Dose-Response Association Between Accelerometer-Assessed Physical Activity and Incidence of Functional Disability in Older Japanese Adults: A 6-Year Prospective Study

Segmental phase angle and the extracellular to intracellular water ratio are associated with functional disability in community-dwelling older adults: A follow-up study of up to 12 years

BACKGROUND & AIMS

Muscle quality, including phase angle (PhA) and extracellular to intracellular water (ECW/ICW) ratio, assessed using multi-frequency bioelectrical impedance analysis (MF-BIA) to reflect the contractile components of the muscle, muscle cell mass, and membrane condition, is associated with health outcomes. However, its association with the incidence of disabilities remains unclear. The aim of this study was to examine the association between whole-body and segmental PhA, ECW/ICW ratio, and the incidence of functional disability compared to conventional muscle mass.

METHODS

A total of 858 older adults aged ≥65 years without functional disability at baseline were followed up for 12 years. Functional disabilities were identified using the database of the Japanese Long-Term Care Insurance System. Segmental muscle quality was assessed using the raw parameters of MF-BIA, including segmental PhA and the ECW/ICW resistance ratio. For comparison, the appendicular lean mass index (ALMI) and legMI were obtained using MF-BIA.

RESULTS

Functional disability was identified in 258 (30.1%) participants. Cox regression analysis showed that poorer leg PhA and ECW/ICW resistance ratios were significantly associated with a higher incidence of functional disability in both sexes, independent of covariates. A dose-response relationship indicated a higher risk for individuals with values below the median in the spline analysis. Conventional ALMI and legMI were not significantly associated with functional disability.

CONCLUSIONS

PhA and ECW/ICW ratio, especially in the leg, is a better predictor of functional disability than muscle mass. Muscle quality by BIA may be a useful biomarker for screening for future disabilities.

Associations of objectively measured physical activity and sedentary time with all-cause mortality in Japanese older adults: a 10-year prospective study

OBJECTIVE

To examine the associations of accelerometer-measured physical activity and sedentary time with all-cause mortality in older Japanese adults.

METHODS

A total of 1723 independent Japanese adults aged ≥65 years were followed from 2011 to 2021. Moderate-to-vigorous physical activity (MVPA), light physical activity (LPA) and sedentary time were measured using a triaxial accelerometer secured to participants' waists.

RESULTS

Over a median follow-up of 9.9 years, 336 deaths were recorded. When examined as tertiles, higher MVPA (both ≥10 and <10 min bouts) and LPA were associated with a lower mortality risk. Additional adjustment for MVPA attenuated the associations of LPA, but the HRs in the highest tertile remained significant. Longer sedentary time was significantly associated with an increased mortality risk, but not after adjusting for MVPA. In spline analyses, a linear dose-response association with all-cause mortality was observed for LPA, while the HRs declined progressively with higher levels of MVPA until approximately 80 min/day, beyond which they levelled out. Replacing 10 min/day of sedentary time with MVPA but not LPA was associated with a 12% lower risk of morality (HR 0.88; 95% CI 0.83 to 0.93); the HR for replacing 10 min/day LPA with MVPA was 0.89 (95% CI 0.84 to 0.95). These results were materially unchanged when excluding deaths within the first 5 years of follow-up.

CONCLUSION

Physical activity, regardless of intensity, was associated with a lower all-cause mortality risk among older Japanese adults. Replacing sedentary time or LPA with MVPA was associated with a lower mortality risk. The mortality benefit started from a low MVPA dose and additional benefits were associated with higher doses.

Health-Related Benefits and Adherence for Multiple Short Bouts of Aerobic Physical Activity Among Adults

Most adults do not adhere to established aerobic physical activity (PA) guidelines due in part to various barriers. PA snacks, or periodic short bouts of activity (<10 minutes) offer a potential strategy to overcoming such barriers and increasing PA. Previous efforts have been focused on eliciting the health benefits of PA and exercise snacks, yet adherence to this concept has not been examined. The purpose of this review is to summarize the current literature assessing adherence to PA snacks and health-related outcomes associated with PA snacks. PubMed, CINAHL, and SPORTDiscus were searched for literature published between January 2018-September 2023. Studies investigating adherence and/or the health-related outcomes of PA snacks were included. Of 4201 articles identified, 12 studies were included in the review. Most of the studies were randomized (n = 10), focused on adults with a chronic disease/life-long condition or exhibited a sedentary lifestyle (n = 8), and reported positive health outcomes (n = 12; e.g., improvements in cardiometabolic markers and body composition). Five studies reported adherence to supervised and unsupervised PA snack interventions, with high rates ≥92%. This review supports and extends the previously reported health-related benefits of PA snacks. It also shows promise for increasing overall PA and adherence to the PA guidelines.

Seasonal and sex differences in instrumental activities of daily living and objective physical activity among older adults residing in rural areas with snow and cold regions

Objective

To determine the seasonal differences in instrumental activities of daily living (IADL) and objective physical activity among older adults residing in non-urban areas in snowy and cold regions according to sex.

Patients and Methods

Fifty older adults aged ≥65 years were included in the present study. IADL was assessed using the revised Frenchay Activities Index (FAI), and physical activity was measured using a triaxial accelerometer. Comparisons were made between the snowy and non-snowy seasons based on sex.

Results

Compared to the non-snowy season, the female participants exhibited significantly lower scores for outdoor housework, outdoor activity, and overall scores on the FAI during the snowy season. In terms of physical activity, a decrease in the number of steps and light-intensity physical activity, accompanied by an increase in sedentary behavior, was observed in both sexes. High light-intensity physical activity decreased in the snowy season, especially in the female participants. In addition, the total moderate-to-vigorous physical activity (MVPA) and short-bout MVPA (intermittent and lasting <10 minutes) also decreased.

Conclusion

Considering the significant changes in lifestyle and physical activity during the cold snowy season, women should consider performing alternative physical activities other than indoor household chores. Furthermore, men should be encouraged to participate in indoor household chores they typically do not engage in, irrespective of the season.

