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Abstract

BACKGROUND:

Muscle energy technique (MET) is found to be effective for the management of neck pain and in addition to the muscle specific approach, clinicians may also adopt movement specific approach for METs. However, the literature is deficient in terms of comparison of muscle specific and movement specific METs in the management of mechanical neck pain.

OBJECTIVE:

To compare the effects of muscle specific and movement specific METs in the management of mechanical neck pain.

METHODS:

A single blind parallel design randomized controlled trial was conducted on 66 participants with mechanical neck pain ranging from 40–80 mm on visual analogue scale (VAS), aged between 19–44 years with pain and limitation on cervical motion. Once included, the participants were randomly allocated to two groups, namely the muscle specific MET group and the movement specific MET group. Outcome measures included VAS, Neck Disability Index (NDI) and cervical range of motion (ROM).

RESULTS:

No significant differences ( $p>$ 0.05) were observed, neither immediately nor after 5 days, between muscle specific and movement specific MET in terms of VAS, NDI and ROM. However, a significant difference ( $p<$ 0.05) was observed in both groups in terms of pre- and post-analysis for all outcome variables.

CONCLUSIONS:

Both muscle specific and movement specific METs are effective in the management of mechanical neck pain, with no significant differences between the two treatment techniques.

Keywords

Cervical spine muscle energy technique neck pain pain physical therapy range of motion

1. Introduction

Neck is the most common site of musculoskeletal discomfort, the occurrence of which has been reported to be as high as 75.7% in healthy young adults [1, 2]. The buildup of this discomfort leads to neck pain, with a 1 year prevalence ranging from 16.7% to 75.1% [3, 4]. Neck pain can result in functional disability, which may be influenced by factors such as self-efficacy, psychological distress, and fear-avoidance beliefs [5]. One of the most initial and common causes of neck pain includes contractile dysfunction including muscular imbalances, muscular weakness, increased muscle tension and muscle shortening. They are not only the major culprits in impaired postures such as upper crossed syndrome and forward head posture [6, 7, 8], but may also lead to neck pain, decreased cervical range of motion [9] and increased joint reaction forces in the facet and intervertebral joints, eventually leading to degenerative joint disorders.

Physical therapy has been found to be effective in the management of mechanical neck pain [10, 11, 12, 13, 14, 15], with manual therapy and exercise being the most preferred and commonly practiced techniques [16]. There are different types of manual therapy techniques such as joint mobilization, neural mobilization and muscle energy technique (MET) focusing on joints, nerves and muscles respectively [10, 12, 13, 17, 18, 19]. Among manual therapy techniques, METs have not only been observed to be effective in improving pain, function, range of motion, muscle strength and cervical curvature [10, 12, 13, 17] in persons with neck pain, but is also reported to be superior to static stretching in the management of mechanical neck pain [10, 12, 17]. One of the proposed reasons for the superiority of METs over static stretching has been the fact that static stretching only addresses the passive component of the muscle tone whereas METs address both active and passive tone components using the mechanism of either autogenic or reciprocal inhibition [10, 12]. Furthermore, studies have shown autogenic inhibition MET to be more effective than reciprocal inhibition MET in the management of mechanical neck pain [10, 12].

Even though, from a physiological point of view, METs are conventionally muscle specific, being applied to an individual muscle at a time and based on its individual function such as anterior, middle and posterior Scaleni, Sternocleidomastoid, Levator Scapulae and upper fibers of Trapezius in the neck region, the clinical goal of using Muscle Energy Techniques (METs) in patients with mechanical neck pain is to improve the range of motion in the neck, including flexion, extension, lateral flexion, and rotation. This goal is important both from the perspective of clinicians and patients. For this reason, some clinicians may follow a movement specific approach, instead of a muscle specific approach, as the ultimate goal is to improve range of motion. However, it is imperative to point out that there is no existing evidence regarding the comparison of muscle specific and movement specific METs in the management of mechanical neck pain, which is the aim of this study. Thus, in the current study it was hypothesized that there is a statistically significant difference between the effects of muscle specific as compared to movement specific MET on neck pain, range of motion and neck disability in persons with mechanical neck pain.

2. Methods

2.1 Study design

Figure 1.

CONSORT diagram (scheme of study).

A single blind parallel design randomized controlled trial was conducted on 66 participants at Foundation University Islamabad (FUI), from April 2017 to January 2019. The participants were blind to the group allocation.

2.2 Ethics

Ethical approval was acquired from Foundation University Islamabad Ethical Review Committee and Brainstorm Research Ethical Review Committee in accordance with the Declaration of Helsinki and CONSORT guidelines. Informed consent was taken from all participants before inclusion in the study and the participant information was kept confidential.

