Baseline Variability Affects N-of-1 Intervention Effect: Simulation and Field Studies.

The simulation study investigated the relationship between the local linear trend model's data-comparison accuracy, baseline-data variability, and changes in level and slope after introducing the N-of-1 intervention. Contour maps were constructed, which included baseline-data variability, change in level or slope, and percentage of non-overlapping data between the state and forecast values by the local linear trend model. Simulation results showed that baseline-data variability and changes in level and slope after intervention affect the data-comparison accuracy based on the local linear trend model. The field study investigated the intervention effects for actual field data using the local linear trend model, which confirmed 100% effectiveness of previous N-of-1 studies. These results imply that baseline-data variability affects the data-comparison accuracy using a local linear trend model, which could accurately predict the intervention effects. The local linear trend model may help assess the intervention effects of effective personalized interventions in precision rehabilitation.

Effects of Paired Associative Stimulation on Cortical Plasticity in Agonist-Antagonist Muscle Representations.

Paired associative stimulation (PAS) increases and decreases cortical excitability in primary motor cortex (M1) neurons, depending on the spike timing-dependent plasticity, i.e., long-term potentiation (LTP)- and long-term depression (LTD)-like plasticity, respectively. However, how PAS affects the cortical circuits for the agonist and antagonist muscles of M1 is unclear. Here, we investigated the changes in the LTP- and LTD-like plasticity for agonist and antagonist muscles during PAS: 200 pairs of 0.25-Hz peripheral electric stimulation of the right median nerve at the wrist, followed by a transcranial magnetic stimulation of the left M1 with an interstimulus interval of 25 ms (PAS-25 ms) and 10 ms (PAS-10 ms). The unconditioned motor evoked potential amplitudes of the agonist muscles were larger after PAS-25 ms than after PAS-10 ms, while those of the antagonist muscles were smaller after PAS-25 ms than after PAS-10 ms. The γ-aminobutyric acid A (GABAA)- and GABAB-mediated cortical inhibition for the agonist and antagonist muscles were higher after PAS-25 ms than after PAS-10 ms. The cortical excitability for the agonist and antagonist muscles reciprocally and topographically increased and decreased after PAS, respectively; however, GABAA and GABAB-mediated cortical inhibitory functions for the agonist and antagonist muscles were less topographically decreased after PAS-10 ms. Thus, PAS-25 ms and PAS-10 ms differentially affect the LTP- and LTD-like plasticity in agonist and antagonist muscles.

Risk factors for nursing home admission among older adults: Analysis of basic movements and activities of daily living.

This retrospective study aimed to clarify the risk of older adults' nursing home placement in terms of basic movements and activities of daily living (ADLs) by analyzing data from a long-term care insurance certification survey in 2016‒2018 in City A. Of the 21,520 people certified as needing care, 16,865 could be followed up until 2018. Data on sex, age, household structure, and level of care required were obtained. Those who lived at home and at nursing homes were categorized as the "Unchanged group" and the "Changed group," respectively. Multivariate binomial logistic regression analysis was performed, with group type as the dependent variable and basic movement and ADL scores as the independent variables. For factor analysis according to care level, participants were classified into support need levels 1 and 2, care need levels 1 and 2, and care need levels 3, 4, and 5. For those categorized into support need levels 1 and 2, standing on one leg and transferring (basic movements) and urination and face cleaning (ADLs) were associated with nursing home placement. For those in care need levels 1 and 2, getting up and transferring (basic movements) and bathing, urination, face cleaning, and hair styling (ADL) were significantly associated with nursing home placement. For those in care need levels 3, 4, and 5, sitting and transferring (basic movements) and self-feeding and defecation (ADL) were significant. Occupational therapists must focus on older adults' declining ADLs and basic movements and relay the necessary information to patients, families, and other healthcare professionals to ensure appropriate and prompt care delivery.

EEG Oscillations in Specific Frequency Bands Are Differently Coupled with Angular Joint Angle Kinematics during Rhythmic Passive Elbow Movement.

