The effect of stabilization exercises on lumbar lordosis in patients with low back pain

Background and Purpose: There is a hypothesis that restoring the lumbar lordosis will increase a patient’s voluntary muscular strength and decrease back pain symptoms. This study aimed to evaluate the effects of stabilization exercises on lumbar lordosis and functional improvement. Methods: Thirty-two patients with chronic low back pain (LBP) were recruited through simple nonprobability sampling for this double-blind, randomized clinical trial, performed at the Razmejo-Moghadam Physiotherapy Clinic, Zahedan University of Medical Sciences. Participants were randomly assigned to either stabilization exercise group (n = 16) or control group (n = 16). Before and after intervention, we assessed pain (ordinal) through the McGill Pain Questionnaire, disability (ordinal) with the Oswestry Disability Index (ODI), and lumbar curve (degree) with flexible ruler. Twelve sessions daily exercise program was performed for both groups. t-tests were used for data analysis (P < 0.05). Results: Amount of lumbar curve was significantly changed after training in both groups (P < 0.05). Pain score and The ODI also showed significant change after intervention in both groups (P < 0.05).There was no significant differences between both groups in lumbar curve variable (P > 0.05). However, pain score and Oswestry score showed significant differences between two groups after intervention (P < 0.05). Conclusion: The results showed that both lumbar stabilization and routine physiotherapy cause decreasing in pain, disability, and change lumbar lordosis in patients with chronic LBP. Therefore, lumbar curve evaluation and therapeutic exercise for restoration lumbar curve were recommended.

Keywords: Chronic low back pain, lumbar curve, stabilization exercise

The lumbar lordosis serves to provide strength against the compressive forces of gravity.^[1],[2] A normal lumbar lordosis protects the posterior spinal ligament system from excess strain (McKenzie 1981)^[3] and acts as a shock absorber during sudden applied vertical forces ^[4] Gracovetsky ^[5] has illustrated that because of lumbar curve, a human can lift about 3 times his body weight.^[5] Therefore, it is obvious, the role of lumbar curve in biomechanics, and function of human.

Some researchers have examined the relationship between back pain and changes in the angle of the lumbar spine.^[6],[7] Increased lordosis has been advocated as the major cause of postural pain, radiculopathy, and facet pain.^[7],[8] Excessive lordosis leads to increase compression of the apophyseal joint and increase anterior shear force at the lumbosacral junction.^[6],[9]

In addition, there is an assumption that the size of lumbar lordotic curve is related with low back pain (LBP).^[10],[11] This theory is based on anatomy of the back and pelvic muscles.^[10],[11] Pelvic anterior and posterior movements are produced by the couple force of various muscles.^[9] When a person tilts the pelvis posteriorly in a standing position, lumbar lordosis decreases.^[10],[11] The lengths of the lumbar erector spinae and abdominal muscles also, in theory, should influence the size of the lumbar lordotic curve and degree of pelvic inclination in a standing position. For example, if the lumbar erector spinae muscles are shortened and the abdominal muscles are relatively lengthened, the degree of pelvic inclination and size of the lumbar lordosis would be increased. Therefore, in a normal standing position, the degree of pelvic inclination is related to the lumbar curve, and both are related to the performance and length of the back and abdominal muscles.^[10],[11]

Walker et al.^[12] repeated measurements of lumbar lordosis, pelvic tilt, and abdominal muscle performance on 31 asymptomatic physical therapy students. They concluded that no relationship existed between lumbar lordosis and pelvic inclination in a standing position and the independent variable of abdominal muscle performance. The authors suggested that pelvic tilt and lumbar lordosis were likely influenced by a combination of several complex factors.^[12]

Similarly, Heino et al.^[13] examined the relationship between hip extension range of motion, standing pelvic tilt, depth of lumbar lordosis, and abdominal muscle force. They found that there is a weak relationship between variables. No relationship was found among clinical variables commonly observed by physical therapists during a standing postural evaluation of the lumbopelvic complex.^[13]

For this reason, clinicians recommend various exercises be performed in the lying, sitting, or standing positions for LBP.^[9],[14] Yoo ^[15] examined effect of strengthening exercises on back pain, pelvic tilt angle, and lumbar ROM of a LBP patient with excessive lordosis. He suggest that an approach of individual resistance exercises is necessary for the effective and fast strengthening of the pelvic posterior tilt muscles in case of LBP with excessive lordosis.^[15]

The lumbopelvic stabilization model is an active approach to LBP, as proposed by Waddel,^[16] based on a motor control exercises program. The main aim of this program is to reestablish the impairment or deficit in motor control around the neutral zone of the spinal motion segment by restoring the normal function of the local stabilizer muscles.^[16]

