Tai Chi improves standing balance control under reduced or conflicting sensory conditions

OBJECTIVE: To investigate the effects of long-term Tai Chi practice on balance control when healthy elderly Tai Chi practitioners stood under reduced or conflicting somatosensory, visual, and vestibular conditions, as compared with healthy elderly non-Tai Chi practitioners and young subjects. DESIGN: Cross-sectional study. SETTING: University-based rehabilitation center in Hong Kong. PARTICIPANTS: Twenty elderly Tai Chi practitioners (mean experience +/- standard deviation, 7.2+/-7.2 y) were compared with 20 elderly non-Tai Chi practitioners and 20 young, healthy university students. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The amplitude of anteroposterior body sway under different somatosensory, visual, and vestibular conditions was measured using computerized dynamic posturography, whereby subjects underwent 6 combinations of visual and support surface conditions. RESULTS: The Tai Chi practitioners had significantly better balance control than the non-Tai Chi subjects in the visual and vestibular ratios, but not in the somatosensory ratio. Furthermore, there were no significant differences in any of these 3 sensory ratios when the Tai Chi practitioners were compared with those of the young, healthy subjects. CONCLUSIONS: Long-term Tai Chi practice improved balance control in the elderly population when there was an increased reliance on the visual and vestibular systems during stance. Of particular interest is that our elderly Tai Chi practitioners attained the same level of balance control performance as did young, healthy subjects when standing under reduced or conflicting somatosensory, visual, and vestibular conditions.     

Improvement of isokinetic knee extensor strength and reduction of postural sway in the elderly from long-term Tai Chi exercise

OBJECTIVES: To compare isokinetic strength of leg muscles and foot center of pressure (COP) as a measure of sway between long-term Tai Chi practitioners and controls. DESIGN: Cross-sectional study. SETTING: Community setting. PARTICIPANTS: Twenty subjects in the Tai Chi group and 19 subjects in the control group (age, >55 y). INTERVENTION: Subjects in Tai Chi group had practiced Tai Chi for a minimum of 3 years. MAIN OUTCOME MEASURES: Concentric and eccentric strength of knee extensors and flexors at 60 degrees/s and 120 degrees/s, and foot COP displacement during quiet stance with eyes open or closed. RESULTS: People in the Tai Chi group had significantly higher knee extensor strength at all speeds tested (P<.013), and smaller foot COP excursions for both eyes open and eyes closed conditions (P<.05) than people in control group. No significant difference existed in knee flexors between the 2 groups (P<.713). The COP excursions correlated significantly with the eccentric strength of knee extensors (P<.07) but not with the concentric strength of knee extensors (P<.14) or with the isokinetic strength of knee flexors at most of the speeds (P<.27). CONCLUSION: These findings support the hypothesis that the maintenance of eccentric strength of postural muscles in the lower extremities, which is beneficial for maintaining good postural stability, is helped through the long-term practice of Tai Chi.     

Mediolateral sway in single-leg stance is the best discriminator of balance performance for Tai-Chi practitioners

OBJECTIVES: To identify a balance measure that can best distinguish Tai-Chi from non-Tai-Chi practitioners and to examine whether longer Tai-Chi practice results in better balance control. DESIGN: Cross-sectional comparative study. SETTING: Community. PARTICIPANTS: Nineteen Tai-Chi practitioners (who practiced Tai Chi for 30-45min at least 3/wk for >1y) and 19 healthy subjects with regular exercise habits (who practiced Tai Chi for 30-45min at least 3/wk for >1y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Scores on 2 clinical tests (functional reach, gait) and 1 laboratory test (postural sway). RESULTS: Tai-Chi practitioners had better clinical test scores for functional reach, gait speed, stride length, and sway parameters during single-leg stance (P<.05). Sway in mediolateral direction during single-leg stance was the balance performance variable that best discriminated the Tai-Chi group from non-Tai-Chi group. More experience practicing Tai Chi was associated with better balance performance. CONCLUSIONS: Tai-Chi practitioners performed better both in clinical and laboratory tests when compared with subjects who did not practice Tai Chi. More Tai-Chi experience was associated with better postural control.     