Rhythmic passive movements are often used during rehabilitation to improve physical functions. Previous studies have explored oscillatory activities in the sensorimotor cortex during active movements; however, the relationship between movement rhythms and oscillatory activities during passive movements has not been substantially tested. Therefore, we aimed to quantitatively identify changes in cortical oscillations during rhythmic passive movements. Twenty healthy young adults participated in our study. We placed electroencephalography electrodes over a nine-position grid; the center was oriented on the transcranial magnetic stimulation hotspot of the biceps brachii muscle. Passive movements included elbow flexion and extension; the participants were instructed to perform rhythmic elbow flexion and extension in response to the blinking of 0.67 Hz light-emitting diode lamps. The coherence between high-beta and low-gamma oscillations near the hotspot of the biceps brachii muscle and passive movement rhythms was higher than that between alpha oscillation and passive movement rhythm. These results imply that alpha, beta, and gamma oscillations of the primary motor cortex are differently related to passive movement rhythm.

Nonequivalent After-Effects of Alternating Current Stimulation on Motor Cortex Oscillation and Inhibition: Simulation and Experimental Study.

The effects of transcranial alternating current stimulation (tACS) frequency on brain oscillations and cortical excitability are still controversial. Therefore, this study investigated how different tACS frequencies differentially modulate cortical oscillation and inhibition. To do so, we first determined the optimal positioning of tACS electrodes through an electric field simulation constructed from magnetic resonance images. Seven electrode configurations were tested on the electric field of the precentral gyrus (hand motor area). We determined that the Cz-CP1 configuration was optimal, as it resulted in higher electric field values and minimized the intra-individual differences in the electric field. Therefore, tACS was delivered to the hand motor area through this arrangement at a fixed frequency of 10 Hz (alpha-tACS) or 20 Hz (beta-tACS) with a peak-to-peak amplitude of 0.6 mA for 20 min. We found that alpha- and beta-tACS resulted in larger alpha and beta oscillations, respectively, compared with the oscillations observed after sham-tACS. In addition, alpha- and beta-tACS decreased the amplitudes of conditioned motor evoked potentials and increased alpha and beta activity, respectively. Correspondingly, alpha- and beta-tACSs enhanced cortical inhibition. These results show that tACS frequency differentially affects motor cortex oscillation and inhibition.

Sex Differences in Age-Related Physical Changes among Community-Dwelling Adults.

The prevalence of physical functioning limitations is positively correlated with age in both men and women. However, whether the appearance of deterioration differs depending on physical function and sex remains unclear. This study aimed to clarify the modes of age-related changes in physical function and sex differences in middle-aged and older adults. This study comprised 124 (46 men and 78 women) healthy adults aged 30 years or older and examined gender differences in physical function. The results of this study showed that one-leg standing time had the highest rate of age-related decline in both men and women, followed by knee extension strength, skeletal muscle mass, the 5 m walking test, and the timed up and go test. The sex-specific points showed a high rate of decline in trunk forward bending in men and a high rate of decline in forced expiratory volume (1 s) and gradual rate of decline in the bone area ratio in women. After middle age, it is desirable to start monitoring and training balance, muscle function, and walking. Men require early intervention for flexibility, and women require early intervention for respiratory function and continued intervention for bone mineral density.

Impact of different bilateral knee extension strengths on lower extremity performance.

ABSTRACT: Despite the impact of leg muscle strength on lower extremity motor performance-including walking and sit-to-stand transfer-it remains difficult to predict the relationship between bilateral leg muscle strength and lower extremity performance. Therefore, this study was designed to predict lower extremity function through the differential modeling of logarithmic and linear regression, based on knee extension strength.The study included 121 individuals living in the same community. The bilateral strengths of the knee extensors were measured using a handheld dynamometer, and the Timed Up & Go test (TUG) performance time and 5-m minimum walking times were assessed to predict lower extremity motor functions. Bilateral normalized knee extension muscle strengths and lower extremity motor function scores, including walking or TUG performance times, were assessed on the logarithmic and linear models. The Akaike information criterion (AIC) was used to evaluate the coefficient compatibility between the logarithmic regression model and the linear regression model.The AIC value for the linear model was lower than that for the logarithmic model regarding the walking time. For walking time estimation in the linear model, the coefficient value of knee extension strength was larger on the strong than on the weak side; however, the AIC value for the logarithmic model was lower than that for the linear model regarding TUG performance time. In the logarithmic model's TUG performance time estimation, the coefficient value of knee extension strength was larger on the weak than on the strong side.In conclusion, our study demonstrated different models reflecting the relationship between both legs' strengths and lower extremity performance, including the walking and TUG performance times.

