***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: OBJECTIVE To determine whether shoe characteristics affect balance in older women . DESIGN R and omized order , cross-over , controlled comparison . SETTING A retirement village . PARTICIPANTS Thirty women aged 60 to 89 years ( mean 78.7 SD = 8.5 ) . Twenty-five subjects were hostel residents , and five were living independently in the community . OUTCOME MEASURES Postural sway , maximal balance range , and co-ordinated stability . MAIN RESULTS The subjects underwent assessment s of static balance ( body sway ) and dynamic balance ( maximal balance range and co-ordinated stability ) under four conditions : ( 1 ) barefoot , ( 2 ) in st and ard low-heeled shoes ( walking shoes ) , ( 3 ) in st and ard high-heeled shoes , and ( 4 ) in their own shoes . Manova analysis revealed a significant overall shoe condition effect -- subjects performed best in bare feet or low-heeled shoes and worst in high-heeled shoes . There were no significant differences between subjects with and without foot abnormalities in any of the balance measures or test conditions . CONCLUSION These findings suggest that bare feet and walking shoes maximize balance , whereas high-heeled shoes constitute a needless balance hazard for older women STUDY DESIGN Cross-sectional repeated- measures design . OBJECTIVE Determine the effects of circumferential ankle pressure ( CAP ) intervention on  proprioceptive acuity , ankle stiffness , and postural stability . BACKGROUND The application of CAP using braces , taping , and adaptive shoes or military boots is widely used to address chronic ankle instability ( CAI ) . An underlying assumption is that the CAP intervention might improve ankle stability through increased proprioceptive acuity and stiffness in the ankle . METHOD AND MEASURES : A convenience sample of 10 subjects was recruited from the local university community and categorized according to proprioceptive acuity ( high , low ) and ankle stability ( normal , CAI ) .  Proprioceptive acuity was measured when blindfolded subjects were asked to accurately reproduce a self-selected target ankle position before and after the application of CAP .  Proprioceptive acuity was determined in 5 different ankle joint position sense tests : neutral , inversion , eversion , plantar flexion , and dorsiflexion . Joint position angles were recorded electromechanically using a potentiometer . Passive ankle stiffness was computed from the ratio of applied static moment versus angular displacement . Active ankle stiffness was determined from biomechanical analyses of ankle motion following a mediolateral perturbation . Postural stability was quantified from the center of pressure displacement in the mediolateral and the anteroposterior directions in unipedal stance . All measurements were recorded with and without CAP applied by a pediatric blood pressure cuff . Data were analyzed using a separate mixed-model analysis of variance ( ANOVA ) for each dependent variable . Post hoc comparison using Tukey 's honestly significant difference ( HSD ) test was performed if significant interactions were obtained . Significance level was set at P<.05 for all analyses . RESULTS Significant group ( high versus low proprioceptive acuity ) x CAP interactions were identified for postural stability . Passive ankle stiffness was not increased by an application of CAP .  Active ankle stiffness was significantly different between the high and low proprioceptive acuity groups and was not affected by an application of CAP . Significant group ( normal versus CAI ) x CAP interactions were observed for mediolateral center-of-pressure displacement with a main effect of group on neutral joint position sense . CONCLUSIONS Application of CAP increased proprioceptive acuity and demonstrated trends toward increased active stiffness in the ankle , hence improved postural stability . The effects tend to be limited to individuals with low proprioceptive acuity Noise can enhance the detection and transmission of weak signals in certain nonlinear systems , via a mechanism known as stochastic resonance . Here we show that input noise can be used to improve motor control in humans . Specifically , we show that the postural sway of both young and elderly individuals during quiet st and ing can be significantly reduced by applying subsensory mechanical noise to the feet . We further demonstrate with input noise a trend towards the reduction of postural sway in elderly subjects to the level of young subjects . These results suggest that noise-based devices , such as r and omly vibrating shoe inserts , may enable people to overcome functional difficulties due to age-related sensory loss Abstract . Triggering of balance corrections may depend on both leg and trunk proprioceptive inputs . To study this issue and to determine how a total proprioceptive loss in the legs ( ToLPL ) would affect postural reactions in different directions , we investigated the postural control of a patient with a long-st and ing dorsal root ganglionopathy . This patient had absent stretch reflexes at the ankle and knee joints , delayed reflexes