Compromised cognition, but not stepping-down performance, when dual-tasking in stroke survivors.

Descending stairs is an indicator of independence among stroke survivors, but is demanding in terms of both neuromuscular control and cognitive functioning. Previous studies found a compromised performance when stepping down with a concurrent cognitive task among healthy older adults, but whether stroke survivors react similarly is not known. This cross-sectional study thus investigated how stroke survivors responded to a dual-task that involved stepping down and compared their performance with that of control subjects. Thirty-four healthy individuals and 26 stroke survivors reacted to an auditory Stroop test while stepping off a 19-cm high platform. The auditory Stroop test was evaluated with a composite score (dividing accuracy by averaged reaction time). Stepping down performances were quantified with subjects' sway amplitudes in anteroposterior and mediolateral directions after landing and sway velocities of their center of pressure. Stroke survivors demonstrated significantly lower composite scores when dual-tasking (76.4 ± 31.2) than when single-tasking (90.0 ± 25.6), while no significant change in stepping down performance was observed. Stroke survivors also swayed significantly more and with a higher velocity than controls when dual-tasking. The results suggested that stroke survivors adopted a posture-first strategy to deal with this dual-tasking challenge. This study raised the awareness on dual-tasking ability among stroke survivors.

Foot posture index and body composition measures in children with and without developmental coordination disorder.

BACKGROUND: Foot posture which forms the distal supporting structure influences on postural stability. Children with developmental coordination disorder (DCD) who are more likely to be overweight or obese may present with flat foot with symptoms that affect daily activities. The aim of this study was to compare the foot posture and body composition measures between children with and without DCD. In addition, this study aimed to investigate the relationship between foot posture and fat percentage. METHODS: Fifty-nine children with DCD (mean age = 8.07±1.10) and sixty-two typically developing children (mean age = 7.97±1.05) were recruited to the DCD and control group respectively. All children received a foot posture assessment and a whole-body dual-energy X-ray absorptiometry (DXA) scan. Foot Posture Index 6 (FPI-6) total scores, sub-scores and lower limb body composition measures including fat mass, lean mass, total mass, fat percentage and fat mass index were measured. RESULTS: Children with DCD revealed a significantly higher FPI-6 left (1.12; 95% CI: 0.172, 2.061) and right (1.15; 95% CI: 0.218, 2.079) total score. FPI-6 sub-scores (talar head palpation and abduction/adduction forefoot on rearfoot) illustrated significant differences between children with and without DCD. Children with DCD had a significantly higher total fat mass (1247.48g; 95% CI: 121.654, 2373.304), total fat percentage (1.82%; 95% CI: 0.115, 3.525) and fat mass index (0.56kg/m2; 95% CI: 0.036, 1.069). There was a significant relationship between FPI-6 right total score and total fat percentage. CONCLUSION: The findings of this study showed that children with DCD exhibited significantly more pronated foot posture and higher body composition measures compared to typically developing children. Moreover, with FPI-6 right total score significantly related to the total fat percentage, it may require more than just detecting abnormal foot structures in children with DCD but also promoting a healthy lifestyle to prevent obesity.

The effect of Tai Chi training on the dual-tasking performance of stroke survivors: a randomized controlled trial.

OBJECTIVE: To compare the effect of Tai Chi training with conventional exercise on dual-tasking performance among stroke survivors. DESIGN: An assessor-blinded, randomized controlled trial. SUBJECTS: Community-dwelling stroke survivors. SETTING: Community centers and university. INTERVENTIONS: Subjects in the Tai Chi group and the conventional exercise group were trained with the corresponding exercises for 12 weeks (1 hour/session, 2/week). No training was given to the controls. MAIN MEASURES: An auditory Stroop test, a turning-while-walking test, and a dual-tasking condition that combined the two tests were conducted at baseline, after the intervention, and one month later. RESULTS: Forty-seven subjects were randomized into Tai Chi group ( n = 15), conventional exercise group ( n = 17), or control group ( n = 15). There was no significant difference in the outcome measures among the three groups after the intervention and at the one month follow-up assessment. Within-group comparisons showed improvements in dual-tasking performance after Tai Chi training and further improvement during the follow-up period (composite score on the auditory Stroop test: pre-assessment: 73.1 ± 27.6, post-assessment: 89.9 ± 23.4, follow-up assessment: 91.7 ± 26.9; completion time of the turning-while-walking test: pre-assessment: 17.7 ± 6.9 seconds, post-assessment: 15.6 ± 5.2 seconds, follow-up assessment: 14.9 ± 4.9 seconds). CONCLUSION: Tai Chi training does not have superior effect on dual-tasking performance compared with conventional exercise among stroke survivors. Further studies with larger sample size, longer training, and follow-up periods are needed.

Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study.

Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor's ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi (n = 9), conventional exercise (n = 8), and control (n = 9) groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1), after training (time-2), and one month after training (time-3). Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted.

The performance of stroke survivors in turning-while-walking while carrying out a concurrent cognitive task compared with controls.

