over 70% of the population in developed countries experiences low back pain , and its 
 incidence is increasing in developing countries as well ; low back pain is therefore a global 
 problem1 . as varied and complex 
 psychological and social factors are involved , the pain has no definite cause in about 85% 
 of patients2 . low back pain is divided 
 into acute or chronic according to its duration ; if the pain lasts for over 12 weeks , it is 
 defined as chronic low back pain , and 510% of all acute low back pain patients develop 
 chronic low back pain3 . once low back pain becomes serious , physical activities are restricted , and ultimately 
 muscle atrophy occurs as the muscles remain unused for long durations4 . particularly in chronic low back pain patients , the 
 worsening of low back pain caused by reduction in the muscle area and muscular atrophy leads 
 to secondary damage and relapse5 . many low 
 back pain patients develop recurring low back pain due to lumbar instability caused by 
 muscular weakness around the spine and soft tissue damage in the trunk . finally , the 
 reduction in muscular strength , muscular endurance , and flexibility in the lumbar spine and 
 limited range of motion of joints cause relapse of chronic low back pain6 . in particular , chronic low back pain 
 patients have more severe atrophy of low back extensors than of flexors7 . additionally , the aerobic exercise capacity tends to 
 decrease in patients with chronic low back pain owing to the limitation on motion  this must 
 be considered in rehabilitation exercise8 . the reasons for low back pain are still under discussion , and over many years , various 
 exercise methods have been suggested for treating low back pain , including flexion exercise , 
 isometric flexion exercise , extension exercise , passive extension exercise , and intensive 
 dynamic back exercise9 , 10 . although these exercise programs have been recommended 
 and developed over several years in low back pain discussions and rehabilitation centers , a 
 satisfactory outcome has not yet emerged . despite greatly different opinions on the 
 pathogenesis of low back pain among researchers , in addition , 
 therapeutic exercise in which patients participate actively is effective for low back pain 
 after the acute phase , and in particular , different types of exercises applied by 
 physiotherapists show very positive outcomes12 . rehabilitation programs for the relief of low back pain include complex exercises such as 
 selective exercises involving control of trunk muscles , muscle strengthening , muscle 
 stretching , and aerobic exercises13 . recent studies report that aerobic exercise is effective in reducing depression , pain , and 
 dysfunction in low back pain patients14 . 
 however , some studies report that aerobic exercise combined with traditional physical 
 therapy has no additional effect on pain and dysfunction15 . therefore , there are conflicting results concerning the effects of 
 aerobic exercise in low back pain patients , and there is also a lack of clear evidence on 
 this matter . therefore , the purpose of this study was to determine the additional effect of 
 treadmill exercise combined with a low back pain rehabilitation exercise program on low back 
 extensor strength , pain , and dysfunction in patients with chronic low back pain . this study involved 20 men aged 2236  years with chronic low back pain who visited a 
 hospital rehabilitation medicine department ; they were randomly divided into experimental 
 group and a control group , with 10 patients in each group . patients who complained of low 
 back pain lasting for over 3 months were selected as subjects , and patients with 
 musculoskeletal diseases that impaired gait , heart diseases , neurological disorders , or 
 structural spine deformity were excluded . all the subjects of this study signed the consent 
 form for this study voluntarily after the intent and purposes of the study were explained to 
 them . kyungwoon university approved this study , which complies with the ethical standards of 
 the declaration of helsinki . the physical characteristics of the subjects in each group are 
 shown in table 1table 1.physical characteristics of the study participantsgroupage ( years)height ( cm)weight ( kg)bmi ( kg / m)control ( n = 10)27.7  4.2170.2  9.465.5  15.222.3  3.4exercise ( n = 10)29.1  4.8172.5  3.769.1  12.123.1  3.5data are meanssd . the low back pain rehabilitation program was conducted for 30 minutes , thrice 
 a week for 8 weeks for the control and experimental groups . the program consisted of 14 
 exercises including flexion and extension , and it was conducted under the continuous 
 guidance and supervision of an expert in a low back pain treatment room . treadmill exercise was conducted 
 without a slope at a speed of 3.03.5  km / h , which allowed patients to walk comfortably , and 
 the patients were instructed to straighten their back and make initial contact with their 
 heel . for the low back extensor strength test , the medx lumbar extension machine 
 ( h-10000 ; medx , ocala , fl , usa ) was used , and measurement were taken before and after the 
 experiment for both groups . before starting the low back extensor strength test , the tester 
 moved the machine manually and conducted the range of motion ( rom ) exercise 3 times to check 
 that there were no limitations in rom at the designated degree of flexion for the lumbar 
 spine . the test was conducted to measure the maximum isometric torque of the lumbar spine 
