Contrasting characteristics of daily physical activity in older adults by cancer history

Relationship between skeletal mitochondrial function and digital markers of free-living physical activity in older adults

This study examined the association between in vivo skeletal mitochondrial function and digital free-living physical activity patterns-a measure that summarizes biological, phenotypic, functional, and environmental effects on mobility. Among 459 participants (mean age 68 years; 55% women) in the Baltimore Longitudinal Study of Aging, mitochondrial function was quantified as skeletal muscle oxidative capacity via post-exercise phosphocreatine recovery rate (τPCr) in the vastus lateralis muscle of the left thigh, using 31P magnetic resonance spectroscopy. Accelerometry was collected using a 7-day, 24-h wrist-worn protocol and summarized into activity amount, intensity, endurance, and accumulation patterning metrics. Linear regression, two-part linear and logistic (bout analyses), and linear mixed effects models (time-of-day analyses) were used to estimate associations between τPCr and each physical activity metric. Interactions by age, sex, and gait speed were tested. After covariate adjustment, higher τPCr (or poorer mitochondrial function) was associated with lower activity counts/day (β =  - 6593.7, SE = 2406.0; p = 0.006) and activity intensity (- 81.5 counts, SE = 12.9; p < 0.001). For activity intensity, the magnitude of association was greater for men and those with slower gait speed (interaction p < 0.02 for both). Conversely, τPCr was not associated with daily active minutes/day (p = 0.15), activity fragmentation (p = 0.13), or endurance at any bout length (p > 0.05 for all). Time-of-day analyses show participants with high τPCr were less active from 6:00 a.m. to 12:00 a.m. than those with low τPCr. Results indicate that poorer skeletal mitochondrial function is primarily associated with lower engagement in high intensity activities. Our findings help define the connection between laboratory-measured mitochondrial function and real-world physical activity behavior.

Do Measures of Real-World Physical Behavior Provide Insights Into the Well-Being and Physical Function of Cancer Survivors? Cross-Sectional Analysis

BACKGROUND

As the number of cancer survivors increases, maintaining health-related quality of life in cancer survivorship is a priority. This necessitates accurate and reliable methods to assess how cancer survivors are feeling and functioning. Real-world digital measures derived from wearable sensors offer potential for monitoring well-being and physical function in cancer survivorship, but questions surrounding the clinical utility of these measures remain to be answered.

OBJECTIVE

In this secondary analysis, we used 2 existing data sets to examine how measures of real-world physical behavior, captured with a wearable accelerometer, were related to aerobic fitness and self-reported well-being and physical function in a sample of individuals who had completed cancer treatment.

METHODS

Overall, 86 disease-free cancer survivors aged 21-85 years completed self-report assessments of well-being and physical function, as well as a submaximal exercise test that was used to estimate their aerobic fitness, quantified as predicted submaximal oxygen uptake (VO2). A thigh-worn accelerometer was used to monitor participants' real-world physical behavior for 7 days. Accelerometry data were used to calculate average values of the following measures of physical behavior: sedentary time, step counts, time in light and moderate to vigorous physical activity, time and weighted median cadence in stepping bouts over 1 minute, and peak 30-second cadence.

RESULTS

Spearman correlation analyses indicated that 6 (86%) of the 7 accelerometry-derived measures of real-world physical behavior were not significantly correlated with Functional Assessment of Cancer Therapy-General total well-being or linked Patient-Reported Outcomes Measurement Information System-Physical Function scores (Ps≥.08). In contrast, all but one of the physical behavior measures were significantly correlated with submaximal VO2 (Ps≤.03). Comparing these associations using likelihood ratio tests, we found that step counts, time in stepping bouts over 1 minute, and time in moderate to vigorous activity were more strongly associated with submaximal VO2 than with self-reported well-being or physical function (Ps≤.03). In contrast, cadence in stepping bouts over 1 minute and peak 30-second cadence were not more associated with submaximal VO2 than with the self-reported measures (Ps≥.08).

CONCLUSIONS

In a sample of disease-free cancer survivors, we found that several measures of real-world physical behavior were more associated with aerobic fitness than with self-reported well-being and physical function. These results highlight the possibility that in individuals who have completed cancer treatment, measures of real-world physical behavior may provide additional information compared with self-reported and performance measures. To advance the appropriate use of digital measures in oncology clinical research, further research evaluating the clinical utility of real-world physical behavior over time in large, representative samples of cancer survivors is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03781154; https://clinicaltrials.gov/ct2/show/NCT03781154.

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.

Correlates of physical activity and sedentary behavior among cancer survivors and cancer-free women: The Women's Health Accelerometry Collaboration

BACKGROUND

Describing correlates of physical activity (PA) and sedentary behavior (SB) among postmenopausal cancer survivors can help identify risk profiles and can be used to support development of targeted interventions to improve PA and reduce SB in this population.

OBJECTIVE

To describe PA/SB and identify correlates of PA/SB among cancer and cancer-free post-menopausal women.

