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| ORIGINAL ARTICLE |
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| Year : 2022 | Volume
: 16
| Issue : 2 | Page : 60-64 |
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Effectiveness of dynamic strength-endurance training of the neck and scapular muscles in reducing pain and improving function in nonspecific neck pain
S Priya, S Haripriya, Milan Dhungana
Department of Physiotherapy, Laxmi Memorial College of Physiotherapy, Rajiv Gandhi University of Health Sciences, Bengaluru, Karnataka, India
| Date of Submission | 31-Aug-2022 |
| Date of Decision | 21-Nov-2022 |
| Date of Acceptance | 30-Nov-2022 |
| Date of Web Publication | 31-Jan-2023 |
Correspondence Address:
dr. Milan Dhungana
Laxmi Memorial College of Physiotherapy, Rajiv Gandhi University of Health Sciences, Bengaluru, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/pjiap.pjiap_57_22
BACKGROUND: Nonspecific neck pain is a common musculoskeletal disorder causing disability among the general population. Specific dynamic strength-endurance exercises may help maintain improved posture, which in turn can lessen or eliminate recurrent flare-ups of pain. The effect of exercise on patients with chronic nonspecific neck pain has been investigated in several studies. The efficacy is, however, questionable.
AIM: The aim of the study is to find the effectiveness of dynamic strength-endurance training in reducing pain and improving function in nonspecific neck pain.
DESIGN: This study was a pre- and postintervention design.
SETTING: This study was conducted in tertiary care hospital in Mangaluru.
MATERIALS AND METHODS: In this pre- and postexperimental study, dynamic strength-endurance training for cervical and scapular muscles was given to 24 adults fulfilling inclusion criteria for 4 weeks. The Neck Disability Index (NDI) was used for pain and disability assessment, and the Neck Bournemouth Questionnaire (NBQ) and the Northwick Park Neck Pain Questionnaire (NPNQ) were used for pain assessment.
RESULTS: There was a significant reduction in NDI, NBQ, and NPNQ scores exceeding minimal clinically important difference (NDI >7.5 points, NBQ >5.5 points, and NPNQ >7.6 points) after 4 weeks of strength-endurance training of cervical and scapular muscles. There was significant improvement in hold time. Statistically, a significant difference was observed in pre- and posttreatment effect comparison of all outcome measures (P > 0.01).
CONCLUSION: A dynamic strength-endurance training program is effective in reducing pain and disability in a patient with nonspecific neck pain.
Keywords: Neck Bournemouth Questionnaire, neck disability index, neck pain, Northwick Park Neck Pain Questionnaire
How to cite this article:
Priya S, Haripriya S, Dhungana M. Effectiveness of dynamic strength-endurance training of the neck and scapular muscles in reducing pain and improving function in nonspecific neck pain. Physiother - J Indian Assoc Physiother 2022;16:60-4 |
How to cite this URL:
Priya S, Haripriya S, Dhungana M. Effectiveness of dynamic strength-endurance training of the neck and scapular muscles in reducing pain and improving function in nonspecific neck pain. Physiother - J Indian Assoc Physiother [serial online] 2022 [cited 2023 Jun 5];16:60-4. Available from: https://www.pjiap.org/text.asp?2022/16/2/60/368881 |
| Introduction | |  |
International Association for the Study of Pain (IASP) in its classification of chronic pain define cervical spine pain as "pain perceived anywhere in the posterior region of the cervical spine, from superior nuchal line to the first thoracic spinous process."[1] Several studies demonstrated that neck muscle atrophy is strongly correlated with nonspecific neck pain. However, the causal association between neck muscle atrophy and neck pain remains unexplained.[2] In the past decade, several researchers reported that dynamic strengthening of neck muscles for 6–11 weeks in patients with chronic neck pain resulted in reduced neck pain, increase in isometric neck muscle strength, and decrease in disability. However, the efficacy of active strengthening exercises for the management of chronic neck pain has been uncertain in previous studies.[3],[4],[5]
Neck pain is a common musculoskeletal disorder that leads to significant disability in the general population. The prevalence of this condition increases with age and is greater in women than in men. Musculoskeletal disorders of the neck are very common among table workers. Duration of computer use, sustained awkward posture, and prolonged working with visual display units are some of the predisposing factors identified for causing neck pain.[6] Prolonged awkward posture may cause minor damage to the neck muscles which is further aggravated by sudden muscular contraction and this may also lead to the shrinkage of muscles that are not commonly being utilized, thereby inducing mechanical dysfunction and chronic pain. A continuous imbalance between superficial and deep neck flexors causes forward head posture which is very commonly observed in patients with chronic neck pain.[7]
