Isokinetic Assessment of Wrist Muscle Performance Among Egyptian Physical Therapy Students With Chronic Non-Specific Neck Pain
Conditions: Neck Pain
Sponsor: Mohamed Mahmoud Refaey

 
1 
 
Isokinetic Assessment of Wrist Muscles Performance among 
Egyptian Physical Therapy Students with Chronic Non-Specific 
Neck Pain  
 
 
 
 
 
 
BY 
Mohamed Mahmoud Refaey Ahmed Salama 
B.SC. in Physical Therapy (2018) KAFR EL SHEIKH University 
 
 
 
 
 
 
Submitted to Department of Biomechanics in Partial Fulfillment of the 
Requirements for Master Degree in Physical Therapy  
Faculty of physical therapy 
Cairo University 
2023 
 
 

 
2 
 
Supervisors
 
 
 
Prof. Enas Fawzy Youssef 
Professor and Head of Physical Therapy Department  
of Musculoskeletal Disorders and Its Surgery 
Faculty of Physical Therapy 
Cairo University
 
 
 
 
Prof. Anees Saleh Gheit 
Professor and Head of Biomechanics Department  
Faculty of Physical Therapy 
Kafr El sheikh University
 
 
 
 
Dr. Aya Abdelhamied Mohamed Khalil 
Lecturer of Biomechanics 
Department of Biomechanics 
Faculty of Physical Therapy 
Cairo University
 
 
 
 

 
3 
 
Chapter I 
Introduction 
Non-specific neck pain is a condition characterized by a reduction in range 
of motion and the presence of neck pain, without any identifiable pathology or 
abnormal anatomical structure (Zafar et al., 2021). Non-specific neck pain can 
be identified by several signs and symptoms including muscle spasms, trigger 
points, limited range of motion, and headaches. Muscle spasms are 
characterized by rapid, strong, and involuntary contractions of the muscles, 
while trigger points typically cause pain in the center or one side of the back of 
the neck. Individuals with non-specific neck pain may also experience 
headaches and a reduced range of motion in the neck (Cohen, 2015). 
Non-specific neck pain is associated with risk factors such as age, past 
musculoskeletal pain, gender, occupation, headaches, mental health issues, 
smoking, unsatisfactory job, dissatisfaction, difficult work postures, poor 
physical work environment, and inadequate physical ability (Jahre et al., 
2020). Various physical and biomechanical factors have been linked to 
functional limitations in patients experiencing persistent neck pain (Côté et al., 
2016). For example, a strong correlation was found between the level of 
functional disability and the degree of forward head posture in individuals with 
neck pain (Kim and Kim, 2016), despite being recognized as a leading 
contributor to functional impairment in individuals with neck pain, inadequate 
control of the axio-scapular muscles persists as a major issue (Wannaprom et 
al., 2021). 
Nevertheless, there is another opinion that says there is no association 
between forward neck posture and pain in adolescents (Mahmoud et al., 2019). 
Neck flexion while using a smartphone device (also known as "text neck") is 
also not associated with pain in adolescents (Damasceno et al., 2018).  

 
4 
 
In Egypt, a study conducted among medical students showed that 81.1% of 
participants experienced neck pain and/or low back pain. This pain was 
primarily attributed to long hours of studying and reading, especially in the 
clinical years. Participants also reported ergonomic problems and poor 
psychological studying environments (Alian et al., 2021). The study found 
gender differences in pain intensity and prevalence, with males reporting a 
higher prevalence of lifetime lower back pain (AlShayhan & Saadeddin, 2018) 
while females had a higher prevalence of neck and shoulder discomfort, as well 
as pain or numbness in their wrists (Mustafaoglu et al., 2021). 
In 2022, Ortego et al hypothesized that there is a notable association 
between neck problems and upper limb disabilities, although the mechanisms 
underlying this correlation are not yet well understood. Potential factors 
contributing to this association include deconditioning, peripheral nerve 
injuries, and mechanical stress. 
The upper limb is mechanically connected to the neck and shoulder girdle 
via the skeletal and muscular systems. Mechanical loading of the upper limb 
may directly cause discomfort in the neck by increasing stress on the 
ligamentous and articular structures, or by inducing muscle spasm as a 
protective response (Kumar et al., 2018).  
Non-specific neck pain is significantly associated with impaired 
performance of the muscles in the upper limb, leading to upper limb disability 
(Alreni et al., 2015). Upper limb disability (ULD) is a term used to describe the 
limitations someone experiences while engaging in physical activities related to 
the upper limb, such as carrying, lifting, and overhead movements. Adequate 
upper limb strength, endurance, and proprioception are essential for performing 
many job-related tasks effectively (Gillen & Nilsen, 2020). There was a study 
has shown that neck pain can lead to imbalances in muscle function, instability 
in joints, and reduced proprioception in the upper limb (Tabbert et al., 2022).  

 
5 
 
The connection between the neck and the upper limb can be established 
through various systems, including the skeletal, muscular, and neurological 
systems (Alreni et al., 2017). Muscle fatigue is a significant impairment within 
these systems, which refers to the gradual decline in a muscle's capacity to 
generate maximal force. Fatigue can occur due to intensive and repetitive 
maximal contractions or by repeating submaximal contractions over an 
extended period (Cheng et al., 2016). Neck muscle fatigue and pain can affect 
the ability to perceive movement and position of the upper limb 
(Zabihhosseinian et al.,2015).    
The gold standard for measuring wrist muscle performance is the isokinetic 
dynamometer. It is preferred because it allows for a fixed velocity and variable 
resistance that adapts to the user throughout the full range of motion (Muñoz-
Bermejo et al., 2019). The isokinetic device is a tool that can aid in the 
evaluation of muscle function by quantifying muscle strength, torque, and 
endurance (Marklund, 2019). Isokinetic exercise has been a commonly used 
concept in the evaluation and rehabilitation of musculoskeletal function in limbs 
(Mcgrath et al., 2016).  
Isokinetic dynamometer can also be used to measure the work fatigue index, 
which is the percentage change in performance from the beginning to the end of 
an endurance test. This index is a useful measure of muscle endurance and the 
ability to maintain performance over time (Bosquet et al., 2016). Work fatigue 
index refers to the decline in output over multiple repetitions during an 
endurance test (Gerodimos et al., 2017). 
Although it is widely acknowledged that chronic non-specific neck pain is 
linked to hand disability as previously studied on dentists and ministry of health 
care stuff (Fayez, 2014; Kahraman et al., 2017), there is still a gap in 
illustrating the effect of chronic non-specific neck pain on Egyptian physical 
therapy students' functional ability of wrist in the upper limb. However, the 
assessment of extensor / flexor wrist strength ratio has only recently gained 

 
6 
 
attention. Furthermore, there is limited research investigating the strength 
control ratio that incorporates both concentric and eccentric muscle actions, and 
additional scientific evidence is needed to establish the relationship between 
chronic non-specific neck pain and upper limb disability. This study will be 
conducted to set new assessment and rehabilitation goals. This will 
subsequently be translated into home therapy program, contributing to decrease 
the burden of neck pain economically and on health care management. 
 
Statements of the problem: 
Does chronic non-specific neck pain affect peak torque of wrist extensor 
and flexor muscles /body weight among Egyptian physical therapy students? 
Does chronic non-specific neck pain affect extensor / flexor wrist ratio 
among Egyptian physical therapy students? 
Does chronic non-specific neck pain affect wrist extensor and flexor 
muscles endurance among Egyptian physical therapy students?                                                 
 
Purposes of the study: 
To assess the effect of chronic non-specific neck pain on peak torque of 
wrist extensor and flexor muscles /body weight among Egyptian physical 
therapy students.  
To assess the effect of chronic non-specific neck pain on extensor / flexor 
wrist ratio among Egyptian physical therapy students. 
To assess the effect of chronic non-specific neck pain on wrist extensor and 
flexor muscles endurance among Egyptian physical therapy students.  
Significance of the study: 
Several studies have reported the neck region as the most common site of 
pain in college students, including medical students. Additionally, some 

 
7 
 
adolescents have reported pain in their wrists and hands (Alsalameh et al., 
2019). Determinants of musculoskeletal pain include the amount of time spent 
sitting continuously, the frequency of breaks, head position while working at a 
desk, and level of physical activity (Acaröz Candan et al., 2019) 
Neck discomfort is a significant burden that is often associated with 
disability and absenteeism from work (Oliv et al., 2019). Experiencing pain in 
more than one site has been associated with decreased work quality and quantity, 
as it impairs upper limb performance and leads to upper limb disability (Gane 
et al., 2018). 
Non-specific neck pain has been shown to have an impact on hand function. 
(Mahmoud et al., 2020). Non-specific neck pain has a significant correlation 
with impaired upper limb muscle performance, leading to upper limb disability 
(Gurav & panhale, 2017).  
Although it is widely acknowledged that chronic non-specific neck pain is 
linked to hand disability as previously studied on dentists and ministry of health 
care stuff (Fayez, 2014; Kahraman et al., 2017), there is still a gap in 
illustrating the effect of chronic non-specific neck pain on Egyptian physical 
therapy students' functional ability of wrist in the upper limb. However, the 
assessment of extensor / flexor wrist strength ratio has only recently gained 
attention. Furthermore, there is limited research investigating the strength 
control ratio that incorporates both concentric and eccentric muscle actions, and 
additional scientific evidence is needed to establish the relationship between 
chronic non-specific neck pain and upper limb disability. This study will be 
conducted to set new assessment and rehabilitation goals. This will 
subsequently be translated into home therapy program, contributing to decrease 
the burden of neck pain economically and on health care management. 
 