METHODS

Women from the Women's Health Study (N = 16,629) and Women's Health Initiative/Objective Physical Activity and Cardiovascular Health Study (N = 6,079) were asked to wear an accelerometer on the hip for 7 days. Multiple mixed-effects linear regression models were used to identify sociodemographic-, health-, and chronic condition-related correlates (independent variables) associated with PA and SB (dependent variables) among women with (n = 2,554) and without (n = 20,154) a history of cancer. All correlates were mutually adjusted for each other.

RESULTS

In unadjusted analyses, women with a history of cancer took fewer mean daily steps (4,572 (standard deviation 2557) vs 5,029 (2679) steps/day) and had lower mean moderate-to-vigorous PA (74.9 (45.0) vs. 81.6 (46.7) minutes/day) than cancer-free women. In adjusted analyses, for cancer and cancer-free women, age, diabetes, overweight, and obesity were inversely associated with all metrics of PA (average vector magnitude, time in moderate-to-vigorous PA, step volume, time at ≥40 steps/minutes, and peak 30-minute step cadence). In unadjusted analyses, mean SB was similar for those with and without cancer (529.7 (98.1) vs. 521.7 (101.2) minutes/day). In adjusted analyses, for cancer and cancer-free women, age, diabetes, cardiovascular disease, current smoking, overweight, and obesity were positive correlates of SB, while Black or Hispanic race/ethnicity, weekly/daily alcohol intake, and excellent/very good/good self-rated health were inverse correlates of SB.

CONCLUSION

Several sociodemographic, health, and chronic conditions were correlates of PA/SB for postmenopausal women with and without cancer. Future studies should examine longitudinal relationships to gain insight into potential determinants of PA/SB.

Associations between performance-based and patient-reported physical functioning and real-world mobile sensor metrics in older cancer survivors: A pilot study

INTRODUCTION

Older cancer survivors are at increased risk for impaired physical functioning, but current assessments of function are difficult to implement in busy oncology clinics. Mobile devices measuring continuous activity and mobility in daily life may be useful for estimating physical functioning. The goal of this pilot study was to examine the associations between consumer wearable device (a wrist-worn activity tracker) and smartphone sensor data and commonly used clinical measures of physical function in cancer survivors aged 65 and older.

MATERIALS AND METHODS

Older adults within five years of completing primary treatment for any cancer completed standardized questionnaires and performance-based tests to measure physical functioning. Continuous passive data from smartphones and consumer wearable devices were collected for four weeks and linked to patient-reported and performance-based physical functioning as well as patient-reported falls or near falls at the end of the four-week monitoring period. To examine associations between sensor variables and physical functioning, we conducted bivariate Pearson correlations as well as multivariable linear regression analyses. To examine associations between sensor variables and falls, we conducted exploratory receiver operating characteristic curve and multivariable logistic regression analyses.

RESULTS

We enrolled 40 participants (mean age 73 years old, range 65-83; 98% White; 50% female). In bivariate analyses, consumer wearable device features reflecting greater amount and speed and lower fragmentation of walking in daily life were significantly related to better patient-reported function (r= 0.43-0.65) and performance-based physical function (r = 0.56-0.72), while smartphone features reflecting more geographic mobility were related to better performance-based physical function (r = 0.40-0.42) but not patient-reported function. After adjusting for age and comorbidities, only consumer wearable device features remained associated with performance-based physical functioning. In exploratory analyses, peak gait cadence was associated with fall risk even after covariate adjustment.

DISCUSSION

This study provides preliminary evidence that real-world data from consumer devices may be useful for estimating functional performance among older cancer survivors and potentially for remotely and longitudinally monitoring functioning in older patients during and after cancer treatment.

The Association Between Ankle-Brachial Index and Daily Patterns of Physical Activity: Results From the Hispanic Community Health Study/Study of Latinos

BACKGROUND

Peripheral artery disease (PAD) is associated with lower physical activity but less is known about its association with daily patterns of activity. We examined the cross-sectional association between ankle-brachial index (ABI) and objectively measured patterns of physical activity among Hispanic/Latino adults.

METHODS

We analyzed data from 7 688 participants (aged 45-74 years) in the Hispanic Community Health Study/Study of Latinos. ABI was categorized as low (≤0.90, indicating PAD), borderline low (0.91-0.99), normal (1.00-1.40), and high (>1.40, indicating incompressible ankle arteries). Daily physical activity metrics derived from accelerometer data included: log of total activity counts (LTAC), total log-transformed activity counts (TLAC), and active-to-sedentary transition probability (ASTP). Average differences between ABI categories in physical activity, overall and by 4-hour time-of-day intervals, were assessed using linear regression and mixed-effects models, respectively.

RESULTS

In Hispanic/Latino adults, 5.3% and 2.6% had low and high ABIs, respectively. After adjustment, having a low compared to a normal ABI was associated with lower volume (LTAC = -0.13, p < .01; TLAC = -74.4, p = .04) and more fragmented physical activity (ASTP = 1.22%, p < .01). Having a low ABI was linked with more fragmented physical activity after 12 pm (p < .01). Having a high ABI was associated with lower volumes of activity (TLAC = -132.0, p = .03).

