Effects of Core Stability Exercises and Cognitive Tasks Compared to General Exercises and Cognitive Tasks on Chronic Non-specific Back Pain
Phase: NA
Conditions: Chronic Non-specific Low Back Pain
Sponsor: Iran University of Medical Sciences

   Date: 03, 27, 2023 
 
Effects of core stability exercises and cognitive tasks compared to general 
exercises and cognitive tasks on chronic non-specific back pain. 
 
Two groups of exercise therapy approved for chronic low back pain in clinical guidelines are core 
stability exercises (CSE) and general exercises (GE) (1, 2). There is still no consensus on which 
exercises are superior to other exercises in reducing pain and disability in people with chronic non-
specific low back pain (3). For example, Coulombe et al. (4) reported core stability exercises are 
more effective than general exercises. However, Saragiotto et al. (5) concluded that motor control 
exercises are not superior to other forms of interventions. 
Studies found that combining cognitive and motor exercises helps to automate movements (6, 7) 
and postural control (7, 8).  Therefore it is recommended to perform exercises in the form of dual 
tasks. Based on this, it seems that adding cognitive tasks to each group of CSE and GE can have a 
different effect on pain, disability, and postural control strategies. Therefore, this research aims to 
investigate the effect of CSE with cognitive tasks compared to GE with cognitive tasks on pain, 
disability, and postural control strategies of people with non-specific chronic back pain. It is also 
a gap of knowledge in which group of exercises can lead to appropriate postural control strategies 
and changing between the feedforward and feedback control in time. 
Primary objectives: 
1- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on the pain intensity of non-specific chronic low back pain patients. 
2- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on the level of disability of non-specific chronic low back pain 
patients. 
Secondary objectives: 
1- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on postural stability (displacement range in the anterior-posterior 
direction on the Y axis, displacement range in the mediolateral direction on the X axis, velocity 
and total sway area), in the standing position of non-specific chronic low back pain patients. 
2- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on postural control strategies (short-term effective diffusion 
coefficient, long-term effective diffusion coefficient, critical displacement, and critical time) in the 
standing position of non-specific chronic low back pain patients. 
3- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on the level of fear of movement in non-specific chronic low back 
pain patients. 
4- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on the level of fear avoidance behavior in non-specific chronic low 
back pain patients. 
5- Comparison of the effect of core stability exercises with cognitive tasks compared to general 
exercises with cognitive tasks on the quality of life in non-specific chronic low back pain patients. 
Methodology 
The sample size of this study was calculated through G*Power software version 3.1.9.2 and based 
on primary outcome measures, including disability assessment, using the Oswestry disability index 
(ODI) questionnaire to the extent of 30% with a standard deviation of 3.85 and an effect size of 

0.3 (9). Assuming three measurements will do in two groups, a correlation assumption of 0.5 
between the measurements, 90% power, 5% type 1 error, and 26 participants with non-specific 
chronic low back pain (13 participants in each group) will enter the study. Considering the 30% 
possible dropout, equal to 7.8 people in total for both groups, the total number of participants in 
both groups will be 34 people. 
It should be mentioned that we calculated the sample size using both the primary outcome 
measures of pain and disability. Since the sample size was larger on disability, we used this index 
to determine the study's sample size. 
We will do sampling in a simple non-probability way among the people who refer to the physical 
therapy clinics of the Iran University of Medical Sciences. After selecting the participants, we will 
examine them for inclusion and exclusion criteria. If they meet the inclusion criteria and do not 
meet the exclusion criteria, they will sign the consent form. Afterward, the participants will 
complete the demographic information questionnaires and Mini-Mental Status Examination 
(MMSE) score. 
primary outcome measures 
Primary outcome measures in this study phase will include pain and disability. We will use visual 
analog scale (VAS) and the ODI questionnaire to evaluate primary outcome measures before and 
after the intervention period and after three months of follow-up. 
secondary outcome measures 
Primary outcome measures in this study phase will include postural stability parameters 
(displacement range in the anterior-posterior direction on the Y axis, displacement range in the 
mediolateral direction on the X axis, velocity and total sway area), postural control strategies 
parameters (short-term effective diffusion coefficient, long-term effective diffusion coefficient, 
critical displacement, and critical time), fear of movement, fear avoidance behavior, quality of life. 
A force plate (Kistler, 5691A) made in Switzerland will be used to evaluate standing postural 
control. It will measure the center of pressure (COP) trajectories with a frequency of 100 Hz. At 
first, each subject will stand on the force plate, similar to the study of Luca De & Collins (10), in a 
standard position with 10 degrees of external rotation of the feet so that the heels will be 3 cm 
apart (11). The measurement frequency will be 100 Hz (11, 12). For repeatability, foot placement 
will be marked on the force plate for all participants during the first test. During the trial, subjects 
will stand bare feet while their hands hang comfortably close to their body. Evaluations will be 
done in 8 conditions, including eyes open on a firm surface, eyes closed on a firm surface, eyes 
open on a firm surface with a cognitive task, eyes closed on a firm surface with a cognitive task, 
eyes open on foam, eyes closed on foam, eyes open on the foam with doing a cognitive task, eyes 
closed on the foam with a cognitive task. Each of the evaluations will last for 60 seconds, and 
according to the studies conducted in the field of generalizability of the variables of the postural 
control strategy (12, 13), Each condition consists of five trials. The average of these five trials will 
be used for the final analysis. The order of tests will be done randomly for each subject with eyes 
open and closed, as well as with and without cognitive tasks. During the evaluation with open 
eyes, participants will look at a screen at a distance of 4 meters, which is level with their heads. 
The subjects will stand still as much as possible and avoid sudden movements, deep breathing, and 
coughing. All tests will be recorded 5 seconds after the person will place on the force plate. A two-
minute break will be taken between all five trials to control fatigue. 
Participants will complete a postural task while listening to a continuous sequence of numbers as 
a cognitive task (14). This continuous sequence consists of 20 random three-digit numbers, each 
presented in three seconds. Then, a number (1 to 9) will be chosen randomly, and the participant 

