lumbar spine instability has been reported to be the leading cause of chronic back 
 pain1 . an a abnormal vertebral joint 
 creates mechanical lesions and pains in the lumbar spine , decreasing stability and 
 increasing the range of motion , resulting in functional degeneration2 . these negative patterns have a variety of forms such as 
 aging , medical history , and exercise deficiency and present serious problems in the age 
 group of 2040 , due to developments of modern society and recent changes in various working 
 forms of work3 , 4 . herniated nucleus pulposus ( hnp ) is a representative disease of the functional vertebral 
 unit that occurs when the pulposus nucleus is exposed by rupture of the annulus fibrosus and 
 it is a disease that causes chronic back pains5 , 6 . chronic back pain patients not only have 
 weak deep muscles of the lumbar region and muscle imbalance compared to normal subjects , but 
 also show reduction in the re - positioning ability which leads to problem with the stability 
 of the spine , due to the reduction in proprioceptive sense , which causes lumbar pain and 
 recurrence7 , 8 . they include exercises 
 for increasing muscle strength , improving functions , and maintaining posture as well as 
 preventing excessive movements of the lumbar spine9 . exercise rehabilitation approaches for strength and stability are 
 important even after surgical treatments , due to degeneration and restricted activities10 , 11 
 and conservative methods of treatment by exercise have been recommended for the purpose of 
 preventing recurrence of pain and improving functions12,13,14,15,16 . thus , exercise therapies based on the stabilization exercises are 
 considered to be necessary for preventing chronic pain and reductions in functional 
 capabilities by the reduction of functional instability in various of type and the 
 improvement of motor functional capabilities of the lumbar joints . therefore , this study aims to help adult women with lumbar disc herniation recover muscle 
 strength and stability through 8-week lumber extension strength exercise programs , and to 
 provide data for constructing an integrated exercise program . in this study , an 8-week exercise program for lumbar muscle extension strength and 
 stabilization was performed by 26 females older than 20 with lumbar disc herniation . this 
 study was approved by the hankuk university of foreign studies and the institution where it 
 was performed , and it complied with the ethical principles of the declaration of helsinki . 
 the purposes and process of the study were fully explained to the subjects and their consent 
 was obtained before participation . the subjects mean  sd was 27.2  4.4  years old their mean  
 sd height was 162.3  5.1  cm and their mean  sd weight was 55.4  7.1  kg . the programs was conducted for a total of 8 weeks , 60 minutes a session , twice a week , to 
 improve strength and stabilize lumbar extension . the exercise program was divided into 
 warm - up exercises , main exercises and cool - down exercises . the warm - up exercises and 
 cool - down exercises were conducted focusing on the range of joint motion ( rom ) without pain , 
 utilizing cycles and steppers for 10 minutes , alternately . for the purpose of improving the 
 lumbar stability and resistance muscles , the main exercises were designed to be individually 
 conducted in the form of a circuit training in which the number of repetitions increased 
 gradually , utilizing sling and weight exercise equipment . a lumbar extension strength machine ( medx , medx inc . , ocala , fl , usa ) was utilized for the 
 evaluation of lumbar extensor strength . the maximum static muscular strength of lumbar 
 extension was measured at 7 different angles of lumbar flexion : 0 , 12 , 24 , 36 , 48 , 60 , and 
 72 degrees . passive tests were conducted to determine whether to limit the range of motion 
 before measurement . the tests were conducted 12 times at 45 lbs in accordance with the medx 
 exercise measurement guidelines . the measurement was performed after fixing the pelvis and 
 thigh of the subjects on the support . then , the motion of the lumbar spine was limited 
 during measurement by adjusting the footrest . the subjects were asked to increasingly extend 
 the lumbar spine by sufficiently considering the limited angular range of motion of the 
 joints . the measurements were performed in the same manner at every angle by maintaining 
 maximum muscle contraction for about 2 seconds . for the physical stability 
 measurements , the total weight distribution index ( wdi ) was calculated by assessing the 
 degree of interaction and coordination of the lower body through body away while maintaining 
 a standing posture . for data processing , the statistical program spss ( spss inc . , the mean and standard deviation of the measurements was calculated for all metrics . to 
 compare the difference between the pre - exercise and post - exercise state of the 8-week 
 exercise program , the paired t - test was used and statistical significance was accepted for 
 values of p < 0.05 . significant differences were observed in lumbar extension strength ( les ) between 
 pre - exercise and post - exercise at every angle of lumbar flexion , but no significant 
 difference was found in wdi ( % ) ( table 
 1table 1.changes of the les and wdivariableanglepre - exercisepost - exerciseles ( ft - lbs)061.8  33.880.1  31.6**1278.7  33.898.8  33.6**2487.6  36.5116.5  32.7***3698.6  35.9129.7  32.3***48104.7  35.0137.6  30.2***60113.1  36.9146.5  30.5***72122.3  40.1158.7  34.7***wdi ( % ) 5.9  3.35.0 2.8values are mean  sd , les : lumbar extension strength , wdi : weight distribution 
