Effectiveness of neck stabilisation and dynamic exercises on pain intensity, depression and anxiety among patients with non-specific neck pain: a randomised controlled trial

2.1 Participants

The participants in this study were patients with NsNP, aged between 22 and 65 years and recruited between October 2013 and February 2015 from the National Orthopaedic Hospital in Dala, Kano (NOHDK). NOHDK is a specialist hospital with 200 beds that provides a tertiary health care service to the northern part of Nigeria. The participants were included if they: had been diagnosed with NsNP; had moderate to severe neck pain and were able to comprehend instruction in English or the Hausa language; were not involved in any other form of exercise training during the course of the programme; and had reported a NsNP of at least 6 weeks’ duration. They were excluded if they had: co-morbidities that influenced overall well-being, for example, sickle cell anaemia; specific disorders of the cervical spine, such as disk prolapse, spinal stenosis, postoperative conditions, history of severe trauma, spasmodic torticollis, frequent migraine, fibromyalgia, shoulder diseases, inflammatory rheumatic diseases and psychiatric illness; obvious spinal deformity or neurological disease, or history of cardiovascular diseases contraindicated to exercise; Beck Depression scores of <11, Beck Anxiety scores <1; and/or were below 18 years of age. All research instruments were translated into the local language during the pilot study.

2.2 Sample size determination

The sample size for the study (N) was determined using Cohen’s table [11] at α=0.05, degree of freedom (u)=k−1, where k is the number of groups in this study, which is equal to 3. Therefore, at α=0.05, u=2, effect size (f)=0.35 (medium value) from the pilot study and power (w)=80, group sample size (n)=20. Sample size (N) for the study was a minimum of 60 patients with NsNP. An extra 12 participants (20%) were added to make room for dropouts (attrition). Therefore, a minimum of 72 participants were recruited for this study, with each group having at least 24 participants.

2.3 Design

This study was a prospective, parallel, single-blinded, randomised controlled clinical trial design that had been registered with the Pan Africa Clinical Trial Registry (PACTR 201402000727807).

2.4 Procedure

Ethical approval for the study was sought and obtained from the Health Research Ethics Committee of University of Ibadan and University College Hospital, Ibadan (UI/EC/14/0003). In addition, ethical approval was obtained from the National Orthopaedic Hospital in Dala, Kano (NOHD/RET/ETHIC/60).

2.5 Clinical assessment

Volunteers were recruited through referral, if they expressed an interest in participating after the aims and purposes of the research were explained to them. Prospective participants were then assessed and screened during their first appearance by the researcher for inclusion into the study. The confirmatory test used for NsNP included: X-ray or magnetic resonance imaging (MRI), if it was available, to rule out any red flag or specific neck diseases; physical tests (compression, distraction, vertebral artery test); and laboratory tests, if available. The Beck Depression Inventory (BDI) was employed to screen participants for depression. Those with scores of >11 were included. For anxiety, the Beck Anxiety Inventory (BAI) was used to screen participants. Those with scores of ≥1 were included. They were then guided through the informed consent process and were required to sign or thumbprint a consent form. After signed, written consents had been obtained, what followed was the participants’ random allocation to the three study groups – NSEG or NSDEG or NDEG. The demographic and baseline questionnaires were administered to the participants by the researcher after the randomisation. The researcher then scheduled appointments for the interventions.

2.6 Sampling and randomisation technique

There are 196 patients with neck pain at that period 123 referred for physiotherapy and 35 were excluded because they did not meet the inclusion criteria. Patients referred for physiotherapy by doctors were recruited for the study by means of a consecutive sampling technique. The subjects were screened to determine whether they met the inclusion criteria for the research. Patients who met these criteria were randomised into three groups, viz. the neck stabilisation exercise group (NSEG), the neck stabilisation plus dynamic exercise group (NSDEG), and the neck dynamic exercise group (NDEG), as they became available. One hundred and twenty-three participants met the eligibility criteria, while the 35 who did not were excluded from the study. Randomisation was achieved through the means of sealed envelopes, which were prepared in advance and marked inside with an A or B or C, indicating the NSEG, NSDEG and NDEG, respectively. The randomisation was performed by a third party, who was completely unaware of the study content. The envelopes were picked without the replacement.