2.3 Sample size calculation

Sample size was calculated using a minimal detectable change of 10.2 for Neck Disability Index (NDI) [20], with a pooled standard deviation of 13.19, a confidence level of 0.05 and a power of 0.8, based on which a total sample size of 56 was calculated, using the Harvard Sample Size Calculator [21]. However to account for potential drop outs a sample of 66 participants was included in the study.

2.4 Participant selection and random allocation

A total of 66 participants with mechanical neck pain ranging from 40–80 mm on visual analogue scale (VAS), aged between 19–44 years with pain and limitation on cervical motion were included in the study via purposive sampling. Participants with a positive history of fracture, surgery or trauma in the neck region, cervical radiculopathy, myelopathy, spondylosis, or syringomyelia, thoracic outlet syndrome, infection, any malignancy, inflammatory, or rheumatic disorders, and vascular syndromes such as vertebrobasilar insufficiency were excluded from the study [10, 12]. The participants were first screened by a medical practitioner. Once included, the participants were randomly allocated into two groups, namely the muscle specific MET group and the movement specific MET group, via coin toss method. The participants were not aware of their allocated treatment group, nor were they aware of the treatment other participants were receiving to ensure blinding. Treatment practitioner and outcome assessor was the same person and was not blind to the participant allocation.

2.5 Intervention

All participants were given 10 minutes of Trans Cutaneous Electrical Nerve Stimulation in combination with hot pack, followed by 3 sets of Maitland’s unilateral postero-anterior glide (10–15 oscillations) regardless of the group they were allocated to [10, 12, 18]. After the aforementioned protocol the participants of both the groups were given 3–5 repetitions of post-isometric relaxation (PIR) MET with 30% to 50% of maximal isometric contraction for 7 to 10 seconds, followed by 5 seconds of rest and then a stretch was maintained for 10 to 60 seconds [10, 12, 22, 23]. However, the approach of PIR was either muscle or movement specific based on the treatment group.

In the muscle specific MET group, the participants were given post-isometric relaxation MET targeted at muscles of the neck region that are prone to get short, including anterior, middle and posterior Scaleni, Sternocleidomastoid, Levator Scapulae and upper fibers of Trapezius muscle [10, 12]. In the movement specific group, the participants were given post-isometric relaxation MET targeted at specific movements of the cervical spine including flexion, extension, rotation and lateral flexion. The participant was asked to perform a specific movement such as rotation towards the right side, and then the participant was instructed to try to perform a movement towards the opposite side (rotation towards left) using 30% to 50% of maximal force while the therapist resisted the movement for 7 to 10 seconds, and then the participant was asked to relax, following which the therapist would move the head and neck towards the point of restriction (rotation towards right) where the therapist would maintain a stretch for 10 to 60 seconds. All participants received consecutive treatment sessions for 5 days.

2.6 Outcome measures

Table 1
Participant characteristics at baseline

Variables	Muscle specific MET	Movement specific MET	$P$ -value
Gender	24 (Females) 9 (Males)	24 (Females) 9 (Males)	1.000
	Mean $\pm$ S.D	Mean $\pm$ S.D
Age (years)	41.61 $\pm$ 12.20	41.00 $\pm$ 12.08	0.840
Weight (kg)	75.27 $\pm$ 11.37	75.00 $\pm$ 11.16	0.922
Height (feet)	5.43 $\pm$ 0.34	5.42 $\pm$ 0.34	0.884
BMI	27.80 $\pm$ 4.64	27.71 $\pm$ 4.69	0.942
VAS (cm)	7.58 $\pm$ 0.50	7.67 $\pm$ 0.65	0.525
NDI (%)	45.71 $\pm$ 14.16	45.58 $\pm$ 12.22	0.967
ROM ( ${}^{\circ}$ )
Flexion	27.24 $\pm$ 1.60	30.97 $\pm$ 10.18	0.110
Extension	32.88 $\pm$ 15.72	32.45 $\pm$ 13.43	0.907
Rotation (Right)	45.91 $\pm$ 11.90	47.67 $\pm$ 11.97	0.552
Rotation (Left)	48.33 $\pm$ 13.71	50.97 $\pm$ 14.70	0.454
Lateral flexion (Right)	24.88 $\pm$ 6.40	26.15 $\pm$ 5.53	0.391
Lateral flexion (Left)	29.12 $\pm$ 6.94	29.88 $\pm$ 7.77	0.677

BMI, body mass index; MET, muscle energy technique; VAS, visual analogue scale; NDI, neck disability index; ROM, range of motion; S.D, standard deviation.

The outcome measures included VAS for pain, Neck Disability Index (NDI) for function and goniometry for cervical range of motion (ROM). Pain and ROM were measured at baseline, after 1 ${}^{\text{st}}$ treatment session and after 5 consecutive treatment sessions. However, NDI was measured at baseline and after 5 consecutive treatment sessions only. NDI was considered as the primary outcome, based on which sample size was also calculated.

