisk JW , Kemper HC , Schuit AJ , et al. Adolescent skinfold thickness is a better predictor of high body fatness in adults than is body mass index: the Amsterdam Growth and Health Longitudinal Study . Am J Clin Nutr . 2007 ; 85 : 1533 - 9 .
34. Sarría A , García-Llop LA , Moreno LA , Fleta J , Morellón MP , Bueno M. Skinfold thickness measurements are better predictors of body fat percentage than body mass index in male Spanish children and adolescents . Eur J Clin Nutr . 1998 ; 52 : 573 - 6 .
35. Grantham J , Henneberg M. Adiposity is associated with improved neuromuscular reaction time . Med Hypotheses . 2014 ; 83 : 593 - 8 .
36. Gunstad J , Lhotsky A , Wendell CR , Ferrucci L , Zonderman AB . Longitudinal examination of obesity and cognitive function: results from the Baltimore Longitudinal Study of Aging . Neuroepidemiology. 2010 ; 34 : 222 - 9 .