Validity and reliability of a ruler drop test to measure dual-task reaction time, choice reaction time and discrimination reaction time.

BACKGROUND: The aim of this study was to determine the absolute and relative reliability of the Ruler Drop Test (RDT) for assessing dual-task, choice, and discrimination reaction time. In addition, the construct validity of the RDT is examined in comparison to the Deary-Liewald reaction time (DLRT). METHODS: Tests were administered by the same evaluator, one week apart. Intraclass Correlation Coefficient (ICC3.1) was used to measure relative reliability, and the standard error of measurement (SEM) and minimal detectable change (MDC95) were used to measure absolute reliability. Spearman correlation test was used to measure construct validity. RESULTS: The results showed that the relative reliability was good for the choice ruler drop (ICC = 0.81), moderate for the dual-task ruler drop test (ICC = 0.70) and discrimination ruler drop test (ICC = 0.72), and good for simple ruler drop test. However, the simple ruler drop test had poor reliability (ICC = 0.57). The RDT shows construct validity compared to the DLRT. CONCLUSION: We conclude that the RDT is a suitable instrument for measuring dual-task, choice and discrimination reaction time. Future studies should explore the reliability of these measures in other populations.

Optimal Dose and Type of Physical Activity to Improve Glycemic Control in People Diagnosed With Type 2 Diabetes: A Systematic Review and Meta-analysis.

BACKGROUND: The optimal dose or type of physical activity to control glycosylated hemoglobin (HbA1c) in people with diabetes remains unknown. Current guidelines do not include consideration of baseline HbA1c for activity prescription. PURPOSE: To examine the dose-response relationship between physical activity and HbA1c (%) in individuals with type 2 diabetes. DATA SOURCES: A systematic search was performed in Embase, MEDLINE, Scopus, CINAHL, SPORTDiscus, and Web of Science. STUDY SELECTION: We included trials that involved participants diagnosed with type 2 diabetes that included any type of physical activity as intervention. DATA EXTRACTION: Pre- and postintervention HbA1c data, population and interventions characteristics, and descriptive statistics were collected to calculate change scores for each study arm. DATA SYNTHESIS: We used Bayesian random-effects meta-analyses to summarize high-quality evidence from 126 studies (6,718 participants). The optimal physical activity dose was 1,100 MET min/week, resulting in HbA1c reductions, ranging from -1.02% to -0.66% in severe uncontrolled diabetes, from -0.64% to -0.49% in uncontrolled diabetes, from -0.47% to -0.40% in controlled diabetes, and from -0.38% to -0.24% in prediabetes. LIMITATIONS: The time required to achieve these HbA1c reductions could not be estimated due to the heterogeneity between interventions' duration and protocols and the interpersonal variability of this outcome. CONCLUSIONS: The result of this meta-analysis provide key information about the optimal weekly dose of physical activity for people with diabetes with consideration of baseline HbA1c level, and the effectiveness of different types of active interventions. These results enable clinicians to prescribe tailored physical activity programs for this population.

Optimal dose and type of physical activity to improve functional capacity and minimise adverse events in acutely hospitalised older adults: a systematic review with dose-response network meta-analysis of randomised controlled trials.

