human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Study Design . Three factors mixed- design with 1 between-subject and 2 within-subject factors . Objective . To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain ( LBP ) . Summary of Background Data . The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity . Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients . It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy individuals . To the authors ’ knowledge this has not been investigated before . Methods . Postural stability was measured by center of pressure parameters while nonspecific LBP ( n = 22 ) and healthy ( n = 22 ) subjects r and omly performed quiet st and ing task with 3 levels of difficulty ( rigid-surface eyes open , rigid-surface eyes-closed , and foam-surface eyes-closed ) in isolation or concurrently with an easy or difficult digits backward cognitive task . Results . Subjects with nonspecific LBP had less postural sway than healthy subjects , while postural sway decreased with increase in the level of cognitive difficulty . Nonspecific LBP and healthy subjects had larger postural sway at more difficult sensory conditions such as rigid-surface eyes-closed and foam-surface eyes-closed . The response to dual-tasking was not significantly different between the 2 groups . Conclusion . The dual-tasking did not change the postural performance of nonspecific LBP subjects with low level of pain and disability differently compared to healthy subjects Background The purpose of the present study was to examine the differential effect of core stability exercise training and conventional physiotherapy regime on altered postural control parameters in patients with chronic low back pain ( CLBP ) . As heterogeneity in CLBP population moderates the effect of intervention on outcomes , in this study , interventions approaches were used based on sub-groups of CLBP . Methods This was an allocation concealed , blinded , sequential and pragmatic control trial . Three groups of participants were investigated during postural perturbations : 1 ) CLBP patients with movement impairment ( n = 15 , MI group ) r and omized to conventional physiotherapy regime 2 ) fifteen CLBP patients with control impairment r and omized to core stability group ( CI group ) and 3 ) fifteen healthy controls ( HC ) . Results The MI group did not show any significant changes in postural control parameters after the intervention period however they improved significantly in disability scores and fear avoidance belief question naire work score ( P < 0.05 ) . The CI group showed significant improvements in Fx , Fz , and My variables ( p < 0.013 , p < 0.006 , and p < 0.002 respectively with larger effect sizes : Hedges 's g > 0.8 ) after 8 weeks of core stability exercises for the adjusted p values . Postural control parameters of HC group were analyzed independently with pre and post postural control parameters of CI and MI group . This revealed the significant improvements in postural control parameters in CI group compared to MI group indicating the specific adaptation to the core stability exercises in CI group . Though the disability scores were reduced significantly in CI and MI groups ( p < 0.001 ) , the post intervention scores between groups were not found significant ( p < 0.288 ) . Twenty percentage absolute risk reduction in flare-up rates during intervention was found in CI group ( 95 % CI : 0.69 - 0.98 ) . Conclusions In this study core stability exercise group demonstrated significant improvements after intervention in ground reaction forces ( Fz , Mz ; g > 0.8 ) indicating changes in load transfer patterns during perturbation similar to HC group . Trial registration UTRN095032158 - This study evaluated the degree to which the disturbance to posture from respiration is compensated for in healthy normals and whether this is different in people with recurrent low back pain ( LBP ) , and to compare the changes when respiratory dem and is increased . Angular displacement of the lumbar spine and hips , and motion of the centre of pressure ( COP ) , were recorded with high resolution and respiratory phase was recorded from ribcage motion . With subjects st and ing in a relaxed posture , recordings were made during quiet breathing , while breathing with increased dead-space to induce hypercapnoea , and while subjects voluntarily increased their respiration to match ribcage expansion that was induced in the hypercapnoea condition . The relationship between respiration and the movement parameters was measured from the coherence between breathing and COP and angular motion at the frequency of respiration , and from averages triggered from the respiratory data . Small angular changes in the lumbopelvic and hip angles were evident at the frequency of respiration in both groups . However , in quiet st and ing , the LBP subjects had a greater displacement of their COP that was associated with respiration than the control subjects . The LBP group had a trend for less hip motion . There were no changes in the movement parameters when respiratory dem and increased involuntarily via hypercapnoea , but when respiration increased voluntarily , the amplitude of motion and the displacement of the COP increased in both groups . The present data suggest that the postural compensation to respiration counteracts at least part of the disturbance to posture caused by respiration and that this compensation may be less effective in people with LBP Background Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain , whereby the altered postural sway includes both higher mean sway velocities and larger sway area . No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults ( aged 50 or less ) with non-specific low back pain . Methods Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled .  