Forty participants with low back ache in the age group of 18-45 years who reported to the Physiotherapy outpatient department were screened clinically for the evidence of non-specific low back pain. Participants who reported a recent onset of low back pain (duration of <3 months) and the following signs and symptoms were admitted over a period of one year from February 2011 to January 2012; localized low back pain at or above the waist level, decreased lumbar extension (assessed qualitatively while standing), and increased localized pain with lumbar extension during standing.

Exclusion criteria included history of spinal surgery, subjects administered epidural injection, Low Back Pain because of any specific pathology, any clinical condition that contraindicates Mobilization, subjects with neurological deficits, knee and ankle pathology causing limitation of motion, subjects with psychological low back pain, subjects with mental disorders, any history of injury in past 3 months, hyper-mobility and neurological impairments. Participants signed consent form approved by institutional review committee of KLE University. Simple randomisation was employed using computer generated table of random numbers. One investigator managed the assignment scheme and provided the assignment to the treating physiotherapists in a series of consecutively numbered opaque envelopes. Allocation was concealed from the outcome assessor and participants at all times and from the physiotherapist until the point of treatment. Both the groups received the selected treatment for seven consecutive days [Table/Fig-1].

[Table/Fig-1]:

Flow diagram depicting entire procedure of the study.

Outcome measures included pain measured by Visual Analogue scale which is a 10 cm straight line with numbers 0 to 10 where 0 symbolises no pain and 10 symbolises the worst tolerable pain [12]. Participants were asked to mark a point on this line as per the severity of pain which indicates present pain level. Lumbar extension range measured by modified Schober method. With the participant in standing position, examiner marks a mark approximately at fifth lumbar vertebra, then one finger 10cm above the mark and another 5 cm below the mark [13]. Then the participant was asked to bend backwards with hands on hips. The reduction in distance between the two points is measured by a measuring tape. The function was assessed by Modified Oswestry Disability Questionnaire. Each item was scored from 0-5. The maximum score was therefore 50. The obtained score can be multiplied by 2 to produce a percentage score [14]. Outcome measures were assessed prior to intervention, immediately after the first session of intervention and at the end of seven sessions of intervention.

Participants assigned to group A were first put prone on treatment table with pillow under abdomen. First, the investigator applied PA pressure to the spinous process of each lumbar vertebra using small amplitude movements (grade I). The pressure should reproduce the discomfort experienced while bending backward in standing. If no pain was reproduced with grade 1 of mobilisation then further higher grades were used (grades II–IV). Once the vertebral level where discomfort similar to bending backward in standing was identified, session of mobilisation was initiated. Initially, the most painful lumbar segment was treated with graded posterior-to-anterior oscillations. Three bouts of 40-second oscillations were applied to this segment at a frequency of 1 to 2 Hz and at the amplitude tolerated by the patient. Following mobilization of the most painful segment, 2 bouts of 40-second oscillations (up to grade IV but short of symptom reproduction) were administered to each of the remaining lumbar vertebral levels. The total time for the PA mobilization intervention was approximately 10 minutes [6]. Participants assigned to Prone press-ups were asked to perform a press-up manoeuvre as far as possible without reproducing lumbar pain with standing extension. Initially the participants were prone on a treatment table with pillow under abdomen. The participant pressed the top half of the body upward into spinal extension, while the pelvis remained on the treatment table. The participant was instructed to move to maximum pain-free lumbar extension. The end-range position was held for 5 seconds. Ten repetitions were performed. For each repetition, the participant moved slightly higher, within the limits of discomfort. If the participants could successfully complete 10 repetitions without increase in discomfort then a second and third series of press-up manoeuvres were performed. All participants completed 30 repetitions. Approximate time taken for the entire session was 10 minutes [8].

Paired t-test was used for within group comparisons and unpaired t-test for between group comparisons, p-value set at less than 0.05. All power calculations were based on an alpha level of 0.05 for a one-tailed test.

Average pain scores were lower after intervention than before intervention in both the groups. Subjects in the PA mobilization group reported a post-treatment pain score of 1.6±1.0, which did differ significantly from the post-treatment pain score of 3.2±1.43 reported by subjects in the press-up group. Average lumbar extension was greater after intervention than before intervention across both the groups. On an average subjects in PA group demonstrated 5.1±0.7 cm of lumbar extension which differed significantly from post-treatment lumbar extension of 3.2±1.1 as demonstrated by press-up group. Average disability scores were lower after intervention than before intervention in both the groups. Subjects in PA group reported post-treatment score of 5.3±6.1 which differed significantly to post-treatment score of 18.6±7.4 as reported by press-up group [Table/Fig-2,3].

The age group of the participants was in range of 18 to 45 years. Participants above 45 years of age experience low back pain due to degenerative changes in lumbar spine. Hence participants above 45 years of age have not been included in the study as the study involves nonspecific low back pain. In present study age distribution and anthropometric variables showed no statistical difference in the groups which represents the homogeneity of participants.

