Protocol for the San Diego Nathan Shock Center Clinical Cohort: a new resource for studies of human aging.

INTRODUCTION: While it is well recognised that aging is a heterogeneous process, our understanding of the determinants of biological aging and its heterogeneity remains unclear. The San Diego Nathan Shock Center (SD-NSC) Clinical Cohort aims to establish a resource of biospecimens and extensive donor clinical data such as physical, cognitive and sensory function to support other studies that aim to explore the heterogeneity of normal human aging and its biological underpinnings. METHODS AND ANALYSIS: The SD-NSC Clinical Cohort is composed of 80 individuals across the adult human lifespan. Strict inclusion and exclusion criteria are implemented to minimise extrinsic factors that may impede the study of normal aging. Across three visits, participants undergo extensive phenotyping for collection of physical performance, body composition, cognitive function, sensory ability, mental health and haematological data. During these visits, we also collected biospecimens including plasma, platelets, peripheral blood mononuclear cells and fibroblasts for banking and future studies on aging. ETHICS AND DISSEMINATION: Ethics approval from the UC San Diego School of Medicine Institutional Review Board (IRB #201 141 SHOCK Center Clinical Cohort, PI: Molina) was obtained on 11 November 2020. Written informed consent is obtained from all participants after objectives and procedures of the study have been fully explained. Congruent with the goal of establishing a core resource, biological samples and clinical data are made available to the research community through the SD-NSC.

Fatness but Not Fitness Linked to BrainAge: Longitudinal Changes in Brain Aging during an Exercise Intervention.

PURPOSE: Fitness, physical activity, body composition, and sleep have all been proposed to explain differences in brain health. We hypothesized that an exercise intervention would result in improved fitness and body composition and would be associated with improved structural brain health. METHODS: In a randomized controlled trial, we studied 485 older adults who engaged in an exercise intervention ( n = 225) or a nonexercise comparison condition ( n = 260). Using magnetic resonance imaging, we estimated the physiological age of the brain (BrainAge) and derived a predicted age difference compared with chronological age (brain-predicted age difference (BrainPAD)). Aerobic capacity, physical activity, sleep, and body composition were assessed and their impact on BrainPAD explored. RESULTS: There were no significant differences between experimental groups for any variable at any time point. The intervention group gained fitness, improved body composition, and increased total sleep time but did not have significant changes in BrainPAD. Analyses of changes in BrainPAD independent of group assignment indicated significant associations with changes in body fat percentage ( r (479) = 0.154, P = 0.001), and visceral adipose tissue (VAT) ( r (478) = 0.141, P = 0.002), but not fitness ( r (406) = -0.075, P = 0.129), sleep ( r (467) range, -0.017 to 0.063; P range, 0.171 to 0.710), or physical activity ( r (471) = -0.035, P = 0.444). With linear regression, changes in body fat percentage and VAT significantly predicted changes in BrainPAD ( ß = 0.948, P = 0.003) with 1-kg change in VAT predicting 0.948 yr of change in BrainPAD. CONCLUSIONS: In cognitively normal older adults, exercise did not appear to impact BrainPAD, although it was effective in improving fitness and body composition. Changes in body composition, but not fitness, physical activity, or sleep impacted BrainPAD. These findings suggest that focus on weight control, particularly reduction of central obesity, could be an interventional target to promote healthier brains.

Shared-Medical Appointment for Screening and Risk Assessment for Fall Prevention.