at the hips , but normal muscle strength . Postural control was probed with support-surface movements driven by two different experimental protocol s. The first protocol concentrated on leg muscle responses by varying ankle inputs during pitch plane perturbations . The second protocol focussed on the directional sensitivity of upper body responses using combined roll and pitch tilt perturbations . For both protocol s , identical techniques were used to record ankle torques , angular velocities of the upper legs and trunk , and surface EMG from leg , hip and trunk muscles . For the first protocol , pitch plane stance perturbations with three different ankle inputs were imposed by a movable support surface . A simultaneous 4-cm rearward translation and 4-deg toe-up rotation produced an 80-deg/s " enhanced ankle input " , a simple toe-up rotation gave a 40-deg/s " normal " ankle input and a simultaneous 4-cm rearward translation and 4-deg " toe-down " rotation yielding a 0-deg/s " nulled ankle input " . Responses in the ToLPL patient were compared to those of healthy controls and those of patients with lower-leg proprioceptive loss ( LLPL ) . Following normal and enhanced ankle input perturbations , stretch reflexes were absent in ankle and knee joint muscles of the ToLPL patient . Balance correcting responses in the lower legs were diminished and delayed by some 45 ms . In quadriceps , balance-correcting responses were larger than normal , peaked earlier and were not delayed . During the nulled ankle input condition , the ankle muscle responses in the ToLPL patient were again diminished and delayed by 40 ms with respect to both normal subjects and LLPL patients . However , the ToLPL patient again generated an earlier , larger , balance correcting response in quadriceps . For the second protocol , combinations of roll and pitch perturbations were also delivered by a moving support surface . The amplitude was 7.5 deg at 50 deg/s . Eight different directions were applied r and omly ( pure " toes down " , pure " toes up " and directions at 45-deg intervals of roll ) . As with the first protocol pre-stimulus background muscle activity was excessive in all trunk and most leg muscles . Responses to roll tilt produced several striking changes from normal in the ToLPL patient . First reflexes in gluteus medius were delayed . Second , the trunk roll which commences around 30 ms in normals was in the opposite direction . This roll was accompanied by oppositely directed stretch reflexes in paraspinal muscles . Third , directional sensitivity of balance corrections was far more roll oriented in leg and trunk muscles . Fourth , some tilt directions caused a deactivation response of background activity . This " deactivation strategy " strongly contrasted with the strategy of controls who had low pre-stimulus background activity and activated responses around 100 ms to correct postural instability . These findings provide new insights into the generation of pitch and roll plane directed balance corrections based on the interaction of proprioceptive trigger signals from the ankles , knees and hips . Without proprioceptive input from the ankle and knee , ankle muscle responses are delayed but not absent . Upper leg and trunk responses are not delayed . This suggests that most , if not all , lower leg balance correcting responses are triggered by hip and , possibly , trunk proprioceptive inputs . When leg proprioceptive input is absent , balance correcting responses lose pitch plane sensitivity . The solution used by the patient to overcome these deficits was to markedly raise background muscle activity levels , presumably to provide a stiffer body structure . The lack of trunk flexibility and lateral instability this produced for roll tilts was offset by the ability to compensate by using a hitherto not described " deactivation response " strategy . The patient had a clinical picture usually described as " deafferented " ; yet our roll tilt perturbations revealed delayed reflex responses in hip muscles . With vestibulospinal and neck-proprioceptive inputs , these responses may have helped with the development of compensation processes for the total leg proprioceptive deficit BACKGROUND One of the more pervasive effects of aging is loss of cutaneous sensation , which appears to correlate with impaired postural control and increased risk of falling . This study examined the potential for compensating for the destabilizing effects of reduced cutaneous sensitivity by placing a raised edge underneath the perimeter of the plantar foot surface , so as to facilitate sensation from the stability boundaries of the base of support . METHODS The main experiment involved 14 healthy older adults ( aged 65 - 73 ) selected because they were known , from a previous study , to have moderate plantar cutaneous insensitivity . We also report results of an initial experiment involving 7 healthy young adults ( aged 23 - 31 ) . In both experiments , we studied effects of the plantar facilitation on control of rapid stepping reactions evoked by unpredictable postural perturbation , applied via sudden platform movement in