2.6.1 Visual Analogue Scale (VAS)

The VAS is a pain assessment tool consisting of a 0–100 mm or 0–10 cm line. Patients were instructed to indicate their level of pain severity by placing a mark on the line, with higher scores representing greater levels of pain. VAS has been established as a valid and reliable instrument for evaluating neck pain, and is frequently utilized as an outcome measure. A minimum clinically important difference of 4.6 to 21.4 mm has been documented in VAS scores for neck pain, indicating its sensitivity to changes in pain intensity [24].

2.6.2 Cervical Range of Motion (ROM)

The ROM of the cervical spine was quantified using a universal goniometer. All pre- and post-treatment ROM measurements were performed in sitting position by the same investigator. The Intra-class Correlation Coefficient (ICC) for the intra-rater reliability of universal goniometer has been observed to be 0.83, 0.86, 0.84–0.85 and 0.78-0.90 [25], and the interrater-reliability has been observed to be 0.78, 0.83, 0.77–0.83 and 0.84–0.87 for cervical flexion, extension, lateral flexion and rotation respectively [26]. Research has shown decreased ROM to be related with poorer outcomes and greater or optimum ROM is linked with more favorable outcomes in neck pain [27].

2.6.3 Neck disability index (NDI)

NDI is a 10 item self-reported condition specific functional status questionnaire and is the most frequently used self-reported outcome measure for patients with neck pain [28] with an established validity and a test-retest reliability of $r=$ 0.89 [29]. Each section is scored from 0 to 5, with 0 meaning ‘No pain’ and 5 meaning ‘Worst imaginable pain’, with a maximum total score of 50 points and a minimum score of 0 points. In the current study, NDI was quantified as the raw score and then converted to and interpreted as the percentage score. Higher score shows a poorer outcome and lower score signifies a more favorable outcome, with a minimum detectable change of 10–10.2% [20, 29].

2.7 Statistical analysis

The data was analyzed using Statistical Package for Social Sciences (SPSS v 21). Shapiro Wilk and Kolmogorov Smirnov tests were used to determine the normality of data. Independent $t$ -test was used for inter-group comparison at base line and follow up. For pre and posttreatment comparison, repeated measures ANOVA was used for VAS and ROM, and paired $t$ -test was used for NDI. Chi square test was used for the comparison of two groups in terms of gender. Confidence interval was kept at 95% and $p$ -value of less than 0.05 was considered significant.

3. Results

A total of 66 participants were included in the study with 18 males and 48 females, with an equal male to female ratio in both groups. No significant differences were observed between the two groups at base line in terms of age, weight, height, body mass index (BMI), VAS, NDI and ROM (Table 1).

3.1 Pain and function

Table 2
Inter group comparison after 1 ${}^{\text{st}}$ treatment session

Variable	Muscle specific MET	Movement specific MET	Mean difference	Standard error difference	95% confidence interval		$P$ -value
	Mean $\pm$ S.D	Mean $\pm$ S.D			Upper	Lower
VAS (cm)	5.21 $\pm$ 1.27	5.27 $\pm$ 1.38	$-$ 0.06061	0.32576	$-$ 0.71138	0.59017	0.853
ROM ( ${}^{\circ}$ )
Flexion	38.61 $\pm$ 10.72	43.27 $\pm$ 10.36	$-$ 4.66667	2.59524	$-$ 9.85125	0.51791	0.077
Extension	42.73 $\pm$ 15.74	43.03 $\pm$ 13.85	$-$ 0.30303	3.65038	$-$ 7.59551	6.98945	0.934
Rotation (Right)	64.03 $\pm$ 13.09	65.27 $\pm$ 12.40	$-$ 1.24242	3.13936	$-$ 7.51402	5.02917	0.694
Rotation (Left)	64.97 $\pm$ 13.16	66.76 $\pm$ 12.10	$-$ 1.78788	3.11172	$-$ 8.00425	4.42849	0.568
Lateral flexion (Right)	32.21 $\pm$ 6.20	33.09 $\pm$ 5.33	$-$ 0.87879	1.42297	$-$ 3.72150	1.96393	0.539
Lateral flexion (Left)	36.03 $\pm$ 6.85	36.45 $\pm$ 7.48	$-$ 0.42424	1.76647	$-$ 3.95317	3.10468	0.811

MET, muscle energy technique; VAS, visual analogue scale; NDI, neck disability index; ROM, range of motion; S.D, standard deviation.