Reliability of traditional and fractal dimension measures of quiet stance center of pressure in young, healthy people

OBJECTIVES: To assess reliability of traditional and fractal dimension measures of quiet stance center of pressure (COP). DESIGN: Cross-sectional study. SETTING: University laboratory. PARTICIPANTS: Thirty young healthy men (n=20) and women (n=10) (mean age, 23 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: COP was recorded for 3 trials across 4 conditions: eyes open and eyes closed standing on firm and foam surfaces. Traditional COP variables--peak sway velocity and range of sway, both in the anteroposterior (AP) and mediolateral (ML) directions, and total excursion area, and fractal dimension of the COP in the AP and ML directions--were calculated. Reliability statistics were calculated. RESULTS: Range of sway (AP) was the most reliable traditional variable (intraclass correlation coefficient model 2,1 [ICC(2,1)] range -.28 to .72.). Peak sway velocity (AP) had poorest reliability (ICC(2,1) range, .05-.29). Only 1 of the traditional variables had excellent reliability; total excursion area (firm, eyes closed) (ICC(2,1)=.95). All bar 1 fractal dimension measures had excellent ICCs. Relative technical error of measurement ranged from 4% to 7% for the fractal dimension measures. Coefficients of variation were also very good, ranging from 1.8% to 6.7%. CONCLUSIONS: Fractal dimension measures were more reliable than traditional measures of COP. Although traditional measures are used extensively to assess COP, their reliability is questionable. Fractal dimension measures show promise to reliably quantify COP and warrant further investigation.     

Effects of cervical collars on standing balance.

The effect of cervical collars on standing balance in two age groups was examined. Twenty healthy women aged 60 to 78 years and 20 healthy women aged 18 to 29 years stood on a Kistler force platform with and without a cervical collar. Total, lateral and anteroposterior sway velocity were measured in each of three positions; long-base stance and eyes open, wide-base stance and eyes open, and wide-base stance and eyes closed. Analysis of variance showed no significant difference (p < .05) between the collar and no collar conditions for any of the standing balance measures. Older women had significantly more sway velocity (p < .001) than younger women during long-base standing both with and without the collar. Also they showed significantly more sway velocity in both the total (p < .01) and the anteroposterior (AP) directions (p < .001) of wide-base standing. There were no significant lateral sway velocity differences (p < .05). With eyes closed, sway velocity was greater in all age groups. In the wide-based condition there were significant differences in sway velocity between AP (p < .001) and total and lateral (p < .01). These results indicate that a cervical collar does not disturb standing balance in healthy women in the age groups tested.     

The influence of thoracolumbosacral orthoses on standing balance in patients with adolescent idiopathic scoliosis: a pilot study

Background and aim: The objective of this study was to assess the effect of thoracolumbosacral orthoses (TLSOs) on antero-posterior (AP) sway, medio-lateral (ML) sway and displacement of the center of pressure (COP) during a longitudinal study in patients with adolescent idiopathic scoliosis (AIS). Methods: Eight females aged between 12 and 14.5 years participated in this study. Evaluations were performed prior to the TLSO intervention as a baseline condition, after 1 month, and after 4 months of orthosis use by assessing balance when standing statically on different surfaces. Results: When standing on both lower limbs on a solid surface there were significant differences in ML sway with the eyes both open and closed, and also in A/P sway but only when standing on a solid surface with the eyes open and also when standing on a foam surface with the eyes closed with TLSO use. When standing on the dominant leg, ML sway significantly improved, but AP sway only improved with a foam base surface with the eyes open. Conclusion: This study demonstrated positive effects of wearing a TLSO in improving quiet standing balance and standing on the dominant lower extremity in subjects with AIS after 4 months of brace use.

