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 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 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 STUDY DESIGN A cross-sectional study in patients with recurrent/chronic low back trouble and healthy control subjects . OBJECTIVE To evaluate the effect of paraspinal muscle fatigue on the ability to sense a change in lumbar position . SUMMARY OF BACKGROUND DATA Protection against spinal injury requires proper anticipation of events , appropriate sensation of body position , and reasonable muscular responses . Lumbar fatigue is known to delay lumbar muscle responses to sudden loads . It is not known whether the delay is because of failure in the sensation of position , output of the response , or both . METHODS Altogether , 106 subjects ( 57 patients with low back trouble [ 27 men and 30 women ] and 49 healthy control subjects [ 28 men and 21 women ] ) participated in the study . Their ability to sense a change in lumbar position while seated on a special trunk rotation unit was assessed . A motor rotated the seat with an angular velocity of 1 degree per second . The task in the test involved reacting to the perception of lumbar movement ( rotation ) by releasing a button with a finger movement . The test was performed twice , before and immediately after a fatiguing procedure . During the endurance task , the participants performed upper trunk repetitive extensions against a resistance , with a movement amplitude adjusted between 25 degrees flexion and 5 degrees extension , until exhaustion . RESULTS Patients with chronic low back trouble had significantly poorer ability than control subjects on the average to sense a change in lumbar position ( P = 0.007 ) , which was noticed before and after the fatiguing procedure . Lumbar fatigue induced significant impairment in the sensation of position change ( P < 0.000001 ) . CONCLUSIONS Lumbar fatigue impairs the ability to sense a change in lumbar position . This feature was found in patients and control subjects , but patients with low back trouble had poorer ability to sense a change in lumbar position than control subjects even when they were not fatigued . There seems to be a period after a fatiguing task during which the available information on lumbar position and its changes is inaccurate 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 Study Design : A control group study with repeated measures . Objective : To compare  trunk repositioning parameters  in chronic low back pain ( LBP ) and healthy subjects . Summary and background data : Recent evidence suggests that chronic LBP patients exhibit deficits in trunk proprioception and motor control . Trunk repositioning and the various spatio-temporal parameters related to it can be used to evaluate sensori-motor control and movement strategies . Methods : Fifteen control subjects and 16 chronic LBP subjects participated in this study . Subjects were required to reproduce different trunk position in flexion ( 15 ° , 30 ° and 60 ° ) and extension ( 15 ° ) . In the learning phase preceding each condition , visual feedback was provided . Following these learning trials , subjects were asked to perform ten consecutive trials without any feedback . Movement time , movement time variability and peak velocity were obtained and a temporal symmetry ratio was calculated . Peak angular position variability and absolute error in peak angular position were also calculated to evaluate spatial accuracy . Results : Two subgroups of LBP patients were identified . One subgroup of LBP subjects demonstrated longer movement time and smaller peak velocities and symmetry ratios than normal subjects . No group difference was observed for peak angular position variability and absolute error in peak angular position . Conclusion : Chronic LBP patients , when given a sufficient learning period , were able to reproduce trunk position with a spatial accuracy similar to control subjects . Some LBP subjects , however , showed modifications of movement time , peak velocity and acceleration parameters . We propose that the presence of persistent chronic pain could induce an alteration or an adaptation in the motor responses of chronic LBP subjects 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 BACKGROUND Low back pain is associated with abnormal movement strategies due to changes in neuromuscular control . A plausible contributing factor to low back pain is poor control of trunk muscles , thus underst and ing motor control alterations in this population can guide rehabilitation . Quantification of postural responses following support surface translations is one way to examine motor control impairments in people with low back pain . METHODS Twenty-four healthy subjects [ mean 33 ( SD 11 ) years ] who had no low back pain and 26 subjects [ mean 39 ( SD 13 ) years ] with chronic , recurrent low back 
    Output:
    
agent
