Effect of a virtual reality exercise program accompanied by cognitive tasks on the balance and gait of stroke patients

[Purpose] This study aimed to assess the effect of a virtual reality exercise program accompanied by cognitive tasks on the balance and gait of stroke patients. [Subjects] Twenty stroke patients were randomly assigned to two groups 10 to an experimental group that performed a virtual reality exercise program accompanied by cognitive tasks and 10 to a control group. The control group performed a proprioceptive neuromuscular facilitation exercise program. Balance was measured with the Berg Balance Scale. Gait was assessed using the Timed Up and Go Test. The paired t-test was used to compare groups before and after the experiment. The independent t-test was conducted to assess differences in the degree of change between the two groups before and after the experiment. [Results] Within-group comparison in the experimental group showed significant differences in the Berg Balance Scale and Timed Up and Go Test. In a comparison between groups, the differences in the Berg Balance Scale and Timed Up and Go Test in the experimental group appeared significant compared with the control group. [Conclusion] The results of the experiment indicate that a virtual reality exercise program accompanied by cognitive tasks has a positive effect on the balance and gait of stroke patients.Key words: Virtual reality exercise program accompanied by cognitive tasks, Balance, Gait     

Effect of coordination movement using the PNF pattern underwater on the balance and gait of stroke patients

[Purpose] To investigate the effect of coordination movement using the Proprioceptive Neuromuscular Facilitation pattern underwater on the balance and gait of stroke patients. [Subjects and Methods] Twenty stroke patients were randomly assigned to an experimental group that performed coordination movement using the Proprioceptive Neuromuscular Facilitation pattern underwater and a control group (n =10 each). Both the groups underwent neurodevelopmental treatment, and the experimental group performed coordination movement using the Proprioceptive neuromuscular facilitation pattern underwater. Balance was measured using the Berg Balance Scale and Functional Reach Test, and gait was measured using the 10-Meter Walk Test and Timed Up and Go Test. To compare in-group data before and after the intervention, paired t-test was used. Independent t-test was used to compare differences in the results of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test before and after the intervention between the groups. [Results] Comparison within the groups showed significant differences in the results of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test before and after the experimental intervention. On comparison between the groups, there were greater improvements in the scores of the Berg Balance Scale, Functional Reach Test, 10-Meter Walk Test, and Timed Up and Go Test in the experimental group. [Conclusion] The findings demonstrate that coordination movement using the Proprioceptive Neuromuscular Facilitation pattern under water has a significant effect on the balance and gait of stroke patients.Key words: Coordination movement using the PNF pattern, Balance, Gait     

The association of balance capacity and falls self-efficacy with history of falling in community-dwelling people with chronic stroke

OBJECTIVES: To describe the frequency of falls; to relate capacity-based and self-efficacy measures to fall history; and to determine to what extent capacity-based and self-efficacy measures are explained by subject characteristics and stroke impairments. DESIGN: Cross-sectional. SETTING: Community. PARTICIPANTS: Convenience sample of 50 people with chronic stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Fall history, Falls Efficacy Scale-Swedish Version, fear of falling, and the mood subscore of the Stroke Impact Scale. Balance, strength, and functional mobility were measured using the Berg Balance Scale, timed sit to stand, and Timed Up & Go, respectively. RESULTS: Falls were reported by 40% (n=20) of subjects; 22% (n=11) reported multiple falls. Subjects with fall history had more fear of falling (relative risk [RR], 2.4; 95% confidence interval [CI], 1.1-4.9), had less falls-related self-efficacy (P=.04), and more depressive symptoms (P=.02) than nonfallers. Subjects with multiple fall history had poorer balance (P=.02), more fear of falling (RR=5.6; 95% CI, 1.3-23), and used a greater number of medications (P=.04) than non- and 1-time fallers. Strength partially explained balance, mobility, and falls-related self-efficacy. CONCLUSIONS: Balance and falls-related self-efficacy are associated with fall history and should be addressed in people with chronic stroke.     