The neck stabilisation exercise group (NSEG; n=30), neck stabilisation plus dynamic exercise group (NSDEG; n=28) and neck dynamic exercise group (NDEG; n=31). However, 76 participants completed the study – NSEG; n=28, NSDEG; n=24, NSDEG; n=24. A 13.6% dropout rate (13 out of 89 participants) was observed throughout this study, with 76 volunteers (86.36%) completing its 8-week programme (Fig. 1, flow chart).

Figure 1:

Flow diagram showing the progression of patients through the study.

2.7 Blinding

Participants were blind to group allocation. Blinding is an important component of a valid, randomised controlled trial, because it ensures that treatment expectation is evenly matched between groups [12]. It will not be possible to blind the treating physiotherapists. The outcome assessors and statistician who analysed the data were also blinded to group allocation.

2.8 Measurement of the parameters

2.9 Intervention

2.10 Data analysis

Preliminary analysis was performed to check for normality, linearity and homogeneity of variance, covariance and multi-collinearity, with no serious violations noted with mahal. Distance of 17.922. Descriptive statistics of mean, percentage and standard deviation were employed to describe the data. A one-way between groups and within groups multivariate analysis of variance (MANOVA) was performed to investigate the differences between the stabilisation exercise group, stabilisation plus dynamic group, and dynamic group, and three dependent variables were used – pain, depression and anxiety. Furthermore, post hoc, follow-up analyses were performed to identify where significant differences lay in the MANOVA, with a Bonferroni adjusted α level. The strength of the effect size defined ds of 0.2, 0.5 and 0.8 as small, medium, and large effects, respectively [11]. The α level was set at 0.05. The data analyses were carried out using the IBM SPSS version 23.0 (SPSS Inc., Chicago, IL, USA).

3.1 Characteristics of participants

Eighty-nine participants were recruited for this study. They were randomly allocated to one of three groups: neck stabilisation exercises group (NSEG; n=30), neck stabilisation, plus dynamic exercises group (NSDEG; n=28) and neck dynamic exercises group (NDEG; n=31). Seventy-six participants completed the 8-week programme: NSEG, n=28; NSDEG, n=24; NSDEG, n=24. This gave a 13.6% drop-out rate (of 13 participants), with no intention of any analysis being performed on their data. Participants’ ages ranged from 22 to 67 years, mean 46.81±12.43, 45.13±13.38 and 48.55±11.61 years for NSEG, NSDEG and NDEG, respectively, and socio-demographic variables were presented in Table 2.

3.2 Within and between-groups; comparison of effects of neck stabilisation exercises, neck stabilisation plus dynamic exercises and dynamic exercises of participant

The within-groups comparison for NSEG reveals a significant difference in pain intensity, depression and anxiety scores from baseline, at 4 weeks and 8 weeks of the study (F=62.40, p=0.001, F=13.91, p=0.001 and F=20.93, p=0.001), respectively. Furthermore, the within-group comparison for NSDEG demonstrated that there was a significant difference in pain intensity, depression and anxiety scores from the baseline, at 4 weeks and 8 weeks of the study (F=11.92, p=0.001, F=8.75, p=0.004 and F=9.70, p=0.001). Moreover, the within-group comparison for NDEG showed that there was a significant difference in pain intensity, depression and anxiety scores from the baseline, at 4 weeks and 8 weeks of the study (F=36.63, p=0.001, F=11.99, p=0.001 and F=6.59, p=0.001), respectively.

Table 3 shows the comparisons of pain intensity, depression and anxiety scores between the groups of participants in the NSEG, NSDEG and NDEG, at the baseline of the study. With the aid of the one-way MANOVA, the study revealed that there were no significant differences in scores among the three groups: p=0.159, 0.580 and 0.179, respectively.

At the week 4 of the study, with the aid of MANOVA, the study revealed that there was a significant difference in the pain intensity and anxiety scores across the three groups, with p=0.018 and p=0.011, respectively, however, there were no significant difference in depression scores, at p=0.93. A post hoc test with Bonferroni adjustment was performed for the dependent variables that were significant and it revealed that there were no significant differences between the three groups, with an effect size of 0.10, 0.00 and 0.12, respectively, as shown in Table 4.