Center of pressure parameters were measured by three static bipedal st and ing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface . The perceived pain intensity was assessed by a numeric rating scale ( NRS-11 ) , an equal number of patients ( n = 11 ) was enrolled per pain score . Results Generally , our results confirmed increased postural instability in pain sufferers compared to healthy controls . In addition , regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters . Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points . Conclusions COP mean velocity and sway area are closely related to self-reported pain scores . This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation Study Design . A study of postural control during one‐footed and externally disturbed two‐footed stance among healthy control subjects and patients with chronic low back pain at the beginning of a functional back restoration program and 6 months later at follow‐up examination . Objectives . To study postural control cross‐sectionally among control subjects and patients with low back pain , and to evaluate the effects of functional restoration on the postural control parameters in a follow‐up examination . Summary of Background Data . Deficits of motor skills and coordination have been reported in association with musculoskeletal disorders . It has been found that patients with chronic low back pain have impaired psychomotor control , but the impairment is reversible with successful low back rehabilitation . It is insufficiently known how functional activation and intensive physical training affect postural control . Methods . Sixty‐one healthy volunteers ( 32 men , 29 women ) and altogether 99 patients with low back pain participated in the study . Sixty‐eight patients ( 33 men , 35 women ) had moderate and 31 ( 18 men , 13 women ) had severe low back pain .  Postural stability was measured with a force platform . In two‐footed stance , vibration stimulation on calf and back muscles was used to disturb the balance . Center point of force‐velocity ( cm/sec ) , average position shift in anteroposterior direction ( cm ) , and maximal position shift in lateral direction ( cm ) were used as the parameters . Results . Reliability of all tests was acceptable . Center point of force‐velocity was the most sensitive parameter and the one‐footed measurement the most sensitivetest for evaluating postural stability . At the beginning , the patients with severe low back pain had poorer one‐footed postural control compared with the control subjects ( P = 0.0003 ) . The subgroup of patients with moderate low back pain participated in the restoration program . The outcome of  the restoration program was considered good if the disability because of low back pain ( Oswestry index ) decreased during the restoration program and poor if the disability increased or did not change . The one‐footed postural stability remained primarily at the same level as the initial results in the control and good outcome groups , but became significantly poorer in the poor outcome group . The difference between poor outcome and control groups was statistically significant ( P = 0.04 ) . Conclusions . Impaired postural stability seems to be one factor in multidimensional symptomatology of patients with chronic low back trouble . Postural stability is easily disturbed in case of impairment in strength , coordination , or effective coupling of muscles in the lumbar and pelvic area . Patients with chronic low back pain seem to experience impairment in these functions , which should be taken into consideration when back rehabilitation programs are planned OBJECTIVE To determine whether body balance is perturbed more in low back pain patients than in healthy subjects , under the concept of posturo-kinetic capacity . DESIGN Comparison of posturographic and respiratory parameters between low back pain and healthy subjects . BACKGROUND It has been demonstrated that respiratory movements constitute a perturbation to posture , compensated by movements of the spine and of the hips , and that low back pain is frequently associated with a loss of back mobility . METHOD Ten low back pain patients and ten healthy subjects performed five posturographic tests under three different respiratory rate conditions : quiet breathing ( spontaneous ) , slow breathing ( 0.1 Hz ) and fast breathing ( 0.5 Hz ) . RESULTS Intergroup comparison showed that the mean displacements of the center of pressure were greater for the low back pain group , especially along the antero-posterior axis , where respiratory perturbation is primarily exerted . Inter-condition comparison showed that in slow and fast breathing relatively to quiet breathing , the mean displacement of the center of pressure along the antero-posterior axis was significantly increased only for the low back pain group . CONCLUSION According to the results , respiration presented a greater disturbing effect on body balance in low back pain subjects . RELEVANCE This study provides information on the causes of the impaired body balance associated with chronic low back pain , which could be used to improve treatment strategy Insight into the mechanisms of altered postural control in persons with low back pain ( LBP ) could lead to better interventions for patients with LBP . This study investigated ( 1 ) whether persons with recurrent LBP have an altered body inclination , and ( 2 ) whether anticipation of postural instability further alters body inclination . Thirty-three young healthy individuals and 56 young persons with recurrent LBP participated in this study .  The upright st and ing posture was evaluated by means of two piezo-resistive electrogoniometers and a force platform for the conditions as follows : ( 1 ) quiet stance with and without vision , and ( 2 ) in anticipation of postural instability due to a ballistic arm movement or ankle muscle vibration . No differences in body inclination were observed when visual information was available between the two groups ( P>0.05 ) . However , significant more forward inclination was seen in the persons with recurrent LBP when vision was occluded ( + 7.4 % ) and in anticipation of postural instability ( + 19 % ) ( P<0.05 ) compared to the healthy individuals . The results suggest that young persons with recurrent LBP have an altered body inclination that might be caused by anticipation of postural instability . The adopted forward inclined posture may potentially be a factor in the recurrence of LBP Study Design . A clinical trial comparing a  back pain group with a pain‐free group .  Objectives . To investigate whether proprioceptive deficits existed in a group of individuals reporting low back pain . Summary of Background Data . Little work has so far been conducted on the measurement of proprioception in the spine . Those studies that have been carried out , however , have failed to identify proprioceptive deficits in individuals with back pain . Previous work on peripheral joints has revealed that proprioception is affected with muscular or joint injury or degeneration . Methods . Forty individuals took part in the study , 20 with back pain and 20 with no pain . Participants were required to reproduce a predetermined target position , in st and ing and four‐point kneeling , 10 times in 30 seconds . A computer screen was used to provide visual feedback on position . A mean deviation from the target position was obtained for each individual . A measurement of left elbow position sense was conducted in five individuals from each group to establish differences in short‐term motor memory between the groups . Results . There were no differences between the subject groups in terms of short‐term motor memory ( P > 0.05 ) . A two‐way analysis of variance between subject groups and position to identify differences in accuracy ( deviation from the target ) found that there were differences between subject groups in either position ( P < 0.05 ) . There was no significant difference in accuracy between the positions used ( P > 0.05 ) . Conclusions . Differences in proprioception do exist between individuals with back pain and those free from back pain . Further research needs to be undertaken on proprioceptive exercise programs and their effect on back pain Balance reactions are not routinely evaluated in patients with low back pain . The purpose of this study was to determine if there were differences in static balance and weight distribution between subjects with unilateral low back pain ( N = 15 ) and pain-free controls ( N = 15 ) . Measurements included limits of stability ( % LOS ) , target sway , weight distribution on each lower extremity in quiet st and ing , and center of gravity with measurements of maximal excursion in anterior/posterior and medial/lateral directions . Independent t tests were used to compare data between groups . Compared with control subjects , subjects with low back pain demonstrated greater anterior-posterior center of gravity excursion and total center of gravity excursion with eyes open and greater anterior-post 
    Output:
    
agent
A previous review concluded that postural sway is increased in patients with low back pain ( LBP ) .
In a minority of studies , a decreased sway was found in LBP patients .
There were no systematic differences between studies finding an effect and those reporting no effect of LBP .