Long-Term Changes in Older Adults' Independence Levels for Performing Activities of Daily Living in Care Settings: A Nine-Year Follow-Up Study.

This study aimed to clarify the variability in the independence profiles of specific activities of daily living (ADL) among older men and women. The research subjects were 5872 older adults (1143 men and 4729 women) certified as requiring nursing care or support (based on data obtained from the nursing care insurance certification survey database) who could be surveyed in both 2009 and 2018. Using item response theory, this study compared longitudinal data of difficulties faced by older adults during ADL. The results indicated that among the long-term care insurance-certified persons, in 2009, men had higher ADL difficulty than women in all ADL items, and in 2018, there was no significant difference in items other than dressing and excretion. Furthermore, the difference in the rate of ADL difficulty level over 9 years was significantly higher in women than in men. It was shown that the progression of ADL disability due to aging is faster in men on a yearly basis, but it increases in women with aging. Therefore, it was suggested that the rate of ADL difficulty varies depending on age and sex.

Using machine learning to investigate the relationship between domains of functioning and functional mobility in older adults.

Previous studies have shown that functional mobility, along with other physical functions, decreases with advanced age. However, it is still unclear which domains of functioning (body structures, body functions, and activities) are most closely related to functional mobility. This study used machine learning classification to predict the rankings of Timed Up and Go tests based on the results of four assessments (soft lean mass, FEV1/FVC, knee extension torque, and one-leg standing time). We tested whether assessment results for each level could predict functional mobility assessments in older adults. Using support vector machines for machine learning classification, we verified that the four assessments of each level could classify functional mobility. Knee extension torque (from the body function domain) was the most closely related assessment. Naturally, the classification accuracy rate increased with a larger number of assessments as explanatory variables. However, knee extension torque remained the highest of all assessments. This extended to all combinations (of 2-3 assessments) that included knee extension torque. This suggests that resistance training may help protect individuals suffering from age-related declines in functional mobility.

Modification of Eye-Head Coordination With High Frequency Random Noise Stimulation.

The vestibulo-ocular reflex (VOR) plays an important role in controlling the gaze at a visual target. Although patients with vestibular hypofunction aim to improve their VOR function, some retain dysfunction for a long time. Previous studies have explored the effects of direct current stimulation on vestibular function; however, the effects of random noise stimulation on eye-head coordination have not previously been tested. Therefore, we aimed to clarify the effects of high frequency noisy vestibular stimulation (HF-nVS) on eye-head coordination related to VOR function. Thirteen healthy young adult participants with no serious disease took part in our study. The current amplitude and density used were 0.4 mA and 0.2 mA/cm2, respectively, with a random noise frequency of 100-640 Hz. The electrodes were located on both mastoid processes. The stimulus duration and fade in/out duration were 600 and 10 s, respectively. Subjects oscillated their head horizontally, gazing at the fixation point, at 1 Hz (0.5 cycles/s) for 30 repetitions. The coordination of eye-head movements was measured by eye-tracking and a motion capture system. Peak-to-peak angles for eye and head movement and deviation of the visual line from the fixation target revealed no significant differences between HF-nVS and sham. The lag time between the eye and head movement with HF-nVS post-stimulation was significantly shorter than that of the sham. We found that HF-nVS can reduce the lag time between eye and head movement and improve coordination, contributing to a clear retinal image. This technique could be applied as a form of VOR training for patients with vestibular hypofunction.

Association between self-reported walking speed and calcaneal stiffness index in postmenopausal Japanese women.