CONCLUSIONS

Having a low or high ABI is associated with lower and more fragmented physical activity in Hispanic/Latino adults. In adults with low ABI, physical activity is more fragmented in the afternoon to evening. Longitudinal research is warranted to expand these findings to guide targeted interventions for PAD or incompressible ankle arteries.

Sarcopenia and malignancies: epidemiology, clinical classification and implications

Sarcopenia is a progressive systemic skeletal muscle disorder characterized by a pathological decline in muscle strength, quantity, and quality, which frequently affects the elderly population. The majority of cancer patients are of advanced age. Patients may already have sarcopenia prior to cancer development, and those with cancer are prone to developing sarcopenia due to hypercatabolism, inflammation, reduced physical fitness, anorexia, adverse effects, and stress associated with anticancer therapy. Based on the timing, sarcopenia in patients with cancer can be categorized into three: pre-existing sarcopenia before the onset of cancer, sarcopenia related to cancer, and sarcopenia related to cancer treatment. Sarcopenia not only changes the body composition of patients with cancer but also increases the incidence of postoperative complications, reduces therapeutic efficacy, impairs quality of life, and results in shortened survival. Different therapeutic strategies are required to match the cancer status and physical condition of patients with different etiologies and stages of sarcopenia. Here, we present a comprehensive review of the epidemiology and diagnosis of sarcopenia in patients with cancer, elucidate the complex interactions between cancer and sarcopenia, and provide evidence-based strategies for sarcopenia management in these patients.

Associations between patterns of physical activity, pain intensity, and interference among older adults with chronic pain: a secondary analysis of two randomized controlled trials

Background: Clinical management of chronic pain often includes recommendations to engage in physical activity (PA), though there are little data on the interplay between pain symptoms and key aspects of PA participation (e.g., intensity and bout duration) among older adults. Herein we investigate the longitudinal relationships between changes in PA behavior and changes in pain intensity and interference among low-active older adults with obesity and chronic pain. Methods: Participants (N = 41) were enrolled in two randomized pilot trials wherein they were assigned to an intervention focused on participation in frequent PA across the day, or to a low-contact control. Participants completed the 3-item PROMIS pain intensity scale and 8-item PROMIS pain interference scale before and after the interventions. Participants also wore an ActivPAL accelerometer for 7 days before and during the final week of the interventions. Results: A series of linear regression analyses demonstrated that increased time spent stepping at a high-light intensity in very short bouts was associated with increased pain intensity scores. By contrast, increased time spent stepping at a high-light intensity in bouts of 5-20 min was associated with reductions in pain intensity and interference scores. Increased time spent stepping at a moderate intensity overall was associated with reduced pain intensity scores, and time spent stepping at a moderate intensity for 10-20 min associated with reduced pain interference. Conclusion: These findings suggest older adults with chronic pain may benefit by moving at high-light or moderate intensities in brief bouts of at least 5 min in duration.

Validation, Recalibration, and Predictive Accuracy of Published V̇O 2max Prediction Equations for Adults Ages 50-96 Yr

PURPOSE

Maximal oxygen uptake ( ) is the criterion measure of cardiorespiratory fitness. Lower cardiorespiratory fitness is a strong predictor of poor health outcomes, including all-cause mortality. Because testing is resource intensive, several non-exercise-based V˙O 2max prediction equations have been published. We assess these equations' ability to predict measured V˙O 2max , recalibrate these equations, and quantify the association of measured and predicted V˙O 2max with all-cause mortality.

METHODS

Baltimore Longitudinal Study of Aging participants with valid V˙O 2max tests were included ( n = 1080). Using published V˙O 2max prediction equations, we calculated predicted V˙O 2max and present performance metrics before and after recalibration (deriving new regression estimates by regressing measured V˙O 2max on Baltimore Longitudinal Study of Aging covariates). Cox proportional hazards models were fit to quantify associations of measured, predicted, and recalibration-predicted values of V˙O 2max with mortality.

RESULTS

Mean age and V˙O 2max were 69.0 ± 10.4 yr and 21.6 ± 5.9 mL·kg -1 ·min -1 , respectively. The prediction equations yielded root mean square error values ranging from 4.2 to 20.4 mL·kg -1 ·min -1 . After recalibration, these values decreased to 3.9-4.2 mL·kg -1 ·min -1 . Adjusting for all covariates, all-cause mortality risk was 66% lower for the highest quartile of measured V˙O 2max relative to the lowest. Predicted V˙O 2max variables yielded similar estimates in unadjusted models but were not robust to adjustment.

CONCLUSIONS

Measured V˙O 2max is an extremely strong predictor of all-cause mortality. Several published V˙O 2max prediction equations yielded the following: 1) reasonable performance metrics relative to measured V˙O 2max especially when recalibrated, and 2) all-cause mortality hazard ratios similar to those of measured V˙O 2max , especially when recalibrated, yet 3) were not robust to adjustment for basic demographic covariates likely because these were used in the equation for predicted V˙O 2max .