Cognitive frailty and functional disability in older adults: A 10-year prospective cohort study in Japan

Cognitive frailty is considered a clinical entity associated with a high risk for adverse health outcomes. However, its clinical significance remains poorly understood. This study investigated the association between cognitive frailty and risk for functional disability among community-dwelling older adults. In total, 1,597 Japanese adults aged ≥ 65 years that were free of dementia and functional disability at baseline were prospectively followed for 10 years. Cognitive frailty was defined as the presence of both physical frailty (using Cardiovascular Health Study criteria) and cognitive impairment (Mini-Mental State Examination score < 26 points). Functional disability was identified using Japan's Long-term Care Insurance System database. Cox proportional hazard models were used to estimate the hazard ratios (HR) for cognitive frailty on the risk for functional disability. Functional disability was identified in 488 participants during follow-up. A multiplicative interaction effect between cognitive impairment and physical frailty on the risk of disability was observed (p = 0.045). Compared with the robust group, the multivariable-adjusted HRs (95% confidence interval) for functional disability were 3.70 (2.37‒5.77) for cognitive frailty, 2.51 (1.81‒3.47) for physical pre-frailty with cognitive impairment, 2.16 (1.42‒3.29) for cognitive impairment only, 1.95 (1.36‒2.80) for physical frailty only, and 1.94 (1.53‒2.46) for physical pre-frailty only. These associations remained after adjusting for the competing risk for death and in sensitivity analyses to minimize potential reverse causality. Cognitive frailty is associated with an increased risk for functional disability in community-dwelling older adults. Cognitive frailty may be a clinically important target for the prevention of functional disability.

Taiso practice and risk of functional disability and dementia among older adults in Japan: The JAGES cohort study

Background

Taiso is a Japanese term encompassing meanings akin to calisthenics. Taiso is a widely used exercise program in Japan but whether it prevents functional disability and dementia remains unclear. This study aimed to elucidate the association between practicing Taiso, especially focusing on the well-known Radio-Taiso, and functional disability and dementia in older adults in Japan.

Methods

This population-based prospective cohort study used data from the Japan Gerontological Evaluation Study (JAGES). The participants were 18,016 people aged 65 years or older who resided in 19 municipalities in Japan and were not certified as needing long-term care at the start of follow-up. The outcomes were all functional disability, moderate-to-severe functional disability, and dementia, during an average of 5.3 years of follow-up. Four groups were created based on type of Taiso practice (None, Radio-Taiso only, Other Taiso only, or Both). The Cox proportional hazards model adjusted for age, sex, equivalized income, educational attainment, household composition, employment status, diseases requiring treatment, activities of daily living, depression, cognitive impairment, and walking duration.

Results

The analysis included data from 11,219 individuals. The mean age of respondents was 74.2 years and 46.3% were men. Compared with the no-practice group, the Other Taiso only group showed a notably decreased risk of all functional disability (hazard ratio [95% CI] 0.87 [0.78-0.96]). The Other Taiso only group was associated with a significant reduction in the hazard ratio for moderate-to-severe functional disability (0.81 [0.70-0.93]). Decreases in the hazard ratio for dementia were also observed in the Radio-Taiso only (0.82 [0.68-0.9998]) and Other Taiso only groups (0.81 [0.70-0.93]).

Conclusions

Practicing Taiso, including Radio-Taiso, may reduce the risk of dementia in older adults, while practicing other types of Taiso may reduce the risk of functional disability.

Data Analytics in Physical Activity Studies With Accelerometers: Scoping Review

BACKGROUND

Monitoring free-living physical activity (PA) through wearable devices enables the real-time assessment of activity features associated with health outcomes and provision of treatment recommendations and adjustments. The conclusions of studies on PA and health depend crucially on reliable statistical analyses of digital data. Data analytics, however, are challenging due to the various metrics adopted for measuring PA, different aims of studies, and complex temporal variations within variables. The application, interpretation, and appropriateness of these analytical tools have yet to be summarized.

OBJECTIVE

This research aimed to review studies that used analytical methods for analyzing PA monitored by accelerometers. Specifically, this review addressed three questions: (1) What metrics are used to describe an individual's free-living daily PA? (2) What are the current analytical tools for analyzing PA data, particularly under the aims of classification, association with health outcomes, and prediction of health events? and (3) What challenges exist in the analyses, and what recommendations for future research are suggested regarding the use of statistical methods in various research tasks?

METHODS

This scoping review was conducted following an existing framework to map research studies by exploring the information about PA. Three databases, PubMed, IEEE Xplore, and the ACM Digital Library, were searched in February 2024 to identify related publications. Eligible articles were classification, association, or prediction studies involving human PA monitored through wearable accelerometers.

RESULTS

After screening 1312 articles, 428 (32.62%) eligible studies were identified and categorized into at least 1 of the following 3 thematic categories: classification (75/428, 17.5%), association (342/428, 79.9%), and prediction (32/428, 7.5%). Most articles (414/428, 96.7%) derived PA variables from 3D acceleration, rather than 1D acceleration. All eligible articles (428/428, 100%) considered PA metrics represented in the time domain, while a small fraction (16/428, 3.7%) also considered PA metrics in the frequency domain. The number of studies evaluating the influence of PA on health conditions has increased greatly. Among the studies in our review, regression-type models were the most prevalent (373/428, 87.1%). The machine learning approach for classification research is also gaining popularity (32/75, 43%). In addition to summary statistics of PA, several recent studies used tools to incorporate PA trajectories and account for temporal patterns, including longitudinal data analysis with repeated PA measurements and functional data analysis with PA as a continuum for time-varying association (68/428, 15.9%).

CONCLUSIONS

Summary metrics can quickly provide descriptions of the strength, frequency, and duration of individuals' overall PA. When the distribution and profile of PA need to be evaluated or detected, considering PA metrics as longitudinal or functional data can provide detailed information and improve the understanding of the role PA plays in health. Depending on the research goal, appropriate analytical tools can ensure the reliability of the scientific findings.

Physical Activity Fragmentation and Falls in Older Adults: Findings From the National Health and Aging Trends Study

BACKGROUND

Physical activity (PA) may be an important fall prevention strategy. Current PA guidelines emphasize total PA dose, but daily patterning of PA is underappreciated. With aging, PA bouts become less frequent and shorter in duration (ie, more fragmented). PA fragmentation may be an indicator of fall risk, but the relationship is not well understood. This study examined daily PA accumulation and patterns with fall risk in older adults.

METHODS

Participants (n = 685, 54.3% women, 61.5% aged 70-79 years) from the National Health and Aging Trends Study with wrist-worn accelerometry PA data from Round 11 (baseline) and sample person interviews with fall data from Round 12 (follow-up) were included. PA variables were categorized into tertiles and incident falls were defined as ≥1 self-reported fall in the year following the PA assessment between baseline and follow-up. A modified Poisson approach was used to estimate the relative risk of both PA accumulation and fragmentation with falls.

RESULTS

Overall, 40.0% reported an incident fall. After adjustment for sociodemographic and health characteristics, those in the highest tertile of total PA accumulation had lower fall risk (aRR = 0.74, 95% CI: 0.57, 0.95) and those in the highest tertile of PA fragmentation had increased fall risk (aRR = 1.33, 95% CI: 1.03, 1.73). Models were attenuated after adjustment for physical functioning.