Table 3

Inter group comparison after 5 ${}^{\text{th}}$ treatment session

Variable	Muscle specific MET	Movement specific MET	Mean difference	Standard error difference	95% confidence interval		$P$ -value
	Mean $\pm$ S.D	Mean $\pm$ S.D			Upper	Lower
VAS (cm)	2.42 $\pm$ 1.60	2.42 $\pm$ 1.54	$<$ 0.001	0.38696	$-$ 0.77306	0.77306	1.000
NDI (%)	17.93 $\pm$ 17.70	19.00 $\pm$ 17.55	$-$ 1.07152	4.33795	$-$ 9.73758	7.59455	0.806
ROM ( ${}^{\circ}$ )
Extension	68.64 $\pm$ 11.82	66.33 $\pm$ 12.12	2.30303	2.94729	$-$ 3.58486	8.19092	0.437
Rotation (Right)	78.12 $\pm$ 12.16	79.79 $\pm$ 10.73	$-$ 1.66667	2.82290	$-$ 7.30606	3.97273	0.557
Rotation (Left)	77.97 $\pm$ 10.92	79.36 $\pm$ 10.13	$-$ 1.39394	2.59308	$-$ 6.57421	3.78633	0.593
Lateral flexion (Right)	39.12 $\pm$ 5.14	39.82 $\pm$ 4.91	$-$ 0.69697	1.23798	$-$ 3.17012	1.77618	0.575
Lateral flexion (Left)	41.12 $\pm$ 4.95	41.52 $\pm$ 5.60	$-$ 0.39394	1.30041	$-$ 2.99180	2.20392	0.763

MET, muscle energy technique; VAS, visual analogue scale; NDI, neck disability index; ROM, range of motion; S.D, standard deviation.

A significant difference ( $p<$ 0.05) was observed between pre- and post-treatment scores of VAS and NDI in both groups. However, no significant differences ( $p>$ 0.05) were observed between the two groups in terms of VAS immediately after treatment nor after 5 consecutive treatment sessions (Tables 2 and 3). Furthermore, no significant difference ( $p>$ 0.05) were observed between the two groups in terms of NDI after 5 consecutive treatment sessions (Table 3).

3.2 Cervical ROM

A significant difference ( $p<$ 0.05) was observed between pre- and post-treatment scores of ROM in all directions in both groups. However, no significant differences ( $p>$ 0.05) were observed between the two groups in terms of ROM immediately after treatment nor after 5 consecutive treatment sessions (Tables 2 and 3).