Kinematic effect of Nintendo WiiTM sports program exercise on obstacle gait in elderly women with falling risk

[Purpose] This study evaluated the changes in balance ability and obstacle gait after lumbar stabilization exercise and Nintendo Wii^TM Sports in elderly at risk for falls. [Subjects and Methods] Twenty-four elderly women with at risk for falls were randomly divided into the control, lumbar stabilization exercise, and Nintendo Wii Sports groups. Static balance was measured by the Berg Balance Scale and functional reach test, dynamic balance by the timed up-and-go test, and obstacle negotiation function by crossing velocity and maximum vertical heel clearance. [Results] Both the lumbar stabilization exercise and Nintendo Wii Sports groups showed significant improvements in obstacle negotiation function after the exercise compared to the control group. Berg Balance Scale and functional reach test scores were greater in the lumbar stabilization exercise group, while the timed up-and-go test time was significantly better in the Nintendo Wii Sports groups. [Conclusion] Lumbar stabilization exercises and Nintendo Wii Sports improve falling related balance and obstacle negotiation function in elderly women at risk for falls.Key words: Elderly women, Falls, Nintendo Wii Sports     

Berg平衡量表在脑卒中患者中的内在信度和同时效度

目的：探讨Berg平衡量表在脑卒中患者中的内在信度和同时效度。方法：40例符合入选标准的脑卒中偏瘫患者参与本研究。对患者进行Berg平衡量表、计时起立-步行测验和Barthel指数的评价。结果：Berg平衡量表的Cronbach α系数为0.864,14项目的Cronbach α系数范围为0.844—0.869,Berg平衡量表折半信度系数为0.915。Berg平衡量表与效标工具计时起立-步行测验和Barthel指数之间显著相关。结论：Berg平衡量表在脑卒中患者中具有良好的内在信度和同时效度。     

Effects of mechanical horseback riding on the balance ability of the elderly

[Purpose] This study was conducted to evaluate the effect of mechanical horseback riding exercise on the balance ability of the elderly. [Subjects and Methods] Ten elderly patients were assigned to an experimental group, and they performed 15 min of horseback riding. Another 10 elderly patients were assigned to a control group, and they performed 15 min of one-leg standing exercise. Both exercises were repeated five times a week for a total of six weeks. The participants’ balance ability was evaluated. [Results] The horseback-riding group showed significant differences between the pre-and post-test balance abilities as assessed by the Berg Balance Scale (BBS) and the Timed Up and Go (TUG) test. [Conclusion] Horseback riding effectively improves the balance ability of the elderly. Horseback riding should be considered as a therapeutic method for the physical therapy of the elderly.Key words: Balance ability, Elderly, Mechanical horseback riding     

平衡仪反馈训练法和Bobath平衡训练法对偏瘫患者平衡和功能性行走能力的影响

目的：探讨平衡仪反馈训练法和Bobath平衡训练法对偏瘫患者平衡和功能性行走能力的影响。方法：将符合试验条件的住院卒中患者分层随机分为试验组（20例）和对照组（20例）,两组对象在试验开始前Berg平衡得分（BBS）、“起立-走”计时试验（Up＆Go）比较差异无显著性意义。试验组的平衡训练使用平衡仪视觉反馈法,对照组平衡训练使用Bobath平衡训练法,测试指标采用BBS和Up＆Go,在试验开始前和训练6周后各评定1次。结果：训练6周后试验组的BBS、Up＆Go均优于对照组比较差异具有显著性意义。结论：使用平衡仪训练对改善脑卒中患者的平衡和行走功能比单纯的Bobath平衡训练法更有效。     

Balance-related efficacy compared with balance function in patients with acute stroke

It is well known that patients who have suffered a stroke have problems with balance and have feelings of unsteadiness. The aim of this study was to analyse the correlation between how patients estimate their perceived confidence in task performance without falling and the objective assessment of balance made by a physiotherapist, and whether the Falls Efficacy Scale (FES(S)) is to be recommended for use in patients in the acute phase of stroke. Sixty patients divided into two groups assessed their belief to perform daily life activities without fear of falling using the FES(S) and were assessed by using the Berg Balance Scale (BBS) and Timed Up and Go (TUG) by a physiotherapist. Group 1 assessed themselves before, whereas Group 2 assessed themselves after the objective assessment. The correlation between the FES(S) and the TUG was moderate to good, but these two scales consider different aspects and dimensions of balance, ability, and belief and are therefore not interchangeable. The correlation between FES(S) and BBS was low to moderate. The conclusion of this study was that the FES(S) is not to be recommended as a single measurement in the acute phase of stroke because it does not measure actual balance function.     