Patterns of Daily Physical Movement, Chronic Inflammation, and Frailty Incidence

INTRODUCTION

Low physical activity is a criterion of phenotypic frailty defined as an increased state of vulnerability to adverse health outcomes. Whether disengagement from daily all-purpose physical activity is prospectively associated with frailty and possibly modified by chronic inflammation-a pathway often underlying frailty-remains unexplored.

METHODS

Using the Study to Understand Fall Reduction and Vitamin D in You data from 477 robust/prefrail adults (mean age = 76 ± 5 yr; 42% women), we examined whether accelerometer patterns (activity counts per day, active minutes per day, and activity fragmentation [broken accumulation]) were associated with incident frailty using Cox proportional hazard regression. Baseline interactions between each accelerometer metric and markers of inflammation that include interleukin-6, C-reactive protein, and tumor necrosis factor-alpha receptor 1 were also examined.

RESULTS

Over an average of 1.3 yr, 42 participants (9%) developed frailty. In Cox regression models adjusted for demographics, medical conditions, and device wear days, every 30 min·d -1 higher baseline active time, 100,000 more activity counts per day, and 1% lower activity fragmentation was associated with a 16% ( P = 0.003), 13% ( P = 0.001), and 8% ( P < 0.001) lower risk of frailty, respectively. No interactions between accelerometer metrics and baseline interleukin-6, C-reactive protein, or tumor necrosis factor-alpha receptor 1 were detected (interaction P > 0.06 for all).

CONCLUSIONS

Among older adults who are either robust or prefrail, constricted patterns of daily physical activity (i.e., lower total activity minutes and counts, and higher activity fragmentation) were prospectively associated with higher risk of frailty but not modified by frailty-related chronic inflammation. Additional studies, particularly trials, are needed to understand if this association is causal.

Wrist-Worn Accelerometry, Aging, and Gait Speed in the Baltimore Longitudinal Study of Aging

Wrist-worn accelerometry metrics are not well defined in older adults. Accelerometry data from 720 participants (mean age 70 years, 55% women) were summarized into (a) total activity counts per day, (b) active minutes per day, (c) active bouts per day, and (d) activity fragmentation (the reciprocal of the mean active bout length). Linear regression and mixed-effects models were utilized to estimate associations between age and gait speed with wrist accelerometry. Activity counts per day, daily active minutes per day, and active bouts per day were negatively associated with age among all participants, while positive associations with activity fragmentation were only observed among those ≥65 years. More activity counts, more daily active minutes, and lower activity fragmentation were associated with faster gait speed. There were baseline age interactions with annual changes in total activity counts per day, active minutes per day, and activity fragmentation (Baseline age × Time, p < .01 for all). These results help define and characterize changes in wrist-based physical activity patterns among older adults.

Intervening on physical activity and sedentary behavior in older adults

Participating in sufficient levels of physical activity is important for sustaining health and quality of life across the age span. The United States Physical Activity Guidelines recommend individuals of all ages "move more, more often" by frequently engaging in aerobic activity while avoiding prolonged bouts of sitting. This is indicative of a slow shift in focus in the study of active aging that has occurred in the last two decades. Historically, researchers interested in the influence of physical activity on older adults' health and quality of life focused on discrete sustained bouts of intense activity (i.e., structured exercise). More recently the widespread usage of accelerometers contributed to a large body of evidence demonstrating that long periods spent sedentary were associated with a host of negative health outcomes ranging from poorer cardiometabolic health to poorer physical functioning and elevated risk of death. These findings often persisted when controlling for time spent in higher-intensity physical activity, spurring separate fields of intervention research concerned with promoting exercise or reducing sedentary time. Novel data emerging in recent years on the importance of an individual's overall activity profile (i.e., amount and patterning of light and moderate-to-vigorous activity) has driven yet another shift in focus toward interventions focused explicitly on movement profiles. In this narrative review, we discuss the evolution of thought regarding older adults' physical activity behaviors. We highlight successes and challenges in first promoting structured and prolonged exercise, later in targeting sedentary behavior, and most recently in attempting to intervene on activity profiles. We end our review by highlighting current gaps in research and important future directions.

Longitudinal changes in daily patterns of objectively measured physical activity after falls in older adults with varying degrees of glaucoma

BACKGROUND

Visually impaired older adults have a greater risk of falling, making them particularly susceptible to fall-related health consequences and restricted physical activity. Unclear however, is the relationship between having falls and longitudinal changes in daily patterns of objectively measured physical activity in older adults with visual impairments.

METHODS

We created a three-year prospective cohort study (Falls in Glaucoma Study) of older adults with primary or suspected glaucoma at the Johns Hopkins Wilmer Eye Institute from 2013 to 2015. Cumulative incidence of falls was determined through self-reported fall calendars over 12 months. Participants were then classified into one of three groups: multiple fallers (≥2 falls), single fallers (1 fall), and non-fallers (0). Daily physical activity was measured over 1 week using a waist-bound accelerometer during baseline and three-year follow-ups. Activity fragmentation was defined as the reciprocal of the mean activity bout length, with higher fragmentation reflecting shorter, more fractured bouts of continuous activity. Multivariate linear mixed-effects models were used to assess three-year longitudinal changes in: 1) activity fragmentation, and 2) accumulation of activity across six three-hour intervals from 5 AM to 11 PM.