In a population-based study done on prevalence and factors associated with neck pain, it was found that the prevalence of neck pain was 20.3%.[8],[9] A study which was done on the Indian population found that the 1-year prevalence of neck pain and work-related neck pain was 43.3% and 28.3%, respectively. It was reported more among females as compared to males.[10] Biomechanically, sustained forward flexion of the neck results in increased comprehensive loading on the cervical spine and creep response in surrounding soft tissue. Furthermore, the source of pain is excessive loading of the cervical and shoulder muscle, especially in low-load repetitive work which promotes overactivity of low-threshold motor units (MUs).[11]
Several researchers have found the beneficial effect of dynamic strength training and dynamic endurance training of neck muscles in individuals with mechanical neck pain.[1],[12],[13],[14],[15] A systematic review by Louw et al. also supported this and concluded that dynamic strength training and endurance training could be a means of reducing pain and improving function and quality of life.[16] However, studies on combined dynamic strength and endurance training together and their relative effectiveness are limited. Therefore, this study was carried out to determine whether dynamic strength endurance training is effective in reducing pain and improving function in a patient with nonspecific neck pain.
| Materials and Methods | | |
This 4-week interventional study was conducted at a tertiary hospital in Dakshina Kannada. Ethical clearance was obtained from the institutional ethical committee. Clinical trial was registered under the Clinical Trial Registry of India (CTRI/2022/01/039185). A total of 21 participants between the age group of 25 and 60 years with nonspecific neck pain were recruited using a convenience sampling technique. Participants having any recent surgeries to the neck or upper back, history of a whiplash injury, open wounds in the neck region, acute pain and inflammation, fracture, and psychological illness were excluded from the study. Before the treatment, the purpose and procedure of the study were explained to all participants, and written informed consent was taken. Hold time in sphygmomanometer – chin tucked in supine at 30 mm Hg, the Northwick Park Neck Pain Questionnaire (NPNQ), the Neck Bournemouth Questionnaire (NBQ), and the Neck Disability Index (NDI) were used to rate the participant's pain and functional disability.
Intervention
The treatment protocol began with warm-up, i.e., all neck movements (isolated and combined) and stretching of the muscles of the cervical region such as the upper trapezius, sternocleidomastoid, and other cervical muscles. For the activation and training of the deep neck flexors, the patient was in a supine position. For craniocervical flexion and gentle axial extension, the patient was taught to perform a slow, controlled nodding motion of the head on the upper cervical spine resembling a "yes" motion. A folded towel was placed under the occipital area if a patient had a significant forward head posture, so the extension of the head-on neck does not occur. The motion was facilitated with manual cues to ensure the longus colli is contracting and sternocleidomastoid is at a relative state of rest. Once the patient was able to activate the motion, the pressure cuff was used as biofeedback to monitor the amount of cervical flattening and to measure the muscular endurance for holding the contraction. The blood pressure cuff was inflated to 20 mm Hg and the patient was instructed to nod and increase the pressure up to 30 mm Hg and to hold for 10 s. This was done in three sets with 10 repetitions each.
For lower cervical and upper extensor activation and training, the patient was kept in a prone position with his/her forehead on the treatment table and arm at the side. The patient was instructed to lift the forehead off the treatment table, keeping the chin tucked and eyes focused on the table to maintain the neutral spine position and to hold for 10 s.[17] This was done in 1 set with 10 repetitions. With the above exercise, dynamic strengthening exercises for scapular muscles were also combined. The exercises given were scapular retraction for rhomboids and middle trapezius, scapular retraction combined with shoulder horizontal abduction/extension for rhomboids, middle trapezius, and posterior deltoid, also known as "T" exercise, scapular retraction, and shoulder horizontal abduction combined with external rotation for rhomboids, trapezius, posterior deltoid, infraspinatus, and teres minor. Each of the above exercises was done in 3 sets of 10 repetitions each.