The effects of incremental speed-dependent treadmill training on postural instability and fear of falling in Parkinson's disease

OBJECTIVE: To detect the effectiveness of incremental speed-dependent treadmill training on postural instability, dynamic balance and fear of falling in patients with idiopathic Parkinson's disease. DESIGN: Randomized controlled trial. SETTING: Ankara Education and Research Hospital, 2nd PM&R Clinic, Cardiopulmonary Rehabilitation Unit. SUBJECTS: Fifty-four patients with idiopathic Parkinson's disease in stage 2 or 3 of the Hoehn Yahr staging entered, and 31 patients (21 training, 10 control) had outcome data. INTERVENTIONS: Postural instability of patients with Parkinson's disease was assessed using the motor component of the Unified Parkinson's Disease Rating Scale (UPDRS), Berg Balance Test, Dynamic Gait Index and Falls Efficacy Scale. Twenty-one patients with Parkinson's disease participated in an eight-week exercise programme using incremental speed-dependent treadmill training. Before and after the training programme, balance, gait, fear of falling and walking distance and speed on treadmill were assessed in both Parkinson's disease groups. MAIN MEASURES: Walking distance and speed on treadmill, UPDRS, Berg Balance Test, Dynamic Gait Index and Falls Efficacy Scale. RESULTS: Initial total walking distance of the training group on treadmill was 266.45 +/- 82.14 m and this was progressively increased to 726.36 +/- 93.1 m after 16 training session (P < 0.001). Tolerated maximum speed of the training group on treadmill at baseline was 1.9 +/- 0.75 km/h and improved to 2.61 +/- 0.77 km/h (P < 0.001). Berg Balance Test, Dynamic Gait Index and Falls Efficacy Scale scores of the training group were improved significantly after the training programme (P < 0.01). There was no significant improvement in any of the outcome measurements in the control group (P > 0.05). CONCLUSIONS: Specific exercise programmes using incremental speed-dependent treadmill training may improve mobility, reduce postural instability and fear of falling in patients with Parkinson's disease.     

Effects of Resistance Exercise Using Thera-band on Balance of Elderly Adults: A Randomized Controlled Trial

[Purpose] This study investigated the effects of resistance exercise using Thera-band on balance of elderly adults. [Methods] Subjects (age range, 60–70 years) were randomly assigned to an experimental (n=12) or control group (n=12). The experimental group performed stretching and resistance exercises, and the control group performed stretching exercises only. Before and after the 5-week intervention, the participants’ static and dynamic balance were evaluated using the Berg Balance Scale, the Timed Up & Go Test, and the Tetrax Portable Multiple System (Tetrax Ltd., Ramat Gan, Israel) after 5 weeks. [Results] After the intervention, the values of the Tetrax in the weight distribution index with eyes open and that with eyes closed and the stability test index with eyes open were significantly lower in the resistance exercise group than in the control group, and the pre-test values were was significantly higher than the post-test values. However, there were no significant differences between groups in the values of the Berg Balance Scale, the Timed Up & Go Test, and the Tetrax stability test index with the eyes closed. [Conclusion] The findings of this study indicate that resistance exercise using the Thera-band is possible to improve the static and dynamic balance of elderly adults.Key words: Stretching, Resistance exercise, Balance     

Investigating the effects of appropriate fitting footwear on functional performance level,balance and fear of falling in older adults: A comparative-observational study

The aim of the study was to assess the characteristics of footwear altogether and to compare the effect of appropriate-fitting and ill-fitting footwear on functional performance, balance, and fear of falling (FoF) in older adults. Individuals who wore appropriate-fitting (n = 61) or ill-fitting footwear (n = 92) were enrolled in the study. Footwear was evaluated using the Footwear Assessment Scale (FAS). The participants were assessed using the Berg Balance Scale (BBS) for balance, the Timed Up and Go test for functional performance and the Activities-specific Balance Confidence scale for FoF. Tests were conducted twice for each individual with or without footwear. Differences between the groups were analyzed using the MANOVA for scores of balance, performance and fear of falling and Chi-squared test for homogeneity. The Paired t-test was used to compare test scores with or without footwear. It was concluded that appropriate-fitting footwear improves balance, reduces fear of falling and may affect functional performance positively.ClinicalTrials.gov No: NCT04151654     