FINDINGS

In adjusted models accounting for visual field damage and other factors, multiple fallers demonstrated greater annual declines (per year) in daily active bouts (-1.79 bouts/day, 95% confidence interval [CI]: -3.35, -0.22), daily active minutes (-17.15 min/day, 95% CI: -26.35, -7.94), and increased fragmentation (1%, 95% CI: 0, 2%) over the three-year follow-up period as compared to non-fallers; no such changes were seen when comparing single fallers and non-fallers. In time-of-day analyses, multiple fallers experienced greater annual declines in average hourly steps over all periods of the day, though the rate of decline was only significant between 5 PM and 8 PM (-27.07 steps/hour, 95% CI: -51.15, -2.99) compared to non-fallers.

INTERPRETATION

In an older population with visual impairment, multiple falls over 12 months were associated with more transient and fragmented activity over a subsequent three-year period, and activity declines during evening hours, compared to non-fallers. These findings suggest that multiple fallers with visual impairment may be at high risk for a decline in physical capacity and endurance, warranting clinical interventions.

FUNDING

The research was supported in part by National Institutes of Health Grant EY022976.

Objectively measured patterns of daily physical activity and phenotypic frailty

BACKGROUND

Self-reported low physical activity is a defining feature of phenotypic frailty but does not adequately capture physical activity performed throughout the day. This study examined associations between accelerometer-derived patterns of routine daily physical activity and frailty.

METHODS

Wrist accelerometer and frailty data from 638 participants (mean age 77 (SD=5.5) years; 44% women) were used to derive five physical activity metrics: active minutes/day, sedentary minutes/day, total activity counts/day, activity fragmentation (reciprocal of the average active bout length) and sedentary fragmentation (reciprocal of the average sedentary bout length). Robust, pre-frail and frail statuses were identified using the physical frailty phenotype defined as having 0, 1-2, or ≥3 of the following criterion: weight loss, exhaustion, slowness, self-reported low activity, and weakness. Frailty was collapsed into not frail (robust and prefrail) and frail, and each frailty criteria was dichotomized. Multiple logistic regression was used to model each accelerometer metric. Separate frailty criteria and interactions with age and sex were also examined.

RESULTS

With higher amounts and intensity of daily activity (more active minutes, fewer sedentary minutes, higher activity counts) and lower activity fragmentation, the odds of frailty were lower compared to robust/prefrail states (p<0.02 for all). For interactions, only an age by sedentary fragmentation interaction on the odds of frailty was observed (p=0.01). For each separate criteria, accelerometer metrics were associated with odds of slowness, low activity, and weakness.

CONCLUSION

Less favorable patterns of objectively measured daily physical activity are associated with frailty and the components of slowness, low self-reported activity, and weakness.

Association Between Brain Volumes and Patterns of Physical Activity in Community-Dwelling Older Adults

BACKGROUND

Larger brain volumes are often associated with more free-living physical activity (PA) in cognitively normal older adults. Yet, whether greater brain volumes are associated with more favorable (less fragmented) PA patterns, and whether this association is stronger than with total PA, remains unknown.

METHODS

Brain magnetic resonance imaging and wrist-worn accelerometer data were collected in 301 participants (mean age = 77 [SD = 7] years, 59% women) enrolled in the Baltimore Longitudinal Study of Aging. Linear regression models were fit to examine whether brain volumes (cc) were cross-sectionally associated with: (a) total daily PA minutes and (b) activity fragmentation (mean number of PA bouts / total PA minutes × 100). Sensitivity analyses were conducted by adjusting for counterpart PA variables (eg, fragmentation covariate included in the PA minutes model).

RESULTS

Greater white matter volumes in the parietal and temporal lobes were associated with higher daily PA minutes (2.6 [SE = 1.0] and 3.8 [0.9] min/day, respectively; p < .009 for both) after adjusting for demographics, behavioral factors, medical conditions, gait speed, apolipoprotein E e4 status, and intracranial volume. Greater temporal white matter volume was associated with lower fragmentation (-0.16% [0.05], p = .003). In sensitivity analyses, observed associations between brain volumes and daily PA minutes remained significant while associations with fragmentation no longer remained significant.

CONCLUSIONS

Our results suggest white matter brain structure in cognitively normal older adults is associated with the total amount of PA and, to a lesser extent, the PA accumulation patterns. More work is needed to elucidate the longitudinal relationship between brain structure and function and PA patterns with aging.

Assessment of Physical Activity in Adults using Wrist Accelerometers

The health benefits of physical activity have been widely recognized, yet traditional measures of physical activity including questionnaires and category-based assessments of volume and intensity provide only broad estimates of daily activities. Accelerometers have advanced epidemiologic research on physical activity by providing objective and continuous measurement of physical activity in free-living conditions. Wrist-worn accelerometers have become especially popular due to low participant burden. However, the validity and reliability of wrist-worn devices for adults have yet to be summarized. Moreover, accelerometer data provide rich information on how physical activity is accumulated throughout the day, but only a small portion of these rich data have been utilized by researchers. Lastly, new methodological developments that aim to overcome some of the limitations of accelerometers are emerging. The purpose of this review is to provide an overview of accelerometry research, with a special focus on wrist-worn accelerometers. We describe briefly how accelerometers work, summarize the validity and reliability of wrist-worn accelerometers, discuss the benefits of accelerometers including measuring light-intensity physical activity, and discuss pattern metrics of daily physical activity recently introduced in the literature. A summary of large-scale cohort studies and randomized trials that implemented wrist-worn accelerometry is provided. We conclude the review by discussing new developments and future directions of research using accelerometers, with a focus on wrist-worn accelerometers.

