The effect of lumbar stabilization exercise on the pulmonary function of stroke patients.

[Purpose] This study was aimed at assessing the effect of lumbar stabilization exercise on the pulmonary function of stroke patients.
[Subjects and Methods] The subjects were randomly allocated into lumbar stabilization exercise group and a general physical therapy group. The program consisted of 30-min sessions conducted 3 days a week for 8 weeks. Pulmonary function was assessed based on lung performance parameters, including forced vital capacity, forced expiratory volume at 1 second, ratio of forced expiratory volume at 1 second to forced vital capacity, and peak expiratory flow.
[Results] In the assessment of pulmonary function, the values of all the lung performance parameters were significantly increased in the lumbar stabilization exercise group but were significantly decreased in the general physical therapy group.
[Conclusion] These results indicate that lumbar stabilization exercise had a more positive effect on pulmonary function than general physical therapy.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Stroke is a leading cause of major disabilities in social, psychological, and physical functions1). The decline in the pulmonary function of stroke patients is caused by reduced physical activity2). Meanwhile, the decline in the cardiopulmonary function of these patients is related to decreased oxygen transport ability caused by prolonged bed rest3). Respiration provides oxygen for activities of daily living (ADL); as a result, respiratory disturbances influence patients’ ADL. Therefore, respiratory problems are crucial factors in the rehabilitation and survival of stroke patients4). Kim et al. reported that stroke patients exhibited a respiratory pattern of restrictive lung disease. The characteristics of restrictive lung disease include decreased forced vital capacity (FVC)5). In addition, the stroke patients in their study showed reduced FVC and peak expiratory flow (PEF)4).

Various physical therapies to improve the pulmonary function have been applied, such as thoracic spine mobility exercises and respiratory exercises including diaphragm breathing, ventilator muscle training, glossopharyngeal breathing and pursed-lip breathing6). In addition, machines such as resistance breathing equipment, reverse testing equipment, and incentive spirometer are used in breathing therapies7).

Respiratory impairment causes weakening of trunk muscles8). Deep abdominal muscle strengthening exercise was effective at increasing vital capacity. Especially the transverse abdominis muscle influences the partial stabilization of the lumbar spine9). The transverse abdominis, internal oblique, and external oblique muscles stabilize the trunk. In particular, the transverse abdominis muscle, together with the multifidus muscle, plays a major role in stabilizing the lumbar region10). Among other expiratory muscles (rectus abdominis, internal oblique, and external oblique), the transverse abdominis muscle is the most active during easy breathing11). It has the largest activity change relative to other abdominal muscles, even during maximal inspiratory breathing12). Gollee et al. reported that abdominal muscle stimulation also improved the lung function of paretic patients with decreased functional residual capacity13).

In previous studies on stroke patients, respiratory therapies that used various breathing exercises were reported. However, research on the clinical applications of general exercise therapy is lacking. The present study aimed to verify the efficacy of lumbar stabilization exercise (LSE) and LSE with abdominal stimulation used in clinical practice, and to identify the effects of the LSE method on the pulmonary function of stroke patients.

SUBJECTS AND METHODS

This study was conducted with patients from B Hospital (Suwon, Gyeonggido) who had had a stroke >6 months previously. The subjects selected were those without orthopedic diseases such as congenital defects involving the thoracic cage or fractured ribs, and those who scored>24 points in the Korean version of the Mini-Mental State Examination. The study purpose and methods were explained to the subjects, and only those who consented to participate were included in the study. The study protocol was approved by the local ethics committee of the Yongin University (2–1040966-AB-N-01–201503-HSR-026–1).

The subjects were 40 stroke patients. They were randomly and equally divided into two groups, namely a LSE group and a general physical therapy (GPT) group. However, during the study, two subjects were discharged from the hospital before the study completion and one subject dropped out of the study. As a result, 18 subjects in the LSE group and 19 subjects in the GPT group underwent the trial. The intervention was conducted three times per week, for a total of 8 weeks. The general characteristics of the subjects are shown in Table 1.

Table 1.

