Intergroup comparison of pain score was significantly reduced in both the treatment groups, but Group B showed more reduction in pain compared to Group A after 6 weeks of treatment. NRS score in week 1 and week 3 scores among the subjects did not differ significantly between 2 groups. The week 6 mean pain score was significantly higher in Group B compared to group A.

Intragroup comparison of pain in Group A and Group B showed significantly reduced NRS score in week 3 and week 6 compared to week 1 NRS score. The week 6 pain score was significantly lower compared to week 3 mean pain score.

The intergroup comparison in the week 3 and week 6 mean CCFT score (activation score) was significantly higher in Group B compared to Group A. Week 1 CCFT score (performance index) did not show any significant difference between the two study groups. Week 3 and week 6 CCFT score (performance index) was significantly higher in Group B compared to Group A.

The intragroup comparison in Group A and B, week 3 and week 6 CCFT score (activation score) was significantly higher compared to week 1 CCFT score. The week 6 mean CCFT score was significantly higher compared to week 3 mean CCFT score.

In group A and B, Week 3 and week 6 CCFT score (performance index) was significantly higher compared to week 1 CCFT score. Week 6 CCFT score was significantly higher compared to week 3 CCFT score.

The intergroup comparison of the NDI score of week 1, week 3 and week 6 did not show any significant difference between two study groups. The intragroup comparison in Group A and B, the NDI score of week 3 and week 6 was significantly lower compared to week 1 NDI score. Week 6 NDI score was significantly lower compared to week 3 NDI score. Our research found that NDI was decreased from 16.14 to 2.34 by pressure biofeedback unit training, and from 13.93 to 2.52 by mini stability ball exercises, both of which were statistically significant differences.

Overall results of this study showed that both the groups i.e. Group A which consisted of mini stability ball exercise along with conventional treatment and Group B which included pressure biofeedback unit training with conventional treatment demonstrated significant reduction in pain intensity measured by NRS (Numeric pain rating scale) score, increased endurance of deep cervical flexors measured by CCFT (cranio-cervical flexion test) score and reduced functional disability, measured by NDI (Neck disability index) score. However, Group B improved to a greater extent in pain reduction, endurance and functionality improvement than Group A.

Pain in the neck and disability are linked. The relationship between neck pain and disability is not straightforward as these are subjective measures and may therefore be influenced by factors such as physiology, psychosocial and environment. Since neck pain is one of the most common complaints seen in many people, tendency for recurrence and chronicity is partly attributable to persistent changes in cervical neuromuscular control that have been well documented in patients with neck pain, this in turn will result in reduced endurance of deep cervical neck flexors and may lead to further progression disability. Therefore, if neck pain increases, there is reduced endurance of deep cervical flexors which will result in disability on a long run.

Because deep cervical flexors consist of mixed muscle fibers, neck pain may lead to the transformation of type I fibers into type IIB fibers, which suggests a loss of postural support capacity and segmental cervical muscle control. A similar process of muscle-fibre transformation has been demonstrated in laboratory-based research of patients with persistent cervical pain, with muscle biopsies showing these changes in two of the deep cervical muscles, i.e. the longus colli and longus capitis. Pain-induced neuromuscular adaptation results in inhibition, inability to selectively activate the deep cervical muscles and disruption of the deep cervical muscle feedforward mechanism. [18]

Possible pain reduction mechanism may be attributed to increased endorphins following training and better neuromuscular control, muscle contraction from exercise training stimulates mechanoreceptors, including muscle spindles, Golgi tendon organ, and joint proprioceptors. Signals from the receptors cause the release of endogenous opioids and stimulate the release of endorphins from the pituitary gland. Muscle contractions activate muscle ergoreceptors (stretch receptors). These secretions may cause both peripheral and central pain to be blocked. Neck exercises allow the musculotendinous proprioceptors to downgrade their stretch reflex responses using operant conditioning techniques and multiple practice sessions. The intrafusal fibers may be reset, discontinuing the cycle of muscle tension, impaired circulation with metabolite accumulation and pain associated with myogenic (myofascial) pain. [17]

In accordance with this studyZaheen et al. pressure biofeedback provides extrinsic feedback which gives the patient knowledge of performance. A therapist provides the information through the apparatus and by attending to the information the patient forms a “closed loop”. Feedback helps in motor learning which is a set of processes associated with practice or experience leading to permanent changes in the capability of responding. Biofeedback techniques are used to augment the patient’s sensory feedback mechanisms through precise information about body processes that might otherwise be inaccessible. The basis for this approach is that repeated activation of the deep cervical flexor muscles may induce neuroplastic changes that in turn will lead to improved recruitment of the trained muscle during complex functional tasks. The increased activation of the deep cervical flexor muscles post training may reflect both central and peripheral adaptations. ^[8] Pressure biofeedback can be utilized during rehabilitation to give the patient visual real-time feedback to facilitate a neutral spine position during exercise.

Other mechanisms, such as nociceptor sensitization due to intra-muscular shear forces are also considered to play a role in which 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. [17] Therefore, using DCF training as a rehabilitation program for non-specific neck pain is based on the rationale that DCF plays a major role in the stabilization of the head and neck posture.