The proportion of studies finding between-group differences did not increase with increased complexity of sensory manipulations .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Study Design . Three factors mixed- design with 1 between-subject and 2 within-subject factors . Objective . To compare the main effects and interactions of postural and cognitive difficulty on quiet stance between subjects with and without nonspecific low back pain ( LBP ) . Summary of Background Data . The interference between postural control and cognitive tasks depends on factors such as sensorimotor/cognitive integrity . Changes in peripheral sensory and muscular systems as well as cognitive processes have been observed in LBP patients . It was hypothesized that the effect of cognitive task on postural performance might be different in subjects with nonspecific LBP as compared with healthy individuals . To the authors ’ knowledge this has not been investigated before . Methods . Postural stability was measured by center of pressure parameters while nonspecific LBP ( n = 22 ) and healthy ( n = 22 ) subjects r and omly performed quiet st and ing task with 3 levels of difficulty ( rigid-surface eyes open , rigid-surface eyes-closed , and foam-surface eyes-closed ) in isolation or concurrently with an easy or difficult digits backward cognitive task . Results . Subjects with nonspecific LBP had less postural sway than healthy subjects , while postural sway decreased with increase in the level of cognitive difficulty . Nonspecific LBP and healthy subjects had larger postural sway at more difficult sensory conditions such as rigid-surface eyes-closed and foam-surface eyes-closed . The response to dual-tasking was not significantly different between the 2 groups . Conclusion . The dual-tasking did not change the postural performance of nonspecific LBP subjects with low level of pain and disability differently compared to healthy subjects Background The purpose of the present study was to examine the differential effect of core stability exercise training and conventional physiotherapy regime on altered postural control parameters in patients with chronic low back pain ( CLBP ) . As heterogeneity in CLBP population moderates the effect of intervention on outcomes , in this study , interventions approaches were used based on sub-groups of CLBP . Methods This was an allocation concealed , blinded , sequential and pragmatic control trial . Three groups of participants were investigated during postural perturbations : 1 ) CLBP patients with movement impairment ( n = 15 , MI group ) r and omized to conventional physiotherapy regime 2 ) fifteen CLBP patients with control impairment r and omized to core stability group ( CI group ) and 3 ) fifteen healthy controls ( HC ) . Results The MI group did not show any significant changes in postural control parameters after the intervention period however they improved significantly in disability scores and fear avoidance belief question naire work score ( P < 0.05 ) . The CI group showed significant improvements in Fx , Fz , and My variables ( p < 0.013 , p < 0.006 , and p < 0.002 respectively with larger effect sizes : Hedges 's g > 0.8 ) after 8 weeks of core stability exercises for the adjusted p values . Postural control parameters of HC group were analyzed independently with pre and post postural control parameters of CI and MI group . This revealed the significant improvements in postural control parameters in CI group compared to MI group indicating the specific adaptation to the core stability exercises in CI group . Though the disability scores were reduced significantly in CI and MI groups ( p < 0.001 ) , the post intervention scores between groups were not found significant ( p < 0.288 ) . Twenty percentage absolute risk reduction in flare-up rates during intervention was found in CI group ( 95 % CI : 0.69 - 0.98 ) . Conclusions In this study core stability exercise group demonstrated significant improvements after intervention in ground reaction forces ( Fz , Mz ; g > 0.8 ) indicating changes in load transfer patterns during perturbation similar to HC group . Trial registration UTRN095032158 - This study evaluated the degree to which the disturbance to posture from respiration is compensated for in healthy normals and whether this is different in people with recurrent low back pain ( LBP ) , and to compare the changes when respiratory dem and is increased . Angular displacement of the lumbar spine and hips , and motion of the centre of pressure ( COP ) , were recorded with high resolution and respiratory phase was recorded from ribcage motion . With subjects st and ing in a relaxed posture , recordings were made during quiet breathing , while breathing with increased dead-space to induce hypercapnoea , and while subjects voluntarily increased their respiration to match ribcage expansion that was induced in the hypercapnoea condition . The relationship between respiration and the movement parameters was measured from the coherence between breathing and COP and angular motion at the frequency of respiration , and from averages triggered from the respiratory data . Small angular changes in the lumbopelvic and hip angles were evident at the frequency of respiration in both groups . However , in quiet st and ing , the LBP subjects had a greater displacement of their COP that was associated with respiration than the control subjects . The LBP group had a trend for less hip motion . There were no changes in the movement parameters when respiratory dem and increased involuntarily via hypercapnoea , but when respiration increased voluntarily , the amplitude of motion and the displacement of the COP increased in both groups . The present data suggest that the postural compensation to respiration counteracts at least part of the disturbance to posture caused by respiration and that this compensation may be less effective in people with LBP Background Increased center of pressure excursions are well documented in patients suffering from non-specific low back pain , whereby the altered postural sway includes both higher mean sway velocities and larger sway area . No investigation has been conducted to evaluate a relationship between pain intensity and postural sway in adults ( aged 50 or less ) with non-specific low back pain . Methods Seventy-seven patients with non-specific low back pain and a matching number of healthy controls were enrolled .  Center of pressure parameters were measured by three static bipedal st and ing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface . The perceived pain intensity was assessed by a numeric rating scale ( NRS-11 ) , an equal number of patients ( n = 11 ) was enrolled per pain score . Results Generally , our results confirmed increased postural instability in pain sufferers compared to healthy controls . In addition , regression analysis revealed a significant and linear increase in postural sway with higher pain ratings for all included COP parameters . Statistically significant changes in mean sway velocity in antero-posterior and medio-lateral direction and sway area were reached with an incremental change in NRS scores of two to three points . Conclusions COP mean velocity and sway area are closely related to self-reported pain scores . This relationship may be of clinical use as an objective monitoring tool for patients under treatment or rehabilitation Study Design . A study of postural control during one‐footed and externally disturbed two‐footed stance among healthy control subjects and patients with chronic low back pain at the beginning of a functional back restoration program and 6 months later at follow‐up examination . Objectives . To study postural control cross‐sectionally among control subjects and patients with low back pain , and to evaluate the effects of functional restoration on the postural control parameters in a follow‐up examination . Summary of Background Data . Deficits of motor skills and coordination have been reported in association with musculoskeletal disorders . It has been found that patients with chronic low back pain have impaired psychomotor control , but the impairment is reversible with successful low back rehabilitation . It is insufficiently known how functional activation and intensive physical training affect postural control . Methods . Sixty‐one healthy volunteers ( 32 men , 29 women ) and altogether 99 patients with low back pain participated in the study . Sixty‐eight patients ( 33 men , 35 women ) had moderate and 31 ( 18 men , 13 women ) had severe low back pain .  Postural stability was measured with a force platform . In two‐footed stance , vibration stimulation on calf and back muscles was used to disturb the balance . Center point of force‐velocity ( cm/sec ) , average position shift in anteroposterior direction ( cm ) , and maximal position shift in lateral direction ( cm ) were used as the parameters . Results . Reliability of all tests was acceptable . Center point of force‐velocity was the most sensitive parameter and the one‐footed measurement the most sensitivetest for evaluating postural stability . At the beginning , the patients with severe low back pain had poorer one‐footed postural control compared with the control subjects ( P = 0.0003 ) . The subgroup of patients with moderate low back pain participated in the restoration program . The outcome of  the restoration program was considered good if the disability because of low back pain ( Oswestry index ) decreased during the restoration program and poor if the disability increased or did not change . The one‐footed postural stability remained primarily at the same level as the initial results in the control and good outcome groups , but became significantly poorer in the poor outcome group . The difference between poor outcome and control groups was statistically significant ( P = 0.04 ) . Conclusions . Impaired postural stability seems to be one factor in multidimensional symptomatology of patients with chronic low back trouble . Postural stability is easily disturbed in case of impairment in strength , coordination , or effective coupling of muscles in the lumbar and pelvic area . Patients with chronic low back pain seem to experience impairment in these functions , which should be taken into consideration when back rehabilitation programs are planned OBJECTIVE To determine whether body balance is perturbed more in low back pain patients than in healthy subjects , under the concept of posturo-kinetic capacity . DESIGN Comparison of