 extensors according to degree of flexion ( 72 , 60 , 48 , 36 , 24 , 12 , 0 ) starting from 
 the 72 position ( table 2table 2.comparison of the average change in low back extensor strength between both 
 groupsdegreegrouppre - testpost - testscore0control97.3  59.2130.6  73.433.3  28.2exercise99.1  59.6141.5  60.242.4  30.112control130.3  77.6157.6  80.727.3  24.2exercise125.1  57.4179.6  60.954.5  28.624control148.3  81.7181.2  80.932.9  28.4exercise146.8  64.6214.2  52.167.4  36.036control166.7  83.4198.6  86.631.9  19.6exercise157.9  63.7220.8  51.462.9  28.148control183.1  87.7218.0  96.634.9  25.8exercise174.9  62.6233.6  57.658.7  30.860control203.4  97.4240.9  107.837.5  31.4exercise189.1  66.1247.9  61.958.8  25.572control214.5  10.9257.2  113.642.7  27.2exercise208.2  73.9258.6  67.350.4  37.5data are meanssd . two - way anova test ( grouptime ) : 
 p<0.05 ; p<0.01 ; p<0.001 ) ) . two - way anova test ( grouptime ) : 
 p<0.05 ; p<0.01 ; p<0.001 ) to evaluate the level of low back pain in the patient group , the visual analog scale ( vas ) 
 was used . on a 10-cm - long horizontal straight line with  no pain  and  very severe pain  
 written on the left and right end respectively , the patients marked the pain intensity they 
 were currently feeling directly with a pen . the oswestry low back pain disability questionnaire was developed by fairbank et al.16 to measure the relief and aggravation of 
 the symptoms of low back pain patients . in this study , a revised questionnaire was used17 , and this tool consisted of a total of 10 
 detailed questions concerning such things as low back pain intensity , self - management , 
 lifting motion , sitting , standing , sleeping , social life , traveling , and job performance . 
 for each question , the total number of points given ranges from a maximum of 60 points to a minimum of 
 10 points , and the higher the score , the more severe the dysfunction . two - way repeated measure analysis of variance ( anova ) was conducted for all data analyses 
 in order to express the average and standard deviation values and to test the group trends 
 before and after the exercise program . comparisons of changes in the average values of 
 measurement variables before and after the 8-week exercise program were analyzed using the 
 paired samples t - test . in addition , the variation (  ) between baseline measurements and 
 measurements after 8 weeks of exercise was calculated (  score = changed score between 
 before and after 8 weeks of exercise ) . all statistical analyses were conducted using the pc 
 version of the statistical package for the social sciences ( spss version 21.0 ; ibm 
 corporation , armonk , ny , usa ) , and statistical significance was set at p < 0.05 . according to angle , the changes in low back extensor strength showed significant 
 interaction effects of measurement time and group at 12 ( p = 0.034 ) , 24 ( p = 0.029 ) , and 
 36 ( p = 0.011 ) . however , at 48 , 60 , and 72 , both the control group and experimental 
 group showed no interaction effect despite showing an increasing trend in low back extensor 
 strength after the experiment compared with before the experiment . the vas and oswestry low back pain disability questionnaire scores showed a decreasing 
 trend after the experiment compared with before the experiment , both in the control group 
 and the experimental group . however , there was no interaction effect of the additional 
 treadmill exercise in the experimental group compared to the control group ( table 3table 3.changes in the visual analog scale and oswestry low back pain disability 
 scoresvariablegrouppre - testpost - testscorevascontrol36.3  17.420.5  13.115.8  13.5exercise31.3  17.916.9  9.314.4  12.3oswestry questionnairecontrol16.5  3.514.4  5.02.1  3.0exercise14.9  3.011.7  1.73.2  2.0data are meanssd . score = change in score , paired t - test : p<0.05 ; 
 p<0.01 ; p<0.001 . two - way anova test ( grouptime ) : 
 p<0.05 ; p<0.01 , p<0.001 . vas : visual 
 analog scale , oswestry questionnaire : oswestry low back pain disability 
 questionnaire ) . score = change in score , paired t - test : p<0.05 ; 
 p<0.01 ; p<0.001 . two - way anova test ( grouptime ) : 
 p<0.05 ; p<0.01 , p<0.001 . vas : visual 
 analog scale , oswestry questionnaire : oswestry low back pain disability 
 questionnaire rapid economic 
 development and a sedentary lifestyle have brought about a reduction in physical activity 
 and changes in physical function and posture , leading to the incidence of low back pain . in most low back pain patients , muscular weakness and imbalance around the lumbar spine caused 
 by lack of exercise are the major factors that cause activity impairment . this is because 
 muscular weakness and imbalance lead to low back pain , and this pain limits the range of 
 motion and prevents the proper exertion of muscular strength . generally , low back pain 
 patients reduce their physical activity to avoid the pain caused during the performance of 
 their daily routine activities18 , leading 
 to a vicious circle of relapse and chronicization of low back pain , which in turn reduces 
 aerobic exercise capacity ( cardiorespiratory fitness)19 . the reduction of activities of daily living ( adl ) after the 
 occurrence of low back pain causes sarcopenia and reduces muscular strength , muscular 
 endurance , and cardiopulmonary function , leading to an increase in the likelihood of 
 development of metabolic risk factors20 . therefore , performing aerobic exercise to improve low back extensor strength is important . 