BACKGROUND: Turning-while-walking is one of the commonest causes of falls in stroke survivors. It involves cognitive processing and may be challenging when performed concurrently with a cognitive task. Previous studies of dual-tasking involving turning-while-walking in stroke survivors show that the performance of physical tasks is compromised. However, the design of those studies did not address the response of stroke survivors under dual-tasking condition without specifying the task-preference and its effect on the performance of the cognitive task. OBJECTIVE: First, to compare the performance of single-tasking and dual-tasking in stroke survivors. Second, to compare the performance of stroke survivors with non-stroke controls. METHODS: Fifty-nine stroke survivors and 45 controls were assessed with an auditory Stroop test, a turning-while-walking test, and a combination of the two single tasks. The outcome of the cognitive task was measured by the reaction time and accuracy of the task. The physical task was evaluated by measuring the turning duration, number of steps to turn, and time to complete the turning-while-walking test. RESULTS: Stroke survivors showed a significantly reduced accuracy in the auditory Stroop test when dual-tasking, but there was no change in the reaction time. Their performance in the turning-while-walking task was similar under both single-tasking and dual-tasking condition. Additionally, stroke survivors demonstrated a significantly longer reaction time and lower accuracy than the controls both when single-tasking and dual-tasking. They took longer to turn, with more steps, and needed more time to complete the turning-while-walking task in both tasking conditions. CONCLUSIONS: The results show that stroke survivors with high mobility function performed the auditory Stroop test less accurately while preserving simultaneous turning-while-walking performance. They also demonstrated poorer performance in both single-tasking and dual-tasking as compared with controls.

Changes of heart rate variability and prefrontal oxygenation during Tai Chi practice versus arm ergometer cycling.

[Purpose] Exercise has been shown to improve cardiovascular fitness and cognitive function. Whether the inclusion of mind over exercise would increase parasympathetic control of the heart and brain activities more than general exercise at a similar intensity is not known. The aim of this study was to compare the effects of Tai Chi (mind-body exercise) versus arm ergometer cycling (body-focused exercise) on the heart rate variability and prefrontal oxygenation level. [Subjects and Methods] A Tai Chi master was invited to perform Tai Chi and arm ergometer cycling with similar exercise intensity on two separate days. Heart rate variability and prefrontal oxyhemoglobin levels were measured continuously by a RR recorder and near-infrared spectroscopy, respectively. [Results] During Tai Chi exercise, spectral analysis of heart rate variability demonstrated a higher high-frequency power as well as a lower low-frequency/high-frequency ratio than during ergometer cycling, suggesting increased parasympathetic and decreased sympathetic control of the heart. Also, prefrontal oxyhemoglobin and total hemoglobin levels were higher than those during arm ergometer exercise. [Conclusion] These findings suggest that increased parasympathetic control of the heart and prefrontal activities may be associated with Tai Chi practice. Having a "mind" component in Tai Chi could be more beneficial for older adults' cardiac health and cognitive function than body-focused ergometer cycling.

The effect of performing a dual-task on postural control and selective attention of older adults when stepping backward.

[Purpose] The purpose of the study was to investigate the postural control and cognitive performance of older adults when stepping backward with and without a concurrent cognitive task. [Subjects and Methods] Thirty young adults and twenty-eight older adults (mean age=21.3 ± 1.2 and 72.2 ± 5.7 years, respectively) were recruited. Participants were asked to step backward and then maintain a single-leg stance for 10 seconds with and without a concurrent auditory response task. The reaction time and error rate while performing the cognitive task were recorded. Postural stability after stepping back was measured in terms of total sway path and total sway area. [Results] The older subjects had significantly longer reaction times and higher error rates in both single- and dual-tasking. When dual-tasking, both groups had significantly longer reaction times than when single-tasking. Only the older adults showed significantly higher error rates. The older adults also had significantly longer total sway paths and larger total sway areas of single-leg stance after stepping back. Neither group showed a significant difference in total sway path and sway area between single- and dual-tasking. [Conclusion] Older adults have poorer cognitive performance and postural stability during both single- and dual-tasking. They tend to prioritize postural control over cognition in dual-tasking.

Fall risk in Chinese community-dwelling older adults: A physiological profile assessment study.

AIM: The short-form Physiological Profile Assessment (PPA) is increasingly used in clinical practice for assessing fall risk in older people. However, a normative database is only available for Caucasian populations. The purpose of the present study was to develop a normative database for Hong Kong Chinese older people and examine the fall risk profile of this population. METHODS: A total of 622 participants aged 60-95 years were recruited. Participants underwent the PPA (containing tests of contrast sensitivity, proprioception, quadriceps strength, reaction time and sway), and composite fall risk scores were computed. Participants were then followed up for falls for 1 year. RESULTS: Quadriceps strength and lower limb proprioception scores were comparable with those reported for Caucasian populations. However, contrast sensitivity, simple reaction time and postural sway scores were relatively poor. The average composite fall risk score was 1.7 ± 1.5, showing a "moderate" fall risk when compared with the Caucasian norms. Despite the relatively poor physical performances and moderately high fall risk scores, the incidence of one plus falls in the 1-year follow-up period was just 16.4%, with just 2.6% reporting two plus falls. The area under the curve for composite fall risk scores in discriminating fallers from non-fallers was 0.53 (95% CI 0.45-0.60). CONCLUSIONS: Despite poorer performance in PPA tests, the incidence of prospective falls in a Hong Kong Chinese population was low. In consequence, the PPA could not discriminate well between fallers and non-fallers. The present study provided normality data for short-form PPA measures for older Chinese people as a reference for further studies.