BACKGROUND: Osteoporosis and related fractures, a worldwide public health issue of growing concern, is characterized by compromised bone strength and an increased risk of fracture. Here we show an association between self-reported walking speed and bone mass among community-dwelling postmenopausal Japanese women aged 50 years and older. DESIGN; CROSS-SECTIONAL STUDY: Setting and Participants; The survey population included 1008 postmenopausal women 50-92 years of age residing in rural communities. METHODS: Self-reported walking speed was ascertained by asking the participants: "Is your walking speed faster than others of the same age and sex?" to which participants responded "yes (faster)" or "no (moderate/slower)." Calcaneal stiffness index was measured. RESULTS: Women with a faster self-reported walking speed were younger and had a lower BMI, higher stiffness index, and higher grip strength than women with a slower walking speed. Multiple linear regression analysis adjusted for age, BMI, grip strength, comorbidity, current smoking, and alcohol drinking status showed a significant association between faster self-reported walking speed and higher calcaneal stiffness index (p <  0.001). CONCLUSIONS: Our findings suggest that questionnaires of walking speed may be useful for predicting bone mass and that a fast self-reported walking may benefit bone health in postmenopausal women.

Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women.

BACKGROUND: An increase in serum undercarboxylated osteocalcin concentrations suggests vitamin K deficiency. Clinical intervention studies suggested that the vitamin K supplementation might contribute to preventing bone loss in postmenopausal women. Evidence on the relationship between serum undercarboxylated osteocalcin (ucOC) levels and bone parameters of quantitative ultrasound (QUS) is limited. We examined the correlation between serum ucOC concentrations and bone status as measured by QUS among middle-aged and older Japanese men and women. METHODS: The subjects were community-dwelling men (n = 358) and women (n = 503) aged ≥ 40 years in Japan. Heel QUS parameters, including the stiffness index, speed of sound, and broadband ultrasound attenuation, were measured. Serum ucOC concentrations were measured by electrochemiluminescence immunoassay. Grip strength was measured in the dominant hand. Information on alcohol drinking, current smoking, exercise, and menopause in women was collected. RESULTS: Serum ucOC concentrations were significantly associated with age in both sexes. Serum ucOC concentrations in men were higher at ≥ 80 years than those in the age groups of 40-49, 50-59, and 60-69 years. Serum ucOC concentrations in women were higher in the age groups of 50-59 and 60-69 years than those at 40-49 years. Partial correlation analysis adjusting for covariates (age, body mass index, grip strength, alcohol drinking, current smoking, and exercise in men; age, body mass index, grip strength, alcohol drinking, current smoking, exercise, and menopause in women) showed that serum ucOC concentrations were negatively significantly correlated with all QUS parameters in women. Serum ucOC concentrations were not correlated with them in men. CONCLUSIONS: Vitamin K deficiency, evaluated with higher serum ucOC, was correlated with poor bone status in women.

[Association between fear of falling and activities of daily living among community-dwelling Japanese older adults].

Objectives　This study aimed to explore the association of difficulties in activities of daily living (ADL) (activities related to bending, spine extension, standing endurance, and walking) with fear of falling among community-dwelling older adults.Methods　We recruited 642 older adults (men, n=267; women, n=375) aged 65 years and over. The mean age was 72.2±5.1 years. Fear of falling, falls in the previous year, pain (low back pain or knee pain), comorbidity, and cataracts were assessed using a self-administered questionnaire. ADL difficulties were assessed individually, such as activities related to bending (getting in or out the car, picking up a lightweight object, putting on socks or stockings, and lifting a 5 kg object from the floor), spine extension (reaching an object above your head), standing endurance (standing on your feet for 2 h), and walking (walking 100 m on a level surface, climbing 10 steps without stopping, and walking down 10 steps). The independent association between fear of falling and each ADL difficulties was assessed using logistic regression analysis.Results　Participants with fear of falling, compared with those without fear of falling, had an older age (74.8 and 71.6 in men, 73.3 and 71.0 in women, respectively; P<0.01), more falls in the previous year (21% and 9% in men, 28% and 11% in women, respectively; P<0.05), pain (80% and 61% in men, 82% and 64% in women, respectively; P<0.01), and comorbidity (23% and 15% in women, respectively; P<0.05). Multivariate logistic regression analysis identified each ADL difficulties except walking 100 m on a level surface as being independently associated with fear of falling after adjusting for age, body mass index, sex, falls in the previous year, pain, and comorbidity.Conclusion　ADL difficulties, such as activities related to bending, spine extension, standing endurance, and walking, except for walking 100 m on a level surface, were associated with fear of falling.