OBJECTIVE: To identify the optimal dose and type of physical activity to improve functional capacity and reduce adverse events in acutely hospitalised older adults. DESIGN: Systematic review and Bayesian model-based network meta-analysis. DATA SOURCES: Four databases were searched from inception to 20 June 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials that assessed the effectiveness of a physical activity-based intervention on at least one functional outcome in people aged ≥50 years hospitalised due to an acute medical condition were included. Pooled effect estimates (ie, standardised mean differences for functional capacity and the ratio of means for adverse events) were calculated using random treatment effects network meta-analysis models. RESULTS: Nineteen studies (3842 participants) met the inclusion criteria. Approximately 100 Metabolic Equivalents of Task per day (METs-min/day) (~40 min/day of light effort or ~25 min/day of moderate effort activities) was the minimal dose to improve the functional capacity of acute hospitalised older adults (standardised mean difference (SMD)=0.28, 95% credible interval (CrI) 0.01 to 0.55). The optimal dose was estimated at 159 METs-min/day (~70 min/day of light effort or ~40 min/day of moderate effort activities; SMD=0.41, 95% CrI 0.08 to 0.72). Ambulation was deemed the most efficient intervention, and the optimal dose was reached at 143 METs-min/day (~50 min/day of slow-paced walking; SMD=0.76, 95% CrI 0.35 to 1.16), showing a high evidential power (87.68%). The minimal effective ambulation dose was estimated at 74 METs-min/day (~25 min/day of slow-paced walking; SMD=0.25, 95% CrI 0.01 to 0.41). Physical activity interventions resulted in a decrease in the rate of adverse events compared with usual care at discharge (ratio of means=0.96, 95% CrI 0.95 to 0.97; median time 7 days). CONCLUSIONS: This meta-analysis yielded low to moderate evidence supporting the use of in-hospital supervised physical activity programmes in acutely hospitalised older adults. As little as ~25 min/day of slow-paced walking is sufficient to improve functional capacity and minimise adverse events in this population. TRIAL REGISTRATION NUMBER: PROSPERO CRD42021271999.

Environmental tobacco smoke exposure and 24-h movement guidelines in Spanish young people.

Background: No prior research has investigated how exposure to environmental tobacco smoke is related to the combination of 24-h movement behaviors among young populations thus far. The aim of this study was to examine the associations between exposure to secondhand smoke and the 24-h movement guidelines. Methods: This is a cross-sectional study using data from the last available wave of the Spanish National Health Survey [2017], a nationally representative survey of the Spanish children and adult population. The final sample included 4,378 (49.0% girls) Spanish young people aged 2-14 years. Results: A lower likelikood of meeting screen time (ST) and all three 24-h movement guidelines were found in those exposed to environmental tobacco smoke in unadjusted models. After adjusting for several covariates, meeting screen time [odds ratio (OR) =0.76; 95% confidence interval (CI), 0.59-0.97], sleep duration (OR =0.75; 95% CI, 0.58-0.96), and all three 24-h movement guidelines (OR =0.63; 95% CI, 0.44-0.91) reached significance after adjusting for potential confounders. Conclusions: Given the inverse associations found, environmental tobacco smoke exposure should be a relevant factor to consider when promoting 24-h behaviors in the young population. Avoiding exposure to tobacco smoke in the environment is essential, as it can potentially influence the 24-h movement behaviors of young people, and consequently, the health benefits associated with such behaviors.

Exercise to treat psychopathology and other clinical outcomes in schizophrenia: A systematic review and meta-analysis.

BACKGROUND: Psychopathology and side effects of antipsychotic drugs contribute to worsening physical health and long-term disability, and increasing the risk of mortality in these patients. The efficacy of exercise on these factors is not fully understood, and this lack of knowledge may hamper the routine application of physical activity as part of the clinical care of schizophrenia. AIMS: To determine the effect of exercise on psychopathology and other clinical markers in patients with schizophrenia. We also looked at several moderators. METHOD: MEDLINE, Web of Science, Scopus, CINAHL, SPORTDiscus, PsycINFO, and Cochrane Library databases were systematically searched from inception to October 2022. Randomized controlled trials of exercise interventions in patients 18-65 years old diagnosed with schizophrenia disorder were included. A multilevel random-effects meta-analysis was conducted to pool the data. Heterogeneity at each level of the meta-analysis was estimated via Cochran's Q, I2, and R2. RESULTS: Pooled effect estimates from 28 included studies (1,460 patients) showed that exercise is effective to improve schizophrenia psychopathology (Hedges' g = 0.28, [95% CI 0.14, 0.42]). Exercise presented stronger effects in outpatients than inpatients. We also found exercise is effective to improve muscle strength and self-reported disability. CONCLUSIONS: Our meta-analysis demonstrated that exercise could be an important part in the management and treatment of schizophrenia. Considering the current evidence, aerobic and high-intensity interval training exercises may provide superior benefits over other modalities. However, more studies are warranted to determine the optimal type and dose of exercise to improve clinical outcomes in people with schizophrenia.