Statistical analysis
According to the study done by Borisut et al.[1] assuming P < 0.05, 95% confidence interval, 80% power, and with 10% relative allowable error sample size estimated for the study is 21. The Shapiro–Wilk test was used to find the normality of distribution; mean and standard deviation were used as a measure of central tendency and measure of dispersion to quantify the variables. Paired T test was used to test the significant difference in Hold Time, NDI, NBQ, NPNQ before and after the treatment. The statistical package of SPSS V 26 (IBM® SPSS® v 26) was used for data analysis.
| Results | | |
Thirty-two individuals with nonspecific neck pain were assessed for compatibility with eligibility criteria. Twenty-one (n = 21) met the eligibility criteria and agreed to participate in the study [Table 1]. Data are normally distributed (P > 0.05 on Shapiro–Wilk test). There is a significant reduction in NDI, NBQ, and NPNQ scores exceeding minimal clinically important difference (NDI >7.5 points, NBQ >5.5 points, and NPNQ >7.6 points) after 4 weeks of strength-endurance training of cervical and scapular muscles. There was significant improvement in hold time. Statistically, significant difference was observed in pre- and posttreatment effect comparison of all outcome measures (P > 0.01).
| Discussion | | |
All 21 participants included in this study have completed the full course of 4 weeks of their respective treatment under supervision. The patients have shown a significant reduction in pain and improved function after 4 weeks of dynamic strength endurance training protocol. This suggests that the protocol followed is effective in reducing neck pain and improving neck function.
Both endurance and strength training serve rehabilitation, prophylactic, and sports purposes to restore, maintain, develop, or enhance cardiorespiratory and muscular fitness. However, they represent extremely different types of physical activity. Endurance training is based on the repeated activation of muscles and improves the ability of muscles to perform contractions for a prolonged period without fatigue. On the other hand, strength training utilizes high-intensity exercises of muscle performed in a series of repetitions with incremental weight and thus improves strength. Adaptation of muscle to physical activity follows the specificity principle. Physical training evokes changes in the ultrastructural and functional level of the neuromuscular system and leads to alteration in MU physiology. The alteration in the neuromuscular system depends on the type of training used, and the extent of training effect depends on the frequency, intensity, and duration of employed training.[18] In the same way, it was found that the strength and endurance of the patients who went through the treatment protocol were improved so the pain and disability score of the patient after 4 weeks of treatment were decreased.
A study done by Stagg et al. revealed that a single bout of exercise increases the production of endogenous opioids, leading to transient antinociception, and repeated exercise produces long-lasting antinociception.[18] Mayer et al. found that resistance training through a repetitive full range of motion exercise around the lumbar spine (in chronic low back pain) may affect disc metabolism itself, with the possibility that the exercise program could improve metabolic exchange in lumbar discs and aid in repair. This can be a possible mechanism for relieving pain and reducing disability in our study too.[19]
Pain in the neck (cervical pain) may have different origins. It is understood that the term cervical pain does not refer to the disease itself, but rather to a symptom or a manifestation of a painful muscular disorder.[20] Cervical pain usually has multifactorial clinical aspects, since it may involve individual risk factors (either physical or emotional characteristics), or be related to ergonomics and work activities. Pathoanatomic cause of mechanical neck pain is rarely identifiable although the cause of neck pain may be associated with the degenerative process or pathology identified during diagnostic imaging, the tissue that is causing the patient neck pain is most often unknown. Mechanical neck pain commonly arises insidiously and is generally multifactorial in origin, including one or more of the following: poor posture, anxiety, depression, neck strain, and sporting and occupational activities.