Relationship between bone turnover markers and the heel stiffness index measured by quantitative ultrasound in post-menopausal Japanese women.

Background: Osteoporosis in women is a serious health problem. The relationships between biochemical markers of bone turnover and bone mineral density (BMD) in women have been reported, but no study has examined relationships between tartrate-resistant acid phosphatase-5b (TRACP-5b) or bone-specific alkaline phosphatase (BAP) and bone mass measured by quantitative ultrasound (QUS) in Japanese post-menopausal women. Aim: To investigate the serum TRACP-5b and BAP levels and to determine their associations with the heel stiffness index measured by QUS in post-menopausal women. Subjects and methods: The subjects were 510 post-menopausal women who were invited to participate in periodic health examinations in 2011-2013 (the Unzen Study). The heel stiffness index (bone mass) was measured by QUS. Serum samples were collected and TRACP-5b and BAP levels were measured. Results: Multiple regression analysis showed that a higher log (TRACP-5b) was correlated with a lower stiffness index (p = 0.014) and log (BAP) was not correlated with stiffness index after adjusting for covariates (p = 0.136). Conclusion: Higher rates of bone resorption are associated with a lower stiffness index in Japanese post-menopausal women. These results may indicate that high bone resorption affects bone mass more than bone formation, resulting in a low bone mass.

Relationship between bone turnover markers and the heel stiffness index measured by quantitative ultrasound in middle-aged and elderly Japanese men.

The aim of the present study was to investigate the age-related patterns and the relationships between serum levels of tartrate-resistant acid phosphatase-5b (TRACP-5b) or bone-specific alkaline phosphatase (BAP), and the heel stiffness index measured by quantitative ultrasound (QUS) in 429 Japanese men, with special emphasis on 2 age groups (40-59 years and 60 years or over). The heel stiffness index (bone mass) was measured by QUS. Serum samples were collected, and TRACP-5b and BAP levels were measured. The stiffness index was significantly decreased with age. Log (TRACP-5b) was significantly increased with age, but Log (BAP) was stable. Generalized linear models showed that higher levels of Log (TRACP-5b) and Log (BAP) were correlated with a lower stiffness index after adjusting for covariates in men aged 60 years or over, but not in men aged 40 to 59 years. In conclusion, higher rates of bone turnover markers were associated with a lower stiffness index only in elderly men. These results may indicate a different mechanism of low bone mass among different age groups of men.

Prevalence of fear of falling and associated factors among Japanese community-dwelling older adults.

To determine the prevalence of fear of falling and associated factors among Japanese community-dwelling older adults.Cross-sectional study between 2011 and 2013.Community in which residents voluntarily attended a health examination.We recruited 844 older adults (male, n = 350; female, n = 494) aged 60 to 92 years from among those who presented at the health examination.We assessed fear of falling, falls in the previous year, pain, comorbidity, and cataracts. Five times chair stand time was applied as an indicator of physical performance.The prevalence of fear of falling was 26.9% and 43.3% among the men and women, respectively. Men and women who feared falling were older (P < .01), had longer 5 times chair stand time (P < .01), and more falls in the previous year (P < .05), pain (P < .01), and comorbidity (P < .05). Multivariate logistic regression analysis identified advanced age (odds ratios [OR], 1.57; 95% confidence interval [CI], 1.03-2.39), falls in the previous year (OR, 2.44; 95%CI, 1.29-4.64), and pain (OR, 1.82; 95%CI, 1.03-3.22) in men, and advanced age (OR, 1.59; 95%CI, 1.13-2.24), longer 5 times chair stand times (OR, 1.28; 95%CI, 1.04-1.59), falls in the previous year (OR, 2.59; 95%CI, 1.54-4.34), and pain (OR, 1.65; 95%CI, 1.06-2.55) in women as being independently associated with fear of falling.The prevalence of fear of falling was similar to previous reports. Advanced age, falls in previous year, and pain were associated with fear of falling in men. A longer 5 times chair stand time was also associated with fear of falling among older adult women. Maintenance of physical function and pain management might be important for older adults with fear of falling.

Association of vertebral compression fractures with physical performance measures among community-dwelling Japanese women aged 40 years and older.