Associations between Hospitalization and Device-Assessed Physical Activity in a Representative Sample of Older Adults.

BACKGROUND: Evidence investigating associations between hospitalization and physical activity is scarce and limited to specific populations of older adults. OBJECTIVE: The current study aimed to describe the impact of past hospitalization on current physical activity levels of a large representative sample of European older adults with accelerometry data. METHODS: A representative sample of 856 European older adults aged 50 years and over was included in this study. Hospital admission and utilization (i.e., accumulated times and length of stay in hospital) in the last 12 months were self-reported retrospectively. Physical activity volume (mg) and distribution of intensity (intensity gradient) were assessed with thigh-worn accelerometers. RESULTS: Multivariate linear regressions indicated that hospital admission (15% of the sample) was associated with reduced physical activity volume (-4.29 mg; 95% confidence interval (95% CI), -9.07 to 0.47) of participants. Each additional hospital admission was associated with lower volume (-2.29 mg; 95% CI, -4.65 to 0.06) and poorer distribution of intensity (-0.07; 95% CI, -0.11 to -0.04). Total length of stay was not associated with physical activity. CONCLUSIONS: This study suggests that hospital admission and the number of times admitted, but not accumulated length of stay, may curb physical activity levels of older adults. Public health strategies to promote successful aging should target post-hospitalization physical activity.

High Fragmented Physical Activity as an Early Risk Indicator of Frailty and Mortality in Adults Aged 50 Years and Over.

INTRODUCTION: This study aimed to explore the associations of activity fragmentation with frailty status and all-cause mortality in a representative US sample of people 50 years and over. METHODS: This prospective study used data from the 2003-2006 waves of the National Health and Nutrition Examination Survey (NHANES). Participants 50 years or over were included in the study (n = 2,586). Frailty status was assessed using a valid modification of the Fried criteria. Linked data from the National Death Index registry were used to ascertain mortality. Physical activity fragmentation was measured by accelerometry. To calculate activity fragmentation, an active-to-sedentary transition probability was calculated as the number of physical activity bouts divided by the total sum of minutes spent in physical activity. Age, gender, ethnicity, education, mobility issues, drinking status, smoking status, BMI, and self-reported chronic diseases were reported in the NHANES study. RESULTS: An increment of 1 SD in activity fragmentation was associated with an increased likelihood of frailty (odds ratio [95% confidence interval] = 1.36 [1.13-1.664]). Compared with participants in the high activity fragmentation/low physical activity category, participants in the low activity fragmentation/low physical activity and low activity fragmentation/high physical activity categories were associated with a lower likelihood of frailty. We found a nonlinear association between activity fragmentation and all-cause mortality. Compared with participants in the high activity fragmentation/low physical activity category, participants in the low activity fragmentation/low physical activity, low activity fragmentation/high physical activity, and high activity fragmentation/high physical activity categories were associated with a lower mortality risk. Participants with a low fragmented activity pattern may also overcome some of the detrimental effects associated with sedentary behavior. CONCLUSIONS: Our results suggest that a high fragmented physical activity pattern is associated with frailty and risk of mortality in adults and older adults. This association was independent of total volume of physical activity and time spent sedentary.

Acute Effects of Augmented Reality Exergames versus Cycle Ergometer on Reaction Time, Visual Attention, and Verbal Fluency in Community Older Adults.