An efficacy study on improving balance and gait in subacute stroke patients by balance training with additional motor imagery: a pilot study

[Purpose] The few studies conducted on subacute stroke patients have focused only on gait function improvement. This study therefore aimed to confirm the effect of balance training with additional motor imagery on balance and gait improvement in subacute stroke patients. [Subjects and Methods] Participants were divided into an experimental or control group. The experimental group received balance training for 20 minutes/day with mental imagery for 10 minutes/day, three days/week, for four weeks. The control group received only balance training for 30 minutes. Before and after the 12 sessions, balance and gait ability were assessed by the researcher and a physical therapist. [Results] After completion of the 4-week intervention, Berg Balance Scale, Timed Up and Go test, Functional Reach Test, and Four Square Step test scores significantly increased in the experimental group. In the control group, Berg Balance Scale and Functional Reach Test scores significantly improved. Changes in the Timed Up and Go test, Functional Reach Test, and Four Square Step Test scores after intervention were significantly higher in the experimental than in the control group. [Conclusion] Specific balance training with additional motor imagery may result in better rehabilitation outcomes of gait and balance ability than balance training alone.Key words: Balance, Gait, Motor imagery     

Therapeutic effects of reaching with forward bending of trunk on postural stability,dynamic balance,and gait in individuals with chronic hemiparetic stroke

[Purpose] The objective of this study was to perform forward bending of the trunk and reaching training in chronic stroke patients and to investigate subsequent changes in trunk control, dynamic balance, and gait. [Subject] Twenty-three chronic stroke patients were randomly divided into two groups, with 10 patients in the forward bending of the trunk and reaching group and 13 patients in the control group. [Methods] Both groups underwent 30 minutes of rehabilitation therapy, five days a week, for four weeks. The forward bending of the trunk and reaching group additionally performed forward bending of the trunk and reaching training five times a week for four weeks, which involved four sets of pressing buttons 35 times, for a total of 140 button presses per session. The subjects were tested before and after training using the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, Six-Minute Walking Test, and 10-Meter Walking Test. Trunk control, dynamic balance, and walking ability were compared between the two groups. [Result] The results of the study showed that the results of the Trunk Impairment Scale, Berg Balance Scale, Timed Up and Go Test, Six-Minute Walking Test improved significantly in the FBR group, while there were no significant differences in the control group. [Conclusion] This study results suggest that forward bending of the trunk and reaching training can be an effective exercise method for chronic stroke patients.Key words: Postural control, Stroke, Trunk     

Does whole-body vibration training in the horizontal direction have effects on motor function and balance of chronic stroke survivors? A preliminary study

[Purpose] The objective of this study was to investigate the effects of whole-body vibration (WBV) in the horizontal direction on the motor function and balance of chronic stroke survivors. [Subjects and Methods] This study was a randomized controlled trial. Twenty-one individuals with chronic stroke from an inpatient rehabilitation center participated in the study. The participants were allocated to either the WBV training group or the control group. The WBV training group (n = 12) received whole-body vibration delivered in the horizontal direction (15 min/day, 3 times/week, 6 wks) followed by conventional rehabilitation (30 min/day, 5 times/week, 6 wks); the control group (n = 9) received conventional rehabilitation only (30 min/day, 5 times/week, 6 wks). Motor function was measured by using the Fugl-Meyer assessment, and balance was measured by using the Berg Balance Scale (BBS) and the Timed Up and Go (TUG) test before and after the interventions. [Results] After the interventions, all variables improved significantly compared with the baseline values in the WBV training group. In the control group, no significant improvements in any variables were noted. In addition, the BBS score in the WBV training group increased significantly compared with that in the control group. [Conclusion] WBV training with whole-body vibration delivered in the horizontal direction may be a potential intervention for improvement of motor function and balance in patients who previously experienced a stroke.Key words: Stroke, Whole-body vibration, Motor function     

The Effects of Cognitive Activity Combined with Active Extremity Exercise on Balance,Walking Activity,Memory Level and Quality of Life of an Older Adult Sample with Dementia