• Implications for Rehabilitation

• Due to a change in body shape such as that caused by scoliosis, human posture changes and spinal deformities affect the position of the center of support, and thus balance ability may change.

• AIS subjects have poor standing stability compared to a healthy matched control group.

• Brace wearing had positive effect in improving quiet standing balance and standing on the dominant lower extremity in subjects with AIS undergoing brace treatment after 4 months of TLSO use.

     

A retrospective analysis of balance control parameters in elderly fallers and non-fallers

Background

A cross-sectional retrospective study of parameters reflecting balance function in elderly fallers and non-fallers was conducted to better understand postural control mechanisms in individuals prone to falls.

Methods

Ninety-nine old adults (65–91 years, mean age 78.4 (SD 5.7)) from two self-care residential facilities participated in the study. Foot center-of-pressure (CoP) displacement data were collected during narrow base upright stance eyes closed conditions and analyzed using summary statistics and Stabilogram-Diffusion Analysis (SDA) for mediolateral (ML) and anteroposterior (AP) directions. Subjects were instructed to minimize body sway.

Findings

Twenty-nine of the subjects reported at least one fall and 69 subjects reported no falls in the past six months. The SDA showed significantly higher short-term diffusion coefficients and critical displacements in fallers in the ML but not the AP direction. Mean sway area and ML-CoP sway range were also larger in fallers.

Interpretation

The greater ML critical displacement seen in fallers suggests that balance corrections on average occurred at higher sway amplitudes in this population. This is consistent with an ML decrease in the sensitivity of their postural control system. A higher short-term diffusion coefficient is consistent with increased muscle stiffness, a possible compensation for lost control sensitivity. Testing balance function under narrow stance conditions provides a modest increase in task difficulty that may help reveal pre-conditions of the balance control system that could increase the risk of falls.     

Trunk Position Sense in Older Tai Chi Sword Practitioners

To examine whether older Tai Chi sword practitioners had developed better trunk position sense than healthy control subjects, 16 female Tai Chi sword practitioners from a local community Tai Chi Club in Hong Kong were compared with 11 female healthy control subjects. Active trunk repositioning was used to test trunk proprioceptive acuity. Tai Chi sword practitioners made significantly smaller absolute angle errors than control subjects in trunk rotation to the left (2.2° ± 0.9° vs. 4.4° ± 2.7°; p = 0.006) and to the right (2.1° ± 0.9° vs. 4.2° ± 2.9° of control; p = 0.01), but there were negligible improvements in trunk forward flexion (3.9° ± 3.0° and 4.8° ± 3.0°, respectively; p = 0.46). These results demonstrate that Tai Chi sword practitioners had developed better position sense in trunk rotation but not in trunk flexion than healthy older subjects.     

Comparison of the kinetic characteristics of standing and sitting Tai Chi forms

Purpose. To compare the kinetic characteristics of Tai Chi forms performed in standing and seated positions.

Methods. An experienced Tai Chi master was invited to perform the Tai Chi Qi Qong 18-form while standing and seated. Two force platforms were used to track the centre of pressure (COP) during the Tai Chi movements. Centre of mass (COM) displacement was measured using a video motion analysis system.

Results. In standing, the maximum COP displacements in the anteroposterior and mediolateral directions ranged from 2.6% to 9.5%, and 0.3% to 29.6% of the subject's height, respectively. The maximum COP displacements in sitting were smaller, with mean displacements of 0.7% and 0.1% of height in the anteroposterior and ML directions, respectively. The subject's COM moved in the vertical direction in slow, coordinated and smooth patterns.

Conclusions. The kinetic data on each of the 18 Tai Chi forms studied can guide the choice of suitable Tai Chi forms for balance training. Sitting Tai Chi is recommended for rehabilitating the balance of frail older adults who have difficulty standing. Because of the minimal demands of sitting Tai Chi for balance control, progressing to practice in standing as quickly as possible is recommended.     