CONCLUSIONS

PA fragmentation may identify fall risk in older adults. Longitudinal studies are needed to disentangle the temporal sequencing of the complex relationship between PA and physical functioning across the life course.

Dose-response associations between physical activity and sedentary time with functional disability in older adults with or without frailty: a prospective cohort study

Purpose

Evidence regarding the dose-response curve shapes of physical activity (PA) and sedentary time (ST) in older adults with functional disability (FD) is extremely limited. Moreover, these associations may differ depending on with/without frailty. We examined the dose-response associations between moderate-to-vigorous PA (MVPA) and ST with FD among older adults with/without frailty.

Methods

We included 7,480 initially nondisabled adults (3,795 men and 3,685 women) aged 65-84 years in Ota City, Tokyo, Japan. MVPA and ST were evaluated using the International Physical Activity Questionnaire-Short Form. FD was prospectively identified using a nationally unified database of the long-term care insurance system. Frailty was determined using Check-List 15, validated against Fried's frailty criteria. Multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of MVPA and ST for FD were calculated, and dose-response curves were examined using restricted cubic splines.

Results

During 3.6 years of follow-up, 1,001 (13.4%) participants had FD. Among all participants, compared with no MVPA, the HRs for FD reduced linearly up to approximately 2000 metabolic equivalents (METs)■min/week of MVPA, and the lowest HR (HR: 0.61, 95% CI: 0.51-0.74) was reached at around 3,000-4,000 METs■min/week. Although the shape of this association was consistent regardless of with/without frailty, the magnitude of the association tended to be stronger in frail older adults than in non-frail older adults. Compared with those for the median (300 min/day) of ST, the HRs for FD increased linearly as ST reached approximately 600 min/day or more, independent of MVPA, with a maximum HR of 1.31 (95% CI: 1.01-1.71) for 1,080 min/day among all participants. This association was more pronounced among non-frail older adults but not statistically significant among frail older adults.

Conclusion

Higher MVPA levels consistently reduced the incidence of FD regardless of frailty in a significant inverse nonlinear dose-response manner. A significant positive nonlinear dose-response association between ST and FD risk was identified among non-frail older adults but not among frail older adults. Increasing MVPA and reducing prolonged ST are important for preventing FD among non-frail older adults. However, reducing ST alone may be insufficient; increasing MVPA, even if by only small increments, is highly recommended for frail older adults.

Lifestyle factors and incident functional disability among a rural ageing population in South Africa

OBJECTIVE

The study aimed to assess the relationship between lifestyle factors and incident functional disability in South Africa.

METHODS

Longitudinal data (N = 4113) from two consecutive waves in 2014/2015 and 2018/2019 in Agincourt, South Africa, were analysed.

RESULTS

Moderate sedentary behaviour (AOR: 1.84, 95% CI: 1.31-2.58) and being overweight (AOR: 1.61, 95% CI: 1.10-2.36) increased the odds of incident functional disability among men. Moderate and high sedentary behaviour (AOR: 1.83, 95% CI: 1.31, 2.57, and AOR: 1.83, 95% CI: 1.08-3.10) increased the odds, and frequent fruit intake (AOR: 0.41, 95% CI: 0.19-0.91) and moderate physical activity (AOR: 0.47, 95% CI: 0.30-0.75) decreased the odds of incident functional disability among women.

CONCLUSIONS

Sedentary behaviour and being overweight increased odds, and physical activity and frequent fruit intake decreased odds of incident functional disability among ageing men and/or women in South Africa.

Utilization of Japanese long-term care-related data including Kaigo-DB: An analysis of current trends and future directions

Despite high expectations from the government and researchers regarding data utilization, comprehensive analysis of long-term care (LTC)-related data use has been limited. This study reviewed the use of LTC-related data, including Kaigo-DB, in Japan after 2020. There was an increase in studies using LTC-related data in Japan between 2020 and 2021, followed by a stabilization period. The national government provided 13.5% of this data (6.5% from Kaigo-DB), while prefectures and municipalities contributed 85.2%, and facilities provided 1.3%. The linked data used in 90.4% of the studies primarily consisted of original questionnaire or interview surveys (34.6%) and medical claims (34.0%). None of the studies based on Kaigo-DB utilized linked data. In terms of study design, cohort studies were the most common (84.6%), followed by descriptive (5.1%), cross-sectional (3.2%), and case-control studies (1.3%). Among the 138 individual-based analytical descriptive studies, the most frequently used LTC-related data as an exposure was LTC services (26.8%), and the most common data used as an outcome was LTC certification or care need level (43.5%), followed by the independence degree of daily living for the older adults with dementia (18.1%). To enhance the use of LTC-related data, especially the valuable national Kaigo-DB, insights can be gleaned from how researchers effectively utilize municipal and prefectural data. Streamlining access to Kaigo-DB and enabling its linkage with other datasets are promising for future research in this field.

Accelerometer-measured physical activity and sample-based frailty in older women: does pattern really matter?

Background

The relationship between the patterns of physical activity (PA) and frailty, including its various subdomains, remains poorly understood. Therefore, this study aims to investigate the correlations between the patterns of physical activity and frailty and its various subdomains in community-dwelling older women.

Methods

A cross-sectional study investigated the association between physical activity and frailty in 1,099 women aged between 60 to 70 years. Triaxial accelerometers were used to measure bouted PA (a minimum duration of 10 min) and sporadic PA (a duration of <10 min). Fried's frailty phenotype was utilized to evaluate the status of frailty. Data were analyzed using logistic regression and the receiver operating characteristic (ROC) curve.

Results

Bouted moderate-to-vigorous PA (MVPA) and sporadic MVPA were associated with decreased odds of being prefrail and frail, and the optimal cutoff values were 6 and 19.7 for the prefrail stage and 6.6 and 19.4 min/day for the frail stage, respectively. Bouted light PA (LPA) was associated with decreased odds of being prefrail, and the optimal cutoff value was 170.2 min/day. Additionally, bouted and sporadic MVPA were associated with decreased odds of being slow and their optimal cutoff values were 5 and 19.1 min/day, respectively. Sporadic MVPA was associated with decreased odds of exhaustion, and the cutoff was 19.7 min/day. Bouted MVPA and LPA were associated with decreased odds of having low PA, and the cutoff values were 4.4 and 163.2 min/day, respectively.

Conclusion

Any MVPA, regardless of bout duration, could be used as a suitable PA program to improve and prevent frailty in older women, such as bouted MVPA (4-5 times/week) or sporadic MVPA (20 min/day). The improvement effect of bouted and sporadic MVPA on the frailty of older people may not be affected by the subdomain. Additionally, bouted LPA was suitable for the management of prefrailty.