At week 8 of the study, the pain intensity and depression and anxiety scores were compared with MANOVA. The study demonstrated significant differences in the pain intensity scores between the three groups – at p=0.001, and depression scores at p=0.041 – while there were no significant differences in the anxiety scores between the three groups, at p=0.358, as shown in Table 5. The post hoc test with Bonferroni adjustment demonstrated that only pain intensity was significant among the three groups and lay in the NSEG, as shown in Table 6, with an effect size of 0.37, 0.08 and 0.02, respectively.

4.1 Limitation

This study compared the effects of stabilisation and dynamic exercises on pain intensity, anxiety and depression in patients with NsNP. One limitation of this study is that the long-term effects of stabilisation and dynamic exercises cannot be obtained, because the research only assesses effects for up to 8 weeks, therefore, its results should be interpreted with caution. Furthermore, it has no general applicability, as it can only be applied to the NsNP patients’ population. Another limitation of the research includes the inability to blind the research assistant who delivered the intervention because, in standard RCT, both participants and those who deliver interventions are blinded, but in physiotherapy there are obstacles associated with this. Self-reported outcomes, such as VAS and Beck Depression and Anxiety scales, are also limited, as they can be influenced by placebo effects and outcome expectation. Moreover, some participants might have been taking other analgesics, which might have influenced the intervention and this would have lay beyond the control of the researcher.

4.2 Effect of stabilisation exercise, dynamic exercise, stabilisation plus dynamic exercise on pain, depression and anxiety

The age of the participants ranged from 22 to 67 years, a range consistent with those of patients affected by neck pain in most epidemiological studies [21], [22]. The results obtained in this study demonstrated that there were no significant differences in the physical characteristics of participants at the baseline, including age, pain intensity, depression and anxiety. This implied that the three groups were comparable at the point of commencement of the programme. It can therefore be concluded that the results obtained at different time points during the course of the study could have been largely due to the effect of the various treatment interventions.

Stabilisation exercises significantly reduced pain intensity, depression and anxiety in patients with NsNP. This finding was consistent with the results of previous studies on the effect of neck stabilisation exercises on NsNP [23], [24], [25], [26], [27]. Dynamic exercises in this study significantly reduced pain in patients with NsNP. The effect of dynamic exercises was comparable with the previous studies that used dynamic exercises in the management of NsNP [19], [28].

Neck pain not only interferes with sleep daytime functional activities, but also affects the neurotransmitters in a person’s brain that are responsible for sensory input processing and memory storage, thus changing the manner in which pain is perceived and dealt with. As a consequence, these patients often become depressed and/or anxious, in addition to the fact that the chronic symptoms of neck pain can lead patients to avoid social settings, favourite physical activity and even work or sex. Ironically, because these patients had chronic pain, they might have been taking pain medication, which itself could contribute to depression. In addition, some of the pain drugs could cause nausea, which in turn caused appetite and weight loss [29]. Furthermore, changes in pain, anxiety and depression of patients after treatment might be due to dynamic exercises that led to general body relaxation, thus an increase in plasma β-endorphins [30]. Furthermore, strengthening and stabilisation exercises have some effect in reducing stress hormones and muscle tension, and will thus decrease anxiety levels [23]. Therefore, stabilisation and dynamic exercises might have more positive effects in reducing psychosocial symptoms such as depression and anxiety.

4.3 Comparison of the effectiveness of neck stabilisation exercises, dynamic exercises and stabilisation, plus dynamic exercises

Neck stabilisation exercises led to a higher, more significant improvement in pain only at the week-8 point, however, there were no differences between the three groups. This is inconsistence with the finding of Celenay et al. [23] and Yildiz et al. [2] whose reported that stabilisation exercise or stabilisation with a combination of another intervention is effective in reducing pain depression and anxiety in patients with neck pain. Looking at the effect size of the present study, though, we can conclude that the difference was small, based on the Cohen [11] classification of effect size. So, we can say that the difference was negligible and, in a real sense, both exercises were effective in reducing the pain among patients with NsNP. Also, concerning depression at week 8 of the study, a significant difference was noted, but when controlled for type 1 error using Bonferroni adjustment, it was discovered that there were no significant differences among them. From the results, the neck stabilisation exercises group showed the greatest pain reduction and depression reduction, followed by the neck stabilisation plus dynamic exercises group and then the neck dynamic exercises group.