BACKGROUND: This study aims to investigate the acute effects of an augmented reality session and a cycle ergometer session compared to no exercise on the reaction times, cognitive flexibility, and verbal fluency of older adults. METHODS: Each participant did a familiarization with cognitive tests and the following three sessions: cycle ergometer, no exercise (control group), and augmented reality exergame (Portable Exergame Platform for Elderly) sessions. The participants were randomized in a within-group design into one of six possible combinations. Each moment had a 30 min duration, and after the session, the participants performed a Trail Making Test, a verbal fluency test, and a Deary-Liewald reaction time task. The data were analyzed with a one-way ANOVA with a Bonferroni adjustment. RESULTS: The analysis between the no exercise, cycle ergometer, and augmented reality sessions showed no significant differences in the cognitive measurements. CONCLUSIONS: One session of the cycle ergometer exercise or the augmented reality exergames does not acutely improve the reaction times, cognitive flexibility, or verbal fluency in the elderly.

Optimal Number of Steps per Day to Prevent All-Cause Mortality in People With Prediabetes and Diabetes.

OBJECTIVE: We aimed to examine the dose-response associations between the number of steps per day and all-cause mortality among adults with prediabetes and diabetes. RESEARCH DESIGN AND METHODS: This prospective study used data from 1,194 U.S. adults with prediabetes and 493 with diabetes for whom accelerometer-derived steps per day could be retrieved. Mortality was ascertained through the National Death Index (February 25, 2019). Splines were used to assess the dose-response associations between steps per day and all-cause mortality. RESULTS: Over ∼9 years of follow-up, 200 adults with prediabetes and 138 with diabetes died. Nonlinear associations akin to an L shape were observed. We estimated an optimal dose of ∼10,000 steps per day to reduce the risk of all-cause mortality for both individuals with prediabetes and those with diabetes. CONCLUSIONS: Accumulating more steps per day up to ∼10,000 steps per day may lower the risk of all-cause mortality of adults with prediabetes and diabetes.

Effects of respiratory muscle training on respiratory efficiency and health-related quality of life in sedentary women with fibromyalgia: a randomised controlled trial.

OBJECTIVES: Fibromyalgia syndrome (FM) is a complex disease that is mainly characterised by chronic pain, fatigue, and sleep disturbances and may be precipitated or worsened by many stressors. The aim of this study was to examine the effects of respiratory muscle training (RMT) on respiratory efficiency and health-related quality of life (HRQoL) in women with FM. METHODS: A total of 30 women with FM were included in the intention to treat analyses: 15 were assigned to the RMT group and 15 to the control group. The intervention consisted of 12 weeks of RMT. The primary outcome was the change in pulmonary function assessed by global body plethysmography at 12 weeks compared with baseline. Secondary outcomes included changes of scores in HRQoL assessed by the Short Form 36 Health Survey-Portuguese version. RESULTS: The maximal inspiratory pressure (MIP) improved by 17.5% (p-value = .033), maximal expiratory pressure (MEP) improved 21.6% (p-value = 0.045) and maximum occlusion pressure (P0.1 max) increased 27.7% (p-value = 0.007). HRQoL improved in the dimensions of physical function, physical role, bodily pain and vitality (p-value <0.05). CONCLUSIONS: RMT results in a significant improvement of respiratory efficiency and HRQoL after 12 weeks. RMT could be an effective therapy to enhance respiratory function and quality of life in women with FM.

Physical and Motor Fitness Tests for Older Adults Living in Nursing Homes: A Systematic Review.

This systematic review aimed to identify the physical/motor fitness tests for nursing home residents and to examine their psychometric properties. Electronic databases were searched for articles published between January 2005 and October 2021 using MeSh terms and relevant keywords. Of the total of 4196 studies identified, 3914 were excluded based on title, abstracts, or because they were duplicates. The remaining 282 studies were full-text analyzed, and 41 were excluded, resulting in 241 studies included in the review. The most common physical component assessed was muscle strength; 174 (72.2%) studies assessed this component. Balance (138 studies, 57.3%) and agility (102 studies, 42.3%) were the second and third components, respectively, most widely assessed. In this review, we also describe the most used assessment tests for each physical/motor component. Some potentially relevant components such as manual dexterity and proprioception have been little considered. There are few studies assessing the psychometric properties of the tests for nursing home residents, although the data show that, in general, they are reliable. This review provides valuable information to researchers and health-care professionals regarding the physical/motor tests used in nursing home residences, helping them select the screening tools that could most closely fit their study objectives.