Relationship between Phase Angle and Physical Activity Intensity among Community-Dwelling Older Adults in Japan: A Cross-Sectional Study

This cross-sectional study aimed to determine the association between phase angle (PhA) and physical activity intensity in community-dwelling older Japanese adults. The intensity and time of physical activity for predicting high PhA were also examined. This study involved 67 community-dwelling older adults (mean age: 78.3 ± 5.5; female: 83.6%). We measured the physical activity and body composition of the participants. Physical activity was measured using a triaxial accelerometer, and light-intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA) hours per day were calculated from the results. Body composition was measured using Inbody S10, and the PhA was calculated from the measurements of the right side of the body. Bayesian statistical modeling revealed an association between PhA and MVPA (β = 0.256; p = 0.022; 95% Bayesian confidence interval [CI] = 0.001, 0.012), but not LPA (β = -0.113; p = 0.341; 95% Bayesian CI = -0.002, 0.001), even after adjustment for confounders. The cutoff value of MVPA predicting high PhA, calculated by the receiver operator characteristic curve, was 19.7 min/d (sensitivity = 0.906; specificity = 0.429). These results can be used to develop strategies to increase PhA in older adults and suggest that MVPA is important in this population.

Dose-response Associations of Physical Activity and Sitting Time With All-cause Mortality in Older Japanese Adults

PURPOSE

Although examining the dose-response curves of physical activity (PA) and sitting time with health-related outcomes is an important research agenda, the results for older Japanese adults are extremely limited. We examined the dose-response associations of PA and sitting time with all-cause mortality among older Japanese.

METHODS

Initially, 8,069 non-disabled residents (4,073 men; 3,996 women) aged 65-84 years of Ota City, Japan, were analyzed. Moderate-to-vigorous PA (MVPA) and sitting time were evaluated using the International Physical Activity Questionnaire-Short Form. Multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of MVPA and sitting time for all-cause mortality were calculated, and the dose-response curves were examined using restricted cubic splines (RCS).

RESULTS

During 4.1 years of follow-up, 458 participants (5.7%; 331 men and 127 women) died. Compared with the low MVPA (<600 metabolic equivalents [METs]·minutes/week) group, HR for mortality gradually reduced in moderate (600-3,000 METs·minutes/week) and high (>3,000 METs·minutes/week) MVPA groups (moderate: HR 0.66; 95% CI, 0.54-0.82; high: HR 0.58; 95% CI, 0.45-0.75; P < 0.001 for trend). RCS showed that the HR for mortality reduced linearly up to approximately 2,000 METs·minutes/week of MVPA, and maximal risk reduction was seen at approximately 3,000-4,500 METs·minutes/week of MVPA. No significant dose-response association of sitting time with mortality was observed.

CONCLUSION

Higher MVPA levels reduced all-cause mortality risk, in a significant inverse non-linear dose-response manner. Sitting time was not significantly associated with all-cause mortality. It is important to disseminate the significance of even a slight increase in the MVPA for reducing mortality risk.

The relationship between working status in old age and cause-specific disability in Japanese community-dwelling older adults with or without frailty: A 3.6-year prospective study

AIM

To examine the effects of employment engagement, classified by frailty and working status, on the incidence of disability in urban community-dwelling older adults.

METHODS

We used data from 6386 initially nondisabled residents aged 65-84 years from Ota City, Tokyo, Japan, in 2016. The observation duration was 3.6 years. Self-administered questionnaires applied the Cox proportional hazard model by assessing the existence of frailty through Check-List 15 (with a score ≥4 indicating the state of frailty), controlling for age, sex, living situation, education level, equivalent income, chronic conditions, body mass index, instrumental activities of daily living, self-rated health, drinking and smoking status, and social activities. We evaluated the predictive value of working status (full-time, part-time, temporary, or nonworker) at baseline for cause-specific disability (dementia-type vs. non-dementia-type) incidence, identified using the long-term care insurance system's nationally unified database.

RESULTS

Of the 6386 participants, 806 (63/1134 full-time workers; 58/1001 part-time workers; 61/547 temporary workers; 624/3704 nonworkers) presented with disabilities during the 3.6-year-long duration. Adjustments for conventional covariates showed that nonfrail full-time and part-time workers, as well as frail full-time workers, had significantly lower risks of all-cause disability incidence. Furthermore, nonfrail and frail full-time workers had significantly lower risks of dementia-type and nondementia-type disabilities, respectively.

CONCLUSIONS

The incidence of disability in older adults was influenced by working and frailty status. Engaging in full-time work thus prevents disabilities in older adults, regardless of their frailty status. Meanwhile, nonfrail older adults are able to avoid disabilities even when engaging in part-time work. Geriatr Gerontol Int 2023; 23: 855-863.

Physical Activity in Community-Dwelling Older Adults: Which Real-World Accelerometry Measures Are Robust? A Systematic Review

Measurement of real-world physical activity (PA) data using accelerometry in older adults is informative and clinically relevant, but not without challenges. This review appraises the reliability and validity of accelerometry-based PA measures of older adults collected in real-world conditions. Eight electronic databases were systematically searched, with 13 manuscripts included. Intraclass correlation coefficient (ICC) for inter-rater reliability were: walking duration (0.94 to 0.95), lying duration (0.98 to 0.99), sitting duration (0.78 to 0.99) and standing duration (0.98 to 0.99). ICCs for relative reliability ranged from 0.24 to 0.82 for step counts and 0.48 to 0.86 for active calories. Absolute reliability ranged from 5864 to 10,832 steps and for active calories from 289 to 597 kcal. ICCs for responsiveness for step count were 0.02 to 0.41, and for active calories 0.07 to 0.93. Criterion validity for step count ranged from 0.83 to 0.98. Percentage of agreement for walking ranged from 63.6% to 94.5%; for lying 35.6% to 100%, sitting 79.2% to 100%, and standing 38.6% to 96.1%. Construct validity between step count and criteria for moderate-to-vigorous PA was rs = 0.68 and 0.72. Inter-rater reliability and criterion validity for walking, lying, sitting and standing duration are established. Criterion validity of step count is also established. Clinicians and researchers may use these measures with a limited degree of confidence. Further work is required to establish these properties and to extend the repertoire of PA measures beyond "volume" counts to include more nuanced outcomes such as intensity of movement and duration of postural transitions.