Background: The median age of Americans is rising and fall risk increases with age. While the causes of falls are multifactorial, falls risk can be reduced. Only a small percentage of older-adults report being asked about fall risk or falls. The CDC has initiated a Stopping Elderly Accidents, Deaths and Injuries (STEADI) toolkit, but penetration into practice has been slow. To address this, we implemented a Falls Prevention Shared Medical Appointment (SMA) at an academic internal medicine clinic. Methods: Patients were referred to the SMA and scheduled per their preference virtually or in-person. Patients attended a nurse visit for appropriate fallrisk related screening, followed by the SMA with two physicians for review of medical history, fall screening results and implementation of fall reduction strategies. Follow-up survey of the patients assessed program effectiveness. Results: Fifty-two patients were seen/assessed between November 2021 and February 2023 with SMAs ranging from 3 to 5 patients with an average age of 77 (=/- 6.7). Questionnaire self-reported risk factors, self-reported strength, and polypharmacy were associated with objective markers of increased fall risk. Survey results indicate acceptability of this model. Conclusion: Falls prevention SMAs can be effective. More work is needed to further delineate and refine cohort selection.

Support for inadvertent undereating in female adolescent athletes with clinical indicators of low energy availability.

OBJECTIVES: This study evaluated pathways to low energy availability in a sample of female adolescent athletes (n = 464). DESIGN: Cross-sectional. METHODS: Participants (age 13-18 y) underwent assessments for height, weight, eating attitudes and behaviors, and menstrual function. Bone mineral density and body composition were evaluated by dual-energy x-ray absorptiometry in a subset of participants (n = 209). Athletes were classified with clinical indicators of low energy availability if they met criteria for 1) primary or secondary amenorrhea or 2) clinical underweight status (body mass index-for-age < 5th percentile). Disordered eating was assessed using the Eating Disorder Examination Questionnaire. RESULTS: Thirty (6.5%) athletes exhibited clinical indicators of low energy availability, with higher estimates in leanness than non-leanness sports (10.9% vs. 2.1%, p < 0.005). Among athletes with clinical indicators of low energy availability, 80% (n = 24) did not meet criteria for disordered eating, eating disorder, or report the desire to lose weight. Athletes with (vs. without) clinical indicators of low energy availability exhibited lower lumbar spine (-1.30 ±â€¯1.38 vs. -0.07 ±â€¯1.21, p < 0.001) and total body (-0.30 ±â€¯0.98 vs. 0.53 ±â€¯0.97, p < 0.006) bone mineral density Z-scores. CONCLUSIONS: A majority of female adolescent athletes with clinical indicators of low energy availability did not exhibit characteristics consistent with intentional dietary restriction, supporting the significance of the inadvertent pathway to low energy availability and need for increased nutrition education in this population.

Associations of Lean Mass, Muscular Strength, and Physical Function with Trabecular Bone Score in Older Adults.

INTRODUCTION/BACKGROUND: Trabecular bone score (TBS) is an indirect measurement of bone quality and microarchitecture determined from dual-energy X-ray absorptiometry (DXA) imaging of the lumbar spine. TBS predicts fracture risk independent of bone mass/density, suggesting this assessment of bone quality adds value to the understanding of patients' bone health. While lean mass and muscular strength have been associated with higher bone density and lower fracture risk among older adults, the literature is limited regarding the relationship of lean mass and strength with TBS. The purpose of this study was to determine associations of DXA-determined total body and trunk lean mass, maximal muscular strength, and gait speed as a measure of physical function, with TBS in 141 older adults (65-84 yr, 72.5 +/- 5.1 yr, 74% women). METHODOLOGY: Assessments included lumbar spine (L1-L4) bone density and total body and trunk lean mass by DXA, lower body (leg press) and upper body (seated row) strength by one repetition maximum tests, hand grip strength, and usual gait speed. TBS was derived from the lumbar spine DXA scan. Multivariable linear regression determined the contribution of proposed predictors to TBS. RESULTS: After adjusting for age, sex, and lumbar spine bone density, upper body strength significantly predicted TBS (unadjusted/adjusted R2= 0.16/ 0.11, ß coefficient =0.378, p=0.005), while total body lean mass index showed a trend in the expected direction (ß coefficient =0.243, p=0.053). Gait speed and grip strength were not associated with TBS (p>0.05). CONCLUSION: Maximum strength of primarily back muscles measured as the seated row appears important to bone quality as measured by TBS, independent of bone density. Additional research on exercise training targeting back strength is needed to determine its clinical utility in preventing vertebral fractures among older adults.