BACKGROUND: Numerous reported studies have shown that vertebral compression fractures are associated with impaired function or disability; however, few examined their association with objective measures of physical performance or functioning. METHODS: We examined the association of vertebral compression fractures with physical performance measures in 556 Japanese women aged 40-89 years. Lateral spine radiographs were obtained and radiographic vertebral compression fractures were assessed by quantitative morphometry, defined as vertebral heights more than 3 SD below the normal mean. Measures of physical performance included walking speed, chair stand time and functional reach. Adjusted means of performance-based measures according to the number and severity of vertebral compression fractures were calculated using general linear modeling methods. RESULTS: After adjusting for age, body mass index, back pain, number of painful joints, number of comorbidities and regular physical activities, the walking speed of women with two or more compression fractures (1.17 m/s) was significantly slower than that of women without compression fracture (1.24 m/s) (p = 0.03). Compared with women without compression fracture, chair stand time was longer in women with two or more compression fractures (p = 0.01), and functional reach was shorter (p = 0.01). No significant differences were observed in walking speed, chair stand time, or functional reach between women with one compression fracture and those without compression fracture. CONCLUSIONS: Having multiple vertebral compression fractures affects physical performance in community-dwelling Japanese women. Poor physical functioning may lead to functional dependence, accelerated bone loss, and increased risk for falls, injuries, and fractures. Preventing vertebral compression fracture is considered important for preserving the independence of older adults.

Exercise intervention implemented by trained volunteers improves health-related quality of life among Japanese community-dwelling older females: an intervention study.

[Purpose] This study aimed to evaluate the sustainability and efficacy of exercise intervention, as implemented by professionally trained volunteers, on the health-related quality of life among Japanese community-dwelling older females. [Subjects and Methods] We conducted a non-randomized observational prospective study of a six-month exercise intervention delivered by volunteers or health professionals. Health-related quality of life was scored using the Short Form 36 Health Survey before and after the intervention. Participants were classified into three groups, comprising those with improved health, maintained health, and reduced health. [Results] Among 127 Japanese community-dwelling females aged >65 years, 50 of 62 (80.6%) females involved in the intervention conducted by volunteers, and 55 of 65 (84.6%) females involved in the intervention conducted by health professionals, completed the six-month intervention program. Scoring revealed that interventions by both volunteers and health professionals had a maintaining or improving effect on scores in >70% of participants instead of an expected six-month aging decline. [Conclusion] Exercise intervention by trained volunteers was sustainable and effective for improving the health-related quality of life among Japanese community-dwelling older females. Professionally trained volunteers could benefit communities in helping older persons avoid the need for daily nursing care through promoting health activities.

Age-specific risk factors for incident disability in activities of daily living among middle-aged and elderly community-dwelling Japanese women during an 8-9-year follow up: The Hizen-Oshima study.

AIM: The purposes of the present study were to investigate risk factors for incident disability in activities of daily living (ADL) among middle-aged and older women, and to determine whether there are differences in risk factors according to age groups. METHODS: The participants were 264 Japanese women aged 40 years and older. A self-administered questionnaire was used to survey participants about difficulty in carrying out selected basic and instrumental ADL at baseline and at follow up. ADL disability was defined as difficulty carrying out three or more ADL. Information on knee joint or back pain and comorbidities (heart disease, lung disease, stroke or diabetes mellitus) was obtained using a self-administered questionnaire at baseline. Physical performance measurements (grip strength, chair stand time, rapid walking speed and functional reach) were also carried out at baseline. RESULTS: The prevalence of incident ADL disability was 44 (27.5%) in women aged 40-64 years, and 57 (54.8%) in women aged ≥65 years (P < 0.001). Multiple logistic regression analysis showed that decreased grip strength and having pain were significantly associated with a higher risk for incident ADL disability among women aged 40-64 years. For women aged ≥65 years, decreased rapid walking speed, having a comorbidity and having pain were associated with incident ADL disability. CONCLUSIONS: The present study showed that a different set of risk factors was associated with incident ADL disability among women aged 40-64 years and women aged ≥65 years. Age-specific screening and intervention strategies are necessary for effective prevention of incident ADL disability. Geriatr Gerontol Int 2017; 17: 1096-1101.