Audio-biofeedback improves balance in patients with bilateral vestibular loss

OBJECTIVE: To evaluate the effectiveness of an audio-biofeedback (ABF) system for improving balance in patients with bilateral vestibular loss (BVL). DESIGN: Before-after trial. SETTING: University balance disorders laboratory. PARTICIPANTS: Nine subjects with BVL and 9 unaffected subjects as controls. INTERVENTION: Trunk acceleration ABF while standing on foam with eyes closed. MAIN OUTCOME MEASURE: Balance stability was evaluated according to the following parameters: the root mean square of (1) the center of pressure (COP) displacements and of (2) the trunk accelerations; the COP bandwidth; the time spent by the participant within +/-1 degrees threshold from their baseline COP position; and the mean accelerations of the trunk while the participant was swaying outside this +/-1 degrees threshold. RESULTS: Participants with BVL had significantly larger postural sway than did unaffected participants. Those with BVL, while using ABF, decreased sway area by 23%+/-4.9%, decreased trunk accelerations by 46%+/-9.9%, and increased time spent within +/-1 degrees sway threshold by 195%+/-34.6%. CONCLUSIONS: ABF improved stance stability of participants with BVL by increasing the amount of postural corrections.     

Effects of vestibular and neck proprioceptive stimulation on posture as a function of hypnotizability

Previous studies on the role of hypnotizability in postural control indicate that the body sway of subjects with high or low hypnotizability to hypnosis is differentially modulated by eye closure. The aim of this study was to investigate whether hypnotizability also modulates the postural response to electrical vestibular stimulation and to head rotation in nonhypnotized individuals. The center of pressure (CoP) displacements were monitored in highs and lows standing on a stabilometric platform with closed eyes during basal conditions and electrical vestibular stimulation in 3 different positions of the head. Results showed that the CoP stimulus-locked displacements as well as the CoP mean position, area, and mean velocity were similar in highs and lows, but only in lows did the head position modulate the mean velocity. This finding might reflect a difference in sensory-motor integration between the 2 groups.     

Effect of 12 weeks of Tai Chi training on soleus Hoffmann reflex and control of static posture in older adults

Chen Y-S, Zhou S, Cartwright C. Effect of 12 weeks of Tai Chi training on soleus Hoffmann reflex and control of static posture in older adults.

Objective

To investigate the effect of 12 weeks of Tai Chi training on soleus (SOL) Hoffmann reflex (H-reflex) modulation and postural control in standing under 4 sensory conditions in older adults.

Design

Experimental research design with pre- and posttraining tests in a training group and a control group.

Setting

University biomechanics laboratory.

Participants

Community-dwelling older adults (N=34) were assigned to a training (n=20; mean ± SD age, 72.9±4.4y) and a control (n=14; mean ± SD age, 72.9±6.5y) group.

Intervention

Tai Chi participants attended a 1-hour session of Yang style Tai Chi, 3 sessions a week, for 12 weeks, while control participants maintained their regular daily activities during the same period.

Main Outcome Measures

SOL H-reflex (maximal amplitudes of H-reflex [H_max] and M-wave [M_max] waves) and mean displacement of the center of pressure (COP) in the anterior-posterior (COP_A-P) and medial-lateral (COP_M-L) directions were measured during bipedal standing, with the feet placed on a forceplate and the heels 6cm apart, under 4 sensory conditions: stable surface with eyes open, stable surface with eyes closed, unstable surface with eyes open, and unstable surface with eyes closed.

Results

SOL H_max/M_max ratio in the Tai Chi group was upregulated significantly in all 4 sensory tasks after the 12-week Tai Chi training (P<.05). No significant change in COP measurements (mean displacement of COP_A-P and COP_M-L) was found in either the Tai Chi or control group after the 12-week period.