Delimitations:  
 

 
8 
 
 Egyptian physical therapy students with chronic non- specific neck pain 
from faculties of physical therapy with referral from orthopedic surgeons by 
diagnosis with non-specific neck pain. 
 The duration of non-specific neck pain is more than 3 months without 
neurological manifestations. 
 The smartphone application forward head posture will be used to measure 
craniovertebral angle (CVA) in a standing position (Gallego-Izquierdo et al., 
2020).  
 Numerical Pain Rating Scale is used to assess pain intensity (Sharma et al., 
2017). Neck pain intensity on the numerical Pain Rating Scale will be between 
3 to 8. 
 Arabic version of the Neck Disability Index (NDI) is used to assess patients' 
self-reported neck pain-related disability (Young et al., 2019). Neck pain-
related disability on the Neck Disability Index will be between 5-14points (10 – 
28%) mild disability and 15-24points (30-48%) moderate disability. 
 Arabic version of the Fatigue Severity Scale is used to evaluate subject 
perceptions of hand function, activities of daily life, pain, and work 
performance (Al-Sobayel et al., 2016).  
 Patient's age ranges from 18 to 23 years. 
 Body mass index for patients will not be less than 18.5 and not more than 
29.5 (Alasadi, 2018). 
 Selected subjects will be assigned to two equal groups: the study group (GA) 
(chronic non-specific neck pain subjects) and the control group (GB) (without 
neck pain subjects). 
 

 
9 
 
Basic Assumption:  
 All subjects will conduct and follow the instructions of the study. 
 All subjects will exert their maximum effort during assessment. 
Hypotheses: 
There will be no significant effect of chronic non-specific neck pain on 
peak torque of wrist extensor muscles /body weight. 
There will be no significant effect of chronic non-specific neck pain on 
peak torque of wrist flexor muscles /body weight. 
There will be no significant effect of chronic non-specific neck pain on 
extensor / flexor wrist ratio. 
There will be no significant effect of chronic non-specific neck pain on 
wrist extensor muscles endurance. 
There will be no significant effect of chronic non-specific neck pain on 
wrist flexor muscles endurance. 
 
 
 
 
 
 
 

 
10 
 
Chapter II 
Literature review 
The wrist is the most important region in the upper limb as its role in daily 
activities like reaching, grasping, griping, and forming precise movements like 
writing and sewing. The wrist is made up by the distal radius, ulna, carpal bones, 
and metacarpal bases are only a few of the bones that constitute three joint areas 
the distal radioulnar (DRUJ), midcarpal, and carpometacarpal (Regal et al., 
2020).  
Under normal conditions, the interosseous ligaments connecting the bones 
of the proximal carpal row insulate the midcarpal joint from each other and the 
radiocarpal joint from the distal radioulnar joint (DRUJ) by triangle 
fibrocartilaginous cartilage (TFCC) (Gietzen et al., 2022). The head of the ulna, 
the sigmoid notch area of the distal radius, the distal radioulnar joint capsule, 
and triangle fibrocartilaginous cartilage (TFCC) make up distal radioulnar joint 
(DRUJ). The distal radioulnar joint (DRUJ) and radiocarpal joint are normally 
separate joints (Ng et al., 2017).  
The overall wrist motion during ulnar deviation is mostly influenced by the 
radiocarpal joint and the midcarpal joint to a lesser extent. The arthrokinematics 
of extension and flexion are supported by the coordinated convex-on-concave 
rotations at the radiocarpal and midcarpal joints. When the wrist is fully 
extended, all the muscles that cross on the palmar side of the wrist and the 
palmar radiocarpal ligaments stretch, stabilizing the wrist by creating tension in 
these strained tissues (closed packed position of wrist) (Magee, 2020).  
As it is an ellipsoid-shaped synovial joint, the wrist can conduct flexion and 
extension as well as abduction and adduction. Although many muscles cross the 
wrist joint, only a small number of them are specifically used for wrist 
movement. These muscles are the extensor carpi radialis brevis (ECRB) and 
extensor carpi radialis longus (ECRL), which both contribute to wrist extension 

 
11 
 
and radial deviation; extensor carpi ulnaris (ECU), which is responsible for 
wrist extension and ulnar deviation; flexor carpi radialis (FCR), which flexes 
and abducts (radial deviation) the wrist; and the extrinsic hand muscles, flexor 
digitorum superficialis (FDS) and extensor digitorum (ED), span the wrist and 
interphalangeal joints flexing and extending the digits (Tortora & Derrickson, 
2018).  
Also, a complicated network of collagen fascicles created by the ligaments 
of the wrist perform a variety of tasks, including limiting joint displacement, 
directing motion, and maybe giving afferent brain feedback about the 
mechanical state of the joint (Hall, 2022).  
The neck and wrist are interconnected anatomically, and any dysfunction in 
one area can lead to compensations or problems in the other (Fiebert, 2021). 
The lower cervical spine prefers to flex while the middle cervical spine extends 
which make the ideal lordotic human cervical spine (Akçali, 2020). It holds the 
head's weight in an upright posture (the equivalent of 10 pounds) (Hansraj, 
2014). 
       High-density concentrations of muscle spindles have been discovered in the 
deep cervical muscles and suboccipital muscles of the neck (Saleh et al., 2018). 
When cervical muscles are not working properly like an imbalance between the 
deep cervical flexors and the stabilizers on the back of the neck, there is a loss 
of proper alignment and posture that results in cervical impairment and neck 
pain (Rani & Kaur, 2022).  
The cervical spine is made up of the superficial anterior, deep anterior, 
superficial posterior, and deep posterior muscle groups. These muscle groups 
must be flexible, balanced, and coordinated for the cervical spine to function 
normally. The neck is a complex structure, and several muscles in it help keep it 
stable and work properly. Chronic neck pain has been linked to diminished 
capacity and strength in the deep neck muscles, which account for 80% of the 
mechanical steadiness (longitudinal dynamic stability) in the cervical area and 

 
12 
 
with prolonged postures of flexed neck (Alshahrani et al., 2021; Namwongsa 
et al., 2018).  
Neck pain has become a major public health concern due to its increasing 
prevalence and impact on daily life (Ben Ayed et al., 2019). It is estimated that 
up to 70% of individuals will experience neck pain at some point in their lives. 
The condition can lead to decreased physical functioning, reduced quality of life, 
and increased healthcare costs. Additionally, neck pain is a major contributor to 
work-related disability and absenteeism, resulting in significant economic 
burden. With the rise of sedentary lifestyles and increased use of technology, 
the incidence of neck pain is likely to continue to rise (Kazeminasab et al., 
2022). 
Musculoskeletal pain is a common issue among students, particularly those 
in medical fields, due to prolonged periods of studying and reading. According 
to a recent study conducted in Saudi Arabia, the prevalence of neck pain among 
medical students was found to be 68.5% (Dighriri et al., 2019). Other studies 
have also reported neck pain as the most frequently reported pain site among 
college-aged students (Behera et al., 2020). Poor ergonomics and psychological 
stress associated with academic workload have been identified as contributing 
factors to the high prevalence of neck pain among students (Dighriri et al., 
2019; Hasan et al., 2018). Moreover, prolonged sitting without taking 
sufficient breaks, along with improper head posture while working at a desk, 
have also been associated with neck pain in students (Acaröz Candan et al., 
2019).  
Non-specific neck pain is often associated with reduced range of motion and 
pain in the neck area. This type of pain can occur without any identifiable 
pathology or structural abnormality, and may be accompanied by muscle spasm, 
trigger points, headaches, and limited range of motion (Wingbermühle et al., 
2018). Despite its prevalence, the underlying causes of non-specific neck pain 

 
13 
 
remain poorly understood, although factors such as poor posture, stress, and 
repetitive strain injuries have been implicated (Dixon et al., 2017).  
Neck pain is a prevalent and burdensome condition that can result from a 
variety of factors. According to a recent study, the most common causes of neck 
pain include muscle strain and tension, poor posture, and degenerative changes 
in the cervical spine (Lawrence et al., 2022). In addition, psychological factors 
such as stress and anxiety can contribute to the development of neck pain and 
can exacerbate existing symptoms (Ortego et al., 2016). Other risk factors for 
neck pain include age, gender, and occupation, with individuals in physically 
demanding jobs or those that require prolonged periods of sitting at a desk being 
at higher risk (Lawrence et al., 2022; Ortego et al., 2016). 
Neck pain is a widespread issue that can lead to disability and decreased 
productivity. Recent studies suggest that neck pain is a significant problem in 
the workplace and can lead to decreased work performance and absenteeism 
(Bealas et al., 2017). In response, healthcare providers are shifting toward a 
more holistic approach that considers not only the physical symptoms of neck 
pain but also the impact on daily activities and social participation. The 
American Physical Therapy Association released guidelines for the 
management of neck pain that emphasized the importance of patient-centered 
care and the use of multidisciplinary approaches to address the complex nature 
of neck pain (Maistrello et al., 2022).  
Non-specific neck pain is a common condition that can have a significant 
impact on upper limb function. Studies have shown that individuals with neck 
pain often experience reduced grip strength, decreased range of motion, and 
impaired hand function (Asiri et al., 2021; Bracht et al., 2017). These 
functional impairments may be due to muscle weakness and imbalances, altered 
neural activation patterns, and changes in proprioception and kinesthetic 
awareness (Canu et al., 2019). As a result, healthcare providers are 
emphasizing the importance of incorporating upper limb assessments and 