Accelerometer-measured sedentary behavior and risk of functional disability in older Japanese adults: a 9-year prospective cohort study

BACKGROUND

The associations of sedentary time and patterns with functional disability among older adults remain unclear, and few studies have accounted for the co-dependency of sedentary behavior and physical activities when modeling sedentary behavior with risk of functional disability. We aimed to examine the associations between sedentary time and patterns and risk of incident functional disability, and assess whether replacing sedentary time with light physical activity (LPA) or moderate-to-vigorous intensity physical activity (MVPA) is associated with reduced risk of functional disability in community-dwelling older adults.

METHODS

A total of 1,687 Japanese adults aged ≥ 65 years without functional disability at baseline were prospectively followed-up for 9 years (2011-2020). Functional disability was ascertained using the national database of Japan's Long-term Care Insurance System. Sedentary time and patterns, LPA, and MVPA were measured using a tri-axial accelerometer secured to participants' waists.

RESULTS

During follow-up, 466 participants developed functional disability. Compared with the lowest quartile of total sedentary time, the multivariable-adjusted hazard ratios (95% confidence intervals) of functional disability for the second, third, and top quartiles were 1.21 (0.91‒1.62), 1.45 (1.10‒1.92), and 1.40 (1.05‒1.88) (p for trend = 0.01). After further adjusting for MVPA, total sedentary time was no longer significantly associated with the risk of functional disability (p for trend = 0.41). Replacing 10 min/day of sedentary time with the same amount of MVPA (but not LPA) was significantly associated with a 12% reduced risk of functional disability (hazard ratio [95% confidence interval]: 0.88 [0.84‒0.92]). No significant association was observed between sedentary bout length and functional disability.

CONCLUSION

Higher levels of total sedentary time were associated with an increased risk of incident functional disability. However, this association was not independent of MVPA. Replacing sedentary time with MVPA, but not LPA, was associated with reduced risk of functional disability in older adults.

Adherence to the physical activity guideline beyond the recommended minimum weekly amount: impacts on indicators of physical function in older adults

Introduction

The extent to which additional health benefits of accumulating twice the minimum amount of time in moderate-to-vigorous physical activity (MVPA) affects indicators of physical function in older adults is unclear. Therefore, the aim of the present study was to assess indicators of physical function in older adults who accumulate at least 150 but less than 300 min/week of MVPA compared to those accumulating at least 300 min/week.

Methods

Indicators of physical function, including handgrip strength, 5 times sit-to-stand test (5-STS), squat jump and 6-min walk test (6MWT) were assessed in a sample of 193 older men (n = 71, 67 ± 2 years), and women (n = 122, 67 ± 2 years), who all accumulated at least 150 weekly minutes of MVPA. Time in MVPA was assessed by accelerometry during 1 week and engagement in muscle strengthening activities (MSA) was assessed by self-report. Protein intake was assessed by a food-frequency-questionnaire. Participants were classified as physically active (≥150 but <300 min of MVPA per week) or as highly physically active (≥300 min of MVPA per week).

Results

Factorial analysis of variance revealed that older adults accumulating at least 300 min of MVPA per week had a significantly (p < 0.05) better 6MWT performance and overall physical function compared to the less active group. These findings remained significant after further adjustment for MSA, sex, waist circumference and protein intake. In contrast, no significant differences in indicators of muscle strength were observed between the two groups.

Discussion

Adherence to twice the recommended minimum amount of weekly MVPA time is related to a better physical function, evidenced by a better walking performance compared to adherence to the minimum weekly amount of MVPA. This finding emphasizes the benefits of accumulating daily MVPA beyond the minimum recommended amount to optimize the ability to perform activities of daily living, thus reducing the burden of physical disability and related health-care costs.

Acceptable walking and cycling distances and functional disability and mortality in older Japanese adults: An 8-year follow-up study

We prospectively investigated the association between acceptable travel distances (i.e., walking and cycling) and the incidence of functional disability and mortality among older Japanese adults. A baseline survey was conducted in 2013 among 7618 individuals aged ≥65 years in Kasama City, Japan, and they were tracked through the city's database until 2021. Acceptable travel distances were assessed using a questionnaire. Outcomes (i.e., functional disability and mortality) were gathered as binary (incident or not) with survival time. A multivariable-adjusted Cox proportional-hazards model indicated that shorter acceptable walking and cycling distances were markedly linked with higher risks of functional disability and mortality. In conclusion, acceptable distances of ≤500 m for walking and ≤1 km for cycling were associated with higher risks of functional disability and mortality among older adults.

Predictive ability of the total score of the Kihon checklist for the incidence of functional disability in older Japanese adults: An 8-year prospective study

AIM

To investigate the association between the total score of the Kihon checklist (t-KCL score) and functional disability over an 8-year follow-up period, and to examine whether the t-KCL score in the basic model with risk factors contributes to the incremental predictive ability for functional disability among older adults.

METHODS

We followed 2209 older adults aged ≥65 years without functional disability at baseline. The t-KCL score was determined using a baseline survey questionnaire. Functional disability was defined based on information from long-term care certifications. The association between the t-KCL score and functional disability was examined using the Cox proportional hazards model. The incremental predictive ability of the t-KCL score for functional disability was evaluated by the difference of the C-statistic, category-free net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

RESULTS

The median follow-up period was 7.8 years, and 557 participants developed functional disability. The adjusted hazard ratio (95% confidence interval [CI]) of functional disability for a 1-point increase of the t-KCL score was 1.08 (1.06-1.10). Adding the t-KCL score to the basic model significantly improved the C-statistic (95% CI) from 0.747 (0.728-0.768) to 0.760 (0.741-0.781). When the t-KCL score was added to the basic model, the NRI and IDI were 0.187 (95% CI: 0.095-0.287) and 0.020 (95% CI: 0.012-0.027), respectively.

CONCLUSIONS

The t-KCL score had an independent positive association with functional disability over an 8-year follow-up. Furthermore, adding the t-KCL score to the basic model improved the predictive ability for functional disability. Geriatr Gerontol Int 2022; 22: 723-729.

Predictive validity of the modified Kihon Checklist for the incidence of functional disability among older people: A 3-year cohort study from the JAGES

AIM

The original Kihon Checklist, validated to predict the incidence of functional disability, has been modified to capture both functional ability (can/cannot) and performing state (do/do not). However, the predictive validity of the modified Kihon Checklist remains unverified. Therefore, this study intends to verify the predictive validity of the modified Kihon Checklist and to clarify whether predictive discrimination differs between the classification method of functional ability and performing state.

METHODS

The participants comprised 67 398 older people who responded to the Japan Gerontological Evaluation Study (2016). They were followed for 3.1 years on average. Cox's proportional hazards model with incidence of functional disability as the endpoint was used to calculate the hazard ratio, adjusted for sex and age. The independent variables were judged by two classification methods, functional ability and performing state, using nine indicators based on the modified Kihon Checklist. Additionally, we examined whether the two classification methods produced different C-index estimates.