Effects of Mindfulness Training and Exercise on Cognitive Function in Older Adults: A Randomized Clinical Trial.

Importance: Episodic memory and executive function are essential aspects of cognitive functioning that decline with aging. This decline may be ameliorable with lifestyle interventions. Objective: To determine whether mindfulness-based stress reduction (MBSR), exercise, or a combination of both improve cognitive function in older adults. Design, Setting, and Participants: This 2 × 2 factorial randomized clinical trial was conducted at 2 US sites (Washington University in St Louis and University of California, San Diego). A total of 585 older adults (aged 65-84 y) with subjective cognitive concerns, but not dementia, were randomized (enrollment from November 19, 2015, to January 23, 2019; final follow-up on March 16, 2020). Interventions: Participants were randomized to undergo the following interventions: MBSR with a target of 60 minutes daily of meditation (n = 150); exercise with aerobic, strength, and functional components with a target of at least 300 minutes weekly (n = 138); combined MBSR and exercise (n = 144); or a health education control group (n = 153). Interventions lasted 18 months and consisted of group-based classes and home practice. Main Outcomes and Measures: The 2 primary outcomes were composites of episodic memory and executive function (standardized to a mean [SD] of 0 [1]; higher composite scores indicate better cognitive performance) from neuropsychological testing; the primary end point was 6 months and the secondary end point was 18 months. There were 5 reported secondary outcomes: hippocampal volume and dorsolateral prefrontal cortex thickness and surface area from structural magnetic resonance imaging and functional cognitive capacity and self-reported cognitive concerns. Results: Among 585 randomized participants (mean age, 71.5 years; 424 [72.5%] women), 568 (97.1%) completed 6 months in the trial and 475 (81.2%) completed 18 months. At 6 months, there was no significant effect of mindfulness training or exercise on episodic memory (MBSR vs no MBSR: 0.44 vs 0.48; mean difference, -0.04 points [95% CI, -0.15 to 0.07]; P = .50; exercise vs no exercise: 0.49 vs 0.42; difference, 0.07 [95% CI, -0.04 to 0.17]; P = .23) or executive function (MBSR vs no MBSR: 0.39 vs 0.31; mean difference, 0.08 points [95% CI, -0.02 to 0.19]; P = .12; exercise vs no exercise: 0.39 vs 0.32; difference, 0.07 [95% CI, -0.03 to 0.18]; P = .17) and there were no intervention effects at the secondary end point of 18 months. There was no significant interaction between mindfulness training and exercise (P = .93 for memory and P = .29 for executive function) at 6 months. Of the 5 prespecified secondary outcomes, none showed a significant improvement with either intervention compared with those not receiving the intervention. Conclusions and Relevance: Among older adults with subjective cognitive concerns, mindfulness training, exercise, or both did not result in significant differences in improvement in episodic memory or executive function at 6 months. The findings do not support the use of these interventions for improving cognition in older adults with subjective cognitive concerns. Trial Registration: ClinicalTrials.gov Identifier: NCT02665481.

Adolescent Endurance Runners Exhibit Suboptimal Energy Availability and Intakes of Key Nutrients.