posturographic and respiratory parameters between low back pain and healthy subjects . BACKGROUND It has been demonstrated that respiratory movements constitute a perturbation to posture , compensated by movements of the spine and of the hips , and that low back pain is frequently associated with a loss of back mobility . METHOD Ten low back pain patients and ten healthy subjects performed five posturographic tests under three different respiratory rate conditions : quiet breathing ( spontaneous ) , slow breathing ( 0.1 Hz ) and fast breathing ( 0.5 Hz ) . RESULTS Intergroup comparison showed that the mean displacements of the center of pressure were greater for the low back pain group , especially along the antero-posterior axis , where respiratory perturbation is primarily exerted . Inter-condition comparison showed that in slow and fast breathing relatively to quiet breathing , the mean displacement of the center of pressure along the antero-posterior axis was significantly increased only for the low back pain group . CONCLUSION According to the results , respiration presented a greater disturbing effect on body balance in low back pain subjects . RELEVANCE This study provides information on the causes of the impaired body balance associated with chronic low back pain , which could be used to improve treatment strategy Insight into the mechanisms of altered postural control in persons with low back pain ( LBP ) could lead to better interventions for patients with LBP . This study investigated ( 1 ) whether persons with recurrent LBP have an altered body inclination , and ( 2 ) whether anticipation of postural instability further alters body inclination . Thirty-three young healthy individuals and 56 young persons with recurrent LBP participated in this study .  The upright st and ing posture was evaluated by means of two piezo-resistive electrogoniometers and a force platform for the conditions as follows : ( 1 ) quiet stance with and without vision , and ( 2 ) in anticipation of postural instability due to a ballistic arm movement or ankle muscle vibration . No differences in body inclination were observed when visual information was available between the two groups ( P>0.05 ) . However , significant more forward inclination was seen in the persons with recurrent LBP when vision was occluded ( + 7.4 % ) and in anticipation of postural instability ( + 19 % ) ( P<0.05 ) compared to the healthy individuals . The results suggest that young persons with recurrent LBP have an altered body inclination that might be caused by anticipation of postural instability . The adopted forward inclined posture may potentially be a factor in the recurrence of LBP Study Design . A clinical trial comparing a  back pain group with a pain‐free group .  Objectives . To investigate whether proprioceptive deficits existed in a group of individuals reporting low back pain . Summary of Background Data . Little work has so far been conducted on the measurement of proprioception in the spine . Those studies that have been carried out , however , have failed to identify proprioceptive deficits in individuals with back pain . Previous work on peripheral joints has revealed that proprioception is affected with muscular or joint injury or degeneration . Methods . Forty individuals took part in the study , 20 with back pain and 20 with no pain . Participants were required to reproduce a predetermined target position , in st and ing and four‐point kneeling , 10 times in 30 seconds . A computer screen was used to provide visual feedback on position . A mean deviation from the target position was obtained for each individual . A measurement of left elbow position sense was conducted in five individuals from each group to establish differences in short‐term motor memory between the groups . Results . There were no differences between the subject groups in terms of short‐term motor memory ( P > 0.05 ) . A two‐way analysis of variance between subject groups and position to identify differences in accuracy ( deviation from the target ) found that there were differences between subject groups in either position ( P < 0.05 ) . There was no significant difference in accuracy between the positions used ( P > 0.05 ) . Conclusions . Differences in proprioception do exist between individuals with back pain and those free from back pain . Further research needs to be undertaken on proprioceptive exercise programs and their effect on back pain Balance reactions are not routinely evaluated in patients with low back pain . The purpose of this study was to determine if there were differences in static balance and weight distribution between subjects with unilateral low back pain ( N = 15 ) and pain-free controls ( N = 15 ) . Measurements included limits of stability ( % LOS ) , target sway , weight distribution on each lower extremity in quiet st and ing , and center of gravity with measurements of maximal excursion in anterior/posterior and medial/lateral directions . Independent t tests were used to compare data between groups . Compared with control subjects , subjects with low back pain demonstrated greater anterior-posterior center of gravity excursion and total center of gravity excursion with eyes open and greater anterior-post 
    Output:
    