Table 4
Pre- and post-treatment analysis muscle specific MET

Variable	$P$ -value	Post-hoc analysis
		(I) time	(J) time	Mean difference	Std. error	Sig	95% confidence interval for difference
				(I $-$ J)			Lower bound	Upper bound
Pain	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	2.364 ${}^{*}$	0.208	$<$ 0.001	1.838	2.889
			5 ${}^{\text{th}}$ session	5.152 ${}^{*}$	0.289	$<$ 0.001	4.421	5.882
		1 ${}^{\text{st}}$ session	Baseline	$-$ 2.364 ${}^{*}$	0.208	$<$ 0.001	$-$ 2.889	$-$ 1.838
			5 ${}^{\text{th}}$ session	2.788 ${}^{*}$	0.278	$<$ 0.001	2.086	3.490
		5 ${}^{\text{th}}$ session	Baseline	$-$ 5.152 ${}^{*}$	0.289	$<$ 0.001	$-$ 5.882	$-$ 4.421
			1 ${}^{\text{st}}$ session	$-$ 2.788 ${}^{*}$	0.278	$<$ 0.001	$-$ 3.490	$-$ 2.086
NDI	$<$ 0.001			${}^{*}$ NDI was measured only at baseline and after 5 treatment sessions
				$-$ 27.7803	0.31394		$-$ 34.1599	$-$ 21.4007
Flexion	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 11.364 ${}^{*}$	1.219	$<$ 0.001	$-$ 14.444	$-$ 8.283
			5 ${}^{\text{th}}$ session	$-$ 29.788 ${}^{*}$	2.121	$<$ 0.001	$-$ 35.147	$-$ 24.429
		1 ${}^{\text{st}}$ session	Baseline	11.364 ${}^{*}$	1.219	$<$ 0.001	8.283	14.444
			5 ${}^{\text{th}}$ session	$-$ 18.424 ${}^{*}$	1.879	$<$ 0.001	$-$ 23.172	$-$ 13.676
		5 ${}^{\text{th}}$ session	Baseline	29.788 ${}^{*}$	2.121	$<$ 0.001	24.429	35.147
			1 ${}^{\text{st}}$ session	18.424 ${}^{*}$	1.879	$<$ 0.001	13.676	23.172
Extension	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 9.848 ${}^{*}$	1.432	$<$ 0.001	$-$ 13.467	$-$ 6.230
			5 ${}^{\text{th}}$ session	$-$ 35.758 ${}^{*}$	2.535	$<$ 0.001	$-$ 42.162	$-$ 29.353
		1 ${}^{\text{st}}$ session	Baseline	9.848 ${}^{*}$	1.432	$<$ 0.001	6.230	13.467
			5 ${}^{\text{th}}$ session	$-$ 25.909 ${}^{*}$	2.218	$<$ 0.001	$-$ 31.514	$-$ 20.305
		5 ${}^{\text{th}}$ session	Baseline	35.758 ${}^{*}$	2.535	$<$ 0.001	29.353	42.162
			1 ${}^{\text{st}}$ session	25.909 ${}^{*}$	2.218	$<$ 0.001	20.305	31.514
Rotation	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 18.121 ${}^{*}$	1.860	$<$ 0.001	$-$ 22.819	$-$ 13.423
(right)			5 ${}^{\text{th}}$ session	$-$ 32.212 ${}^{*}$	2.099	$<$ 0.001	$-$ 37.515	$-$ 26.910
		1 ${}^{\text{st}}$ session	Baseline	18.121 ${}^{*}$	1.860	$<$ 0.001	13.423	22.819
			5 ${}^{\text{th}}$ session	$-$ 14.091 ${}^{*}$	1.523	$<$ 0.001	$-$ 17.938	$-$ 10.244
		5 ${}^{\text{th}}$ session	Baseline	32.212 ${}^{*}$	2.099	$<$ 0.001	26.910	37.515
			1 ${}^{\text{st}}$ session	14.091 ${}^{*}$	1.523	$<$ 0.001	10.244	17.938
Rotation	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 16.636 ${}^{*}$	2.388	$<$ 0.001	$-$ 22.668	$-$ 10.604
(left)			5 ${}^{\text{th}}$ session	$-$ 29.636 ${}^{*}$	2.648	$<$ 0.001	$-$ 36.326	$-$ 22.947
		1 ${}^{\text{st}}$ session	Baseline	16.636 ${}^{*}$	2.388	$<$ 0.001	10.604	22.668
			5 ${}^{\text{th}}$ session	$-$ 13.000 ${}^{*}$	1.559	$<$ 0.001	$-$ 16.938	$-$ 9.062
		5 ${}^{\text{th}}$ session	Baseline	29.636 ${}^{*}$	2.648	$<$ 0.001	22.947	36.326
			1 ${}^{\text{st}}$ session	13.000 ${}^{*}$	1.559	$<$ 0.001	9.062	16.938
Lateral	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 7.333 ${}^{*}$	0.948	$<$ 0.001	$-$ 9.729	$-$ 4.938
flextion			5 ${}^{\text{th}}$ session	$-$ 14.242 ${}^{*}$	1.067	$<$ 0.001	$-$ 16.938	$-$ 11.547
(right)		1 ${}^{\text{st}}$ session	Baseline	7.333 ${}^{*}$	0.948	$<$ 0.001	4.938	9.729
			5 ${}^{\text{th}}$ session	$-$ 6.909 ${}^{*}$	0.553	$<$ 0.001	$-$ 8.306	$-$ 5.512
		5 ${}^{\text{th}}$ session	Baseline	14.242 ${}^{*}$	1.067	$<$ 0.001	11.547	16.938
			1 ${}^{\text{st}}$ session	6.909 ${}^{*}$	0.553	$<$ 0.001	5.512	8.306
Lateral	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 6.909 ${}^{*}$	0.982	$<$ 0.001	$-$ 9.391	$-$ 4.428
flextion			5 ${}^{\text{th}}$ session	$-$ 12.000 ${}^{*}$	1.145	$<$ 0.001	$-$ 14.892	$-$ 9.108
(left)		1 ${}^{\text{st}}$ session	Baseline	6.909 ${}^{*}$	0.982	$<$ 0.001	4.428	9.391
			5 ${}^{\text{th}}$ session	$-$ 5.091 ${}^{*}$	0.551	$<$ 0.001	$-$ 6.483	$-$ 3.699
		5 ${}^{\text{th}}$ session	Baseline	12.000 ${}^{*}$	1.145	$<$ 0.001	9.108	14.892
			1 ${}^{\text{st}}$ session	5.091 ${}^{*}$	0.551	$<$ 0.001	3.699	6.483

VAS, visual analogue scale; NDI, neck disability index; ROM, range of motion; S.D, standard deviation.