RESULTS

Incidence of functional disability occurred in 6232 participants (9.2%). The adjusted hazard ratio of those to whom the nine indicators applied was significantly higher than that of those to whom they did not. The range of the hazard ratio was 1.50-3.82 for both classification methods. The C-index was slightly higher when the classification was based on performing state than when it was based on on functional ability.

CONCLUSIONS

Although predictive discrimination was slightly higher for the performing state than for functional ability, the predictive validity of the modified Kihon Checklist was confirmed for both. Geriatr Gerontol Int 2022; ••: ••-••.

Patterns of Accelerometer-Measured Physical Activity and Health Outcomes in Adults: A Systematic Review

PURPOSE

The aim of this study was to systematically review the literature on accelerometer-measured physical activity and health outcomes in adults.

METHODS

Eight electronic databases were searched for relevant articles published up to March 2021. Only population-based studies of adults (age ≥18 yr) that directly compared two or more categories of physical activity (i.e., bout duration, intensity, and daily/weekly frequency) with a health outcome (e.g., mortality, cardiometabolic, healthy aging, depression, sleep, and brain structure) were included.

RESULTS

Of the 15,923 publications retrieved, 52 articles were included. Twenty-eight studies directly compared the associations between physical activity accumulated in different bout durations, 31 studies directly compared the associations between physical activity accumulated in different intensities, and 9 studies directly compared the associations between the effects of varying daily and weekly frequencies of physical activity, with health outcomes. Most showed no differences in relationships with health outcomes when physical activity was accumulated in short (<10-min) or long (≥10-min) bouts. Overall, there were no differences in the relationships with most health outcomes when different intensities and daily/weekly frequencies were compared. However, in most studies, researchers did not adjust their analyses for total volume of physical activity. Moreover, variations in researcher-driven decisions about data collection and processing methods made it difficult to compare study findings.

CONCLUSIONS

These findings suggest that physical activity accumulated in many patterns of bout duration, intensity, or daily/weekly frequency is associated with a range of beneficial health outcomes in adults. Lack of adjustment for total volume of physical activity in most studies and inconsistent methods for defining components of physical activity prevent firm conclusions about which specific patterns of bout duration, intensity, and daily/weekly frequency are most important for health benefits.

Isotemporal Substitution of Sedentary Behavior With Moderate to Vigorous Physical Activity Is Associated With Lower Risk of Disability: A Prospective Longitudinal Cohort Study

OBJECTIVE

The purpose of the study was to estimate, using an isotemporal substitution model, the effect of replacing sedentary behavior (SB) with physical activity on the incidence of disability in community-dwelling older adults.

METHODS

This 2-year longitudinal cohort study enrolled 3691 community-dwelling older adults (57.2% women; mean age = 74.0 [SD = 5.0] years). Individuals with dementia, stroke, Parkinson disease, depression, low Mini-Mental State Examination scores, dependence on basic activities of daily living, and missing data were excluded. Physical activity and potential confounding factors were investigated as a baseline survey of disability incidence, defined by Japanese long-term care insurance certification, for 2 years in 2 regions. Physical activity data (SB, light-intensity physical activity, and moderate- to vigorous-intensity physical activity [MVPA]) were measured using triaxial accelerometers for 14 days, and daily mean time spent in each physical activity parameter was computed in increments of 10 minutes. The relationship between baseline physical activity and disability incidence adjusted for potential confounders was analyzed using multilevel Cox proportional hazards regression analyses with an isotemporal substitution model.

RESULTS

The disability incidence rate was 3.8%, excluding individuals who could not be followed-up. Replacing 10 minutes of SB per day with MVPA was associated with a decreased disability incidence (hazard ratio = 0.870; 95% CI = 0.766-0.988), whereas no evidence was found for replacing SB with light-intensity physical activity (hazard ratio = 0.980; 95% CI = 0.873-1.10).

CONCLUSIONS

Replacing SB with MVPA was associated with a lower risk of disability. These findings are helpful for establishing disability prevention strategies.

IMPACT

These results suggest that feasible changes in daily behavior, such as replacing 10 minutes of SB with MVPA daily, might have a protective effect on disability incidence. Clarifying these associations is useful for developing disability prevention strategies and may help reduce the incidence of disability in community-dwelling older adults.

Comorbid depression and obesity, and its transition on the risk of functional disability among middle-aged and older Chinese: a cohort study

Background

Evidence has indicated that depression and obesity were associated with functional disability, independently. However, little is known about the detrimental impact of comorbid depression and obesity, as well as its transition on functional disability. This study investigated the association of baseline depression-obesity status and its dynamic change with incident functional disability among middle-aged and older Chinese.

Methods

This cohort study included 5507 participants aged ≥45 years from the 2011 and 2015 waves of China Health and Retirement Longitudinal Study. Depression was defined with a score ≥ 10 using the 10-item Centre for Epidemiologic Studies Depression Scale. Obesity was defined as body mass index ≥28 kg/m². Participants were cross-classified by depression and obesity status at baseline, and its change during follow-up. Logistic regression models were constructed to evaluate the association of baseline depression-obesity status and its transition with incident functional disability defined by the Katz index of activities of daily living scale.

Results

Over four-year follow-up, 510 (9.3%) participants developed functional disability. Individuals with baseline comorbid depression and obesity had the highest risk of functional disability (OR = 2.84, 95% CI: 1.95–4.15) than non-depressive participants without obesity, or those with depression or obesity alone. When investigating the dynamic changes of depression-obesity status on functional disability incidence, those with stable comorbidity throughout two surveys had the greatest risk of functional disability (OR = 4.06, 95% CI: 2.11–7.80). Progression of depression-obesity status was associated with increased risk of functional disability, while regression from baseline to follow-up was linked to attenuated risk estimates.

Conclusions

Among middle-aged and older Chinese adults, the risk of functional disability was exaggerated with comorbid depression and obesity. Our data further suggest that transitions of depression and obesity over time are associated with the risk of developing functional disability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-02972-1.

Dose-response relationships of sarcopenia parameters with incident disability and mortality in older Japanese adults

BACKGROUND

Sarcopenia-related parameters may have differential impacts on health-related outcomes in older adults. We examined dose-response relationships of body composition, muscle strength, and physical performance with incident disability and mortality.