Conclusions

An increase in SOL H_max/M_max ratio during static postural tasks is observed after 12 weeks of Tai Chi training in older adults under all 4 sensory conditions. However, training-induced changes in H-reflex were not accompanied by improvement of performance in the static postural control tasks.     

The effects of practicing sitting Tai Chi on balance control and eye-hand coordination in the older adults: a randomized controlled trial

Abstract

Purpose: The purpose of this study was to examine the effects of 3 months of sitting Tai Chi training on the sitting balance control and eye-hand coordination of older adults subjects. Methods: We randomly assigned 59 older adults from four residential care facilities to either sitting Tai Chi group or mobilizing exercises group as control. The sitting Tai Chi group underwent 3 months of training with a total of 36 sessions (1 hour/session, 3 sessions/week). The outcome measures included sitting balance tests (testing sequential weight shifting and forward reaching in a sitting position) and eye-hand coordination tests (reaction time, movement time and accuracy in finger pointing task). Results: The Tai Chi practitioners showed significant improvement in their sequential weight shifting while sitting (improved by 29.0%, p?≤?0.05) and in their maximum reaching distance from a sitting position (improved by 21.2%, p?≤?0.05). No such improvements were found in the control group. In the eye-hand coordination test, the sitting Tai Chi practitioners had significant improvements in accuracy (improved by 17.3%, p?≤?0.05). Also, no improvement was found in the control group. Conclusions: The results demonstrate 3-months of sitting Tai Chi training can improve sitting balance and accuracy in finger pointing task in the older adults.

• Implications for Rehabilitation

• Traditional Tai Chi poses difficulties for older adults with poor standing balance.

• This pilot study showed that a 3 months sitting Tai Chi training can improve sitting balance and accuracy in the finger pointing task in the older adults.

• Sitting Tai Chi can be a therapy option for older adults with poor standing balance.

     

Coordination exercise and postural stability in elderly people: Effect of Tai Chi Chuan

OBJECTIVE: To evaluate the effects of coordination exercise on postural stability in older individuals by Chinese shadow boxing, Tai Chi Chuan (TCC). DESIGN: Cross-sectional study. SETTING: Research project in a hospital-based biomechanical laboratory. PARTICIPANTS: The TCC group (n = 25) had been practicing TCC regularly for 2 to 35 years. The control group (n = 14) included healthy and active older subjects. INTERVENTION: Static postural stability test: progressively harder sequential tests with 6 combinations of vision (eyes open, eyes closed, sway-referenced) and support (fixed, sway-referenced); and dynamic balance test: 3 tests of weight shifting (left to right, forward-backward, multidirectional) at 3 speeds. MAIN OUTCOME MEASURES: Static and dynamic balance of Sensory Organization Testing (SOT) of the Smart Balance Master System. RESULTS: In static postural control, the results showed no differences between the TCC or control group in the more simple conditions, but in the more complicated SOT (eyes closed with sway surface, sway vision with sway surface), the TCC group had significantly better results than the control group. The TCC group also had significantly better results in the rhythmic forward-backward weight-shifting test. Duration of practice did not seem to affect the stability of elder people. CONCLUSION: The elderly people who regularly practiced TCC showed better postural stability in the more challenged conditions than those who do not (eg, the condition with simultaneous disturbance of vision and proprioception). TCC as a coordination exercise may reduce the risk of a fall through maintaining the ability of posture control.     