Table 5

Pre- and post-treatment analysis movement specific MET

Variable	$P$ -value	Post-hoc analysis
		(I) time	(J) time	Mean difference	Std. error	Sig	95% confidence interval for difference
				(I $-$ J)			Lower bound	Upper bound
Pain	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	2.394 ${}^{*}$	0.208	$<$ 0.001	1.867	2.921
			5 ${}^{\text{th}}$ session	5.242 ${}^{*}$	0.258	$<$ 0.001	4.592	5.893
		1 ${}^{\text{st}}$ session	Baseline	$-$ 2.394 ${}^{*}$	0.208	$<$ 0.001	$-$ 2.921	$-$ 1.867
			5 ${}^{\text{th}}$ session	2.848 ${}^{*}$	0.239	$<$ 0.001	2.245	3.452
		5 ${}^{\text{th}}$ session	Baseline	$-$ 5.242 ${}^{*}$	0.258	$<$ 0.001	$-$ 5.893	$-$ 4.592
			1 ${}^{\text{st}}$ session	$-$ 2.848 ${}^{*}$	0.239	$<$ 0.001	$-$ 3.452	$-$ 2.245
NDI	$<$ 0.001			${}^{*}$ NDI was measured only at baseline and after 5 treatment sessions
				$-$ 26.5748	2.99321		$-$ 32.6718	$-$ 20.4779
Flexion	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 12.303 ${}^{*}$	1.206	$<$ 0.001	$-$ 15.351	$-$ 9.255
			5 ${}^{\text{th}}$ session	$-$ 28.424 ${}^{*}$	2.195	$<$ 0.001	$-$ 33.970	$-$ 22.879
		1 ${}^{\text{st}}$ session	Baseline	12.303 ${}^{*}$	1.206	$<$ 0.001	9.255	15.351
			5 ${}^{\text{th}}$ session	$-$ 16.121 ${}^{*}$	1.679	$<$ 0.001	$-$ 20.362	$-$ 11.880
		5 ${}^{\text{th}}$ session	Baseline	28.424 ${}^{*}$	2.195	$<$ 0.001	22.879	33.970
			1 ${}^{\text{st}}$ session	16.121 ${}^{*}$	1.679	$<$ 0.001	11.880	20.362
Extension	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 10.576 ${}^{*}$	1.368	$<$ 0.001	$-$ 14.032	$-$ 7.120
			5 ${}^{\text{th}}$ session	$-$ 33.879 ${}^{*}$	2.352	$<$ 0.001	$-$ 39.822	$-$ 27.936
		1 ${}^{\text{st}}$ session	Baseline	10.576 ${}^{*}$	1.368	$<$ 0.001	7.120	14.032
			5 ${}^{\text{th}}$ session	$-$ 23.303 ${}^{*}$	1.913	$<$ 0.001	$-$ 28.135	$-$ 18.471
		5 ${}^{\text{th}}$ session	Baseline	33.879 ${}^{*}$	2.352	$<$ 0.001	27.936	39.822
			1 ${}^{\text{st}}$ session	23.303 ${}^{*}$	1.913	$<$ 0.001	18.471	28.135
Rotation	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 17.606 ${}^{*}$	1.868	$<$ 0.001	$-$ 22.326	$-$ 12.886
			5 ${}^{\text{th}}$ session	$-$ 32.121 ${}^{*}$	1.819	$<$ 0.001	$-$ 36.718	$-$ 27.525
		1 ${}^{\text{st}}$ session	Baseline	17.606 ${}^{*}$	1.868	$<$ 0.001	12.886	22.326
			5 ${}^{\text{th}}$ session	$-$ 14.515 ${}^{*}$	1.165	$<$ 0.001	$-$ 17.459	$-$ 11.571
		5 ${}^{\text{th}}$ session	Baseline	32.121 ${}^{*}$	1.819	$<$ 0.001	27.525	36.718
			1 ${}^{\text{st}}$ session	14.515 ${}^{*}$	1.165	$<$ 0.001	11.571	17.459
Rotation	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 17.606 ${}^{*}$	1.868	$<$ 0.001	$-$ 22.326	$-$ 12.886
(right)			5 ${}^{\text{th}}$ session	$-$ 32.121 ${}^{*}$	1.819	$<$ 0.001	$-$ 36.718	$-$ 27.525
		1 ${}^{\text{st}}$ session	Baseline	17.606 ${}^{*}$	1.868	$<$ 0.001	12.886	22.326
			5 ${}^{\text{th}}$ session	$-$ 14.515 ${}^{*}$	1.165	$<$ 0.001	$-$ 17.459	$-$ 11.571
		5 ${}^{\text{th}}$ session	Baseline	32.121 ${}^{*}$	1.819	$<$ 0.001	27.525	36.718
			1 ${}^{\text{st}}$ session	14.515 ${}^{*}$	1.165	$<$ 0.001	11.571	17.459
Rotation	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 17.606 ${}^{*}$	1.868	$<$ 0.001	$-$ 22.326	$-$ 12.886
(left)			5 ${}^{\text{th}}$ session	$-$ 32.121 ${}^{*}$	1.819	$<$ 0.001	$-$ 36.718	$-$ 27.525
		1 ${}^{\text{st}}$ session	Baseline	17.606 ${}^{*}$	1.868	$<$ 0.001	12.886	22.326
			5 ${}^{\text{th}}$ session	$-$ 14.515 ${}^{*}$	1.165	$<$ 0.001	$-$ 17.459	$-$ 11.571
		5 ${}^{\text{th}}$ session	Baseline	32.121 ${}^{*}$	1.819	$<$ 0.001	27.525	36.718
			1 ${}^{\text{st}}$ session	14.515 ${}^{*}$	1.165	$<$ 0.001	11.571	17.459
Lateral	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 6.939 ${}^{*}$	0.981	$<$ 0.001	$-$ 9.417	$-$ 4.461
flexion			5 ${}^{\text{th}}$ session	$-$ 13.667 ${}^{*}$	1.006	$<$ 0.001	$-$ 16.209	$-$ 11.124
(right)		1 ${}^{\text{st}}$ session	Baseline	6.939 ${}^{*}$	0.981	$<$ 0.001	4.461	9.417
			5 ${}^{\text{th}}$ session	$-$ 6.727 ${}^{*}$	0.411	$<$ 0.001	$-$ 7.766	$-$ 5.688
		5 ${}^{\text{th}}$ session	Baseline	13.667 ${}^{*}$	1.006	$<$ 0.001	11.124	16.209
			1 ${}^{\text{st}}$ session	6.727 ${}^{*}$	0.411	$<$ 0.001	5.688	7.766
Lateral	$<$ 0.001	Baseline	1 ${}^{\text{st}}$ session	$-$ 6.576 ${}^{*}$	1.069	$<$ 0.001	$-$ 9.276	$-$ 3.876
flexion			5 ${}^{\text{th}}$ session	$-$ 11.636 ${}^{*}$	1.207	$<$ 0.001	$-$ 14.685	$-$ 8.588
(left)		1 ${}^{\text{st}}$ session	Baseline	6.576 ${}^{*}$	1.069	$<$ 0.001	3.876	9.276
			5 ${}^{\text{th}}$ session	$-$ 5.061 ${}^{*}$	0.526	$<$ 0.001	$-$ 6.389	$-$ 3.732
		5 ${}^{\text{th}}$ session	Baseline	11.636 ${}^{*}$	1.207	$<$ 0.001	8.588	14.685
			1 ${}^{\text{st}}$ session	5.061 ${}^{*}$	0.526	$<$ 0.001	3.732	6.389

