Shuhei Mori

Reliability and Validity of Gait Analysis by Android-Based Smartphone

Smartphones are very common devices in daily life that have a built-in tri-axial accelerometer. Similar to previously developed accelerometers, smartphones can be used to assess gait patterns. However, few gait analyses have been performed using smartphones, and their reliability and validity have not been evaluated yet. The purpose of this study was to evaluate the reliability and validity of a smartphone accelerometer. Thirty healthy young adults participated in this study. They walked 20 m at their preferred speeds, and their trunk accelerations were measured using a smartphone and a tri-axial accelerometer that was secured over the L3 spinous process. We developed a gait analysis application and installed it in the smartphone to measure the acceleration. After signal processing, we calculated the gait parameters of each measurement terminal: peak frequency (PF), root mean square (RMS), autocorrelation peak (AC), and coefficient of variance (CV) of the acceleration peak intervals. Remarkable consistency was observed in the test-retest reliability of all the gait parameter results obtained by the smartphone (p<0.001). All the gait parameter results obtained by the smartphone showed statistically significant and considerable correlations with the same parameter results obtained by the tri-axial accelerometer (PF r=0.99, RMS r=0.89, AC r=0.85, CV r=0.82; p<0.01). Our study indicates that the smartphone with gait analysis application used in this study has the capacity to quantify gait parameters with a degree of accuracy that is comparable to that of the tri-axial accelerometer.

Fear of falling is associated with prolonged anticipatory postural adjustment during gait initiation under dual-task conditions in older adults

Little is known about dynamic balance control under dual-task conditions in older adults with fear of falling (FoF). The purpose of this study was to examine the effect of FoF on anticipatory postural adjustment (APA) during gait initiation under dual-task conditions in older adults. Fifty-seven elderly volunteers (age, 79.2 [6.8] years) from the community participated in this study. Each participant was categorised into either the Fear (n=24) or No-fear (n=33) group on the basis of the presence or absence of FoF. Under single- and dual-task conditions, centre of pressure (COP) data were collected while the participants performed gait initiation trials from a starting position on a force platform. We also performed a 10-m walking test (WT), a timed up & go test (TUG), and a functional reach test (FR). The reaction and APA phases were measured from the COP data. The results showed that under the dual-task condition, the Fear group had significantly longer APA phases than the No-fear group, although no significant differences were observed between the 2 groups in the reaction and APA phases under the single-task condition and in any clinical measurements (WT, TUG, and FR). Our findings suggest that specific deficits in balance control occur in subjects with FoF during gait initiation while dual tasking, even if their physical functions are comparable to subjects without FoF.

DUAL-TASK WALK IS A RELIABLE PREDICTOR OF FALLS IN ROBUST ELDERLY ADULTS

National Institute on Aging (NIA). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIA or the National Institutes of Health. Dr. Markland received support through a Veterans Health Administration Career Development Award. Author Contributions: Alayne D. Markland: study concept and design, data analysis, interpretation of data, and manuscript preparation. Patricia S. Goode, Kathryn L. Burgio, and Holly E. Richter: study concept and design, interpretation of data, and critical review of the manuscript. David T. Redden: study concept and design, data analysis, interpretation of data, and critical review of the manuscript. Patricia S. Baker and Richard M. Allman: study concept and design, acquisition of subjects and data, interpretation of data, and critical review of the manuscript. Sponsor’s Role: The sponsors had no active role in the design, methods, subject recruitment, data collection, analysis, or manuscript preparation.

Effects of Balance Training on Muscle Coactivation During Postural Control in Older Adults: A Randomized Controlled Trial