This systematic review covered all the relevant literature , but none of the included studies offered a valid , reliable and feasible method to assess neuromotor capacity in everyday physiotherapy clinical practice
***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 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 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 STUDY DESIGN A cross-sectional study in patients with recurrent/chronic low back trouble and healthy control subjects . OBJECTIVE To evaluate the effect of paraspinal muscle fatigue on the ability to sense a change in lumbar position . SUMMARY OF BACKGROUND DATA Protection against spinal injury requires proper anticipation of events , appropriate sensation of body position , and reasonable muscular responses . Lumbar fatigue is known to delay lumbar muscle responses to sudden loads . It is not known whether the delay is because of failure in the sensation of position , output of the response , or both . METHODS Altogether , 106 subjects ( 57 patients with low back trouble [ 27 men and 30 women ] and 49 healthy control subjects [ 28 men and 21 women ] ) participated in the study . Their ability to sense a change in lumbar position while seated on a special trunk rotation unit was assessed . A motor rotated the seat with an angular velocity of 1 degree per second . The task in the test involved reacting to the perception of lumbar movement ( rotation ) by releasing a button with a finger movement . The test was performed twice , before and immediately after a fatiguing procedure . During the endurance task , the participants performed upper trunk repetitive extensions against a resistance , with a movement amplitude adjusted between 25 degrees flexion and 5 degrees extension , until exhaustion . RESULTS Patients with chronic low back trouble had significantly poorer ability than control subjects on the average to sense a change in lumbar position ( P = 0.007 ) , which was noticed before and after the fatiguing procedure . Lumbar fatigue induced significant impairment in the sensation of position change ( P < 0.000001 ) . CONCLUSIONS Lumbar fatigue impairs the ability to sense a change in lumbar position . This feature was found in patients and control subjects , but patients with low back trouble had poorer ability to sense a change in lumbar position than control subjects even when they were not fatigued . There seems to be a period after a fatiguing task during which the available information on lumbar position and its changes is inaccurate 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 Study Design : A control group study with repeated measures . Objective : To compare  trunk repositioning parameters  in chronic low back pain ( LBP ) and healthy subjects . Summary and background data : Recent evidence suggests that chronic LBP patients exhibit deficits in trunk proprioception and motor control . Trunk repositioning and the various spatio-temporal parameters related to it can be used to evaluate sensori-motor control and movement strategies . Methods : Fifteen control subjects and 16 chronic LBP subjects participated in this study . Subjects were required to reproduce different trunk position in flexion ( 15 ° , 30 ° and 60 ° ) and extension ( 15 ° ) . In the learning phase preceding each condition , visual feedback was provided . Following these learning trials , subjects were asked to perform ten consecutive trials without any feedback . Movement time , movement time variability and peak velocity were obtained and a temporal symmetry ratio was calculated . Peak angular position variability and absolute error in peak angular position were also calculated to evaluate spatial accuracy . Results : Two subgroups of LBP patients were identified . One subgroup of LBP subjects demonstrated longer movement time and smaller peak velocities and symmetry ratios than normal subjects . No group difference was observed for peak angular position variability and absolute error in peak angular position . Conclusion : Chronic LBP patients , when given a sufficient learning period , were able to reproduce trunk position with a spatial accuracy similar to control subjects . Some LBP subjects , however , showed modifications of movement time , peak velocity and acceleration parameters . We propose that the presence of persistent chronic pain could induce an alteration or an adaptation in the motor responses of chronic LBP subjects 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 BACKGROUND Low back pain is associated with abnormal movement strategies due to changes in neuromuscular control . A plausible contributing factor to low back pain is poor control of trunk muscles , thus underst and ing motor control alterations in this population can guide rehabilitation . Quantification of postural responses following support surface translations is one way to examine motor control impairments in people with low back pain . METHODS Twenty-four healthy subjects [ mean 33 ( SD 11 ) years ] who had no low back pain and 26 subjects [ mean 39 ( SD 13 ) years ] with chronic , recurrent low back 
    Output:
    