will count mentally how many times that number will be repeated in the string of randomly 
distributed numbers (for example, counting the number of times that the number 2 is repeated in 
the sequence 221, 326, 471, etc.). After the test, participants will present their answers. If the 
difference between the number calculated by the participant and the correct number is three or 
more, the test will be repeated. The three-digit sequences and the preselected digit will be changed 
on each trial to reduce the chance of memorization. Using fingers to count will be prohibited to 
maintain maximum cognitive effort.  
Other secondary outcome measures in this study will include fear of movement, fear-avoidance 
beliefs, and quality of life, which will be determined using Tampa questionnaires and fear-
avoidance beliefs questionnaire (FABQ), and SF-12. 
Patients with non-specific chronic back pain will be randomly divided into two groups: A: 
intervention group, which includes core stability exercises with cognitive tasks, and group B: 
control group, which consists of general exercises with cognitive tasks. The patients will be treated 
for six weeks with a frequency of three sessions a week. For sixteen sessions, based on the exercise 
program provided by Shamsi et al. (15) ( Appendix 7), which is modified from the exercise 
program of Koumantakis et al. (16). The training sessions for both groups include two parts with 
and without cognitive tasks so that in the first four sessions the exercises will be done without 
cognitive tasks and in the subsequent twelve sessions with cognitive tasks. The two groups will 
have similar types of cognitive tasks and the time of adding these tasks to the exercises. 
Before starting the therapeutic exercise in each session, patients will warm up, including five 
minutes of cycling and eight stretching exercises (hamstring, quadriceps, tensor fascia/iliotibial 
band complex, and lateral trunk muscles on both sides) (15). Each stretch will be maintained for 
ten seconds and repeat ten times. The duration of warm-up exercises will be about 15-20 minutes. 
Core stabilization exercises program 
The first four sessions of the core stabilization exercises program (CSE) (appendix 1) aim to 
activate local muscles and improve their efficiency. Therefore, the exercises will be isometric with 
low loading in positions with minimal loading. It is essential to mention that to train the 
participants to be able to activate the muscles with different levels of contraction. First, they 
contract the deep muscles of their back and abdomen at their maximum capacity and then contract 
them again with 30% of the maximum contraction and maintain this level of contraction. This 
exercise will be repeated several times. Pressure biofeedback (17) will be used to train this level 
of contraction in the patients. 
Cognitive tasks in this exercise program will be added to CSE from the fifth session, at the same 
time as the movement in other segments is started, along with maintaining the contraction of the 
transverse abdominal muscles and lumbar multifidus. Different cognitive tasks will be used in each 
session to avoid learning cognitive tasks. 
General body exercise program 
The general exercises (GE) (appendix 1) in this study will include the recruitment of large groups 
of abdominal flexor and lumbar extensor muscles. In this group, therapeutic exercises will not 
emphasize the activity of the local muscles. 
According to Danneels et al. (18), patients with chronic back pain activate the spinal extensor 
muscles during CSE with 30% of their maximum contraction, while during GE, this contraction 
reaches about 60-70%. This amount of contraction has been used in previous studies to treat low 
back pain patients (15, 16). Accordingly, to balance the estimated total trunk muscle force output 
between the groups and to receive the same treatment dose in both groups, the training time will 

be 20 minutes for CSE and 14 minutes for GE (the total training time for all sessions will be an 
order of 320 and 224 minutes). 
 