METHODS

This prospective study included 1765 Japanese residents (862 men; 903 women) aged ≥65 years who participated in health check-ups. Outcomes were incident disability and all-cause mortality. Fat mass index (FMI) and skeletal muscle mass index (SMI), determined using segmental multi-frequency bioelectrical impedance analysis, handgrip strength (HGS), and usual gait speed (UGS) were measured. We determined multivariate-adjusted hazard ratios (HRs) for disability and mortality relative to sex-specific reference values (FMI: medians; SMI: 7.0 kg/m² for men and 5.7 kg/m² for women; HGS: 28 kg for men and 18 kg for women; or UGS: 1.0 m/s for both sexes). Association shapes were examined using restricted cubic splines or fractional polynomial functions.

RESULTS

The median follow-up was 5.3 years; 107 (12.7%) men and 123 (14.2%) women developed disability, and 101 (11.7%) men and 56 (6.2%) women died. FMI did not impact any outcome in men and disability in women, while an FMI ≤ 7.3 kg/m² (median) was significantly associated with higher mortality risk in women, compared with median FMI. SMI did not impact disability in either sex and mortality in women, but showed a significant inverse dose-response relationship with mortality risk in men [HRs (95% confidence intervals) of minimum and maximum values compared with the reference value: 2.18 (1.07-4.46) and 0.43 (0.20-0.93), respectively], independent of HGS and UGS. HGS and UGS showed a significant inverse dose-response relationship with disability in both sexes [HGS: 1.71 (1.00-2.91) and 0.31 (0.09-0.99), respectively, in men, 2.42 (1.18-4.96) and 0.41 (0.20-0.85), respectively, in women; UGS: 2.14 (1.23-3.74) and 0.23 (0.08-0.67), respectively, in men, 3.26 (2.07-5.14) and 0.11 (0.05-0.26), respectively, in women] and mortality in women [HGS: 6.84 (2.84-16.47) and 0.06 (0.02-0.21), respectively; UGS: 2.67 (1.14-6.27) and 0.30 (0.11-0.85), respectively], independent of body composition, but did not impact mortality in men.

CONCLUSIONS

Disability risk was more dependent on muscle strength and physical performance in both sexes. Mortality risk in men was more dependent on muscle mass, and mortality risk in women was influenced by lower fat mass along with muscle strength and physical performance. Although improving muscle strength and physical performance should be the first target for health promotion, it is also necessary to pay attention to body composition to extend life expectancy in older adults.

Association of Daily Physical Activity with Disability in Community-Dwelling Older Adults With/Without Chronic Kidney Disease

OBJECTIVES

Physical activity is recommended for disability prevention in the older adult population; however, the level of physical activity required for older adults with chronic kidney disease (CKD) remains unknown. This study aimed to examine the associations between daily physical activity and disability incidence in older adults with and without CKD to determine relevant daily physical activity levels.

DESIGN

Prospective observational study.

SETTING AND PARTICIPANTS

3,786 community-dwelling older adults aged ≥65 years.

MEASUREMENTS

Mean daily times spent in light- (LPA) and moderate-to-vigorous physical activity (MVPA) were measured using triaxial accelerometers. CKD was defined by a creatinine estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Disability incidence was identified as long-term care insurance certification during a 60-month follow-up period. Associations between physical activity and disability incidence were examined using Cox proportional hazard models stratified by the CKD status. Non-linear and linear associations were tested using the restricted cubic spline.

RESULTS

A total of 1,054 individuals were identified to have CKD. Disability incidence was higher in the CKD group than in the non-CKD group. The adjusted cox proportional hazard models indicated that a 10-minute increase in MVPA time was associated with lower disability incidence in the non-CKD group (hazard ratio [HR], 0.838; 95% confidence interval [CI]: 0.764-0.918) and the CKD group (HR, 0.859; 95% CI: 0.766-0.960). Linear associations were observed in MVPA for the non-CKD and CKD groups.

CONCLUSION

Increasing MVPA was associated with lower disability incidence in older adults with and without CKD. These findings can help devise disability prevention strategies for older CKD patients.

Combined impacts of physical activity, dietary variety, and social interaction on incident functional disability in older Japanese adults

BACKGROUND

This 3.6-year prospective study examined combined impacts of physical activity, dietary variety, and social interaction on incident disability and estimated population-attributable fraction for disability reduction in older adults.

METHODS

Participants were 7,822 initially non-disabled residents (3,966 men; 3,856 women) aged 65-84 years of Ota City, Tokyo, Japan. Sufficiency of moderate-to-vigorous-intensity physical activity (MVPA) ≥150 min/week, dietary variety score (DVS) ≥3 (median), and social interaction (face-to-face and/or non-face-to-face) ≥1 time/week was assessed using self-administered questionnaires. Disability incidence was prospectively identified using the long-term care insurance system's nationally unified database.

RESULTS

During a follow-up of 3.6 years, 1,046 (13.4%) individuals had disabilities. Independent multivariate-hazard ratios (HRs) and 95% confidence intervals of MVPA, DVS, and social interaction sufficiency for incident disability were 0.68 (0.59-0.78), 0.87 (0.77-0.99), and 0.91 (0.79-1.03), respectively. Incident disability HRs (95% CIs) gradually reduced with increased frequency of satisfying these behaviors (any one: 0.82, 0.65-1.03; any two: 0.65, 0.52-0.82; and all three behaviors: 0.54, 0.43-0.69), in an inverse dose-response manner (P < 0.001 for trend). Population-attributable fraction for disability reduction in satisfying any one, any two, and all three behaviors were 4.0% (-0.2, 7.9), 9.6% (4.8-14.1), and 16.0% (8.7-22.8), respectively.

CONCLUSION

Combining active physical activity, dietary variety, and social interaction substantially enhances the impacts on preventing disability among older adults, with evidence of an inverse dose-response manner. Adding the insufficient behavior element to individual habits and preexisting social group activities may be effective in preventing disability in the community.

Associations of objectively measured physical activity and sedentary behaviour with fall-related outcomes in older adults: a systematic review

BACKGROUND

Higher physical activity (PA) and lower sedentary behaviour (SB) are associated with better muscle strength, balance, and functional ability, which are imperative for avoiding falls. This systematic review aimed to describe the association between objectively measured PA and SB with falls, fear of falling, and fractures.

METHODS

Six databases were searched from inception to July 21, 2020 for articles reporting the association of objectively measured PA/SB with falls, fear of falling, and/or fractures in community-dwelling older adults ≥60 years old. Results were synthesized in effect-direction heat maps and albatross plots expressed as Pearson's correlation coefficients (R).