forward , backward , and lateral directions . We also studied effects on " feet-in-place " responses evoked by continuous pseudor and om platform motion in mediolateral and anteroposterior directions . Subjects were blindfolded in all tests . RESULTS Plantar facilitation reduced the incidence of " extra " limb movements , beyond the initial step , during forward-step reactions in the older adults . There also appeared to be an improved ability to control feet-in-place reactions : young subjects were better able to recover balance without stepping when falling backward ( given instructions to " try not to step " ) , and both young and older subjects reduced the extent to which the center of foot pressure approached the posterior foot boundary during continuous anteroposterior platform motion . CONCLUSIONS This study provides evidence that mechanical facilitation of sensation from the boundaries of the plantar surface of the foot can improve the efficacy of certain types of stabilizing reactions evoked by unpredictable postural perturbation . The results may be directly transferable to the design of special footwear insoles to reduce instability and risk of falling in older adults OBJECTIVE To test the hypothesis that shoes with thick , soft midsoles , such as modern running shoes , provide better stability in older individuals than those with thin-hard midsoles . In addition , we examined the relation between footwear comfort and stability and stability when barefoot . DESIGN R and omized-order , cross-over , controlled comparison . SETTING Subjects were drawn from an internal medicine practice . PARTICIPANTS A r and om sample of 25 healthy men , minimum age 60 years . Additional selection criteria were absence of disabilities influencing ability to walk and lack of history of frequent falls . MEASUREMENTS Balance failure frequency , which was defined as falls from the beam per 100 meters of beam walking when 10 passes were made down a 9 M long balance beam .  Comfort rating was based on an ordinal scale . RESULTS Contrary to the hypothesis : ( 1 ) midsole softness was associated with poor stability ( F(2,48 ) = 17.9 , P < 0.0001 ) ; ( 2 ) thick midsoles also provided poor stability ( F(1,24 ) = 7.36 , P < 0.01 ) . When barefoot , subjects showed 19 % higher balance failure frequency than with the poorest shoe and 171 % greater than the best shoe ( t = 5.33 , P < 0.0001 ) . Higher comfort was generally found in shoe types associated with higher balance failure frequency . CONCLUSIONS For optimal stability , shoes with thin , hard soles are preferable for older individuals . Health professionals should exercise caution when recommending shoes with thick , yielding midsoles , such as running shoes , to unstable elderly individuals . Older men and women with a history of falls or who are obviously unstable , should avoid barefoot locomotion OBJECTIVES To test the hypotheses that foot position awareness is related positively to stability , positively to shoe sole hardness , and negatively to shoe sole thickness , and that foot position awareness declines with advancing years . SETTING Older subjects were consecutive volunteers from a medical clinic ; younger subjects were volunteers from the community . DESIGN R and omized-order , cross-over , controlled comparison . PARTICIPANTS Older subjects were a r and om sample of 13 healthy men , mean age 72.58 years , SD + /- 4.50 . Younger subjects were a r and om sample of 13 male subjects from the general population , mean age 28.13 years , SD + /- 3.96 . Additional selection criteria were absence of disabilities influencing ability to walk and no history of frequent falls . MEASUREMENTS Balance failure frequency , defined as falls per 100 meters of beam walking ; rearfoot angle in degrees , measured via an optical position measurement system ; perceived maximum supination when walking , in degrees , estimated by subjects using a ratio scale ; foot position error , in degrees , was defined as the rearfoot angle minus perceived maximum supination . RESULTS Foot position error during walking : ( 1 ) increases with advancing years ; footwear conditions absolute mean error for older sample of 15.48 degrees , SE + /- 1.56 degrees , and younger sample 5.44 degrees , SE + /- 1.03 degrees ( P > .001 ) ; ( 2 ) is positively related to stability ( r = .367 , P < .001 ) ; ( 3 ) is positively related to midsole thickness ( F(1,11 ) = 19.89 , P < .001 ) ; ( 4 ) is negatively related to midsole hardness ( F(2,22 
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No definitive conclusions can be drawn concerning the effects of AFA on balance in older people or in patients with PNSD because of the small number of studies and the weak level of evidence .
The available literature seems to indicate that a training program may be helpful in ensuring the effectiveness of an appliance .
Insoles with tubing or vibrating elements may improve balance , whereas thick or soft soles may deteriorate balance .
The effects of these different types of insoles or soles are consistent with theories about somatosensory mechanisms that play a role in control of balance .