Backgroud: Despite the evidence of an elevated prevalence of low bone mass in adolescent endurance runners, reports on dietary intake in this population is limited.Objectives: This study aimed to evaluate energy availability (EA) and dietary intake among 72 (n = 60 female, n = 12 male) high school cross-country runners.Methods: The sample consisted of a combined dataset of two cohorts. In both cohorts, the Block Food Frequency Questionnaire (FFQ; 2005 & 2014 versions) assessed dietary intake. Fat free mass was assessed using dual-energy x-ray absorptiometry or bioelectrical impedance analysis.Results: Mean EA was less than recommended (45 kcal/kgFFM/day) among male (35.8 ± 14.4 kcal/kg FFM/day) and female endurance runners (29.6 ± 17.4 kcal/kgFFM/day), with 30.0% of males and 60.0% of females meeting criteria for low EA (<30 kcal/kgFFM/day). Calorie intake for male (2,614.2 ± 861.8 kcal/day) and female (1,879.5 ± 723.6 kcal/day) endurance runners fell below the estimated energy requirement for "active" boys (>3,100 kcal/day) and girls (>2,300 kcal/day). Female endurance runners' relative carbohydrate intake (4.9 ± 2.1 g/kg/day) also fell below recommended levels (6-10 g/kg/day). Male and female endurance runners exhibited below-recommended intakes of calcium, vitamin D, potassium, fruit, vegetables, grains, and dairy. Compared to male endurance runners, female endurance runners demonstrated lower relative intakes of energy (kcal/kg/day), protein (g/kg/day), fat (g/kg/day), fiber, vegetables, total protein, and oils.Conclusion: This study provides evidence of the nutritional risk of adolescent endurance runners and underscores the importance of nutritional support efforts in this population.

Fatness, fitness and the aging brain: A cross sectional study of the associations between a physiological estimate of brain age and physical fitness, activity, sleep, and body composition.

Introduction: Changes in brain structure and function occur with aging. However, there is substantial heterogeneity both in terms of when these changes begin, and the rate at which they progress. Understanding the mechanisms and/or behaviors underlying this heterogeneity may allow us to act to target and slow negative changes associated with aging. Methods: Using T1 weighted MRI images, we applied a novel algorithm to determine the physiological age of the brain (brain-predicted age) and the predicted age difference between this physiologically based estimate and chronological age (BrainPAD) to 551 sedentary adults aged 65 to 84 with self-reported cognitive complaint measured at baseline as part of a larger study. We also assessed maximal aerobic capacity with a graded exercise test, physical activity and sleep with accelerometers, and body composition with dual energy x-ray absorptiometry. Associations were explored both linearly and logistically using categorical groupings. Results: Visceral Adipose Tissue (VAT), Total Sleep Time (TST) and maximal aerobic capacity all showed significant associations with BrainPAD. Greater VAT was associated with higher (i.e,. older than chronological) BrainPAD (r = 0.149 p = 0.001)Greater TST was associated with higher BrainPAD (r = 0.087 p = 0.042) and greater aerobic capacity was associated with lower BrainPAD (r = - 0.088 p = 0.040). With linear regression, both VAT and TST remained significant (p = 0.036 and 0.008 respectively). Each kg of VAT predicted a 0.741 year increase in BrainPAD, and each hour of increased TST predicted a 0.735 year increase in BrainPAD. Maximal aerobic capacity did not retain statistical significance in fully adjusted linear models. Discussion: Accumulation of visceral adipose tissue and greater total sleep time, but not aerobic capacity, total daily physical activity, or sleep quantity and/or quality are associated with brains that are physiologically older than would be expected based upon chronological age alone (BrainPAD).

Disordered Eating, Development of Menstrual Irregularity, and Reduced Bone Mass Change After a 3-Year Follow-Up In Female Adolescent Endurance Runners.