Replacing Sedentary Behavior With Physical Activity of Different Intensities: Implications for Physical Function, Muscle Function, and Disability in Octogenarians Living in Long-Term Care Facilities.

BACKGROUND: We investigated the associations of replacing sedentary behavior (SB) with physical activity of different intensities on the physical function of octogenarians living in long-term care facilities. METHODS: This pooled study recruited 427 older adults aged 80 years and older (69.1% female; body mass index: 27.53). For 345 participants who provided valid data, we assessed device-measured time spent in SB, light-intensity physical activity (LIPA), and moderate to vigorous physical activity (MVPA). We assessed lower limb physical function, strength, mobility, and disability. We used compositional data analysis to investigate the associations of replacing SB with physical activity on the outcomes. RESULTS: Reallocation of SB to LIPA and MVPA was associated with a higher number of 30-second Chair Stand cycles (LIPA: +0.21, MVPA: +1.81; P < .001), greater peak force (LIPA: +11.96 N, MVPA: +27.68 N; P < .001), peak power (LIPA: +35.82 W, MVPA: +92.73 W; P < .001), peak velocity (LIPA: +0.03 m/s, MVPA: +0.12 m/s; P < .001), higher levels of grip strength (LIPA: +0.68 kg, MVPA: +2.49 kg; P < .001), and less time in the Time Up and Go (LIPA: -7.63 s, MVPA: -12.43 s; P < .001). CONCLUSIONS: Replacing SB with LIPA or MVPA is associated with physical function and disability of older adults living in long-term care facilities.

Optimal dose and type of exercise to improve cognitive function in older adults: A systematic review and bayesian model-based network meta-analysis of RCTs.

OBJECTIVE: To examine the dose-response relationship between overall and specific types of exercise with cognitive function in older adults. DESIGN: Systematic Review and Bayesian Model-Based Network Meta-Analysis. DATA SOURCES: Systematic search of MEDLINE, Web of Science, Scopus, PsycINFO and SPORTDiscus. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomized controlled trials of exercise interventions in participants aged 50 years or over, and that reported on at least one global cognition outcome. RESULTS: The search returned 1998 records, of which 44 studies (4793 participants; 102 different effect sizes) were included in this review with meta-analysis. There was a non-linear, dose-response association between overall exercise and cognition. We found no minimal threshold for the beneficial effect of exercise on cognition. The estimated minimal exercise dose associated with clinically relevant changes in cognition was 724 METs-min per week, and doses beyond 1200 METs-min per week provided less clear benefits. We also found that the dose-response association was exercise type dependent, and our results show that clinically important effects may occur at lower doses for many types of exercise. Our findings also highlighted the superior effects of resistance exercises over other modalities. CONCLUSIONS: If provided with the most potent modalities, older adults can get clinical meaningful benefits with lower doses than the WHO guidelines. Findings support the WHO recommendations to emphasise resistance training as a critical component of interventions for older adults.

Can Physical Activity Make Up for the Self-Care Disability Effects of Too Much Sitting? A Moderation Analysis in Octogenarians Residing in Living Care Facilities.