 
14 
 
interventions into the management of neck pain, with the goal of improving 
overall function and reducing disability (Alreni et al., 2015; Tsang et al., 
2019). 
Self-administered questionnaires are commonly used for functional 
assessment of neck pain in clinical practice. These tools typically focus on 
evaluating the individual's subjective discomfort, perceived impairment, ability 
to function or manage neck pain, and/or healthcare usage.  
The Numeric Pain Rating Scale (NPRS) is frequently used as an outcome 
measure for assessing pain intensity in adults, including those with chronic pain 
resulting from rheumatic diseases. It is a segmented numeric version of the 
visual analog scale (VAS), where the respondent chooses a whole number 
between 0 and 10 to indicate the intensity of their pain (Sharma et al., 2017). 
Additionally, The Neck Disability Index (NDI) is a condition-specific 
functional status questionnaire that is a modification of the Oswestry Low Back 
Pain Disability Index. It is a patient-completed questionnaire that includes 10 
items related to pain, personal care, lifting, reading, headaches, concentration, 
work, driving, sleeping, and recreation. The NDI has received sufficient support 
and is considered useful, making it the most used self-report measure for 
assessing neck pain (Young et al., 2019). 
Isokinetic dynamometry has emerged as a reliable and valid method for 
assessing muscle strength and joint function in individuals with upper limb 
disorders (Webber et al., 2019). It has been used to evaluate muscle activation 
patterns, joint stability, and proprioception in the shoulder, elbow, and wrist 
regions (Saini et al., 2022). Moreover, isokinetic dynamometers have been used 
to evaluate the efficacy of various rehabilitation interventions, including 
resistance training and neuromuscular electrical stimulation, for improving 
upper limb function in patients with neurological and orthopedic conditions 
(Webber et al., 2019; Hatem et al., 2016). Given the benefits of isokinetic 
dynamometry, it has become an essential tool for clinicians and researchers in 

 
15 
 
the field of upper limb rehabilitation. Furthermore, isokinetic testing of wrist 
flexors and extensors can be used to assess the effectiveness of various 
rehabilitation interventions, such as resistance training and neuromuscular 
electrical stimulation, in improving wrist muscle function in patients with wrist 
disorders (Seven et al., 2019; Ağırman et al., 2017). 
Hislop and Perrine initially introduced the idea of isokinetic motion in 1967, 
although Perrine produced the first isokinetic prototype in 1962, with angular 
velocity ranging from 0 to 3.75 revolution per minute (RPM). But not until 
1968 that the Cybex (0 to 20 rpm), a passive isokinetic device for testing and 
rehabilitation, was introduced to the clinic. The Cybex II was released in 1975 
and has angular velocities (0 to 50 rpm). By 1982, several isokinetic devices 
were produced. The first system capable of an isokinetic eccentric concentric 
contraction was the KinCOM, which was released in 1982. The Lido digital 
system, the Biodex, and the universal Merac were all introduced in 1983, 1985, 
and 1986, respectively (Muñoz-Bermejo et al., 2019).   
Various joint position matching tasks have been employed by many studies 
to assess proprioceptive abilities, and their findings revealed that those with 
neck and upper extremity disability had revealed positive correlation (Shah & 
Sheth, 2018) and additional studies revealed a statistically significant decline in 
wrist and shoulder proprioception in neck pain group compared to the healthy 
control group (Abichandani & Parkar, 2017; Zabihhosseinian et al., 2015). 
Isokinetic testing has been widely used to evaluate wrist strength and 
function. It provides an objective, reliable, and accurate measurement of muscle 
performance and coordination. Researchers have employed various speeds in 
isokinetic testing, such as 30°/sec, 60°/sec, and 120°/sec, depending on the task 
being evaluated. Additionally, both low and high angular velocities are 
frequently used in wrist assessment, with low velocities used for measuring 
maximum voluntary contraction and high velocities used for evaluating muscle 
coordination during functional activities (Hasan et al., 2016). Isokinetic 

 
16 
 
measurements of the wrist joint are taken from each participant at various points, 
including the maximum isometric contraction angle, concentric and eccentric 
strength, and muscle endurance angular velocities (Ribeiro et al., 2021). 
Wrist isokinetic dynamometry has been widely used to evaluate muscle 
function and identify the presence of muscular imbalances in the wrist joint, 
particularly in individuals with upper limb disorders and injuries (Seven et al., 
2019). The assessment of wrist isokinetic strength has been shown to be a 
reliable and valid tool for evaluating the strength and endurance of wrist flexors 
and extensors in both clinical and research settings (Ağırman et al., 2017).  
Although it is widely acknowledged that chronic non-specific neck pain is 
linked to hand disability, the assessment of flexor/extensor wrist strength ratio 
in this group has only recently gained attention. Furthermore, there is limited 
research investigating the strength control ratio that incorporates both 
concentric and eccentric muscle actions, and additional scientific evidence is 
needed to establish the relationship between chronic non-specific neck pain and 
upper limb disability, therefore  in our study, we will be conducted to examine 
wrist muscle performance  through peak torque of wrist extensor and flexor 
muscles to body weight, extensor / flexor wrist strength ratio and wrist extensor 
and flexor muscles endurance in chronic non-specific neck pain among 
Egyptian college students to evaluate functional ability of wrist in the upper 
limb in non-specific neck pain students to set new assessment and rehabilitation 
goals. This will subsequently be translated into home therapy program, 
contributing to decrease the burden of neck pain economically and on health 
care management. 
 
 
 
 

 
17 
 
Chapter III 
Subjects and methods 
 
Our study aims to evaluate peak torque of wrist extensor and flexor muscle /
body weight and extensor / flexor wrist ratio and wrist extensor and flexor 
muscle endurance among Egyptian physical therapy students with chronic non-
specific neck pain. The practical part of the study is expected to be from 
May/2023 to December/2023 and  will be conducted in the isokinetic lab in EL 
DELTA University. 
Design: cross-section study 
Sample size calculation: 
Using G-power software (version 3.1.9.7; Franz Faul, Universitat Kiel, 
Germany) for windows and regarding MANOVA study, alpha level of 0.05, 
confidence level 0.80, and effect size 0.56, calculated from the previous study 
of (Agirman et al., 2017) that used the isokinetic dynamometer for measuring 
the 0peak torque of wrist with a sample of 35, and a two-sided alternative 
hypothesis, the sample size is 39 patients to be able to reject the null hypothesis. 
If 15% dropout rate is anticipated, approximately 44 patients (twenty-two in 
each group) will be recruited. 

 
18 
 
 
1. Students' selection: 
The current study will be conducted on twenty-two non-specific neck pain 
Egyptian physical therapy students a with referral from orthopedic surgeons by 
diagnosis with non-specific neck pain other twenty-two without neck pain 
subjects from outpatient clinic of Faculty of Physical Therapy, EL DELTA 
University. Students' age ranges from 18 to 23 years. Students will be selected 
from faculties of physical therapy. Students will be assigned into two equal 
groups, the study group (GA) (chronic non-specific neck pain students) and the 
control group (GB) (normal students). They will be instructed not to participate 
in any training program until the posttest.  

 
19 
 
Inclusion criteria:  
 
1- Students from both genders (Fayez, 2014). 
2- Duration of the non-specific neck pain is more than 3 months (for 
symptomatic group with no neurological manifestations and with referral 
from orthopedic surgeons by diagnosis with non-specific neck pain) and 
for matched students, they do not have any history of neck pain (Chung 
& Jeong, 2018)  
3- Student' age ranges from 18 to 23 years. 
4- Neck pain intensity on the numerical Pain Rating Scale will be between 
3 to 8. 
5- Neck pain-related disability on the Neck Disability Index will be 
between 5-14points (10 – 28%) mild disability and 15-24points (30-48%) 
moderate disability. 
6- Body mass index for students will not be less than 18.5 and not more 
than 29.5 (Alasadi, 2018). 
Exclusion Criteria: 
Any participant suffered from one of these symptoms will be excluded: 
1- Indications of neurological conditions (i.e., Parkinson's disease, multiple 
sclerosis, head injury, peripheral neuropathy, stroke, or nerve root 
entrapment) (Mahmoud et al., 2020). 
2- Headache caused by a certain diagnosis of headache. 
3- History of cancer, infection, or any other illness symptoms. 
4- History of trauma, whether it was accompanied or not by structural issues 
with the neck, shoulder, or head (such as whiplash) within the last 12 
months or any traumatic spinal cord injury (Park et al., 2016). 
5- Any known cardiovascular problems or cerebrovascular insufficiency 
symptoms. 