The influence of Tai Chi training on the center of pressure trajectory during gait initiation in older adults

OBJECTIVE: To determine if a program of intense Tai Chi exercise that has been shown to reduce the risk of falling in older adults improves postural control by altering the center of pressure (COP) trajectory during gait initiation. DESIGN: Before-after trial. SETTING: Biomechanics research laboratory. PARTICIPANTS: Twenty-eight older adults transitioning to frailty who participated in either a 48-week intervention of intense Tai Chi training or a wellness education (WE) program. INTERVENTIONS: Eight Tai Chi forms emphasizing trunk rotation, weight shifting, coordination, and narrowing of lower-extremity stance were taught twice weekly. WE program participants met once a week and received lectures focused on health.Main outcome measures The COP was recorded during gait initiation both before and after the 48-week intervention by using a forceplate sampling at 300 Hz. The COP trajectory was divided into 3 periods (S1, S2, S3) by identifying 2 landmark events. Displacement and average velocity of the COP trace in the anteroposterior (x) and mediolateral (y) directions, as well as smoothness, were calculated. RESULTS: Tai Chi training increased the posterior displacement of the COP during S1 and improved the smoothness of the COP during S2. CONCLUSIONS: Tai Chi improved the mechanism by which forward momentum is generated and improved coordination during gait initiation, suggesting improvements in postural control.     

Attentional control of postural stability in institutionalised elderly people: effects of a physical exercise program]

OBJECTIVE: We aimed to examine the effect of a physical activity program on postural sway and on the attentional control of postural abilities in elderly frail adults. METHOD: Twelve older adults (age 81.4+/-9 years) institutionalised in a geriatric care institution participated in the physical activity program posture-balance-mobility (PBM) twice a week (1 hour per session) for 12 weeks. We analysed stabilometric data for surface and length of the center of pressure (COP) sway, with eyes open and eyes closed, under single-task and dual-task conditions on a firm floor before and after the training program. During the static postural evaluation and under the dual-task condition, subjects performed an attention-demanding cognitive task, the random number generation task. RESULTS: Only the length of COP sway was more important under the dual-task condition than under the single-task condition (p=0.05). At baseline, cognitive performance was significantly weaker under the dual-task condition (standing) than under the single-task condition (seated), with eyes closed but not eyes open (p<0.05). However, after the training program, the performance of the cognitive task did not significantly differ between the dual-task condition with eyes closed and the single-task condition with eyes closed. CONCLUSION: The training program allowed elderly subjects to improve their ability to perform an attention-demanding cognitive task while standing still, in particular with their eyes closed. Although balance seemed to be less stable under the dual-task condition than under the single-task condition, these results could be interpreted as an improvement of the attentional control of postural stability.     

健康青年人双足间的距离对静态站立平衡功能的影响

目的 探讨健康青年人静态站立时双足间的距离对平衡功能的影响，为平衡功能训练提供理论基础。 方法 选取健康青年受试者30例，其中男7例，女23例，分别在睁眼和闭眼两种方式下，采用平衡评估训练仪评估双足并拢站立、双足分开（50cm）站立和双足最适距离站立3种模式下的静态平衡功能，即压力中心（COP）的相关参数，包括前后摆动幅度标准差、左右摆动幅度标准差、前后平均运动速度、左右平均运动速度、运动椭圆面积、运动长度共6个量化指标，并进行数据分析。 结果 双足最适距离站立时，双侧足跟间平均距离为（18.63±3.67）cm，双侧足尖间平均距离为（29.60±4.93）cm。在睁眼和闭眼状态下，双足并拢站立时的前后摆动幅度标准差、左右摆动幅度标准差、前后平均运动速度、左右平均运动速度、运动椭圆面积和运动长度与双足分开（50cm）站立和最适距离站立时比较，差异均有统计学意义（P<0.05）；睁眼和闭眼状态下，双足最适距离站立时的左右摆动幅度标准差、左右平均运动速度、运动椭圆面积、运动长度与双足分开（50cm）站立时比较，差异均有统计学意义（P<0.05）。 结论 健康青年人在静态站立时，双下肢间有最适距离，在这种距离下，站立静态平衡功能最佳。     

Mirror versus stationary cross feedback in controlling the center of foot pressure displacement in quiet standing in elderly subjects