BACKGROUND Recently, several studies have reported age-associated increases in muscle coactivation during postural control. A rigid posture induced by strong muscle coactivation reduces the degree of freedom to be organized by the postural control system. The purpose of this study was to clarify the effect of balance training on muscle coactivation during postural control in older adults. METHODS Forty-eight subjects were randomized into an intervention (mean age: 81.0 ± 6.9 years) and a control group (mean age: 81.6 ± 6.4 years). The control group did not receive any intervention. Postural control ability (postural sway during quiet standing, functional reach, and functional stability boundary) was assessed before and after the intervention. A cocontraction index was measured during the postural control tasks to assess muscle coactivation. RESULTS Cocontraction index values in the intervention group significantly decreased following the intervention phase for functional reach (p < .0125). Cocontraction index values had a tendency to decrease during functional stability boundary for forward and quiet standing tasks. Functional improvements were observed in some of the tasks after the intervention, that is, functional reach, functional stability boundary for forward, one-leg stance, and timed up and go (p < .05). CONCLUSIONS Our study raised the possibility that balance training for older adults was associated with decreases in muscle coactivation during postural control. Postural control exercise could potentially lead older adults to develop more efficient postural control strategies without increasing muscle coactivation. Further research is needed to clarify in greater detail the effects of changes in muscle coactivation.

Effect of the muscle coactivation during quiet standing on dynamic postural control in older adults

Recently, several studies have reported that muscle coactivation during static postural control increases with aging. Although greater muscle coactivation during quiet standing enhances joint stability, it may reduce dynamic postural control. The purpose of this study was to investigate the effect of muscle coactivation during quiet standing on dynamic postural control. Seventy older adults (81.1 ± 7.2 years) participated in this study. Static postural control was evaluated by postural sway during quiet standing, whereas dynamic postural control was evaluated by the functional reach and functional stability boundary tests. Electromyography of the soleus (SOL) and tibialis anterior (TA) was recorded during quiet standing, then coactivation was evaluated using the co-contraction index (CI). We used multiple regression analysis to identify the effect of muscle coactivation during standing on each dynamic postural control variable using age, body mass index (BMI), gender, timed up and go (TUG) tests, postural sway area and CI during quiet standing as independent variables. TUG tests were added to the model to evaluate the effect of functional mobility on dynamic postural control with a fixed base. The multiple regression analysis revealed that CI during standing was significantly related to all of the dynamic postural control tasks. The functional reach distance was significantly associated with CI during standing, age and TUG (p<0.05). The functional stability boundary for forward and backward were associated only with CI during standing (p<0.05). This study revealed that muscle coactivation during quiet standing is independently associated with dynamic postural control abilities.

Effects of fear of falling on muscular coactivation during walking

Background and aims: Increased fear of falling is associated with greater muscular coactivation during standing postural control. Excessive muscular coactivation reduces the performance of agonist muscles. Although several recent studies have observed increased muscular coactivation during walking in older adults, little is known about the relationship between fear of falling and muscular coactivation during walking. The purpose of this study was to compare muscular coactivation during walking between older adults with fear of falling and older adults without fear of falling. Methods: Thirty-eight healthy older adults (82.3±6.8 years) participated in this study. Walking speed and step length were measured. Electromyography (EMG) data were collected from the tibialis anterior and soleus during walking to calculate the co-contraction index (CI). Subjects were divided into those with fear of falling and those without fear of falling, on the basis of a modified Falls Efficacy Scale (FES). Stepwise multiple regression analysis was used, with CI as the dependent variable, and fear of falling, experience of falling (during the past year), walking speed, step length, and age as independent variables. Results: Mean values of CI during walking, walking speed, and step length were 51.9±11.7%, 0.90±0.40 m/s, and 0.43±0.11 m, respectively. Eight subjects (21.1%) had fallen within the past year, and 19 subjects (50.0%) had fear of falling. All subjects without fear of falling had FES scores of 10 (maximum score). Subjects with fear of falling had a median FES score of 17 (interquartile range, 13 to 25). Stepwise multiple regression analysis revealed that fear of falling remained significantly associated with CI (ps<0.01): CIs for subjects with fear and those without fear were 59.5±12.2% and 46.7±8.5%, respectively. Conclusion: Individuals with a fear of falling have increased muscular co-activation at the ankle joint during walking, at least in a certain subgroup of older adults. Further research is needed to clarify negative and positive effects of muscular coactivation during walking in fearful subjects.

Maladaptive turning and gaze behavior induces impaired stepping on multiple footfall targets during gait in older individuals who are at high risk of falling.