This prospective study evaluated the 3-year change in menstrual function and bone mass among 40 female adolescent endurance runners (age 15.9 ± 1.0 years) according to baseline disordered eating status. Three years after initial data collection, runners underwent follow-up measures including the Eating Disorder Examination Questionnaire and a survey evaluating menstrual function, running training, injury history, and prior sports participation. Dual-energy X-ray absorptiometry was used to measure bone mineral density and body composition. Runners with a weight concern, shape concern, or global score ≥4.0 or reporting >1 pathologic behavior in the past 28 days were classified with disordered eating. Compared with runners with normal Eating Disorder Examination Questionnaire scores at baseline, runners with disordered eating at baseline reported fewer menstrual cycles/year (6.4 ± 4.5 vs. 10.5 ± 2.8, p = .005), more years of amenorrhea (1.6 ± 1.4 vs. 0.3 ± 0.5, p = .03), and a higher proportion of menstrual irregularity (75.0% vs. 31.3%, p = .02) and failed to increase lumbar spine or total hip bone mineral density at the 3-year follow-up. In a multivariate model including body mass index and menstrual cycles in the past year at baseline, baseline shape concern score (B = -0.57, p value = .001) was inversely related to the annual number of menstrual cycles between assessments. Weight concern score (B = -0.40, p value = .005) was inversely associated with lumbar spine bone mineral density Z-score change between assessments according to a multivariate model adjusting for age and body mass index. These finding support associations between disordered eating at baseline and future menstrual irregularities or reduced accrual of lumbar spine bone mass in female adolescent endurance runners.

Hepatic Steatosis is Negatively Associated with Bone Mineral Density in Children.

OBJECTIVE: To evaluate the relationship between hepatic steatosis and bone mineral density (BMD) in children. In addition, to assess 25-hydroxyvitamin D levels in the relationship between hepatic steatosis and BMD. STUDY DESIGN: A community-based sample of 235 children was assessed for hepatic steatosis, BMD, and serum 25-hydroxyvitamin D. Hepatic steatosis was measured by liver magnetic resonance imaging proton density fat fraction (MRI-PDFF). BMD was measured by whole-body dual-energy x-ray absorptiometry. RESULTS: The mean age of the study population was 12.5 years (SD 2.5 years). Liver MRI-PDFF ranged from 1.1% to 40.1% with a mean of 9.3% (SD 8.5%). Across this broad spectrum of hepatic fat content, there was a significant negative relationship between liver MRI-PDFF and BMD z score (R = -0.421, P < .001). Across the states of sufficiency, insufficiency, and deficiency, there was a significant negative association between 25-hydroxyvitamin D and liver MRI-PDFF (P < .05); however, there was no significant association between vitamin D status and BMD z score (P = .94). Finally, children with clinically low BMD z scores were found to have higher alanine aminotransferase (P < .05) and gamma-glutamyl transferase (P < .05) levels compared with children with normal BMD z scores. CONCLUSIONS: Across the full range of liver MRI-PDFF, there was a strong negative relationship between hepatic steatosis and BMD z score. Given the prevalence of nonalcoholic fatty liver disease and the critical importance of childhood bone mineralization in protecting against osteoporosis, clinicians should prioritize supporting bone development in children with nonalcoholic fatty liver disease.

Balance performance and related soft tissue components across three age groups.

With the aging process, falls and related injuries are common and unwanted events among older women. Lost balance is the last step before the frequent experience of falls. After menopause, women's bone conditions regarding health and balance performance steeply decline often resulting in serious injury. Our purpose in the study is to identify balance performance and its associations with soft tissue components among Korean-American (KA) women with three menopausal conditions. Researchers conducted a cross-sectional study with 63 KA women divided into three age groups: 25-35 years (young), 45-55 years old (middle), and 65+ years (old). Lean and fat mass on the entire body, appendicular and gynoid areas were measured by using the dual X-ray absorptiometry. Static and dynamic balance and physical performance (floor sit to stand) were tested. We found that with increased aging, lean mass, fat and body mass index were changed; balance and physical performance decreased significantly. In regression models, age and fat ratio of android/gynoid changes explain static balance and physical performance; appendicular lean mass predicted dynamic balance. With advancing age, maintaining lean mass and proportion of fat accumulation is critical for stable balance.

Cognitive dietary restraint score is associated with lower energy, carbohydrate, fat, and grain intake among female adolescent endurance runners.