Cognitive program 
The exercises of the first four sessions in both groups will be done alone and without cognitive 
tasks. From the fifth session, cognitive tasks will be added to the exercises of both groups. The 
program of cognitive tasks in each session will be common in both groups and done simultaneously 
during CSE and GE. The cognitive tasks program will be as follows: 
In the fifth and sixth sessions: 1) the patient will be asked to name the days of the week in reverse 
order. 2) Words will be presented to the patient by the therapist, and he will read those words 
backward. 
In the seventh and eighth sessions, including 1) the patient will be asked to name the months of 
the year in reverse order. 2) Numbers between 200 and 300 will be counted in ascending order in 
three-digit intervals. 
The cognitive tasks in the 9th and 10th sessions include 1) auditory stroop task, 2) counting random 
numbers between 100 and 200 3) counting numbers between 200 and 300 in ascending order in 7-
digit intervals.  
The cognitive tasks in the 11th and 12th sessions will be: 1) A text will be read to the patients, and 
they will state how many times a particular word was repeated in the text. 2) playing a string of 
two-digit random numbers and asking the patient to repeat those numbers 3) Counting backward 
numbers between 100 and 200 in three-digit intervals. 
The cognitive tasks in the 13th and 14th sessions will be: 1) A text will be read to the individual, 
and he will identify how many times two specific words were repeated in the text. 2) N-Back task 
in which a number will be presented to the patient by the therapist, and the patient must say two 
numbers before that number (N=2). 3) The string of three-digit random numbers will be played, 
and the patients will repeat those numbers. 4) Counting numbers between 200-300 in reverse order 
in three-digit intervals. 
The cognitive tasks in the 15th and 16th sessions will be: 1) A series of two-digit random numbers 
will be played for the patients, then they will repeat these numbers in reverse order. 2) A string of 
three-digit random numbers will be played into the patients, then they will repeat these numbers 
in reverse order. 3) A string of three-digit random numbers with more numbers will be played into 
the patient, then he will be asked to repeat these numbers in reverse order. 4) N-Back task in which 
a number will be presented to the patients by the therapist, and the patients must say 3 numbers 
before that number (N=3). 
data analysis 
Analysis of postural control Dynamics  
The stabilogram diffusion analysis (SDA) method, as described by Collins and De Luca (11, 19), 
will be used to identify open-loop and closed-loop control strategies. In summary, the square of 
displacement (Δri) between consecutive COP data points -separated by a specific time interval 
(Δt)- will be calculated. Then, the square of displacements (Δri) in the specified time interval (Δt), 
from 0 to 10 seconds (0 ≤(Δt)≤ 10), will be calculated on average to make a graph of the average 
square displacement of COP (Δr2) versus Δt based on the following formula will be obtained: 
N is the number of data points for the first 10 seconds of the COP data series, and for certain (Δt), 
m is the number of data intervals. Using this approach, an open-loop and closed-loop diagram 
(OLCL) (Figure 1) shows the squared value of COP displacement (Δr2) as a function of time 
interval (Δt). There are two recognizable regions in the OLCL diagram, named short-term (open 

loop (OL) and long-term (closed-loop (CL)) regions, which are separated by critical time (OL Δt: 
critical time (Δt)c). the critical time is when the slope of the OLCL diagram changes. OLCL 
diagram will achieve three parameters: short-term diffusion coefficients, long-term diffusion 
coefficients, and critical point coordinates.  
 
 
Figure 1. OLCL diagram 
 
Postural stability analysis 
COP displacement will be used to evaluate the postural control in a linear way. The COP signals 
will be filtered using a low-pass filter with a cut-off point of 10 Hz. COP parameters include: 
1-Range of displacement in the anterior-posterior direction along the Y axis: 
Range fore-aft (Rfa) = |YMax – YMin| 
2- Range of displacement in the mediolateral direction along the X axis: 
Range sideways (Rsw) = |XMax – XMin| 
3- The average velocity of total sway 
4- Total sway area