 
20 
 
6- Any known musculoskeletal disorder (i.e., joint replacement, amputation, 
physically limiting arthritis, contractures of fixed deformity or muscular 
dystrophy) which limits physical daily activities (Bidja et al., 2018). 
7- History of orthopedic or neurological conditions such fractures, surgeries 
on the upper limb or hand, carpal tunnel syndrome, De Qurvain's 
syndrome, or diabetic mellitus that result in functional defects of the hand 
strength (Fayez, 2014). 
8- Specific diagnosis of the cervical spine spondylosis, disc prolapse, spinal 
stenosis, cervical fracture, etc. 
9- Subjects are also excluded if they have had any recent (within the last 
three months) treatment for neck pain (Park et al., 2016). 
10- Any medical condition affecting the sensory system (visual, auditory and 
speech problems). 
11- Students are also excluded if they have had forward head posture. 
2. Instrumentations 
For Measurement and Assessment 
 Photogrammetry posture analysis forward head (by the smartphone 
application forward head posture (FHP) as exclusion screening 
procedure to exclude subjects with abnormal forward head.  
 Numerical Pain Rating Scale 
 Arabic version of the Neck Disability Index (NDI)  
 Arabic version of the Fatigue Severity Scale  
 Isokinetic dynamometer  
a) Photogrammetry posture analysis forward head:  
Intra-rater reliability of the mobile application forward head posture had an 
intraclass correlation coefficient of 0.88. The inter-rater reliability generated an 
intraclass correlation coefficient of 0.83 to 0.89. Criterion validity data were 

 
21 
 
above 0.82. The minimum detectable change was 4.96_ for intra-rater and 5.52_ 
for inter-rater reliability. The smartphone application exhibited 94.4% 
sensitivity and 84.6% specificity. The smartphone application forward head 
posture is a valid and reliable tool to measure craniovertebral angle (CVA) in a 
standing position and, therefore, could be a useful assessment tool in clinical 
practice (Gallego-Izquierdo et al., 2020). The CV angle is the best indicator of 
FHP (ShaghayeghFard et al., 2016). An angle less than 50-53 may indicate 
FHP (Lee et al., 2015). Thereby, the smaller the CV angle, the greater the 
disability (Cheung et al., 2009). 
b) Numerical Pain Rating Scale (NPRS):   
 
Numeric Pain Rating Scale (NPRS) has shown high test–retest reliability 
and for construct validity, the NPRS has shown to be highly correlated with 
the VAS in patients with rheumatic and other chronic pain conditions 
(pain>6 months) (Young et al., 2019; Sharma et al., 2017) (Appendix II). 
 
c) The Neck Disability Index (NDI):  
       The Neck Disability Index (NDI) demonstrated excellent internal 
consistency and good test-retest reliability. Content validity was confirmed as 
no floor or ceiling effects were detected for the Neck Disability Index (NDI) 
total score. Construct validity was established with factor analysis revealing 
two-factor subscales explaining 66% of the variance. The Neck Disability Index 
(NDI) showed a strong correlation with a visual analog scale (VAS) and a 
moderate correlation with the global rating of change (GROC) (Lim et al., 
2020; Young et al., 2019) (Appendix III).  
The Neck Disability Index (NDI) (modification of the Oswestry Low Back Pain 
Disability Index). Patient-completed, condition-specific functional status 
questionnaire with 10 items including pain, personal care, lifting, reading, 
headaches, concentration, work, driving, sleeping and recreation. The NDI has 

 
22 
 
sufficient support and usefulness to retain its status as the most used self-report 
measure for neck pain. The NDI can be used to evaluate the patient's status 
presence and to evaluate the evolution during the therapy. 
d) The Fatigue Severity Scale (FSS):  
      Test-retest reliability and internal consistency of the Fatigue Severity Scale 
(FSS) is acceptable (intraclass correlation coefficient model 2,1 = 0.80; 
Cronbach’s 
alpha 
= 
0.84) 
with 
excellent 
internal 
consistency 
(Cronbach's α value 0.93) the concurrent validity of the Fatigue Severity Scale  
(FSS) appeared to be satisfactory due to the significant differences between 
people with MS and control subjects (p < .05). The correlations between Fatigue 
Severity Scale (FSS) and Multiple Sclerosis Impact Scale-29 (MSIS-29) 
physical (r = 0.60) and psychological (r = 0.50) subscale results confirmed the 
convergent validity of the FSS scale. Results also indicated that the best cut-off 
score is between 4 and 5 with a relatively high sensitivity and specificity (Al-
Sobayel et al., 2016; Jerković et a., 2022) (Appendix IV). 
e) Isomed 2000 Isokinetic Dynamometer: 
Isomed 2000 Isokinetic Dynamometer® (D&R Ferstl GmbH, Hemau, 
Germany) was used for collecting the isokinetic parameters. With the use of an 
isokinetic dynamometer like the IsoMed 2000 series, the peak torque and total 
work of isokinetic muscle strength test for wrist joint displayed good to 
excellent intra- and interrater reliability at low and high angular velocities in 
healthy youth (Roth et al., 2017; Xu Jing-fei et al., 2012). 
 

 
23 
 
 
Figure 3-2: Isomed 2000 isokinetic dynamometer for wrist assessment: (a)
 
 
Dynamometer, (b) Wrist attachment, (c) Chest strap, (d) Testing chair, (e) Control unit 
(computer system).
 
 
3. Assessment procedure of the study:  
The following section presents the testing  procedure which will be passed 
by three phases: pre-experimental (preparatory), experimental and analysis of 
the captured data. 
 
A. Pre-experimental (preparatory) phase 
This 
phase 
involved 
participant 
preparation, 
pre-experimental 
instructions, and isokinetic system preparation. 
Participant preparation 
 All the subjects will be included according to inclusion and exclusion 
criteria and they will be selected from outpatients clinics of EL DELTA 
University. Then, after taking their individual demographic data, they 
will be assigned into two groups, the study group (GA) (chronic non-
specific neck pain subjects without neurological manifestations) and the 
control group (GB) (normal subjects).  After that, they will sign an 
informed consent form after receiving a brief orientation session about 
the nature of the study, the study purpose, procedure, possible benefits, 
and risks with preserving each subject privacy. 
a 
b 
c 
d
e 

 
24 
 
Measurement of craniovertebral angle to exclude subjects with abnormal 
forward head posture 
Non-specific neck pain students will be evaluated to assess forward head 
posture by photographic posture analysis method by placing two markers on the 
ground separated by 1.5 m, where the smartphone and the subject will be 
located. Reference markers will be placed on the spinous process of C7 and in 
the swallow of the subjects’ ears, which will be identified through palpitation. 
The subject will be placed on the floor mark, barefoot and standing, lateral to 
the evaluator. At this point. The evaluators will be experienced and trained 
physiotherapists (Gallego-Izquierdo et al., 2020). The ones calculated with the 
FHP app will be classified attending to the presence or not of FHP. The 
presence of FHP (FHP group) will be determined by an angle value lower than 
50, and the absence of FHP (no-FHP group) if the angle value will be greater 
than or equal to 50 (Lee et al., 2015). 
Assessment of pain intensity by Numerical Pain Rating Scale 
Also they will be evaluated to assess to assess pain intensity by Numerical 
Pain Rating Scale (Appendix II) as The Numeric Pain Rating Scale (NPRS) is 
a unidimensional measure of pain intensity in adults, including those with 
chronic pain due to rheumatic diseases. (man in pain, R) The NPRS is a 
segmented numeric version of the visual analog scale (VAS) in which a 
respondent selects a whole number (0–10 integers) that best reflects the 
intensity of his/her pain. The 11-point numeric scale ranges from '0' 
representing one pain extreme (e.g., “no pain”) to '10' representing the other 
pain extreme (e.g., “pain as bad as you can imagine” or “worst pain 
imaginable”). As inclusion criteria, Neck pain intensity on the numerical Pain 
Rating Scale will be between 3 to 8. 
       