This cross-sectional study investigated associations between cognitive dietary restraint (CDR), energy, macronutrient and food group intake, menstrual function, and bone density in female adolescent endurance runners. Participants were forty female adolescent endurance runners. The independent variable was CDR, as assessed by the Three Factor Eating Questionnaire (TFEQ). Runners with CDR subscale scores ≥11 were classified with elevated CDR. The main outcomes measured were dietary intake measured by 24-hour recall for 7 days, menstrual history, and bone mineral density (BMD). Twelve of 40 participants (30.0%) met criteria for elevated CDR. Compared to runners with normal CDR, runners with elevated CDR scores reported consuming lower energy (kcal/kg/day) (37.5 ± 8.6 vs. 44.0 ± 9.6, p = 0.052), lower carbohydrate (g/kg/day) (5.3 ± 1.3 vs. 6.3 ± 1.3, p = 0.042), more fiber (g/day) (24.9 ± 6.7 vs. 20.0 ± 5.3, p = 0.018), more servings of fruit (3.3 ± 1.4 vs. 1.9 ± 1.2, p = 0.003), more servings of vegetables (2.7 ± 1.4 vs. 1.7 ± 0.7, p = 0.004), and fewer servings of grain (7.6 ± 2.4 vs. 9.8 ± 2.4, p = 0.009) per day. Runners with elevated CDR exhibited significantly lower lumbar spine BMD Z-scores (adjusting for BMI) (-0.78 ± 0.19 vs. -0.22 ± 0.12, p = 0.016) than runners with normal CDR. Menstrual history did not significantly differ based on CDR status. Elevated CDR may increase risk of dietary patterns associated with consuming inadequate levels of energy, key nutrients, and developing low BMD in endurance runners. Trial Registration:ClinicalTrials.gov Identifier: NCT01059968.

Quantification of Scan Analysis Errors in GE Lunar DXA Visceral Adiposity in Adults.

Utilization of dual-energy X-ray absorptiometry is increasing in clinical settings and the fitness industry as a viable tool to assess total and regional body composition, including visceral adiposity. Previous research using small samples (<50) has described several pitfalls in patient positioning, scan acquisition, and/or analysis that alter regional body composition values. Our aim was to quantify the largest probable error in measures of total, android, gynoid, and visceral fat caused by incorrect placement of the head cut-line, in a large sample of adults. Total body images (N = 436) from 196 women and 67 men (20-85 years) scanned on a GE Lunar Prodigy densitometer were analyzed using enCORE software in 2 ways: (1) placing the head cut-line just beneath the bony protuberance of the chin according to manufacturer recommendation (correct method); (2) placing the head cut-line at the lowest point below the chin and just above the soft tissue at the shoulders (incorrect method). All other cut-lines were fixed. Mean differences in adiposity were examined using Lin's concordance correlation coefficient; equality of means and variances were evaluated using Bradley-Blackwood F-tests. The limits of agreement were displayed as Bland-Altman plots and calculated as the mean difference ±1.96 times the standard deviation of the difference. Correlation coefficients for paired comparisons of adiposity for correct vs incorrect cut-line placement ranged from 0.983-0.999 for all variables (all p < 0.001). Significant mean differences were 172 ± 130, 201 ± 168, 65 ± 122, and -143 ± 336 g for android, gynoid, visceral, and total fat mass, respectively (all p < 0.0001). These differences exceeded our site's least significant change in 66%, 37%, 29%, and 4% of participant scans for android, gynoid, visceral, and total fat mass, respectively. Our findings underscore the importance of careful review of the manufacturer's auto analysis and consistency in conducting serial scans to ensure accurate and precise measures of regional body fat.

Sport Specialization and Low Bone Mineral Density in Female High School Distance Runners.