VAS, visual analogue scale; NDI, neck disability index; ROM, range of motion; S.D, standard deviation.

4. Discussion

The purpose of the current study was to compare the effects of muscle specific and movement specific METs in the management of mechanical neck pain in terms of pain function and range of motion. In the current study post isometric relaxation (PIR) MET, which is an autogenic inhibition MET was administered to muscle specific as well as the movement specific MET group, as previous studies have shown autogenic inhibition PIR-MET to be superior to both static stretching and reciprocal inhibition MET in the management of mechanical neck pain [10, 12, 30]. In terms of pain both muscle specific and movement specific METs were found to be effective in improving pain, immediately after the 1 ${}^{\text{st}}$ treatment session as well as after 5 consecutive treatment sessions. This finding was in accordance with the findings of the previous studies showing METs to be effective in improving pain in persons with mechanical neck pain as well as cervical spondylosis [10, 13, 17, 31]. Previous studies have shown METs to be even more effective than stretching in relieving pain in persons with mechanical neck pain [10, 17], however one study conducted on persons with cervical spondylosis showed conventional stretching to be more effective than MET in terms of pain [31]. Furthermore, no evidence has been identified regarding the comparison of muscle specific and movement specific METs in the management of mechanical neck pain, however the current study has shown no significant difference between the two treatment methods in terms of pain.

In terms of function both muscle specific and movement specific METs were found to be effective in improving NDI scores after 5 consecutive treatment sessions. This finding was in accordance with the findings of the previous studies showing METs to be effective in improving function in persons with mechanical neck pain as well as cervical spondylosis [10, 13, 17, 31]. Previous studies have shown METs to be even more effective than stretching in improving function and neck related disability in persons with mechanical neck pain [10, 17], however one study conducted on persons with cervical spondylosis showed conventional stretching to be more effective than MET [31] in terms of function and neck related disability Moreover, studies has also shown autogenic inhibition MET to be more effective than reciprocal inhibition MET in terms of improving neck related disability, function and isometric muscle strength in persons with mechanical neck pain [10, 12]. Furthermore, no evidence has been identified regarding the comparison of the effects of muscle specific and movement specific METs on function and neck related disability in persons with mechanical neck pain, however the current study has shown no significant differences between the two treatment methods in terms of NDI.