RESULTS

A total of 43 articles were included, representing 27,629 (range 26 to 5,545) community-dwelling older adults (mean [SD] age 76.6 [8.4] years, 47% female). Longitudinal associations were reported in 13 articles and cross-sectional associations in 30. Falls were reported in 11 articles, fear of falling in 18 and fractures in 2. Higher PA and lower SB were associated with less fear of falling (median [interquartile range] Rs = steps: -0.214 [0.249; -0.148], total PA: -0.240 [0.267; -0.144], and moderate-to-vigorous PA: -0.180 [0.382; -0.121]), but these associations did not extend to falls or fractures, which showed inconsistent effect directions.

CONCLUSION

Fear of falling is associated with less engagement in PA and more SB, thus indicating that it is a psychological barrier to an active lifestyle. Varying effect directions for associations between PA and SB with falls and fractures may provide evidence for non-linear associations and require further research considering details of the fall or fracture incident.

PROSPERO REGISTRATION NUMBER

CRD42018103910.

Potential utility of physical function measures to improve the risk prediction of functional disability in community-dwelling older Japanese adults: a prospective study

Background

While gait speed, one-leg standing balance, and handgrip strength have been shown to be independent predictors for functional disability, it is unclear whether such simple measures of physical function contribute to improved risk prediction of functional disability in older adults.

Methods

A total of 1,591 adults aged ≥ 65 years and without functional disability at baseline were followed up for up to 7.9 years. Functional disability was identified using the database of Japan’s Long-term Care Insurance System. Maximum gait speed, one-leg standing time, and handgrip strength were measured at baseline. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95 % confidence intervals (CIs) for the association of physical function and functional disability incidence. The incremental predictive value of each physical function measure for risk prediction was quantified using the difference in overall C-statistic, category-free net reclassification improvement (NRI), and integrated discrimination improvement (IDI) index.

Results

During follow-up (median: 7.8 years), functional disability was identified in 384 participants. All of the physical function measures were inversely associated with the risk of functional disability, independent of potential confounding factors. The multivariable adjusted HRs (95 % CIs) for functional disability per one standard deviation increment of maximum gait speed, one-leg-standing time, and hand grip strength were 0.73 (0.65–0.83), 0.68 (0.59–0.79), and 0.72 (0.59–0.86), respectively. Incorporation of each of maximum gait speed, one-leg-stand time, and hand grip strength into a basic model with other risk factors significantly improved C-statistic from 0.770 (95 % CIs, 0.751–0.794) to 0.778 (0.759–0.803), 0.782 (0.760–0.805), and 0.775 (0.756–0.800), respectively (all p < 0.05). A model including all three measures had the highest C-statistic of 0.787 (0.765–0.810). The improvements in risk prediction were also confirmed by category-free NRI and IDI index.

Conclusions

Adding any of the three measures to a basic model with other known risk factors significantly improved the prediction of functional disability and addition of all three measures provided further improvement of the prediction in older Japanese adults. These data provide robust evidence to support the practical utility of incorporating these simple physical function measures into functional disability risk prediction tools.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02415-3.

Assessment of causal effects of physical activity on neurodegenerative diseases: A Mendelian randomization study

BACKGROUND

Physical activity has been hypothesized to play a protective role in neurodegenerative diseases. However, effect estimates previously derived from observational studies were prone to confounding or reverse causation.

METHODS

We performed a two-sample Mendelian randomization (MR) analysis to explore the causal association of accelerometer-measured physical activity with 3 common neurodegenerative diseases: Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). We selected genetic instrumental variants reaching genome-wide significance (p < 5 × 10^-8) from 2 largest meta-analyses of about 91,100 UK Biobank participants. Summary statistics for AD, PD, and ALS were retrieved from the up-to-date studies in European ancestry led by the international consortia. The random-effect, inverse-variance weighted MR was employed as the primary method, while MR pleiotropy residual sum and outlier (MR-PRESSO), weighted median, and MR-Egger were implemented as sensitivity tests. All statistical analyses were performed using the R programming language (Version 3.6.1; R Foundation for Statistical Computing, Vienna, Austria).

RESULTS

Primary MR analysis and replication analysis utilized 5 and 8 instrumental variables, which explained 0.2% and 0.4% variance in physical activity, respectively. In each set, one variant at 17q21 was significantly associated with PD, and MR sensitivity analyses indicated them it as an outlier and source of heterogeneity and pleiotropy. Primary results with the removal of outlier variants suggested odds ratios (ORs) of neurodegenerative diseases per unit increase in objectively measured physical activity were 1.52 for AD (95% confidence interval (95%CI): 0.88-2.63, p = 0.13) and 3.35 for PD (95%CI: 1.32-8.48, p = 0.01), while inconsistent results were shown in the replication set for AD (OR = 1.06, 95%CI: 1.01-1.12, p = 0.02) and PD (OR = 0.99, 95%CI: 0.88-0.12, p = 0.97). Similarly, the beneficial effect of physical activity on ALS (OR = 0.51, 95%CI: 0.29-0.91, p = 0.02) was not confirmed in the replication analysis (OR = 0.96, 95%CI: 0.91-1.02, p = 0.22).

CONCLUSION

Genetically predicted physical activity was not robustly associated with risk of neurodegenerative disorders. Triangulating evidence across other studies is necessary in order to elucidate whether enhancing physical activity is an effective approach in preventing the onset of AD, PD, or ALS.

Beetroot supplementation in women enjoying exercise together (BEE SWEET): Rationale, design and methods

Background

Postmenopausal women exhibit higher rates of disability and cardiovascular disease (CVD) with aging compared to men. Whereas habitual exercise training is a known strategy to enhance physiologic function in men and premenopausal women, exercise-related adaptations are often modest in postmenopausal women. We propose dietary nitrate (beetroot juice) administered prior to exercise training may be a feasible approach to improve mobility and cardio-metabolic health outcomes in postmenopausal women.

Methods

Our randomized, placebo-controlled study aims to determine preliminary effects sizes for changes in functional mobility and endothelium-dependent vasodilation across three study arms: exercise only (EX), exercise + placebo (EX + PL), and exercise + beetroot (EX + BR). Thirty-six postmenopausal women are recruited in small cohorts wherein group exercise is implemented to facilitate social support and adherence to an 8-week training progression. Participants are randomized to one of three study arms (n = 12 per group) following baseline assessments. Post-intervention assessments are used to determine pre-post changes in outcome measures including distance covered during a 6 min walk test, walking economy, muscle speed and power, and endothelial-dependent vasodilation as determined by flow-mediated dilation. Measures of feasibility include recruitment, retention, adherence to exercise prescription, perceived exercise session difficulty, and adverse event rates.

Discussion

Evidence-based, translational strategies are needed to optimize exercise training-related adaptations in postmenopausal women. Findings will inform larger randomized clinical trials to determine if pre-exercise consumption of beetroot juice is an efficacious strategy to promote mobility and attenuate CVD disease risk.