OBJECTIVE: To investigate the effect of mirror feedback on postural control during quiet standing in elderly adults. DESIGN: Before and after intervention trials. SETTING: Pneumology center in France. PARTICIPANTS: Eleven elderly adults (mean age, 70.7+/-4.6 y; mean body weight, 64.5+/-15.0 kg; mean height, 161.4+/-12.0 cm). INTERVENTIONS: Participants were asked to stand upright, as immobile as possible, in 2 eyes-open and mirror-feedback conditions. The latter experimental condition consisted of supplying the subjects with their frontal reflection by positioning a mirror in front of them. MAIN OUTCOME MEASURES: Foot center of pressure (COP) displacements in the mediolateral (ML) and anteroposterior (AP) directions were recorded using a force platform. RESULTS: The mirror-feedback condition had different effects on postural sway, depending on the direction: range, variability, and maximal instantaneous speed of the COP displacements decreased in the ML direction, whereas these effects remained unchanged in the AP direction. CONCLUSIONS: This study provided evidence that mirror feedback may put elderly adults at lower risk of falling.     

Effect of dynamic tape on postural sway in individuals with chronic ankle instability

ObjectiveTo examine the effects of dynamic tape on balance control in subjects with chronic ankle instability (CAI).MethodsThis two group experimental pre- and post-treatment design included 18 individuals with CAI and 18 controls. The single-limb stance test with eyes open and closed, standing on a force plate (Accusway Plus; AMTI) for 30 s, was conducted before, 10 min (T1) and 24 h (T24) after a dynamic tape application over the gastrocnemius muscle. Outcome measurements were: mean sway velocity, sway area (circular area), and standard deviation of the body center of pressure path length in both mediolateral and anteroposterior directions. Individuals with poor (unable to perform a single leg test for at least 30 s, eyes closed) vs. good postural stability, were also compared.ResultsIn both groups, a repeated analysis of variance demonstrated a significant time main effect on sway velocity (F = 14.95; p < 0.001) and path length (F = 14.95; p < 0.001) during eyes closed. Post-hoc analysis revealed a significant decrease in T1 values compared to baseline. When comparing individuals with poor vs good stability amongst the CAI group, a statistically significant interaction was observed between group, time on sway velocity and path length (F = 3.92; p < 0.05) during eyes closed. In the poor postural group, most T1 values were significantly lower than baseline.ConclusionsDynamic tape when applied to posterior calf muscles, enhanced balance control with no difference between CAI individuals and controls. The contribution of the tape was greater in those with poor postural stability.     

Comparison of postural control in older adults under different dual-task conditions: A cross-sectional study

Backgroundand purpose: Performing a cognitive task while maintaining postural stability, known as “dual-task” condition, can increase the cognitive demand and reduce the postural control capacity. The inability to allocate attention to postural control under dual-task conditions may lead to balance impairments, particularly in older adults. The present study aimed to compare the effects of different dual-task conditions of backward counting (BC) and visual attention (VA) on older adults’ postural balance performance.MethodsTwenty asymptomatic volunteers (mean age: 70.4 ± 4.1 years) were recruited. Participants stood on a foam surface placed over a force plate, and displacement and sway velocity of their center of pressure (COP) in anterior-posterior (AP) and medial-lateral (ML) directions were recorded under three conditions: BC dual-task, VA dual-task (control of center of mass with a laser pointer), and quiet stance as the control task (CT).ResultsRepeated measures ANOVA showed a significant difference in AP and ML sway velocities between conditions with p-values of 0.039 and 0.042, respectively. The LSD post-hoc test revealed that the BC task significantly increased AP sway velocity compared to the CT (p = 0.013), and the VA task significantly increased ML sway velocity compared to the CT (p = 0.034) and the BC tasks (p = 0.026). There were no statistically significant differences between conditions for ML (p = 0.058) and AP (p = 0.350) displacements and total sway velocity (p = 0.051).ConclusionOlder adults’ postural stability can be impaired under dual-task conditions and the present study revealed that various dual tasks increase postural sway in different directions.