 in this study , additional treadmill exercise was conducted by patients performing a low back 
 pain rehabilitation program for 8 weeks to determine if the addition of this exercise was 
 effective . in this study , changes in low back extensor strength showed a significant interaction 
 effect by angle at 12 , 24 , and 36 , which was considered to be the effect of the treadmill 
 exercise conducted under the supervision of experts who ensured that the patients performed 
 the exercise with their backs straight and made initial contact with their heel . in other 
 words , low back extensors are activated and muscular strength increases by walking properly 
 and improving lordosis ; these findings are attributed to the effect of training the 
 supporting muscles involved in the angle changes of extensors often used in the lumbar 
 region when performing walking exercises . kankaanp et al.21 found that the low 
 back extensors of chronic low back pain patients were weak and got easily tired as compared 
 with those of normal people . lamoth et al.22 concluded that walking training should be considered in 
 rehabilitation programs for chronic low back pain patients , since the stability between 
 their lumbar sections was low and the coordination between the low back extensors was poor . 
 from a rehabilitative perspective , it can be said that walking programs are helpful for 
 simultaneously stabilizing the trunk and controlling the motion of the limbs by 
 strengthening the waist muscles and abdominal muscles supporting the spine . in this study , the vas and oswestry low back pain disability questionnaire scores of the 
 experimental group showed no interaction effect of the additional treadmill exercise as 
 compared with those of the control group . tritilanunt et al.23 found that chronic low back pain patients that performed an aerobic 
 exercise program for 3 months showed a significantly reduced pain index compared with those 
 who performed only lumbar flexion exercise . also , chatzitheodorou et al.14 found that chronic low back pain patients 
 that performed high - intensity aerobic exercise for 12 weeks showed significantly reduced 
 pain , dysfunction , and psychological burdens compared with those who received only 
 conservative physical therapy . however , chan et al.15 found that aerobic exercise combined with an 8-week physical 
 therapy had no additional effect on the alleviation of pain and dysfunction , similar to the 
 findings of this study . the lack of an additional effect of treadmill exercise in this study 
 is attributed to the fact that both groups underwent back mobilization , performed abdominal 
 stabilization exercise , and received back care advice based on ergonomic principles in 
 addition to traditional physical therapy . however , as many studies have reported an 
 additional effect of aerobic exercise , further systematic long - term studies with many 
 subjects are required to confirm the findings of the present study . considering all the outcomes of this study , the changes in low back extensor strength by 
 angle showed an additional effect of treadmill exercise at 12 , 24 , and 36 , and pain level 
 and dysfunction index showed a decreasing trend after the experiment in both groups , with no 
 significant difference between groups . it is thought that treadmill exercise combined with 
 traditional physical therapy has a partial effect on improvement of low back extensor 
 strength .
[ purpose ] the present study examined the influence of treadmill exercise added to a low 
 back pain rehabilitation program on low back extensor strength , pain , and dysfunction in 
 chronic low back pain patients . 
 [ subjects and methods ] twenty men aged 2236  years with 
 chronic low back pain were randomly divided into experimental and control groups of 10 
 patients each . 
 both groups underwent a low back pain rehabilitation program lasting 30  min 
 each , thrice / week for 8 weeks . 
 the experimental group was prescribed an additional 30  min 
 of treadmill exercise without a slope at a speed of 3.03.5  km / h , at which patients could 
 walk comfortably . 
 low back extensor strength was tested using the medx lumbar extension 
 machine , pain level was tested , using the visual analog scale , and dysfunction was tested , 
 using the oswestry low back pain disability questionnaire . [ results ] changes in low back 
 extensor strength by angle showed significant interaction effects between measurement time 
 and group at 12 , 24 , and 36. the results of the visual analog scale and oswestry 
 questionnaire showed a decreasing trend after the experiment in both groups . 
 however , 
 there was no interaction effect of the additional treadmill exercise in the experimental 
 group . 
 [ conclusion ] the combination of a low back pain rehabilitation program and 
 treadmill exercise has a synergistic effect , to some extent , on the improvement of low 
 back extensor strength and should be considered for treatment and rehabilitation of low 
 back pain patients .