Lack of core stability is one of the potential predisposing causes of recurrent LBP.^[17] The motor control and muscle participation are two major components of the spinal stability.^[18] Therefore, stabilization exercise program has become the most popular treatment method in spinal rehabilitation since it has shown its effectiveness in some aspects related to pain and disability. However, some studies have reported that specific exercise program reduces pain and disability in chronic but not in acute LBP although it can be helpful in the treatment of acute LBP by reducing recurrence rate.^[19] Ebrahimi et al.^[20] investigated the effect of core stabilization exercises on LBP and abdominal and back muscle endurance in patients with chronic LBP caused by disc herniation. According to the findings of the study, core stabilization exercises in improving LBP, abdominal, and back muscle endurance in patients with chronic LBP caused by disc herniation have been effective. Hence, cautious prescription of core stabilization exercises for these patients would be beneficial.^[20]

Lumbar lordosis is often measured during the evaluation of patients with LBP as a cause of LBP.^[21],[22] Evaluation of lumbar curve is essential to assess spinal function, select appropriate therapies, and monitor the patient’s recovery. In addition, it is important to measure potential risk factors in LBP.^[23] Although the relationship between lumbar lordosis and chronic LBP was investigated in previous study, there was contradictory between researches.^[24] Based on the several studies, there is no relationship between lumbar lordosis and LBP,^{[22],[24],[25],[26],[27],[28]} but the findings of some of studies mentioned that there is relationship between lumbar lordosis and LBP.^{[29],[30],[31]}

To conclude, investigators have claimed that anthropometric characteristics such as height and body weight,^[32] increased lumbar lordosis,^[33] and diminished muscle force ^[10],[11] can increase the risk of chronic LBP. It would be important for physical therapists to know whether clusters of these characteristics, which can be objectively measured during a routine clinical examination, are commonly associated with chronic LBP. Therefore, the purpose of this study was to document the effect of stabilization exercises on lumbar curve in LBP patient.

Subject

This study was a double-blinded randomized controlled trial. Thirty-two patients with chronic LBP were recruited among of thirty-seven participants who referred for rehabilitation services to the physiotherapy center of Zahedan University of Medical Science. Participants were randomly divided into the two groups by lottery conducted by clinical therapists. There were 16 participants in each group. Participants were not informed about the basics of the study. The administrator and participants were informed about the grouping data. However, the physiotherapist who assessed the participants, measured the outcome, and analyzed the data was blinded about the grouping. All protocols were approved by the Ethical Committee of Zahedan University of Medical Sciences, and all participants signed written informed consents.

Inclusion and exclusion criteria

Thirty-two patients with age between 18 and 50 years, pain in the area between the costal margin and buttocks, with or without reference to the lower extremity that lasted more than 3 months were included in this study. Patients were excluded if they reported a history of recent fracture, trauma or previous surgery at lumbar region, spondylolysis or spondylolisthesis, spinal stenosis, neurological disorders, systemic diseases, pregnancy, cardiovascular diseases, and concomitant treatment with physical therapy modalities.^[34],[35]

Sample size

The sample size was determined based on a pilot study. Ten participants were divided randomly into two equal groups, and the main part of study was conducted on them. The means and standard deviations (SDs) for the parameters from this pilot study, with α = 0.05 and 90% power, were used to calculate the sample size.

Procedure

Lumbar curve measurement

Lumbar lordosis angle measurement through flexible ruler method: the flexible method is used to measure the upper curves of the body including the kyphosis and lordosis. In this technique, the participant stands on a surface on which the feet place is marked barefooted in a natural and comfortable mode. The participant was asked to open his legs as wide as his shoulders facing forward. Then, the examiner was placed behind the participant for determining the reference points.

These points included the posterior superior iliac spines which were evaluated by the two hollow places on the lower part behind the face. These points were marked by means of a marker. Then, these points were connected through a line in a manner that the midpoint was placed on the pin appendage of the second vertebrae Sacral Support S2. For finding the iliac crest, the parts above the iliac crest were pressed by hand so that to make the muscles around it moves a side. The two thumbs reach each other behind the participant horizontally on the back of the participant, where the pin appendage of the first lumbar vertebrae is parallel with it.

Then, by counting the vertebral spine upward, the pin appendage of the first lumbar vertebra was found and marked. Then, the flexible ruler was placed on the L1 and S2 points and pressed tightly to the body so as to avoid any hollow space between the ruler and the participant skin and the ruler takes the curve form of the participant back.

Then, the ruler is removed from the participant back and the curve is drawn on the paper. The noteworthy point is that the line should be drawn from the side that the ruler was in contact with the skin of the participant.^{[10],[11],[36],[37]}

This was done 3 times for each participant and their average was recorded. Then, the lordosis angle of the participants was calculated through the following formula:

In this formula, the curve length (L) indicates the distance between the first lumbar vertebra and the second vertebrae Sacral Support and the height of the curve (H) is the vertical line with maximum distance from the L line.