 
25 
 
  
Assessment of neck pain-related disability by Neck Disability Index 
Also they will be evaluated to assess patients' self-reported neck pain-
related disability, and the Neck Disability Index (NDI) (Appendix III) as the 
Neck Disability Index (NDI) (modification of the Oswestry Low Back Pain 
Disability Index). Patient-completed, condition-specific functional status 
questionnaire with 10 items including pain, personal care, lifting, reading, 
headaches, concentration, work, driving, sleeping and recreation.  
       The NDI can be scored as a raw score or doubled and expressed as a 
percent. Each section is scored on a 0 to 5 rating scale, in which zero means 'No 
pain' and 5 means 'Worst imaginable pain'. Points summed to a total score. The 
test can be interpreted as a raw score, with a maximum score of 50, or as a 
percentage. 0 points or 0% means: no activity limitations, 50 points or 100% 
means complete activity limitation. A higher score indicates more patient-rated 
disability. There is no statement in the original literature on how to handle 
missing data. Mean duration of the test: 3 to 7.8 minutes. 
Some benchmarks can be found in literature: 0-4points (0-8%) no disability, 
5-14points (10 – 28%) mild disability, 15-24points (30-48%) moderate 
disability, 25-34points (50- 64%) severe disability, 35-50points (70-100%) 
complete disability. As inclusion criteria, neck pain-related disability on the 
Neck Disability Index will be between 5-14points (10 – 28%) mild disability 
and 15-24points (30-48%) moderate disability.  
Assessment of hand function and work performance by Fatigue Severity 
Scale 
Additionally, they will be evaluated to evaluate patient perceptions of hand 
function, activities of daily life, pain, and work performance, Arabic version of 
the Fatigue Severity Scale (Appendix V) as the Fatigue Severity Scale is a 9-

 
26 
 
item scale which measures the severity of fatigue and its effect on a person's 
activities and lifestyle in patients with a variety of disorders. A self-report scale 
of nine items about fatigue, its severity and how it affects certain activities. 
Answers are scored on a seven-point scale where 1 = strongly disagree and 7 = 
strongly agree. This means the minimum score possible is nine and the highest 
is 63. The higher the score, the more severe the fatigue is and the more it affects 
the person's activities. It is simple to understand and takes an average of eight 
minutes to answer. 
 The participant’s personal data will be collected. The data include the 
participant’s name, age, address, weight, height, and phone number. 
 All subjects of both groups will be tested for the isokinetic parameters 
twice (on dominant and non-dominant sides). 
 The participant will be allowed to sit on the adjustable seat of the 
isokinetic dynamometer system. 
 The tested arm will be placed on the limb support pad and secured with 
strap. Then the tested hand will be securely fastened with wrist 
attachments.  
 The dominant hand is the one preferred by the participant to write or 
manipulates objects. 
 Shoulder and waist straps will be placed around the chest to secure and 
stabilize the patient. In addition, the untested limb will be placed in a rest 
position and secured by strap, 
Measurement of muscle performance of wrist by isokinetic dynamometer  
This involves: 
1) Measuring peak torque of wrist extensor and flexor muscles /body weight 
among Egyptian physical therapy students. 

 
27 
 
2) Measuring extensor / flexor wrist muscles ratio among Egyptian physical 
therapy students. 
3) Measuring wrist extensor and flexor muscles endurance among Egyptian 
physical therapy students.  
1- pre-experimental testing instructions: 
 Before the actual isokinetic testing procedures, each participant will 
perform one practice series of three sub-maximal wrist extension and 
flexion repetitions to get accommodated with the specificity of the 
isokinetic speed of movement and wrist ROM. That will be done to 
minimize any practice effect during the actual testing procedure. 
2- The isokinetic system preparation: 
 The isokinetic system was powered, initialized, and calibrated. 
 The dynamometer was rotated to 0°and was tilted to 0°. 
 Wrist Attachment of dynamometer will be attached by placing input tube 
on dynamometer then it will be rotated horizontally to the floor to be 
aligned with the dynamometer shaft red dot. 
 The testing chair was rotated to 0° degrees and seat back tilt was set to 85 
degrees. 
 The participant sat on the chair and the wrist axis of rotation will be 
aligned with dynamometer lever arm as discussed later in participant 
preparation. 
 Axis of rotation for this pattern lies between the proximal row of the 
carpals, at the capitate bone, and the radius at the radiocarpal joint. 
 The isokinetic parameters will be tested at angular velocity of 60°/sec. 
The testing velocity was selected from the control panel. The rationale for 
choosing this speed was based on previous studies. The literature 
suggested that wrist measurements will be taken from each participant at 

 
28 
 
the points where the dynamometer equipment was adjusted at 60°/sec for 
measuring muscle strength and 180°/sec for measuring muscle endurance 
angular velocities (Janicijevic et al., 2020). Fast speed is for power, 
whereas slow speed is for strength. Reports by researchers have been 
employing both 60° and 120°/sec in isokinetic assessment for strength 
and power.  
 Before being raised to this position, the dynamometer's range of motion 
will be adjusted to a total of 80 degrees, comprising 40 degrees of wrist 
flexion and 40 degrees of wrist extension (Seven et al., 2019). 
 The concentric/concentric mode was used to measure the wrist muscles 
peak torques, power and endurance. 
B. Experimental phase 
This phase involved experimental testing procedures for measuring peak 
torque of wrist extensor and flexor muscles /body weight, extensor / flexor 
wrist ratio and wrist extensor and flexor muscles endurance among Egyptian 
physical therapy students.  
The experimental testing procedures will be conducted for all the 
participants of both groups. 
 Following warm up, each participant will be positioned according to the 
instruction described before.  
 The personal data of each participant will be introduced into computer, 
which includes participant name, age, sex, identification number and 
weight. 
 The test protocol that will include the wrist ROM, the testing velocities, 
the mode of contraction and the test repetitions will be selected from the 
control panel. 
 Each participant will be instructed to perform five sets of wrist extension 
and flexion at the selected wrist ROM (60°). 

 
29 
 
 Verbal encouragement will be given during the testing procedure to 
maximize the participant’s voluntary effort. 
 Wrist extensors and flexors will be tested at the concentric mode of 
muscle contraction using 60°/sec angular velocity. 
 A 1- min rest will be given between warm up and actual test sequence.  
 Testing procedures will be performed twice, on the dominant and non-
dominant sides for both the study and control groups.  
C. Analysis of the captured data  
After performing isokinetic testing, the final output data were displayed 
after being processed by the relevant isokinetic software in the form of tables 
and graphs. The peak torque normalized for Bodyweight (Nm/Kg) for the wrist 
extensors and flexors/body weight were used to calculate the wrist 
flexor/extensor muscles strength ratio  
 
 
 
Data Analysis:  
The statistical measure will be performed through the statistical package for 
social sciences (SPSS) version 25 for windows. It will be intended to compare 
between the experimental and control groups for the wrist flexors/extensors 
strength ratio for both dominant and non-dominant sides.   
Statistical Analysis: 
 The statistical measure will be performed through the statistical package 
for social sciences (SPSS) version 25 for windows.  
 Descriptive statistics in the form of mean and standard deviation will be 
used. 
Peak torque of wrist flexors 
  Peak torque of wrist extensors 
Wrist strength ratio = 

 
30 
 
 Unpaired T-test will be used to investigate the comparison between two 
groups for numerical data. 
 Chi-Square will be used to investigate the comparison between two 
groups for categorical data. 
 One way between subjects' multivariate analysis of variance (One-way 
MANOVA) is useful in experimental situations where at least some of the 
independent variables are manipulated. 
 The alpha point of 0.05 will be used as a level of statistical significance 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
31 
 
References 
 
Abichandani, D., & Parkar, B. (2017). Comparison of upper limb 
proprioception in chronic mechanical neck pain patients with age-sex 
matched healthy normal. International Journal of Physiotherapy and 
Research, 5(6), 2466-2473.https://doi.org/10.16965/ijpr.2017.191 
 
Acaröz Candan, S., Sahin, U. K., & Akoğlu, S. (2019). The investigation of 
work-related musculoskeletal disorders among female workers in a 
hazelnut factory: Prevalence, working posture, work-related and 
psychosocial factors. International Journal of Industrial Ergonomics, 74, 
102838. https://doi.org/10.1016/j.ergon.2019.102838 
 
Ağırman, M., Kara, A., Durmuş, O., Saral, İ., & Çakar, E. (2017). 
Isokinetic evaluation of wrist muscle strength in patients of carpal tunnel 
syndrome. Eklem hastaliklari ve cerrahisi = Joint diseases & related 
surgery, 28(1), 41–45. https://doi.org/10.5606/ehc.2017.52142 
 
Akçali, Ö. (2020). Comparative Kinesiology of the Human Body || 
Kinesiology of the cervical vertebral column. In Comparative Kinesiology 
of the Human Body (pp. 303-314). https://doi.org/10.1016/B978-0-12-
812162-7.00015-1 
 
Al-asadi, J. N. (2018). O R I G I N A L A RTICL E Handgrip strength in 
medical students: Correlation with body mass index and hand dimensions, 
9(1), 21–26. https://doi.org/10.4103/njcp.njcp_290_17 
 
Alian, S. M., El-Shahawy, E. D., Ragab, H. M., & Yousof, M. A. M. (2021). 
Study of neck and low back pains among students. The Egyptian Journal 
of Hospital Medicine, 83, 831-837. https://doi.org/10.5005/jp-journals-
10050-0072. 
 