General characteristics of the subjects

	LSE group	GPT group
Gender (male/female)	10 / 8	12 / 7
Age (years)	53.7 ± 7.7	58.4 ± 6.3
Weight (kg)	67.0 ± 9.8	68.6 ± 8.8
Height (cm)	165.5 ± 10.7	164.4 ± 8.8
Time since stroke (months)	17.8 ± 6.7	15.0 ± 5.6
Affected side (left/right)	12 / 6	11 / 8
MMSE-K (score)	26.8 ± 1.6	27.2 ± 1.7
K-MBI (score)	77.5 ± 14.7	75.5 ± 13.8
GDS (score)	1.6 ± 0.8	1.8 ± 0.7

Data are presented as mean ± SD. LSE: lumbar stabilization exercise, GPT: general physical therapy, MMSE-K: Mini-Mental State Examination–Korean version, K-MBI: Korean version of the Modified Barthel Index, GDS: global deterioration scale

The LSE was designed according to the method of McGill and Karpowicz14). Eight step exercises were performed (Table 2; Fig. 1). The LSE was performed after a 30-min physical therapy. Each step was repeated three times. The subjects performed a 5-min stretching before and after the exercise. Six physical therapists with more than 1 year of experience in clinical trials were selected for this study. The subjects in the GPT group performed general physical therapies that are normally performed at rehabilitation centers, such as neurodevelopment treatment, mat, and gait training, for 30 min after physical therapy.

Table 2.

Lumbar stabilization exercise program

Warm-up (5 min)	Stretching
Main exercise (30 min)	1. Transverse abdominis contraction exercises
	2. Bridge exercise
	3. Bridge exercise with one leg up
	4. Exercise of consecutively lifting arms and legs in the supine position
	5. Exercise of pushing arms and legs in the supine position
	6. Exercise of lifting legs in the supine position
	7. Exercise of consecutively extending arms and legs in the prone position
	8. Exercise of lifting arms and legs on the same side while in the prone position
Cool- down (5 min)	Stretching

Fig. 1.

Lumbar stabilization exercise program

In order to assess pulmonary function, Fitmate MED (COSMED, Italy) was used to measure FVC, forced expiratory volume at 1 second (FEV1), FEV1/FVC ratio, and PEF. All pulmonary function measurements were performed with the subjects in the sitting position.

The subject waited for the start signal while holding the mouthpiece as tightly as possible to prevent air from escaping through the mouth while staring straight ahead without breathing through the nose. While the subjects were waiting for the start signal, the research inspectors asked them to take normal breaths three times and to breathe in as much as they could and exhale for more than 6 seconds. When the start signal was given, the subjects took three normal breaths, inhaled as much as they could, and exhaled for more than 6 seconds. The inspectors made sure that the subjects exhaled for at least 6 seconds, and the average of three measurements was calculated for each round. Three measurements were performed, once before, during, and after the exercise.

For data processing, the SPSS version 20.0 software for Windows was used. Descriptive statistics were processed by using the general characteristics of the subjects. The independent t-test was used to compare the change in the values of the pulmonary function parameters between the groups. One-way repeated-measures analysis of variance was used to compare in-group data before, during (4 weeks), and after (8 weeks) the intervention. The significance level was set at α=0.05.

RESULTS

In this study, the pulmonary functions of the stroke patients in the LSE or GPT groups were examined. The results of the study are shown in Table 3.

Table 3.

Comparison of pulmonary function test results

		Pre-test	4 weeks	8 weeks	Contrast
FVC (L)	LSE group*	3.4 ± 1.1	3.6 ± 1.2*	4.0 ± 1.1*	1<2<3
	GPT group	3.1 ± 0.9	2.8 ± 0.6	2.8 ± 0.5
FEV1 (L)	LSE group*	2.3 ± 0.9	2.5 ± 1.0*	2.9 ± 0.9*	1<2<3
	GPT group	1.9 ± 0.7	1.6 ± 0.5*	1.6 ± 0.4*	1>2, 1>3
FEV1/FVC (%)	LSE group*	67.2 ± 13.7	70.8 ± 8.7	74.3 ± 11.2*	1<3, 2<3
	GPT group	66.2 ± 15.3	57.6 ± 13.7*	60.0 ± 12.9*	1>2, 1>3
PEF (L/s)	LSE group*	3.3 ± 1.6	3.5 ± 1.4	4.2 ± 1.4*	1<3, 2<3
	GPT group	3.1 ± 1.5	2.7 ± 1.4	2.8 ± 1.1

The numbers under the Contrast column indicates the following: 1: pretest, 2: 4 weeks, and 3: 8 weeks. FVC: forced vital capacity, FEV1: forced expiratory volume at 1 second, PEF: peak expiratory flow. *Significant difference, p<0.05

In the pulmonary function test, the LSE group showed significant differences in the FVC measurements between before, during (4 weeks), and after (8 weeks) exercise therapy (p<0.05). The GPT group did not show any significant differences (p>0.05). The differences in FVC between the two groups were significant during (4 weeks) and after (8 weeks) exercise therapy (p<0.05).