[Purpose] The purpose of this study was to compare the effectiveness of cognitive activity combined with active physical exercise for a sample of older adults with dementia. [Subjects] A convenience sample of 30 patients with dementia (Mini-Mental State Examination score between 16 and 23) was used. Participants were randomly allocated to one of two groups: cognitive activity combined with physical exercise CAE, n=11), and only cognitive activity CA, n=9). [Methods] Both groups participated in a therapeutic exercise program for 30 minutes, three days a week for 12 weeks. The CAE group performed an additional exercise for 30 minutes a day, three days a week for 12 weeks. A Wii Balance Board (WBB, Nintendo, Japan) was used to evaluate postural sway as an assessment of balance. The Berg Balance Scale (BBS) and Modified Falls Efficacy Scale (MFES) were used to assess dynamic balance abilities. The Timed Up-and-Go test (TUG) was used to assess gait, and the Digit Span Test (DST) and 7 Minute Screening Test (7MST) were used to measure memory performance. The Mini-Mental Status Exam-Korean version (MMSE-K), Kenny Self-Care Evaluation (KSCE), and Short Geriatric Depression Scale (GDS) were used to assess quality of life (QOL). [Results] There were significant beneficial effects of the therapeutic program on balance (velocity in EOWB, path length in ECNB, BBS, and MMFE), QOL (MMSE-KC, GDS, KSCE), and memory performance (DSB) in the CAE group compared to CA group, and between pre-test and post-test. [Conclusion] A 12-week CAE program resulted in improvements in balance, memory and QOL. Therefore, some older adults with dementia have the ability to acquire effective skills relevant to daily living.Key words: Dementia, Elderly, Gait     

Whole-body vibration in addition to strength and balance exercise for falls-related functional mobility of frail older adults: a single-blind randomized controlled trial

Objectives: To investigate the effects of whole-body vibration in addition to an exercise programme on functional mobility and related outcomes for frail older fallers. Design: Single-blind randomized parallel group trial. Setting: UK; National Health Service assessment and rehabilitation facility for older people. Participants: Frail older fallers: 38 (80 ± 8.6 years) performed the exercise with whole-body vibration (vibration group), and 39 (82 ± 8.1 years) without (exercise group). Intervention: Sixty minutes supervised exercise class three times weekly for eight weeks ± whole-body vibration (up to 5 × 1 minute, 15-30 Hz and 2-8 mm peak-to-peak). Measurements: Timed Up and Go, 6-m walk, static balance, fear of falling (FES-I) and self-reported health status (SF-12 version 2) were assessed at baseline, four weeks (mobility measures only), eight weeks and six months. Results: Timed Up and Go and 6-m walk improved in both groups at eight weeks (P < 0.01), but significantly more in the vibration group (timed up and go: 38 vs. 20%, P < 0.05); 6-m walk: (36 vs. 18.1%, P < 0.05, respectively). Balance, fear of falling and physical component of the self-reported health status improved similarly in both groups (P < 0.05). At follow-up, no significant differences from baseline remained for any measure. The mean total time experienced was 37% of maximal target. Conclusion: The addition of whole-body vibration to strength and balance exercise resulted in greater improvements in functional mobility than exercise alone, despite achieving lower than anticipated exposure. Gains from neither intervention were sustained at six months.     

正常人动态平衡能力测试的信度及效度分析

目的　对正常人平衡功能进行动态姿势图重复检测 ,分析各参数间的内在一致性、重测信度及不同测试者间的信度 ;并与Berg平衡量表、功能性前伸测量、起立行走计时测定结果比较 ,检验其效标效度。方法　 2名测试者应用BiodexBalanceSystem (BBS)分别对 40名正常受试者 ( 18～ 67岁 )进行 2次 8级平台稳定性动态姿势图测试及稳定性测试 ;同时还应用Berg平衡量表、功能性前伸距离及起立行走计时等方法进行检测。结果　研究结果发现年龄因素对所有检测参数均有影响 ,体重指数对稳定指数及平均方向控制能力有影响。各参数间内部存在一致性 (r =0 .2 2～ 0 .93 ,均P <0 .0 1) ,其重测信度 (r =0 .70～ 0 .99)及不同测试者间信度 (r =0 .71～ 0 .98)较佳 (ICC =0 .88～ 0 .99)。在测试过程中 ,发现不同跌下次数的受试者其年龄差异和测试结果间差异显著相关 (P <0 .0 0 1)。BBS测试数据与Berg平衡量表、功能性前伸测量、起立行走计时测评结果有较高的相关性 (r =0 .72～ 0 .86)。结论　BBS能反映受试者平衡能力的年龄变化趋势 ,具有较高的内在一致性、重测信度及不同测试者间的信度 ,与Berg平衡量表、起立行走计时及功能性前伸测量结果具有一致性 ,可用于平衡功能的定量评定。     