Alreni, A. S. E., Harrop, D., Gumber, A., & McLean, S. M. (2015). 
Measures of upper limb function for people with neck pain: A systematic 
review of measurement and practical properties (protocol). Systematic 
Reviews, 4(1), 43. https://doi.org/10.1186/s13643-015-0034-2 
 
Alreni, A. S. E., Harrop, D., Lowe, A., Potia, T., Kilner, K., & McLean, S. 
M. (2017). Measures of upper limb function for people with neck pain: A 
systematic 
review 
of 
measurement 
and 
practical 
properties. 
Musculoskeletal 
Science 
and 
Practice, 
29(1), 
155-163 
https://doi.org/10.1016/j.msksp.2017.02.004 
 
Alsalameh, A. M., Harisi, M. J., Alduayji, M. A., Almutham, A. A., & 
Mahmood, F. M. (2019). Evaluating the relationship between smartphone 
addiction/overuse and musculoskeletal pain among medical students at 

 
32 
 
Qassim University. Journal of family medicine and primary care, 8(9), 
2953. https://doi.org/10.1007/s10900-016-0271-x 
 
Alshahrani, A., Samy Abdrabo, M., Aly, S. M., Alshahrani, M. S., 
Alqhtani, R. S., Asiri, F., & Ahmad, I. (2021). Effect of Smartphone 
Usage on Neck Muscle Endurance, Hand Grip and Pinch Strength among 
Healthy College Students: A Cross-Sectional Study. International journal 
of 
environmental 
research 
and 
public 
health, 18(12), 
6290. 
https://doi.org/10.3390/ijerph18126290 
 
AlShayhan, F. A., & Saadeddin, M. (2018). Prevalence of low back pain 
among health sciences students. European journal of orthopaedic surgery 
& 
traumatology 
: 
orthopedie 
traumatologie, 28(2), 
165–170. 
https://doi.org/10.1007/s00590-017-2034-5 
 
Al-Sobayel, H. I., Al-Hugail, H. A., Alsaif, R. M., Albawardi, N. M., 
Alnahdi, A. H., Daif, A. M., & Al-Arfaj, H. F. (2016). Validation of an 
Arabic version of Fatigue Severity scale. Saudi Medical Journal, 37(1), 
73–78. https://doi.org/10.15537/smj.2016.1.13055 
 
Asiri, F., Reddy, R. S., Tedla, J. S., ALMohiza, M. A., Alshahrani, M. S., 
Govindappa, S. C., & Sangadala, D. R. (2021). Kinesiophobia and its 
correlations with pain, proprioception, and functional performance among 
individuals 
with 
chronic 
neck 
pain. PLOS 
ONE, 16(7), e0254262. https://doi.org/10.1371/journal.pone.0254262 
 
Beales, D., Kyaw-Myint, S., Smith, A., O, P., Pransky, G., Linton, S., Job, 
J., & Straker, L. (2017). Work Productivity Loss in Young Workers Is 
Substantial and Is Associated With Spinal Pain and Mental Ill-health 
Conditions. Journal 
of 
Occupational 
and 
Environmental 
Medicine, 59(3), 237-245. https://doi.org/10.2307/48501343 
 
Behera, P., Majumdar, A., Revadi, G., Santoshi, J. A., Nagar, V., & 
Mishra, N. (2020). Neck pain among undergraduate medical students in a 
premier institute of central India: A cross-sectional study of prevalence and 
associated factors. Journal of Family Medicine and Primary Care, 9(7), 
3574-3581. https://doi.org/10.4103/jfmpc.jfmpc_206_20 
 
Ben Ayed, H., Yaich, S., Trigui, M., Ben Hmida, M., Ben Jemaa, M., 
Ammar, A., Jedidi, J., Karray, R., Feki, H., Mejdoub, Y., Kassis, M., 
& Damak, J. (2019). Prevalence, Risk Factors and Outcomes of Neck, 
Shoulders and Low-Back Pain in Secondary-School Children. Journal of 
research in health sciences, 19(1), e00440. 
 
Bidja, M., Mishra, N., & Mishra, A. (2018). A Study on Correlation Between 
Neck Pain and Hand Grip Strength and Its Effect on QoL Among Female 

 
33 
 
Beauticians. International Journal of Research and Analytical Reviews, 
5(3), 417. 
 
Bosquet, L., Gouadec, K., Berryman, N., Duclos, C., Gremeaux, V., & 
Croisier, J. L. (2016). The Total Work Measured During a High Intensity 
Isokinetic 
Fatigue 
Test 
Is 
Associated 
With 
Anaerobic 
Work 
Capacity. Journal of sports science & medicine, 15(1), 126–130. 
 
Bracht, M. A., Coan, A. C. B., Yahya, A., & Santos, M. J. D. (2017). Effects 
of cervical manipulation on pain, grip force control, and upper extremity 
muscle activity: A randomized controlled trial. Journal of Manual & 
Manipulative 
Therapy, 
25(1), 
1-11. 
https://doi.org/10.1080/10669817.2017.1393177. 
 
Canu, M., Fourneau, J., Coq, J., Dannhoffer, L., Cieniewski-Bernard, C., 
Stevens, L., Bastide, B., & Dupont, E. (2019). Interplay between 
hypoactivity, muscle properties and motor command: How to escape the 
vicious deconditioning circle? Annals of Physical and Rehabilitation 
Medicine, 62(2), 122-127. https://doi.org/10.1016/j.rehab.2018.09.009 
 
Cheng, A. J., Yamada, T., Rassier, D. E., Andersson, D. C., Westerblad, H., 
& Lanner, J. T. (2016). Reactive oxygen/nitrogen species and contractile 
function in skeletal muscle during fatigue and recovery. The Journal of 
physiology, 594(18), 5149-5160. https://doi.org/10.1113/JP270650 
 
Cheung Lau, H.M., Wing Chiu, T.T., & Lam, T. (2009). Clinical 
measurement of craniovertebral angle by electronic head posture 
instrument: A test of reliability and validity. Manual Therapy, 14(3), 363–
368. 
 
Chung, S., & Jeong, Y. G. (2018). Effects of the craniocervical flexion and 
isometric neck exercise compared in patients with chronic neck pain: A 
randomized controlled trial. Physiotherapy theory and practice, 34(12), 
916-925.  https://doi.org/10.1080/09593985.2018.1430876 
 
Cohen, S. P. (2015). Epidemiology, diagnosis, and treatment of neck pain. 
Mayo 
Clinic 
proceedings, 
90(2), 
284–299. 
https://doi.org/10.1016/j.mayocp.2014.09.008 
 
Côté, P., Wong, J.J., & Sutton, D. (2016). Management of neck pain and 
associated disorders: A clinical practice guideline from the Ontario 
Protocol 
for 
Traffic 
Injury 
Management 
(OPTIMa) 
Collaboration. European 
Spine 
Journal, 
25 
(7), 
2000–2022. 
https://doi.org/10.1007/s00586-016-4467-7 
  
Damasceno, G. M., Ferreira, A. S., Nogueira, L. A. C., Reis, F. J. J., 
Andrade, I. C. S., & Meziat-Filho, N. (2018). Text neck and neck pain in 

 
34 
 
18–21-year-old young adults. European Spine Journal, 27(6), 1249-1254. 
https://doi.org./10.1007/s00586-017-5444-5 
 
Dighriri, Y. H., Akkur, M. A., Alharbi, S. A., Madkhali, N. A., Matabi, K. 
I., & Mahfouz, M. S. (2019). Prevalence and associated factors of neck, 
shoulder, and low-back pains among medical students at Jazan University, 
Saudi Arabia: A cross-sectional study. Journal of family medicine and 
primary 
care, 8(12), 
3826–3831. 
https://doi.org/10.4103/jfmpc.jfmpc_721_19 
 
Dixon, R. G., Khiatani, V., Statler, J. D., Walser, E. M., Midia, M., Miller, 
D. L., Bartal, G., Collins, J. D., Gross, K. A., Stecker, M. S., & Nikolic, 
B. (2017). Society of Interventional Radiology: Occupational Back and 
Neck Pain and the Interventional Radiologist. Journal of Vascular and 
Interventional 
Radiology, 
28(2), 
195–199. 
https://doi.org/0.1016/j.jvir.2016.10.017 
 
Enoka, R. M., & Duchateau, J. (2016). Translating Fatigue to Human 
Performance. Medicine and science in sports and exercise, 48(11), 2228. 
https://doi.org/10.1249/MSS.0000000000000929 
 
Falsiroli Maistrello, L., Zanconato, L., Palese, A., Geri, T., Turolla, A., 
Gianola, S., Dell’Isola, A., Rossettini, G. (2022). Perceptions and 
experiences of individuals with neck pain: A systematic critical review of 
qualitative studies with meta-summary and meta-synthesis. Physical 
Therapy, 102(8), pzac080. https://doi.org/10.1093/ptj/pzac080 
 
Fayez, E. S. (2014). The Correlation between Neck Pain and Hand Grip 
Strength of Dentists. Occupational Medicine & Health Affairs, 02(05). 
https://doi.org/10.4172/2329-6879.1000185. 
 
Fiebert, I. M., Kistner, F., Gissendanner, C., & DaSilva, C. (2021). Forward 
head posture, mobile phone, cervical pain, neck pain. Work, 69(4), 1261-
1270. https://doi.org/10.3233/WOR-213547 
 
Gallego-Izquierdo, T., Arroba-Díaz, E., García-Ascoz, G., Val-Cano, M. A., 
Pecos-Martin, D., & Cano-de-la-Cuerda, R. (2020). Psychometric 
proprieties of a mobile application to measure the craniovertebral angle: A 
validation and reliability study. International Journal of Environmental 
Research 
and 
Public 
Health, 
17(18), 
6628. 
https://doi.org10.3390/ijerph17186521. 
 