In the FEV1 measurements, the LSE group showed significant differences between before, during (4 weeks), and after (8 weeks) exercise therapy (p<0.05); and The GPT group, between before and during (4 weeks) exercise therapy (p<0.05), and between before and after (8 weeks) exercise therapy (p<0.05). However, in the GPT group, the FEV1 values were decreased. The differences between the two groups were significant during (4 weeks) and after (8 weeks) exercise therapy (p<0.05).

In the FEV1/FVC measurements, the LSE group showed significant differences between before and after (8 weeks) exercise therapy (p<0.05), and between during (4 weeks) and after (8 weeks) exercise therapy (p<0.05). The GPT group showed significant differences between before and during (4 weeks) exercise therapy (p<0.05), and between before and after (8 weeks) exercise therapy (p<0.05). However, in the GPT group, the FEV1/FVC values were decreased. The differences in FEV1/FVC ratio between the two groups were significant during (4 weeks) and after (8 weeks) exercise therapy (p<0.05).

In the PEF measurements, the LSE group showed significant differences between before and after (8 weeks) exercise therapy (p<0.05), and between during (4 weeks) and after (8 weeks) exercise therapy (p<0.05). The GPT group did not show any significant differences (p>0.05). The differences in PEF measurements between the two groups were significant after the exercise period (8 weeks; p<0.05).

DISCUSSION

For stroke patients, cardiopulmonary function is an important issue for preservation of life5). Lanini et al. observed significant decreases in maximal respiratory pressure in stroke patients as compared with healthy control subjects15).

Impaired pulmonary function may be a consequence of weakened respiratory muscles and postural trunk dysfunction16). Abdominal muscle strengthening exercises were shown to have positive effects such as improvement in pulmonary function17), and LSE has been used in clinical practice with abdominal muscle stimulation. Gollee et al. suggested the application of abdominal muscle stimulation to increase expiratory flow and tidal volume in order to improve respiratory function13). Accordingly, this study examined the effect of LSE on the pulmonary function of stroke patients. To assess pulmonary function, FVC, FEV1, FEV1/FVC, and PEF were measured.

In this study, the LSE group showed significant increases in FVC, FVC, FEV1/FVC, and PEF values after the exercise intervention, indicating that LSE had a positive effect on the pulmonary function of the stroke patients. By contrast, the GPT group showed a decline in the FVC, FVC, FEV1/FVC, and PEF values after the exercise intervention, indicating that GPT alone cannot improve the pulmonary function of stroke patients.

Kim and Lee reported that deep abdominal muscle training was effective at enhancing pulmonary function9). Jung et al. reported that inspiratory muscle training (IMT) with abdominal stimulation improved the pulmonary function of chronic stroke patients. In their study, the subjects who received IMT with abdominal stimulation showed significant increases in FEV1, PEF, and FEF18). These findings are consistent with those of this study. In addition, the co-contraction of the abdominal muscles fixes the trunk and reduces the stress on the spine19). On the other hand, Kulnik et al. reported that respiratory muscle training did not improve pulmonary function and cough function in patients with acute stroke20). This means that LSE have a more positive effect on pulmonary function than respiratory muscle exercise.

Song and Park reported that chest resistance and expansion exercises were effective for improving pulmonary function and trunk control ability in stroke patients21). Seo et al. reported that a combination of inspiratory diaphragm exercise and expiratory pursed-lip breathing exercise was effective for strengthening weakened pulmonary functions in the rehabilitation of patients with neurological disease22). With these findings, it is hoped that in future studies, the effect of combining respiratory muscle strengthening exercises and LSEs in stroke patients will be investigated.

The findings of this study indicate that LSE may be a more appropriate therapeutic method than GPT for improving pulmonary function in stroke patients. Owing to the limited sample size of this study, the study finding is difficult to generalize to all stroke patients. Therefore, studies with larger patient samples that investigate long-term therapies and their benefits to stroke patients are needed. In addition, further studies are needed to include additional exercise combinations for both lumbar stabilization and respiratory muscle strengthening.