In terms of cervical range of motion both muscle specific and movement specific METs were found to be effective when measured immediately after 1 ${}^{\textit{st}}$ treatment session as well as after 5 consecutive treatment sessions using a universal goniometer. This finding was in accordance with the findings of the previous studies showing METs to be effective in improving cervical range of motion in persons with mechanical neck pain as well as cervical spondylosis [10, 13, 31, 32]. Previous studies have shown METs to be even more effective than stretching in improving cervical range of motion in persons with mechanical neck pain [10], however one study conducted on persons with cervical spondylosis showed conventional stretching to be more effective than MET [31] in terms of range of motion. Moreover, one study has also shown autogenic inhibition MET to be more effective in improving cervical range of motion in persons with mechanical neck pain [10]. Furthermore, no evidence has been identified regarding the comparison of the effects of muscle specific and movement specific METs on cervical range of motion in persons with mechanical neck pain, however the current study has shown no significant differences (p<0.05) between the two treatment methods in terms of range of motion.

Moreover, research has also shown METs to be effective in improving cervical curvature and isometric muscle strength in persons with mechanical neck pain [12, 13], with autogenic inhibition METs being more effective than reciprocal inhibition MET [12], however those outcomes were not observed in the current study. The results of the present study indicate that both muscle-specific and movement-specific muscle energy techniques (METs) are effective interventions for the management of mechanical neck pain, with no significant differences observed between the two groups. It is possible that in direction-specific muscle energy techniques, specific muscle fibers are being targeted in all directions, which could explain the lack of significant differences observed between muscle-specific and movement-specific METs. Additionally, the observed improvements in range of motion may favor direction-specific METs, as the technique is applied in specific movement directions (such as flexion, extension, side bending, and rotation) and range of motion is subsequently measured in those same directions. Therefore, it may have been more appropriate to measure resting muscle tone using electromyography to determine the true effect of the two METs on individual muscles. Nevertheless, the main concerns of patients with neck pain are pain, function/disability, and range of motion, and the current study demonstrated no significant differences between the two MET interventions in terms of those outcomes. The lack of a control group in the study may impact internal validity, as other therapeutic modalities may have contributed to the observed treatment effects beyond the MET interventions. However, previous studies have already shown that METs are superior to conventional static stretching when administered with electrotherapy, heating, and joint mobilization in terms of pain, function, range of motion, and isometric muscle strength among individuals with mechanical neck pain [10, 12]. Moreover, in order to improve the internal validity of the study, the use of more objective measurement tools such as pain pressure threshold (algometry) could have been employed to assess pain. It is important to note that the external validity of the current study’s findings is limited to individuals with mechanical neck pain, as the etiology of neck pain can vary depending on the specific subtype. Hence, the results of this study should be applied with caution when considering other types of neck pain.

5. Conclusion

The current study’s findings indicate that muscle specific and movement specific METs are both effective for reducing pain and disability, as well as improving range of motion in individuals with mechanical neck pain. However, the study did not detect any statistically significant differences between the two techniques in terms of managing mechanical neck pain.

The current study only looked at the immediate and short-term effects of muscle specific and movement specific METs in the management of mechanical neck pain and future studies with long term follow ups should be conducted. Objective measurements such as pain pressure threshold and EMG should be carried out in future studies.

Disclaimer

This manuscript represents a component of a broader investigation on METs in neck pain registered under Ref# FF/FUMC/217-Phy/16, which received approval from the Foundation University Islamabad Ethical Review Committee. Ethical approval specific to the present study was also obtained from the Brainstorm Research Ethical Review Committee (Ref# BR/ERC/2017/1). The study was registered with clinicaltrials.gov (Ref# NCT05063890). A segment of the outcomes of this study was presented at the “18th International Forum for Back and Neck Pain Research in Primary Care”, held at the University of Groningen, The Netherlands, from August 31st to September 1st, 2023. The manuscript underwent a language and grammatical check utilizing AI tools, including ChatGPT and Grammarly.

Informed consent

Consent was taken from all patients participating in the study.

Funding

The current study was funded by Brainstorm Research (brainstormresearch.org) – Internal Funding Grant (Ref# BR/funding/2017/1).

Author contributions

Muhammad Osama was responsible for the conception of the idea, study design, data collection, data analysis, and drafting the manuscript.

Footnotes

Acknowledgments

None to declare.

Conflict of interest

The author was a member of the Brainstorm Research Ethical Review Committee, but was not involved in the ethical review of the current study.

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Effects of muscle specific as compared to movement specific muscle energy technique in mechanical neck pain: A randomized controlled trial

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Methods

2.1 Study design

2.3 Sample size calculation

2.4 Participant selection and random allocation

2.5 Intervention

2.6 Outcome measures

Table 1 Participant characteristics at baseline

2.6.2 Cervical Range of Motion (ROM)

2.6.3 Neck disability index (NDI)

2.7 Statistical analysis

3. Results

3.1 Pain and function

Table 2 Inter group comparison after 1 st treatment session

Table 4 Pre- and post-treatment analysis muscle specific MET

5. Conclusion

Disclaimer

Informed consent

Funding

Author contributions

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Participant characteristics at baseline

Table 2
Inter group comparison after 1 ${}^{\text{st}}$ treatment session

Table 4
Pre- and post-treatment analysis muscle specific MET