Sometimes nociceptor sensitization due to intramuscular shear force may also play a role in causing neck pain, which may further increase Electromyography (EMG), activity of cervical musculatures such as neck extensor muscles and the levator scapulae. In addition, the superficial muscles of the neck–shoulder region, i.e., the sternocleidomastoid, anterior scalene, and upper trapezius muscles, demonstrate increased activities compared to deeper postural stabilizers like the deep cervical flexors. Moreover, several studies have reported significantly lower maximal isometric strength of both cervical flexors and extensors in patients with chronic neck pain compared to healthy controls and one study also found the weakness of the neck rotator muscles.[21] Recent studies have shown that the activities of the deep cervical flexor muscles, such as the longus colli and longus capitis, are impaired in persons with neck pain.[22] Furthermore, the findings of a significant deficit in the ability to maintain low or moderate load by the craniocervical flexors (CCFs) muscles suggest that head-and-neck postural orientation is challenged under prolonged or repetitive circumstances in neck pain patients. The CCF muscles may fatigue prematurely and be incapable of controlling craniocervical orientation. This potentially exposes cervical spine tissues to abnormal mechanical load. Indeed, evidence is emerging that persons with neck pain tend to adopt a more forward head position when distracted.[23]
The symptoms may arise due to stress to the anterior longitudinal ligament in the upper cervical spine and the posterior longitudinal ligament and ligamentum flavum in the lower cervical and thoracic spine, fatigue of the thoracic erector spine and scapular retractor muscles, irritation of the facet joints of the upper cervical spine, and narrowing of the intervertebral foramina in the upper cervical region, which may impinge on blood vessels and nerve root, especially if there are degenerative changes.[17]
A forward head posture commonly involves increased flexion of the lower cervical and upper thoracic region, increased extension of the upper cervical vertebra, extension of the upper cervical vertebra, and extension of the occiput on C1.[24] The forward head posture potentially causes impairment in the muscles of the anterior thorax (intercostal muscles), muscles of the upper extremity originating in the thorax (pectoralis major and minor, latissimus dorsi, and serratus anterior), muscles of the cervical spine, and head attached to the scapula and upper thorax (levator scapulae, sternocleidomastoid, scalene, and upper trapezius), and the muscle of the suboccipital region (rectus capitis posterior major and minor and obliquus capitis inferior and superior).
The impaired muscle performance is due to stretched lower cervical and weak lower cervical and upper thoracic erector spine and scapular retractor muscles (rhomboids and middle trapezius), anterior thorax muscles (suprahyoid and infrahyoid muscles), and capital flexors (rectus capitis anterior and lateral, superior oblique longus colli, and longus capitis).[25]
Researchers have found that strength-endurance training induces changes in the basic biophysical properties of motor neuron that influences their excitability and functional properties resulting in decreased MU firing rates. Furthermore, physiological adaption in muscle fibers such as the increase in capillary density, increased oxidative capacity, increase in fast oxidative-glycolytic (Type IIB), and parallel reduction in fast glycolytic (Type I) muscle fibers were seen in in vivo rat experiments. Furthermore, there was an increase in fatigue-resistant MUs with parallel reduction of fast fatigue MUs after treadmill training. This indicates the transformation of MUs toward fatigue-resistant units with relatively high fatigue resistance. Both endurance and strength training have been shown to raise muscle oxidative capacity (57% and 37%, respectively) but only endurance training has shown to decline glycolytic Adenosine triphosphate (ATP) supply (56%). This means endurance training declined glycolytic ATP production (i.e., rise in aerobic ATP production), delaying the accumulation of lactic acid and thus reducing fatigability.[26] Thus by improving the strength and endurance of the muscles, the pain and disability of the patient who went through the treatment were decreased.
Strength training was found to increase the maximal discharge rate of MUs during the voluntary contraction of skeletal muscles. Strength training increases the force of voluntary contraction thus improving the strength of muscles.[27] The increased strength and/or endurance of neck musculature reduces abnormal loading of the cervical spine, thus relieving stress on connective tissue and bone. This can be a mechanism of relief of pain after strength or endurance training.
| Conclusion | | |
This study concludes that dynamic strength-endurance training is effective in relieving pain and decreasing disability in a patient with nonspecific neck pain.
Acknowledgment
The authors acknowledge Dr. Manjula Suvarna, Assistant Professor/Statistician for her contribution toward sample size calculation, data analysis, and interpretation.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Table 1]
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