Comparison of Two Exercise Programs Using the Falls Efficacy Scale,Berg Balance Scale and Ankle Dorsiflexor Strength in Older Adults

The purpose of this study was to investigate the effectiveness of two exercise programs with three different measurements (Falls Efficacy Scale–FES, Berg Balance Scale–BBS, and bilateral ankle dorsiflexor strength–ADFS) and to determine if these measurements correlate to each other. Thirteen pairs of subjects residing in a senior living community were recruited and matched for age, gender, and assistive device. The matched subjects were randomly divided into one of two exercise groups–resistance group (RG) provided with the exercise combination of resistance strengthening, balance and gait or seated group (SG) provided with seated range of motion exercise. Eleven pairs completed the 12-week exercise program. The results revealed that subjects in the RG made more improvement in fear of falling, balance, and ankle dorsiflexor strength than those in the SG. The decrease of FES score (fear of falling) is moderately correlated with the increase of BBS (balance) and ADFS scores. The improved BBS is also moderately correlated with the increased ADFS.     

Determinants of balance confidence in community-dwelling elderly people

BACKGROUND AND PURPOSE: The fear of falling can have detrimental effects on physical function in the elderly population, but the relationship between a persons' confidence in the ability to maintain balance and actual balance ability and functional mobility is not known. The extent to which balance confidence can be explained by balance performance, functional mobility, and sociodemographic, psychosocial, and health-related factors was the focus of this study. SUBJECTS: The subjects were 50 community-dwelling elderly people, aged 65 to 95 years (mean=81.7, SD=6.7). METHODS: Balance was measured using the Berg Balance Scale. Functional mobility was measured using the Timed Up Go Test. The Activities-specific Balance Scale was used to assess balance confidence. Data were analyzed using Pearson correlation, multiple regression analysis, and t tests. RESULTS: Fifty-seven percent of the variance in balance confidence could be explained by balance performance. Functional mobility and subject characteristics examined in this study did not contribute to balance confidence. DISCUSSION AND CONCLUSION: Balance performance alone is a strong determinant of balance confidence in community-dwelling elderly people.     

Gait speed and related factors in Parkinson’s disease

[Purpose] The aim of this study was to investigate the relationship between gait speed and various factors in ambulatory patients with idiopathic Parkinson’s disease. [Subjects] Fifty ambulatory patients with idiopathic Parkinson’s disease who were admitted to an outpatient clinic were included in this cross-sectional study. [Methods] The Hoehn and Yahr Scale was used for measurement of the disease severity. Gait speed was measured by the 10-Meter Walk Test. Mobility status was assessed by Timed Up and Go Test. The Hospital Anxiety and Depression Scale was used for evaluation of emotional state. Cognitive status was examined with the Mini-Mental State Examination. The Downton Index was used for fall risk assessment. Balance was evaluated with the Berg Balance Scale. Comorbidity was measured with the Cumulative Illness Rating Scale. The 36-Item Short Form Health Survey was completed for measurement of quality of life. [Results] The mean age was 66.7 (47–83) years. Twenty-eight (56%) patients were men. Gait speed was correlated positively with height, male gender, Mini-Mental Examination score, Berg Balance Scale score and physical summary scores of the 36-Item Short Form Health Survey. On the other hand, there was a negative correlation between gait speed and age, disease severity, TUG time, Downton Index, fear of falling, previous falls and the anxiety and depression scores of the Hospital Anxiety and Depression Scale. There was no correlation between gait speed and comorbidity. [Conclusion] The factors related with the slower gait speed are, elder age, clinically advanced disease, poor mobility, fear of falling, falling history, higher falling risk, and mood disorder.Key words: Gait, Fear of falling, Parkinson’s disease