Gane, E. M., McPhail, S. M., Hatton, A. L., Panizza, B. J., & O’Leary, S. P. 
(2018). The relationship between physical impairments, quality of life and 
disability of the neck and upper limb in patients following neck 
dissection. Journal 
of 
Cancer 
Survivorship, 12, 
619-631.  
https://doi.org/10.1007/s11764-018-0697-5  

 
35 
 
 
Gerodimos, V., Karatrantou, K., Psychou, D., Vasilopoulou, T., & 
Zafeiridis, A. (2017). Static and dynamic handgrip strength endurance: 
Test-retest reproducibility. The Journal of Hand Surgery, 42(3), e175-e184. 
https://doi.org/10.1016/j.jhsa.2016.12.014 
 
Gietzen, C. H., Kunz, A. S., Luetkens, K. S., Huflage, H., Christopoulos, G., 
van Schoonhoven, J., Bley, T. A., Schmitt, R., & Grunz, J. P. (2022). 
Evaluation of prestyloid recess morphology and ulnar-sided contrast 
leakage in CT arthrography of the wrist. BMC Musculoskeletal Disorders, 
23, 284. https://doi.org/10.1186/s12891-022-05241-9 
 
Gillen, G., & Nilsen, D. M. (2020). Upper extremity function and 
management. Stroke 
Rehabilitation 
E-Book: 
A 
Function-Based 
Approach, 413. Elsevier Health Sciences. 
 
Gurav, R. S., & Panhale, V. P. (2017). The association between neck pain 
and upper limb disability in patients with non-specific neck pain. Int J 
Allied Med Sci Res, 7(7), 92-97 
 
Hall, S. J. (2022). Basic biomechanics (9th ed.).; International edition.). 
McGraw 
Hill. 
http://gen.lib.rus.ec/book/index.php?md5=32FA421DBF74EABFE45EE60
7ECA6FE89 
 
Hansraj K. K. (2014). Assessment of stresses in the cervical spine caused by 
posture and position of the head. Surgical technology international, 25, 
277–279. PMID: 25393825. 
 
Hasan, M. M., Yaqoob, U., Ali, S. S., & Siddiqui, A. A. (2018). Frequency of 
Musculoskeletal Pain and Associated Factors among Undergraduate 
Students. 
Case 
Reports 
in 
Clinical 
Medicine, 
7(2), 
71-79. 
https://doi.org/10.4236/crcm.2018.72011. 
 
Hasan, N. A. K. A. K., Kamal, H. M., & Hussein, Z. A. (2016). Relation 
between body mass index percentile and muscle strength and endurance. 
Egyptian Journal of Medical Human Genetics, 17(4), 367-372. 
https://doi.org/10.1016/j.ejmhg.2016.01.002 
 
Hatem, S. M., Saussez, G., della Faille, M., Prist, V., Zhang, X., Dispa, D., 
& Bleyenheuft, Y. (2016). Rehabilitation of Motor Function after Stroke: 
A Multiple Systematic Review Focused on Techniques to Stimulate Upper 
Extremity 
Recovery. Frontiers 
in 
Human 
Neuroscience, 10. https://doi.org/10.3389/fnhum.2016.00442 
 
Jahre, H., Grotle, M., Smedbråten, K., Dunn, K. M., & Øiestad, B. E. 
(2020). Risk factors for non-specific neck pain in young adults: A 

 
36 
 
systematic review. BMC Musculoskeletal Disorders, 21(1), 366. 
https://doi.org/10.1186/s12891-020-03379-y 
 
Janicijevic, D., Knezevic, O. M., Garcia-Ramos, A., Cvetic, D., & Mirkov, 
D. M. (2020). Isokinetic Testing: Sensitivity of the Force-Velocity 
Relationship Assessed through the Two-Point Method to Discriminate 
between Muscle Groups and Participants’ Physical Activity Levels. 
International Journal of Environmental Research and Public Health, 
17(22). https://doi.org/10.3390/ijerph17228570 
 
Jerković, A., Proroković, A., Matijaca, M., Ćurković Katić, A., Košta, V., 
Mihalj, M., Dolić, K., Đogaš, Z., & Rogić Vidaković, M. (2022). 
Validation of the fatigue severity scale in Croatian population of patients 
with multiple sclerosis disease: Factor structure, internal consistency, and 
correlates. Multiple Sclerosis and Related Disorders, 58, 103397. 
https://doi.org/10.1016/j.msard.2021.103397 
  
Kahraman, T., Göz, E., & Genç, A. (2017). The association between self-
reported low back pain and lower limb disability as well as the association 
between neck pain and upper limb disability. Agri, 29(1), 1-8. 
https://doi.org/10.5505/agri.2016.65668 
 
Kazeminasab, S., Nejadghaderi, S. A., Amiri, P., Pourfathi, H., Araj-
Khodaei, M., Sullman, M. J. M., Kolahi, A.-A., & Safiri, S. (2022). 
Neck pain: Global epidemiology, trends and risk factors. BMC 
Musculoskeletal Disorders, 23(1), 26. https://doi.org/10.1186/s12891-021-
04957-4 
 
Kim, E.-K., & Kim, J. S. (2016). Correlation between rounded shoulder 
posture, neck disability indices, and degree of forward head posture. 
Journal 
of 
Physical 
Therapy 
Science, 
28(10), 
2929–2932. 
https://doi.org/10.1589/jpts.28.2929 
 
Kumar, V., Abbas, A. K., Aster, J. C., & Robbins, S. L. (2018). Robbins 
basic pathology. Elsevier Health Sciences. 
 
Lawrence, A., Eapen, A. A., Amitha, M. P., Rajith, R., George, R., Thomas, 
V., & Jose, J. (2022). Wearable Smart Cervical Collar with Real-time 
Rehabilitation of Neck Posture Correction. In 2022 IEEE 6th Conference 
on Information and Communication Technology (CICT) (PP.1-5). IEEE. 
https://doi.org/10.1109/CICT56698.2022.9997948. 
 
Lee, K., Han, H., Cheon, S., Park, S., & Yong, M. (2015) The effect of 
forward head posture on muscle activity during neck protraction and 
retraction. Journal of Physical Therapy Science, 27(4), 977–979. 
 

 
37 
 
Lee, S.-P., Hsu, Y.-T., Bair, B., Toberman, M., & Chien, L.-C. (2018). 
Gender and posture are significant risk factors to musculoskeletal 
symptoms during touchscreen tablet computer use. Journal of Physical 
Therapy Science, 30(6), 855-861. https://doi.org/10.1589/jpts.30.855 
 
Lim, H. H. R., Tang, Z. Y., Hashim, M. A. B. M., Yang, M., Koh, E. Y. L., 
& Koh, K. H. (2020). Cross-cultural adaptation, reliability, validity, and 
responsiveness of the Simplified-Chinese version of Neck Disability Index. 
Spine, 45(8), 541-548. https://doi.org/10.1097/BRS.0000000000003325 
 
Magee, D. J., & Manske, R. C. (2020). Orthopedic physical assessment-E-
Book. Elsevier Health Sciences 
 
Mahmoud, A., El Keblawy, A., El-Dein, S., & El Erian, E. (2020). Relation 
between neck pain and hand function in patients with non-specific neck 
pain. International Journal of Recent Advances in Multidisciplinary 
Research, 7(12), 6471-6477.  
 
Mahmoud, N. F., Hassan, K. A., Abdelmajeed, S. F., Moustafa, I. M., & 
Silva, A. G. (2019). The relationship between forward head posture and 
neck pain: a systematic review and meta-analysis. Current reviews in 
musculoskeletal medicine, 12(4), 562-577. https://doi.org/10.1007/s12178-
019-09594-y 
 
Marklund, S., Bui, K. L., & Nyberg, A. (2019). Measuring and monitoring 
skeletal muscle function in COPD: current perspectives. International 
Journal of Chronic Obstructive Pulmonary Disease, 1825-1838.  
 