Association between walking energetics and fragmented physical activity in mid-to-late life

BACKGROUND

Physical activity becomes increasingly fragmented with age, which may be an early marker of functional decline. Energetic cost of walking and energy capacity are also linked with functional decline, but their associations with activity fragmentation, and the potential modifying roles of total daily physical activity and age, remains unclear.

METHODS

493 participants (50-93 years) from the Baltimore Longitudinal Study of Aging underwent measures of: energetic cost of usual-paced overground walking (ml/kg/m), energy demand during slow walking (ml/kg/min) on a treadmill (0.67 m/s, 0% grade),m/s, 0% grade), and average peak walking energy expenditure (ml/kg/min) during a fast-paced 400-m walk. A ratio of slow walking to peak walking energy expenditure ("cost-to-capacity ratio") was calculated. Activity fragmentation was quantified as an active-to-sedentary transition probability (ASTP) using Actiheart accelerometer data. Linear regression models with ASTP as the dependent variable were used to test whether poorer energy cost and capacity were associated with higher ASTP and whether the associations differed by daily physical activity or age.

RESULTS

After adjusting for demographics, body composition, comorbidities and daily physical activity, every 10% higher cost-to-capacity ratio was associated with 0.4% greater ASTP (p=0.005). This association was primarily driven by the least active participants (pinteraction=0.023). Peak walking energy expenditure was only associated with ASTP among participants aged ≥70 years.

CONCLUSIONS

Higher cost-to-capacity ratio and lower energy capacity may manifest as more fragmented physical activity, especially among those less active or aged ≥70 years. Future studies should examine whether an increasing cost-to-capacity ratio or declining energy capacity predicts subsequent activity fragmentation.

Associations between activity fragmentation and subjective memory complaints in middle-aged and older adults

INTRODUCTION

Subjective memory complaints (SMC) are often considered a clinical marker of mild cognitive impairment and dementia and could manifest as shortening of activity bouts throughout the day causing daily activity to accumulate in a more fragmented pattern. In the current study we explored the association between activity fragmentation and SMC in middle-aged and older adults.

METHODS

We used data from 3820 participants in the National Health and Nutrition Examination Survey (2003-2006) with valid accelerometer SMC data. The analyses were conducted in 2020. To calculate activity fragmentation, an active-to-sedentary transition probability was calculated as the number of physical activity bouts (i.e., consecutive minutes registering 100+ counts/min) divided by the total sum of minutes spent in physical activity. A multivariable ordinal logistic regression model was conducted to examine the association between activity fragmentation (scaled) and SMC (yes/no).

RESULTS

Higher activity fragmentation was associated with an increased likelihood of self-reported SMC in the study population (Odd Ratio [95% Confidence Interval] = 1.335 [1.067, 1.669]; Average Marginal Effect [95%CI] = 0.029 [0.006, 0.052]; p-value = 0.021). This association was independent of total physical activity volume.

CONCLUSIONS

The findings provide support that studying fragmented activity patterns can be useful in identifying those at risk for SMC, over and above total volume of physical activity. Future longitudinal studies are required to establish causality and the temporal order of the observed association. Nevertheless, activity fragmentation in middle-aged and older adults may reflect pre-clinical signs of future neurodegenerative processes indicating potential targets for modification through intervention.

The Associations of Activity Fragmentation With Physical and Mental Fatigability Among Community-Dwelling 75-, 80-, and 85-Year-Old People

BACKGROUND

Fatigue related to task standardized by duration and intensity, termed fatigability, could manifest as shortening of activity bouts throughout the day causing daily activity to accumulate in a more fragmented pattern. Our purpose was to study the association of activity fragmentation with physical and mental dimensions of fatigability.

METHODS

A cross-sectional study of 485 community-dwelling 75-, 80-, and 85-year-old people using a thigh-worn accelerometer for 3-7 days. Activity fragmentation was studied as Active-to-Sedentary Transition Probability for 2 operational definitions of physical activity: accelerations equivalent to at least light physical activity and for upright posture. Physical fatigability was assessed as perceived exertion fatigability, performance fatigability severity, and with the Physical Fatigue Subscale of the Situational Fatigue Scale. Mental fatigability was assessed with the Mental Fatigue Subscale of the Situational Fatigue Scale and as a decrease in perceived mental alertness after a 6-minute walk test.