Sample size of present study consisted of 27 females and 13 males that are 65.5% females and 34.5% males. This concludes females are more prone than males for developing low back pain and correlates with findings reported in several other studies [15]. Significant relief of pain was noted in both groups over sessions for 7 days. In the present study, pain was measured by Visual Analogue scale. Oloagan et al., compared reliability of rating low back pain with Visual Analogue Scale and Semantic Differential Scale, concluded that Visual Analogue Scale had superior reliability and validity in rating low back pain [12]. Both the interventions showed statistically significant improvement in terms of pain. Posterior-to-anterior spinal mobilisation proved to be superior in terms of reduction of pain. In the present study reduction in pain level, as quantified by the Visual Analogue Score (VAS), with the application of both postero-anterior mobilisation and prone press-ups is consistent with the findings of previous studies indicating both the techniques reduced low back pain. On average total lumbar extension increased by 3.9 cm following PA mobilisation and 1.6 cm following press-ups. The gain in spinal motion was higher after seven sessions as compared to single session. Several studies have proved short term effects of single session of spinal mobilisation. Moreover, single session of spinal mobilisation, as seen in previous studies has shown statistically significant improvement in extension range but not clinically relevant improvements. Hence, this proves that several sessions of spinal mobilisation are necessary to produce clinically relevant results.

Both the interventions have mechanical and neuro-physiological effect. Passive motion selectively stretches contracted tissues there by increases motion [16]. Muscle spindle afferents and Golgi tendon organ afferents are stimulated by spinal manipulation. Spinal manipulation corrects the altered biomechanics resulting in sensory modulation. Numerous studies show that spinal manipulation increases pain tolerance or its threshold. Painful stimuli will evoke reflex parasympathetic activity. Manipulation has the ability to remove noxious mechanical or chemical stimuli from paraspinal tissues and hence modulate central sensory processing. Spinal manipulation is also thought to affect reflex neural outputs to both muscle and visceral organs. Literature reveals that spinal manipulation elicits paraspinal muscle reflexes and increases motor neuron excitability producing increased recruitment of these musculature [17]. Moreover, repetitive movements enhance the distribution of synovial fluid over the articular cartilage and disk, resulting in less resistance to motion [18]. With the reduction in resistance, movement becomes smooth leading to reduction in pain.

Joint mobilisation reduces dorsal horn activation from a painful stimuli [19]. Several authors have reported elevated pain threshold levels with passive movements to spine [20,21] or the extremities [22–24].

Press-ups manoeuvre might have resulted in decreased muscle guarding leading to increased motion. Mobilisation is known to cause transient inhibitory effect on alpha motor neurons leading to reduced muscle guarding [25]. Pain reduction reported in the present study following PA mobilisation was 78.5% which was consistent with findings of other studies. Chiradejnant et al., reported a 36% reduction in pain following two 1-minute bouts of spinal mobilization in subjects with nonspecific low back pain [16]. Goodsell et al., reported an average pain reduction of 33% following PA mobilisation in subjects with non-specific low back pain [26]. There was 50% pain reduction following press-ups in the present study. Above studies failed to report significant increase in lumbar extension. This is in contrast to the present study in which mobilisation significantly increased lumbar extension range. McCollam and Benson, reported a 7.1% increase in lumbar extension on application of three 1 minute bouts of posterior-to-anterior mobilisation at L3, L4 and L5 [17]. Christopher P, performed a clinical trial on non-specific low back pain and compared the effect of single session of postero-anterior spinal mobilisation and prone press-up. There was significant reduction in the average pain scores for both groups. Similarly, total lumbar extension significantly increased in both the PA mobilization group and the press-up group. However, percentage increase in lumbar extension was greater in mobilisation group [11].

The UK evidence report on the effectiveness of Manual Therapies reviewed the literature and concluded that spinal manipulation/mobilization has moderate quality positive evidence supporting its utilization in the treatment of acute low back pain and high quality positive evidence in treatment of chronic low back pain [27]. Fritz JM reported that Modified Oswestry Disability Questionnaire showed higher levels of test-retest reliability and responsiveness as compared to Quebec Back Pain Disability Scale in subjects with low back pain [14]. In the present study, when the means of Modified Oswestry Disability Questionnaire (MODQ) were analysed, statistically significant improvement was found in both groups and has shown reduced MODQ scores which represent reduction in pain and an improvement in range of motion and functional activities. Mobilisation proved to be superior in reducing functional disability as compared to press ups. Low back pain presents a serious health care problem and produces a huge burden on society. Simple, safe, physical treatment procedures such as posterior-anterior spinal mobilisation and prone press-ups combined with other simple non-invasive intervention such as moist pack could be of great value. This provides a low cost, easy means of treatment in subjects with non-specific low back pain.

Several limitations of this study need to be addressed. The findings of this study cannot be generalised to all low back pain patients as subjects with only non-specific low back pain were considered. There is lack of control group in the study so placebo effect that might have occurred due to any of these interventions cannot be commented upon. The subjects have not been followed up to see the long term sustenance of improvement due to both interventions. These limitations need to be addressed in future investigations.

Participants in both groups reported significantly less pain with bending backward in standing. Lumbar extension significantly improved with both PA mobilization and the press-up exercise. There were significant differences in pain and lumbar extension between the two interventions studied. PA mobilisation proved to be superior in reducing pain and increasing lumbar extension resulting in improved functional outcome.