Mcgrath, T. M., Waddington, G., Scarvell, J. M., Ball, N. B., Creer, R., 
Woods, K., & Smith, D. (2016). The effect of limb dominance on lower 
limb functional performance–a systematic review. Journal of sports 
sciences, 34(4), 289-302.  https://doi.org/10.1080/02640414.2015.1050601 
 
Muñoz-Bermejo, L., López-Pascual, J., & García-Vaquero, M. P. (2019). 
Effectiveness of isokinetic dynamometry in the measurement of wrist 
muscle performance: A systematic review. PloS one, 14(5), e0217148. 
https://doi.org/10.1371/journal.pone.0217148 
 
Mustafaoglu, R., Yasaci, Z., Zirek, E., Griffiths, M. D., & Ozdincler, A. R. 
(2021). 
The 
relationship 
between 
smartphone 
addiction 
and 
musculoskeletal pain prevalence among young population: a cross-
sectional 
study. The 
Korean 
journal 
of 
pain, 34(1), 
72-81. 
https://doi.org/10.3344/kjp.2021.34.1.72 
 
Namwongsa, S., Puntumetakul, R., Neubert, M. S., & Boucaut, R. (2018). 
Factors associated with neck disorders among university student 

 
38 
 
smartphone 
users. Work 
(Reading, 
Mass.), 61(3), 
367–378. 
https://doi.org/10.3233/WOR-182819 
 
Ng, A. W. H., Griffith, J. F., Fung, C. S. Y., Lee, R. K. L., Tong, C. S. L., 
Wong, C. W. Y., Tse, W. L., & Ho, P. C. (2017). MR imaging of the 
traumatic triangular fibrocartilaginous complex tear. Quantitative imaging 
in 
medicine 
and 
surgery, 
7(4), 
443–460. 
https://doi.org/10.21037/qims.2017.07.01 
 
Oliv, S., Gustafsson, E., Baloch, A. N., Hagberg, M., & Sandén, H. (2019). 
Important work demands for reducing sickness absence among workers 
with neck or upper back pain: A prospective cohort study. BMC 
Musculoskeletal Disorders, 20(1), 529. https://doi.org/10.1186/s12891-
019-2909-1 
 
Ortego, G., Lluch, E., Herrero, P., Boudreau, S. A., & Doménech-García, 
V. (2022). Profiling and Association over Time between Disability and 
Pain Features in Patients with Chronic Nonspecific Neck Pain: A 
Longitudinal Study. Journal of Clinical Medicine, 11(5), 1346. 
https://doi.org/10.3390/jcm11051346 
 
Ortego, G., Villafañe, J. H., Doménech-García, V., Berjano, P., Bertozzi, 
L., & Herrero, P. (2016). Is there a relationship between psychological 
stress or anxiety and chronic nonspecific neck-arm pain in adults? A 
systematic review and meta-analysis. Journal of Psychosomatic Research, 
(91), 
S0022399916303889. 
https://doi.org/10.1016/j.jpsychores.2016.09.006 
 
Park, S. J., Lee, R., Yoon, D. M., Yoon, K. B., Kim, K., & Kim, S. H. 
(2016). Factors associated with increased risk for pain catastrophizing in 
patients with chronic neck pain: A retrospective cross-sectional 
study. Medicine, 95(37), 
e4698. 
https://doi.org/10.1097/MD.0000000000004698 
 
Rani, M., & Kaur, J. (2022). Effectiveness of spinal mobilization and postural 
correction exercises in the management of cervicogenic headache: A 
randomized controlled trial. Physiotherapy theory and practice, 1–15. 
Advance 
online 
publication. 
https://doi.org/10.1080/09593985.2022.2037032 
 
Regal, S., Maschke, S., & Li, Z. M. (2020). Hand and wrist biomechanics. 
In Frontiers 
in 
Orthopaedic 
Biomechanics (pp. 
51-68). 
Springer. 
https://doi.org/10.1007/978-981-15-3159-0_4 
 
Ribeiro, P., Ferreira, J. A., Rodrigues, P., Santos, R., & Vilas-Boas, J. P. 
(2021). Isokinetic evaluation of wrist strength and endurance: A review of 

 
39 
 
the 
literature. 
Journal 
of 
Hand 
Therapy, 
34(1), 
44-50. 
https://doi.org/10.1016/j.jht.2019.07.005 
 
Roth, R., Donath, L., Kurz, E., Zahner, L., & Faude, O. (2017). Absolute 
and relative reliability of isokinetic and isometric trunk strength testing 
using the IsoMed-2000 dynamometer. Physical Therapy in Sport, 24, 26-
31. https://doi.org/10.1016/j.ptsp.2016.11.005 
  
Saini, A., Singh, T., & Arora, R. (2022). Isokinetic dynamometer in 
orthopedics: A systematic review. Journal of Clinical Orthopaedics and 
Trauma, 16, 51-57. https://doi.org/10.1016/j.jcot.2021.03.006 
 
Saleh, M. S. M., Rehab, N. I., & Sharaf, M. A. F. (2018). Effect of deep 
cervical flexors training on neck proprioception, pain, muscle strength and 
dizziness in patients with cervical spondylosis: A randomized controlled 
trial. Phys Ther Rehabil, 5(1), 14. https://doi.org//10.7243/2055-2386-5-14 
 
Seven, B., Cobanoglu, G., Oskay, D., & Atalay-Guzel, N. (2019). Test-
Retest Reliability of Isokinetic Wrist Strength and Proprioception 
Measurements. 
Journal 
of 
Sport 
Rehabilitation, 
1-18. 
https://doi.org/10.1123/jsr.2018-0341 
 
ShaghayeghFard, B., Ahmadi, A., Maroufi, N., & Sarrafzadeh, J. (2016). 
Evaluation of forward head posture in sitting and standing positions. 
European Spine Journal, 25 (11), 3577–3582.  
 
Shah, P. P., & Sheth, M. S. (2018). Correlation of smartphone use addiction 
with 
text 
neck 
syndrome 
and 
SMS 
thumb 
in 
physiotherapy 
students. International Journal of Community Medicine and Public 
Health, 5(6), 2512. https://doi.org/10.18203/2394-6040.ijcmph20180001 
 
Sharma, S., Palanchoke, J., Reed, D., & Haxby Abbott, J. (2017). 
Translation, cross-cultural adaptation and psychometric properties of the 
Nepali versions of numerical pain rating scale and global rating of change. 
Health 
and 
Quality 
of 
Life 
Outcomes, 
15(1), 
236. 
https://doi.org/10.1186/s12955-017-0812-8 
 
Tabbert, H., Ambalavanar, U., & Murphy, B. (2022). Neck Muscle 
Vibration Alters Upper Limb Proprioception as Demonstrated by Changes 
in Accuracy and Precision during an Elbow Repositioning Task. Brain 
sciences, 12(11), 1532. https://doi.org/10.3390/brainsci12111532 
 
Tiggemann, C. L., Korndörfer, S. R., & de Oliveira, A. G. (2018). Effects of 
rest interval on isokinetic knee extension/flexion peak torque and fatigue 
indices in young and elderly women. Revista Brasileira de Fisioterapia, 
22(4), 284-290. https://doi.org/10.1590/s1413-35552017005000058 
 

 
40 
 
Tortora, G. J., & Derrickson, B. H. (2018). Principles of anatomy and 
physiology. John Wiley & Sons. 
 
Tsang, S. M., So, B. C., Lau, R. W., Dai, J., & Szeto, G. P. (2019). 
Comparing the effectiveness of integrating ergonomics and motor control 
to conventional treatment for pain and functional recovery of work‐related 
neck–shoulder pain: A randomized trial. European Journal of Pain, 23(6), 
1141-1152   https://doi.org/10.1002/ejp.1381 
 
Wannaprom, N., Treleaven, J., Jull, G., & Uthaikhup, S. (2021). Original 
research: Response rate and comparison of clinical features associated with 
positive or negative responses to a scapular positioning test in patients with 
neck pain and altered scapular alignment: a cross-sectional study. BMJ 
Open, 11(12). https://doi.org/10.1136/bmjopen-2021-057459 
 
Webber, C. M., Shin, A. Y., & Kaufman, K. R. (2019). Assessment of upper 
extremity function. The Journal of Hand Surgery, 44(7), 600-605. 
https://doi.org/10.1016/j.jhsa.2018.10.006 
 
Wingbermühle, R. W., van Trijffel, E., Nelissen, P. M., Koes, B., & 
Verhagen, A. P. (2018). Few promising multivariable prognostic models 
exist for recovery of people with non-specific neck pain in musculoskeletal 
primary care: A systematic review. Journal of Physiotherapy, 64(1), 16-23. 
https://doi.org/10.1016/j.jphys.2017.11.013 
 
Xu, J. F., Wang, J. S., Yu, Y., & He, C. Q. (2012). Intra- and interrater 
reliability in the isokinetic muscle strength test of wrist joint in healthy 
youth. Chinese Journal of Tissue Engineering Research, 16(50), 9401-
9406. https://doi.org/10.3969/j.issn.2095-4344.2012.50.017. 
 
Young, I. A., Dunning, J., Butts, R., Mourad, F., & Cleland, J. A. (2019). 
Reliability, construct validity, and responsiveness of the neck disability 
index and numeric pain rating scale in patients with mechanical neck pain 
without 
upper 
extremity 
symptoms. Physiotherapy 
theory 
and 
practice, 35(12), 
1328-1335. 
https://doi.org/10.1080/09593985.2018.1471763 
 
Zabihhosseinian, M., Holmes, M. W., & Murphy, B. (2015). Neck muscle 
fatigue 
alters 
upper 
limb 
proprioception. Experimental 
brain 
research, 233(5), 1663–1675. https://doi.org/10.1007/s00221-015-4240-x 
 
Zafar, A., Akhtar, S., Sadiq, U., & Sobia, S. (2021). Prevalence Of Non-
Specific Neck Pain Among Surgeons In Different Hospitals Of 
Lahore. American Journal of Health, Medicine and Nursing Practice, 6(2), 
42-47.  https://doi.org/10.47672/ajhmn.742