It was recently reported that the measurement of stepping accuracy while performing a new walking test, a multi-target stepping task (MTST), could contribute to identifying older individuals at high risk (HR) of falling. The present study was designed to identify factors leading HR older individuals to an impaired stepping performance in terms of frequency of maladaptive turning behavior (spin turn) and spatio-temporal patterns of fixations. Eleven HR (80.8±3.6 years), 26 low-risk (LR) (77.1±7.7 years) older individuals, and 20 younger individuals performed the MTST. For the MTST, stepping accuracy was measured with two types of failure (stepping target and avoiding distracters). The frequency of a spin turn (i.e., a crossover step) was compared among the groups. The location and duration of each fixation were also compared. The HR older and younger participants showed a higher rate of spin turns. Whereas the younger participants fixated approximately three steps ahead, the older participants directed their fixation closer toward the imminent footfall target, demonstrating their difficulty to use the visual information regarding the target in a feedforward manner. Such patterns of fixations were significantly associated with the frequency of stepping and avoidance failures. The higher rate of stepping and avoidance failures in the MTST were attributed to maladaptive turning behavior, which is potentially destabilizing, and the tendency to fixate on/around an imminent footfall target, which prevented older individuals from considering the locations of future footfall targets.

Effects of a DVD-Based Seated Dual-Task Stepping Exercise on the Fall Risk Factors Among Community-Dwelling Elderly Adults

OBJECTIVE The purpose of this randomized control trial study was to evaluate the effectiveness of a digital video disc (DVD)-based seated dual-task (DT) stepping exercise to improve the DT walking capability in elderly people. In the DT exercise, participants were asked to perform a verbal fluency task while stepping as quickly as possible. METHODS Eight clusters (n=93) randomized into a DVD group (4 clusters, n=48) and a nonexercise control group (4 clusters, n=45) participated in this trial. In the DVD group, participants received 20 min of group training twice a week for 24 weeks. The exercise class used an exercise DVD that included a 15-min basic exercise and a 5-min DT exercise. No exercise program was prescribed for the control group. The measurements were based on the difference in physical function, including DT walking, between the DVD and control groups. In the DT walking test, participants walked individually at a comfortable speed while carrying a ball on a tray. The relative DT lag was calculated by using simple walking as the comparison condition. The Timed Up and Go test and the 5-chair stand test were also performed. RESULTS The median relative adherence to the study was 87.5% (25th-75th percentile, 83.3%-95.8%) in the DVD group. The outcome measurements, including the DT walking time and DT time lag (p<0.05), among participants in the DVD group were significantly improved. However, other outcome measurements were not significantly different between the two groups (p>0.05). CONCLUSION The current study reports the effectiveness of a DVD-based exercise for the improvement of the DT walking capability. A larger study is needed to confirm the present results. Study of a Web-based exercise regime would be valuable to identify the most effective exercise for prevention of falls and fall-related fractures.

Effect of resistance training on physical performance and fear of falling in elderly with different levels of physical well-being.

among older adults in primary care. J Gen Intern Med 2007; 22: 92–7. 25. St John P, Montgomery P, Tyas L. Alcohol misuse, gender and depressive symptoms in community-dwelling seniors. Int J Geriatr Psychiatry 2008; 24: 369–75. 26. Bolton M, Robinson J, Sareen J. Self-medication of mood disorders with alcohol and drugs in the National epidemiologic survey on alcohol and related conditions. J Affect Disord 2009; 115: 367–75. 27. Robinson J, Sareen J, Cox B et al. Correlates of selfmedication for anxiety disorders. Results from the National epidemiologic survey on alcohol and related conditions. J Nerv Ment Dis 2009; 197: 873–8. 28. Riley J III, King C. Self-report of alcohol use for pain in a multi-ethnic community sample. J Pain 2009; 10: 944–52.

Global brain atrophy is associated with physical performance and the risk of falls in older adults with cognitive impairment

Aim:  Falls are common in patients with cognitive disorder. The purpose of this study was to determine whether global brain atrophy is associated with cognitive function, physical performance and fall incidents in older adults with mild cognitive disorder.