Concerning all of the variables, at weeks 4 and 8 of the study, no significant differences were discovered between the neck stabilisation plus dynamic exercises group and the dynamic exercises group. This may not be unconnected with the time required for dynamic strength training to strengthen the muscles. The results demonstrate the advantage of stabilisation exercises alone over a combination of stabilisation and dynamic exercises, particularly with regard to pain stabilisation exercises, which showed improvements in pain intensity scores both at weeks 4 and 8 of the study, with the latter showing the greatest improvement. However, the differences observed were not significant at week 4, after the Bonferroni adjustment and had a very small effect size. There were no significant differences between the groups after adjusting the significant level from the 0.05 to 0.17 to control for type 1 error in depression scores. Moreover, the effect size at weeks 4 and 8 revealed that the differences were small in terms of pain, depression and anxiety, so this demonstrated that, generally, exercises had the potential effect of improving depression and anxiety. This finding is inconsistence with the finding of the previous studies by Andias et al. [5] exercises has potentials to improves psychological and mental wellbeing in patients with neck pain. Dusunceli et al. [26], in a study on the efficacy of neck stabilisation exercises for neck pain, compared three treatment protocols: physical therapy agent, physical therapy agent plus isometric and stretching exercises, and physical therapy plus stabilisation exercises. Dusunceli et al. [26] concluded that the stabilisation protocol and physical therapy agent for chronic neck pain patients were equally effective in reducing pain and depression. Another study by Chiu et al. [31] examined the efficacy of exercise for patients with chronic neck pain. The intervention included the activation of the deep neck muscles and the dynamic strengthening of the neck muscles, plus infrared irradiation. Chiu et al. [31] concluded that a combined treatment of neck stabilisation exercises, plus physical therapy was a more effective intervention for the management of neck pain, with some advantages in outcomes for pain and disability over the combination of isometric exercises, plus the physical therapy agent or physical therapy agent alone.

The observed effects of the neck stabilisation group, neck stabilisation plus dynamic group and the neck dynamic exercises group in this study could be as a result of the fact that the intervention for each group contained active exercises, with some carried out in extension positions. Many studies have shown that exercises and postures in extension improve and resolve symptoms in patients with NsNP [32]. Previous studies reported that stabilisation with other interventions are equally effective in alleviating clinical symptoms and psychosocial variables associated with neck pain [7], [33]. Although the present study demonstrated that a single specific exercise intervention, in this case stabilisation alone, was effective in reducing pain and depression in patients with NsNP, it also proved that a multimodal approach could also take care of these variables in patients with NsNP. The present study also highlighted that engaging in a specific activity, such as stabilisation exercises, produced better results than a combination of two exercises in reducing pain, depression and anxiety, although both the combination of stabilisation and dynamic exercises and dynamic exercises alone were effective in the management of NsNP. Stabilisation exercises alone had a more positive effect than stabilisation plus dynamic and dynamic exercise. This may have been as a result of strength training with load – in both stabilisation and dynamic, and dynamic alone – perhaps cancelling out the effect of stabilisation in the combination group. As a result, the strength training with load may take more time to show positive effects than stabilisation alone and this is why, in the present study, stabilisation was shown to be the superior of group. The combination of both the stabilisation and dynamic exercises may have led to fatigue in the initial exercises and this may have aggravated the pain in the first instance, before the participants adapted to the programme. This may explain why stabilisation alone may have led to an improvement, rather than a combination of both the stabilisation and dynamic exercises. Moreover, stabilisation exercise alone may be related to activating the deep muscles and strengthening the whole deep and superficial muscles of the neck.

Strength training with weights may be effective in the long term, but this result should be interpreted with caution because the effect size for differences in pain was small. Therefore, the differences may not much. Further studies need to be carried out, to establish the real differences especially in the long-term effects. The research further revealed that stabilisation exercises, stabilisation plus dynamic exercises and dynamic exercises were methods that reduced NsNP in patients with depression and anxiety. Few studies have investigated the effectiveness of exercise on NsNP in the management of patients with depression and anxiety. However, they reported an improvement in this study [23], [34].