BACKGROUND AND PURPOSE: Physical activity can delay the progression of self-care disability in older adults residing in living care facilities. Nonetheless, older adults residing in living care facilities spend most of their time sedentary and do not meet the physical activity recommendation, which may result in increasing self-care disability in this population group. In this study, we aimed to determine whether the association between sedentary time and self-care disability was moderated by moderate-to-vigorous physical activity (MVPA) in older adults residing in living care facilities. METHODS: Sedentary time and MVPA were both measured with accelerometers. Self-care disability was assessed with the Barthel Index. A multivariate regression model was used to ascertain the effects of the interaction between sedentary time and MVPA on the self-care disability of participants. The Johnson-Neyman technique was then used to estimate the exact MVPA threshold at which the effect of sedentary time on self-care disability became nonsignificant. RESULTS: We found a significant effect of sedentary time on self-care disability (standardized ß=-1.66; 95% CI -1.77 to -1.54, P = .013). Results indicated that MVPA moderates the relationship between self-care disability status and sedentary time (standardized ß= 1.14; 95% CI 1.13 to 1.14, P = .032). The Johnson-Neyman technique determined that 51 min/day of MVPA would offset the negative effects of sedentary time on self-care disability. CONCLUSIONS: Our results suggest physical therapists should focus on reducing sedentary time alongside physical activity to prevent the progression to dependency in octogenarians residing in living care facilities.

Cross-sectional examination of 24-hour movement behaviours among 3- and 4-year-old children in urban and rural settings in low-income, middle-income and high-income countries: the SUNRISE study protocol.

INTRODUCTION: 24-hour movement behaviours (physical activity, sedentary behaviour and sleep) during the early years are associated with health and developmental outcomes, prompting the WHO to develop Global guidelines for physical activity, sedentary behaviour and sleep for children under 5 years of age. Prevalence data on 24-hour movement behaviours is lacking, particularly in low-income and middle-income countries (LMICs). This paper describes the development of the SUNRISE International Study of Movement Behaviours in the Early Years protocol, designed to address this gap. METHODS AND ANALYSIS: SUNRISE is the first international cross-sectional study that aims to determine the proportion of 3- and 4-year-old children who meet the WHO Global guidelines. The study will assess if proportions differ by gender, urban/rural location and/or socioeconomic status. Executive function, motor skills and adiposity will be assessed and potential correlates of 24-hour movement behaviours examined. Pilot research from 24 countries (14 LMICs) informed the study design and protocol. Data are collected locally by research staff from partnering institutions who are trained throughout the research process. Piloting of all measures to determine protocol acceptability and feasibility was interrupted by COVID-19 but is nearing completion. At the time of publication 41 countries are participating in the SUNRISE study. ETHICS AND DISSEMINATION: The SUNRISE protocol has received ethics approved from the University of Wollongong, Australia, and in each country by the applicable ethics committees. Approval is also sought from any relevant government departments or organisations. The results will inform global efforts to prevent childhood obesity and ensure young children reach their health and developmental potential. Findings on the correlates of movement behaviours can guide future interventions to improve the movement behaviours in culturally specific ways. Study findings will be disseminated via publications, conference presentations and may contribute to the development of local guidelines and public health interventions.

Global effect of COVID-19 pandemic on physical activity, sedentary behaviour and sleep among 3- to 5-year-old children: a longitudinal study of 14 countries.

BACKGROUND: The restrictions associated with the 2020 COVID-19 pandemic has resulted in changes to young children's daily routines and habits. The impact on their participation in movement behaviours (physical activity, sedentary screen time and sleep) is unknown. This international longitudinal study compared young children's movement behaviours before and during the COVID-19 pandemic. METHODS: Parents of children aged 3-5 years, from 14 countries (8 low- and middle-income countries, LMICs) completed surveys to assess changes in movement behaviours and how these changes were associated with the COVID-19 pandemic. Surveys were completed in the 12 months up to March 2020 and again between May and June 2020 (at the height of restrictions). Physical activity (PA), sedentary screen time (SST) and sleep were assessed via parent survey. At Time 2, COVID-19 factors including level of restriction, environmental conditions, and parental stress were measured. Compliance with the World Health Organizations (WHO) Global guidelines for PA (180 min/day [≥60 min moderate- vigorous PA]), SST (≤1 h/day) and sleep (10-13 h/day) for children under 5 years of age, was determined. RESULTS: Nine hundred- forty-eight parents completed the survey at both time points. Children from LMICs were more likely to meet the PA (Adjusted Odds Ratio [AdjOR] = 2.0, 95%Confidence Interval [CI] 1.0,3.8) and SST (AdjOR = 2.2, 95%CI 1.2,3.9) guidelines than their high-income country (HIC) counterparts. Children who could go outside during COVID-19 were more likely to meet all WHO Global guidelines (AdjOR = 3.3, 95%CI 1.1,9.8) than those who were not. Children of parents with higher compared to lower stress were less likely to meet all three guidelines (AdjOR = 0.5, 95%CI 0.3,0.9). CONCLUSION: PA and SST levels of children from LMICs have been less impacted by COVID-19 than in HICs. Ensuring children can access an outdoor space, and supporting parents' mental health are important prerequisites for enabling pre-schoolers to practice healthy movement behaviours and meet the Global guidelines.