RESULTS

Higher activity fragmentation was associated with higher self-reported physical fatigability, perceived exertion fatigability, and performance fatigability severity, independent of total activity minutes (β = 0.13-0.33, p < .05 for all). Higher activity fragmentation was not associated with mental fatigability in the fully adjusted models. The associations with fatigability indices were similar for both activity fragmentation indicators. Associations of activity fragmentation and performance fatigability severity were similar also among those with the highest intensity-based physical activity volume.

CONCLUSIONS

The findings provide support that studying fragmented activity patterns can be useful in identifying those at risk for high fatigability, even among those with relatively high physical activity level.

Longitudinal Association Between Energy Regulation and Fatigability in Mid-to-Late Life

BACKGROUND

Deficits in energy production and utilization have been linked to higher fatigue and functional decline with aging. Lesser known is whether individuals with a combination of low peak energy capacity and high energy costs for mobility (eg, impaired energy regulation) are more likely to experience the onset and progression of high fatigability with aging.

METHODS

Participants in the Baltimore Longitudinal Study of Aging (n = 651, 49.0% male, mean age 71.9, range 50-94) with ≥2 visits who completed fatigability (Borg rating of perceived exertion [RPE] after a 5-minute 1.5 mph treadmill walk), slow walking energy expenditure (VO2 mL/kg/min), and peak walking energy expenditure (VO2 mL/kg/min), testing between 2007 and 2018. The longitudinal association between each measure of energy expenditure, a ratio of energy cost-to-capacity, and perceived fatigability was modeled using mixed effects models adjusted for age, body composition, and comorbidities. Time to higher perceived fatigability (RPE ≥ 10) was modeled using Cox proportional hazards models.

RESULTS

In continuous analyses, higher slow walking energy expenditure (p < .05) and a higher cost ratio (p ≤ .001) were associated with greater perceived fatigability over time. Cox proportional hazards models using tertiles of the cost ratio suggest that, compared to those in the lowest tertile, those in the middle and highest tertiles had 1.89 (95% confidence interval [CI]: 1.57-5.16) and 2.85 (95% CI: 1.05-3.40) times greater risk of developing higher fatigability, respectively.

CONCLUSION

Findings suggest that strategies to prevent fatigability should consider methods to improve energy regulation by targeting both the independent and combined effects of declining peak capacity and rising energy costs for mobility with aging.

Patterns of Daily Physical Activity across the Spectrum of Visual Field Damage in Glaucoma Patients

PURPOSE

To define and quantify patterns of objectively measured daily physical activity by level of visual field (VF) damage in glaucoma patients including: (1) activity fragmentation, a metric of health and physiologic decline, and (2) diurnal patterns of activity, a measure of rest and activity rhythms.

DESIGN

Prospective cohort study.

PARTICIPANTS

Older adults diagnosed with glaucoma or suspected glaucoma.

METHODS

Degree of VF damage was defined by the average VF sensitivity within the integrated VF (IVF). Each participant wore a hip accelerometer for 1 week to measure daily minute-by-minute activity for 7 consecutive days. Activity fragmentation was calculated as the reciprocal of the average activity bout duration in minutes, with higher fragmentation indicating more transient, rather than sustained, activity. Multivariate linear regression was used to test for cross-sectional associations between VF damage and activity fragmentation. Multivariate linear mixed-effects models were used to assess the associations between VF damage and accumulation of activity across 6 3-hour intervals from 5 am to 11 pm.

MAIN OUTCOME MEASURES

Activity fragmentation and amount of activity (steps) over the course of the day.

RESULTS

Each 5-dB decrement in IVF sensitivity was associated with 16.3 fewer active minutes/day (P < 0.05) and 2% higher activity fragmentation (P < 0.05), but not with the number of active bouts per day (P = 0.30). In time-of-day analyses, lower IVF sensitivity was associated with fewer steps over the 11 am to 2 pm, 2 pm to 5 pm, and 5 pm to 8 pm periods (106.6, 93.1, and 89.2 fewer steps, respectively; P < 0.05 for all), but not over other periods. The activity midpoint (the time at which half of the daily activity is completed) did not vary across level of VF damage.

CONCLUSIONS

At worse levels of VF damage, glaucoma patients demonstrate shorter, more fragmented bouts of physical activity throughout the day and lower activity levels during typical waking hours, reflecting low physiologic functioning. Further work is needed to establish the temporality of this association and whether glaucoma patients with such activity patterns are at a greater risk of adverse health outcomes associated with activity fragmentation.

Measuring Aging and Identifying Aging Phenotypes in Cancer Survivors

Observational data have shown that some cancer survivors develop chronic conditions like frailty, sarcopenia, cardiac dysfunction, and mild cognitive impairment earlier and/or at a greater burden than similarly aged individuals never diagnosed with cancer or exposed to systemic or targeted cancer therapies. In aggregate, cancer- and treatment-related physical, cognitive, and psychosocial late- and long-term morbidities experienced by cancer survivors are hypothesized to represent accelerated or accentuated aging trajectories. However, conceptual, measurement, and methodological challenges have constrained efforts to identify, predict, and mitigate aging-related consequences of cancer and cancer treatment. In July 2018, the National Cancer Institute convened basic, clinical, and translational science experts for a think tank titled "Measuring Aging and Identifying Aging Phenotypes in Cancer Survivors." Through the resulting deliberations, several research and resource needs were identified, including longitudinal studies to examine aging trajectories that include detailed data from before, during, and after cancer treatment; mechanistic studies to elucidate the pathways that lead to the emergence of aging phenotypes in cancer survivors; long-term clinical surveillance to monitor survivors for late-emerging effects; and tools to integrate multiple data sources to inform understanding of how cancer and its therapies contribute to the aging process. Addressing these needs will help expand the evidence base and inform strategies to optimize healthy aging of cancer survivors.