 index . the post - exercise les were found to be very significantly ( p<0.01 ) higher 
 than pre - exercise at 0 degree and 12 degree , and extremity significantly ( p<0.001 ) higher 
 than pre - exercise at 24 , 36 , 48 , and 72 degrees of lumbar flexion . values are mean  sd , les : lumbar extension strength , wdi : weight distribution 
 index . this study attempted to identify the positive impacts that were exerted on extension muscle 
 strength and stability by an 8-week extension strength exercise program which was performed 
 by 26 females with lumbar disc herniation . hnp is caused by the annulus fibrosus that is squeezed into the spinal canal when the 
 pulposus nucleus is torn due to a degenerative intervertebral disc . it has been reported 
 that approximately 29% of the projected and escaped intervertebral discs are associated with 
 the pulposus nucleus17 . chronic back 
 pains resulting from hnp aggravate the instability of the lumbar spine , causing degenerative 
 changes , atrophy of muscle strength , and reduce flexibility and joint range of motion due to 
 trunk damage and instability18 , 19 . lumbar herniated nucleus pulposus does not occur due to 
 lumbar pain or disability , but more frequently occurs due to deterioration of the related 
 muscles or functions interacting with them adjunctively8 . in addition , it is said that the joint range of motion is limited 
 due to the loss of muscle strength and flexibility caused by occupational factors , mode of 
 action , specific changes in posture , or degenerative disease18 . these musculoskeletal diseases can be generally improved by utilizing conservative 
 treatments such as exercise9 , 18 . rehabilitation exercise therapies for muscular strength 
 and stability are important even after surgery10 , 
 16 . various types of composite 
 exercises and core exercises in addition to exercises for muscular strength and stability 
 are currently being utilized8 , 12 . these exercise therapies help to stabilize the lumbar spine through lumbar and 
 trunk dynamic stabilization and exercise modulation , and increase of muscle strength20 . similar to the present study , a study analyzing the impacts of an 8-week functional 
 exercise program for lumbar muscle strength , that was performed by 26 females with 
 degenerative disc findings , found that there were significant differences between 
 pre - exercise and post - exercise15 in 
 lumbar muscle extension strength at all 7 angles of lumbar flexion , proving that exercise 
 participation develops stability of the muscles around the lumbar spine . in addition , a 
 study analyzing the effects of decompression therapy by 4-week joint mobilization that was 
 performed for patients with lumbar herniated nucleus pulposus , reported improvements in 
 joint range of motion in flexion and extension21 , proving its effectiveness . similarly , a study of13 lumbar traction for patients with lumbar 
 herniated nucleus pulposus , and a study11 
 of lumbar discectomy and stabilization exercises for patients with lumbar herniated nucleus 
 pulposus , both reported improvements in flexion and extension . the improvements in functions 
 pursuant to improved muscle strength and stability were statistically significant , as were 
 the results of the studies cited above . therefore , prevention of excessive movement of the 
 lumbar spine and trunk , in the patients with chronic back pains or lumbar herniated nucleus 
 pulposus can be helpful in their daily life because they secure the joint range of motion , 
 thereby improving strength and stability9 . thus , the development of muscular strength for stabilization and integrated exercise for 
 pain reduction and rehabilitation help to maintain the range of joint motion , muscle 
 strength , and balance21,22,23 . for the 
 improvement and rehabilitation of inpaired capacity in daily life due to back 
 pain - associated injuries experienced by about 80% of the population a higher occurrence 
 rate8 , 10 when recurrence is included muscle weakness , and loss15 of balance the development of an 
 integrated exercise program is required . the above results indicate that improving muscle extension strength to enhance and improve 
 the functions the patients with chronic back pain or lumbar herniated nucleus pulposus can 
 help improve muscle functions and increase the range of joint motion thereby exerting a 
 positive impact on physical stability .
[ purpose ] the purpose of this study was to provide the data for constructing an 
 integrated exercise program to help restore muscle strength and stability through 
 extension strength exercise in adult females with lumbar disc herniation . 
 [ subjects and 
 methods ] an 8-week exercise program for lumbar muscle extension strength and stabilization 
 was performed by 26 females older than 20 with lumbar disc herniation findings . [ results ] 
 significant differences 
 were found in lumbar extension muscle strength at every angle of 
 lumbar flexion after participation in the 8-week stabilization exercise program ; but there 
 was no significant difference in the weight distribution index . 
 [ conclusion ] an integrated 
 exercise program aiming to strengthen lumbar spine muscles , reduce pain and stabilize the 
 trunk can help to maintain muscle strength and balance . in addition , improvement in 
 extension strength is expected to be helpful in daily life by securing the range of joint 
 motion and improving the strength and stability .