In our study positive changes are attributed to the implementation of the mini stability ball training, it improves core stability, and portrays the complex interaction of passive (joint articulations and spinal ligaments) and active (neural and muscular) subsystems that maintain intervertebral neutral zones within the physiological limits (Panjabi, 1992). [19, 20] Research also suggests the adaptation gained from stability ball training is likely to result in better coordination of synergistic and stabilizer core muscles (Rutherford and Jones, 1986). [21]The muscles that make up the core can be divided into local and global groups based on location and attachment sites (Bergmark, 1989). [22]

This concluded that, pressure biofeedback unit training is more effective than mini stability ball exercises on non-specific neck pain patients.

Bertozzi L, Gardenghi I, Turoni F et al. Effect of therapeutic exercise on pain and disability in the management of chronic nonspecific neck pain: systematic review and meta-analysis of randomized trials. Phys Ther. 93(8), 2013, 1026-36

Cote P, Cassidy JD, Carroll LJ, et al. The annual incidence and course of neck pain in the general population: a population-based cohort study. Pain J. 112, 2004, 267–73.

Jeroen A.J. Borghouts, Bart W. Koes, Lex M. Bouter. The clinical course and prognostic factors of non-specific neck pain: a systematic review. Int Association for the study of Pain, 77(1), 1998, 1-13

Domenech, MA., Sizer, PS., et al.The deep neck flexor endurance test: Normative data scores in healthy adults. The American Academy of Physical Medicine and Rehabilitation, 3, 2011, 105-110

Grimmer, K. Measuring the endurance capacity of cervical short flexor muscle group. Aust J Physiother. 40, 1994, 251-254

Alka Pawalia, Vikram singh Yadav et al. Deep Neck Flexor Endurance: A Normative Data Score in Normal Healthy Indian Population. Indian journal of applied research, 5(8), 2015, 217-220

Rattaporn Sihawong, Prawit Janwantanakul et al. Exercise therapy for office workers with nonspecific neck pain: a systematic review. Journal of Manipulative and Physiological Therapeutics, 34(1), 2011, 62-71

Md. Nezamuddin, Shahnawaz Anwer, Sohrab Ahmad Khan et al. Efficacy of pressure-biofeedback guided deep cervical flexor training on neck pain and muscle performance in visual display terminal operators. Journal of Musculoskeletal Research, 16(3), 2013.

Sudarat Borisut, Mantana Vongsirinavarat et al. Effects of strength and endurance training of superficial and deep neck muscles on muscle activities and pain levels of females with chronic neck pain. J. phys. Ther. Sci 25, 2013, 1157-1162

Falla D, O'Leary S, Farina D et al.The change in deep cervical flexor activity following training is associated with the degree of pain reduction in patients with chronic neck pain; clinical journal of pain, 28(7), 2012, 628-634

Jerrold S.Petrofsky, Jennifer Batt, Nicceta Davis et al. Core Muscle Activity During Exercise on a Mini Stability Ball Compared With Abdominal Crunches on the Floor and on a Swiss Ball. The Journal of Applied Research, 7(3), 2007, 200725.657

Stanton R, Reaburn PR, Humphries B. The effect of short-term swiss ball training on core stability and running economy. Journal of Strength and Conditioning Research, 18(3), 2004, 522–528

Ilsub Jun, Kyoung Kim. A Comparison of the Deep Cervical Flexor Muscle Thicknesses in Subjects with and without Neck Pain during Craniocervical Flexion Exercises. J. Phys. Ther. Sci, 25(11), 2013, 1373–1375

Jill Lucas Findle, marco monticone, evangelos pappas et al. Biofeedback for neck pain. Cochrane Back and Neck Group 2015.

Sin ho chung, jin gang her, taesung ko et al. Effects of exercise on deep cervical flexors in patient with chronic neck pain. J Phys Ther sci, 24, 2012, 629-632

Parvathy.s, Vaishali Sreejith. A Comparative study between the efficacy of swiss ball exercise v/s pressure biofeedback training on pain, mobility and functional disability in computer professionals with non-specific neck pain. IJMAES, September 3(3), 2017, 379-389

Zaheen Ahmed Iqbal, Reena Rajan, Sohrab Ahmed Khan et al. Effect of Deep Cervical Flexor Muscles Training Using Pressure Biofeedback on Pain and Disability of School Teachers with Neck Pain. J Phys Ther Sci, 25(6), 2013, 657–661

Marloes thoomes-de graaf, Maarten a. Schmitt. The Effect of Training the Deep Cervical Flexors on Neck Pain, Neck Mobility, and Dizziness in a Patient With Chronic Nonspecific Neck Pain After Prolonged Bed Rest: A Case Report. journal of orthopaedic & sports physical therapy, october 2012, volume 42, number 10, 858-865

Panjabi MM. The stabilizing system of the spine. Part I. Function, dysfunction, adaptation, and enhancement. J Spinal Disord, 5, 1992, 383–389

Panjabi MM. The stabilizing system of the spine. Part II. Neutral zone and instability hypothesis. J Spinal Disord, 5, 1992, 390–397

Rutherford OM, Jones DA. The role of learning and coordination in strength training. Eur J Appl Physiol, 55, 1986, 100–105

Bergmark A. Stability of the lumbar spine: A study in mechanical engineering. Acta Orthop Scand, 230, 1989, 20–24.