Pain assessment and functional assessment

The Oswestry Disability Index

The Oswestry Disability Index (also known as the Oswestry LBP Disability Questionnaire) is an extremely important tool that researchers and disability evaluators use to measure a patient’s permanent functional disability. The test is considered the “gold standard” of low back functional outcome tools. For each section, the total possible score is 5: If the first statement is marked, the section score = 0; if the last statement is marked, it = 5.^[38]

McGill Pain Questionnaire

The McGill Pain Questionnaire can be used to evaluate a person experiencing significant pain. It can be used to monitor the pain over time and to determine the effectiveness of any intervention. It was developed at by Dr. Melzack at McGill University in Montreal Canada and has been translated into several languages. In this score, minimum pain score is zero (would not be seen in a person with true pain) and maximum pain score is 78 (the higher the pain score, the greater the pain).^[39],[40]

Intervention

In stabilization training group, participants were trained with stabilization training rehabilitation program for 30 min, 6 days in week, for 12 sessions.^[41] In control group, participants were received routine physiotherapy protocol (TENS, 20 min, and HP, 20 min). After completing the sessions of treatment, all of assessments were measured again.

Statistical analysis

Results were presented as mean values and SD. Criterion of significance was set as P < 0.05. Kolmogorov–Smirnov test was used to describe normal distribution. Independent t-test and paired t-test were used to compare variables between and within groups.

Thirty-two patients with chronic LBP were enrolled in this study. Participants were assigned in stabilization group and control group. [Table 1] provides demographic characteristics of both groups. There were no statistical differences in these variables between both groups. Any participant was not dropped out in both groups.

Paired t-test was used to compare variables before and after intervention. [Table 2] has shown that amount of lumbar curve was significantly changed after training in both groups (P < 0.05). Pain score and Oswestry score also showed significant change after intervention in both groups (P < 0.05).

Independent t-test was used to compare variables between two groups. [Table 2] shows that there was no significant differences between both groups in lumbar curve variable (P > 0.05). However, t-test shows that pain score and Oswestry score showed significant differences between two groups after intervention (P < 0.05).

The findings of this study support the positive effects of stabilization exercise and routine physiotherapy protocol on lumbar curve. However, there was no significant difference between the two interventions. Pain score and Oswestry score also showed significant change after intervention in both groups. In stabilization group, pain score and Oswestry score were more changes than routine physiotherapy group.

Physical therapists frequently examine a patient’s standing posture to determine whether a muscle imbalance exists.^[10] According to Kendall, lordotic posture would be associated with anterior tilt of the pelvis and hip joint flexion, resulting in an increase in standing lumbar lordosis and pelvic inclination. When a lordotic posture is present, Kendall contended the low back and hip flexor muscles are shortened, whereas the abdominal muscles are lengthened.^[42] Based on this hypothesis, several mode of exercise is frequently used by physical therapist for the treatment of LBP and improvement of lumbar lordosis.^{[3],[15],[24]} Specific exercises that activate abdominal and/or back extensor muscles are advocated to reduce pain and disability.^[43] It is claimed that there is a link between local muscle dysfunction and LBP, with the development of clinical instability in which there is an excessive range of abnormal segmental movement without muscular control.^[44] Thus, stabilization exercises have been designed to enhance the neuromuscular control system and correct the dysfunction.^[44],[45] A number of randomized clinical trials have been performed to evaluate the effectiveness of stabilization exercises, and there are some indications of long-term benefit regarding decreased recurrence of LBP episodes and health-care usage.^{[35],[46],[47],[48],[49]} In this study, stabilization exercise was used to improve lumbar curve. Our result showed pain, functional ability, and lumbar curve influenced by stabilization exercise in LBP patients. The findings of this study are consistent with the findings of previous studies. Yoo ^[15] suggests that individual resistance exercises are a necessary approach for the effective and fast strengthening of the pelvic posterior tilt muscles in case of LBP with excessive lordosis.^[15] The goal of Morningstar’s study (2003) also was to restore a normal lumbar lordosis and evaluate its effect on physical strength and function.^[1] Hence, one can conclude that the findings of the present study confirm the findings of previous studies. Some authors have reported reduction of lordosis in LBP patients with discopathy,^[50] but some have reported increased lordosis in patients with spondylolisthesis.^[50],[51] However, patients participating in the present study were chronic LBP.

Youdas et al.^[10] did not confirm a strong relationship between the lengths of the abdominal or one-joint hip flexor muscles and standing posture. Their findings question the current practice of teaching strengthening and stretching exercises to patients with mechanical LBP to correct standing posture.^[10] However, based on our results, it seems that stabilization exercises could be effected on lumbar lordosis in patients with chronic LBP.

Based on the finding of this study, stabilization exercise and routine physiotherapy protocol have positive effect on lumbar curve. However, there was no significant difference between the two interventions. Therefore, lumbar curve evaluation and therapeutic exercise for restoration lumbar curve were recommended.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ATMPH.ATMPH_654_17

[Table 1], [Table 2]