Active-to-Sedentary Behavior Transitions, Fatigability, and Physical Functioning in Older Adults

BACKGROUND

With aging, daily physical activity (PA) becomes less frequent and more fragmented. Accumulation patterns of daily PA-including transitions from active-to-sedentary behaviors-may provide important insights into functional status in older, less active populations.

METHODS

Participants of the Baltimore Longitudinal Study of Aging (n = 680, 50% male, aged 27-94 years) completed a clinical assessment and wore an Actiheart accelerometer. Transitions between active and sedentary states were modeled as a probability (Active-to-Sedentary Transition Probability [ASTP]) defined as the reciprocal of the average PA bout duration. Cross-sectional associations between ASTP and gait speed (m/s), fatigability (rating-of-perceived-exertion [RPE]), 400 m time (seconds), and expanded short physical performance battery score were modeled using linear and logistic regression, adjusted for chronic conditions. Further analyses explored the utility of ASTP over-and-above total daily PA.

RESULTS

In continuous models, each 0.10-unit higher ASTP was associated slower gait (β = -0.06 m/s, SE = 0.01), higher fatigability (β = 0.60 RPE, SE = 0.12), slower 400 m time (β = 16.31 s, SE = 2.70), and lower functioning (β = -0.13 expanded short physical performance battery score, SE = 0.03; p < .001). In categorical analyses, those in the highest tertile of ASTP were >2 times more likely to have high fatigability (rating of perceived exertion ≥10), slow 400 m time (>300 seconds) and reduced functional performance (expanded short physical performance battery score < 3.07) than those in the lowest tertile (p < .01). Further analyses demonstrated ASTP provided additional insight into functional outcomes beyond total daily PA.

CONCLUSION

Fragmented daily PA-as measured by ASTP-is strongly linked with measures of health and functional status and may identify those at risk of high fatigability and reduced functional performance over and above traditional PA metrics.

Association of Total Daily Physical Activity and Fragmented Physical Activity With Mortality in Older Adults

Importance

Fragmented daily physical activity may be a sign of physiological decline that provides more powerful insight into impending mortality than total daily activity.

Objective

To compare and contrast the association between total daily activity and activity fragmentation, which encompasses activity bouts and duration, and mortality risk.

Design, Setting, and Participants

In this cohort study, accelerometer data from 2007 through 2015 and mortality data from 2007 through 2017 were collected from 548 adults aged 65 years and older participating in the Baltimore Longitudinal Study of Aging. The dates of analysis were November 2016 to June 2019, with data collected through December 31, 2017. Using Cox proportional hazards regression, the association between accelerometer-derived patterns of physical activity and mortality was estimated after adjusting for demographic characteristics, lifestyle factors, and comorbidities.

Exposures

Minute-by-minute physical activity data were collected over a 24-hour, 7-day period (excluding times between 11:00 pm and 4:59 am) using an accelerometer. Each minute was labeled either active or sedentary, and 5 features of accelerometer data were extracted: total daily activity (defined as any activity performed throughout the day), activity fragmentation (defined as an active-to-sedentary transition probability), and 3 measures of activity bouts (<5, 5-10, and ≥10 active minutes).

Main Outcomes and Measures

All-cause mortality.

Results

Among 548 well-functioning older adults (mean [SD] age, 75.8 [7.2] years; 262 [47.8%] women), 61 participants (11.1%) died. Total daily physical activity was not associated with mortality risk (hazard ratio [HR], 0.90 [95% CI, 0.75-1.08]; P = .28). However, more fragmented physical activity patterns were associated with greater mortality risk (HR, 1.49 [95% CI, 1.02-2.19]; P = .04) after adjusting for age, sex, race/ethnicity, body mass index, smoking history, employment, self-reported health, grip strength, usual gait speed, comorbidities, and device wear time. In addition, more frequently engaging in activity bouts lasting less than 5 minutes was associated with greater mortality risk (HR, 1.28 [95% CI, 1.01-1.61]; P = .04), whereas activity bouts of 5 to 10 minutes (HR, 0.99 [95% CI, 0.58-1.69]; P = .97) and 10 minutes or longer (HR, 0.81 [95% CI, 0.65-1.01]; P = .06) were not associated with mortality risk.

Conclusions and Relevance

In this cohort study of well-functioning adults aged 65 years and older, fragmented daily physical activity, particularly activity bouts lasting less than 5 minutes, was associated with greater mortality risk. These findings suggest that activity fragmentation in older adults may precede declines in functional capability and overall physical activity that typically indicate impending mortality.