Impact of Social Isolation on Physical Functioning Among Older Adults: A 9-Year Longitudinal Study of a U.S.-Representative Sample.

INTRODUCTION: Social isolation among older adults is associated with poor health and premature mortality, but its impact on physical functioning is not fully understood. Previous studies have typically relied on community samples, cross-sectional data, and suboptimal prospective designs. This study generates more robust evidence by investigating the longitudinal associations between social isolation and physical functioning in a large panel of older adults. METHODS: Analyses were based on 9 waves of data (2011-2019) from a sample of adults aged ≥65 years from the U.S. National Health and Aging Trends Study (N=12,427 individuals; 54,860 person-year observations) and within-individual fixed-effect panel regression models. Analyses were conducted in 2020. Social isolation was measured using the Social Isolation Index, and physical functioning was measured through the Short Physical Performance Battery. RESULTS: In fully adjusted fixed-effect regression models, each 1-unit increase in the Social Isolation Index resulted in an average decrease of 0.27 units in the Short Physical Performance Battery (95% CI= -0.31, -0.24). This relationship was moderated by age, with the Social Isolation Index bearing a significantly and substantially stronger influence on the Short Physical Performance Battery at older ages than at younger ages. CONCLUSIONS: This study confirms that social isolation is associated with deficits in physical functioning among older adults in the U.S. using more robust data and methods than earlier studies. These findings highlight the importance of incorporating strategies to reduce social isolation in policies aimed at promoting successful aging.

Bidirectional and Dynamic Relationships Between Social Isolation and Physical Functioning Among Older Adults: A Cross-Lagged Panel Model of US National Survey Data.

BACKGROUND: Previous studies examining unidirectional relationships between social isolation and physical functioning among older adults may be biased due to reverse causality. This study leveraged data from a US national sample of older adults and a novel estimation method to identify bidirectional associations between these 2 phenomena and their associated temporal dynamics. METHODS: The analyses were based on 9 waves of panel data from a sample of adults aged 65 and older from the US National Health and Aging Trends Study (n = 12 427 individuals) and a cross-lagged panel model. Social isolation was measured using the Social Isolation Index (SII) and physical functioning through the Short Physical Performance Battery (SPPB). RESULTS: One SD increase in the SPPB was associated with a -0.013 SD decrease (95% confidence interval [CI]: -0.023 to -0.004) in the SII a year later, whereas 1 SD increase in the SII was associated with a larger -0.058 SD decrease (95% CI: -0.069 to -0.046) in the SPPB a year later. The SII→SPPB effect lasted for approximately 5 years, whereas the SPPB→SII lasted for approximately 3 years. CONCLUSIONS: This study confirmed the existence of statistically significant bidirectional associations between social isolation and physical functioning among older adults in the United States, net of reverse causation. Because the effect of social isolation dominates, the findings indicate that public health strategies to promote successful aging should prioritize interventions that enrich older adults' social networks. Furthermore, the effect time horizons yielded by the model point to the optimal timing for the re-delivery of interventions.