CONTEXT: Sport specialization may contribute to sport injury and menstrual dysfunction in female high school distance runners. Despite the recent growth in sport specialization, including among high school-aged runners, the association of sport specialization with bone mineral density (BMD) remains poorly described. OBJECTIVE: To evaluate whether sport specialization was associated with BMD in female high school distance runners. DESIGN: Cross-sectional study. SETTING: Six high schools. PATIENTS OR OTHER PARTICIPANTS: Sixty-four female runners (age = 15.6 ± 1.4 years) who competed in cross-country or track distance events and were not currently on birth control medication. MAIN OUTCOME MEASURE(S): Each runner completed a survey on menstrual history and sport participation. Height and weight were measured, and dual-energy x-ray absorptiometry was used to measure whole-body, spine, and hip BMD. Each runner was assigned a sport specialization status: low (participation in ≥1 nonrunning sport and distance-running sport(s) for ≤8 mo/y); moderate (participation in both distance-running sport(s) ≥9 mo/y and ≥1 nonrunning sport(s) or limited to distance-running sport(s) for ≤8 mo/y); or high (participation only in distance-running sport(s) for ≥9 mo/y). Multivariable logistic regression was performed to determine the adjusted odds ratio and 95% confidence interval for sport specialization to BMD values, adjusting for body mass index and gynecological age. RESULTS: Overall, 21.9%, 37.5%, and 40.6% of participants were high, moderate, or low sport specializers, respectively. Low BMD (spine or whole-body BMD z score < -1.0 [standardized by age and sex normative values]) was present in 23 (35.9%) runners. Compared with low sport specializers, high sport specializers were 5 times more likely (adjusted odds ratio = 5.42, 95% confidence interval = 1.3, 23.3; P = .02) to have low BMD. CONCLUSIONS: A high level of sport specialization in high school female distance runners may be associated with a heightened risk for low BMD. Further investigation of this association is warranted due to the health concerns about low BMD in adolescent female runners.

Performance of a commercial multi-sensor wearable (Fitbit Charge HR) in measuring physical activity and sleep in healthy children.

PURPOSE: This study sought to assess the performance of the Fitbit Charge HR, a consumer-level multi-sensor activity tracker, to measure physical activity and sleep in children. METHODS: 59 healthy boys and girls aged 9-11 years old wore a Fitbit Charge HR, and accuracy of physical activity measures were evaluated relative to research-grade measures taken during a combination of 14 standardized laboratory- and field-based assessments of sitting, stationary cycling, treadmill walking or jogging, stair walking, outdoor walking, and agility drills. Accuracy of sleep measures were evaluated relative to polysomnography (PSG) in 26 boys and girls during an at-home unattended PSG overnight recording. The primary analyses included assessment of the agreement (biases) between measures using the Bland-Altman method, and epoch-by-epoch (EBE) analyses on a minute-by-minute basis. RESULTS: Fitbit Charge HR underestimated steps (~11.8 steps per minute), heart rate (~3.58 bpm), and metabolic equivalents (~0.55 METs per minute) and overestimated energy expenditure (~0.34 kcal per minute) relative to research-grade measures (p< 0.05). The device showed an overall accuracy of 84.8% for classifying moderate and vigorous physical activity (MVPA) and sedentary and light physical activity (SLPA) (sensitivity MVPA: 85.4%; specificity SLPA: 83.1%). Mean estimates of bias for measuring total sleep time, wake after sleep onset, and heart rate during sleep were 14 min, 9 min, and 1.06 bpm, respectively, with 95.8% sensitivity in classifying sleep and 56.3% specificity in classifying wake epochs. CONCLUSIONS: Fitbit Charge HR had adequate sensitivity in classifying moderate and vigorous intensity physical activity and sleep, but had limitations in detecting wake, and was more accurate in detecting heart rate during sleep than during exercise, in healthy children. Further research is needed to understand potential challenges and limitations of these consumer devices.

Mindfulness, Education, and Exercise for age-related cognitive decline: Study protocol, pilot study results, and description of the baseline sample.

BACKGROUND/AIMS: Age-related cognitive decline is a pervasive problem in our aging population. To date, no pharmacological treatments to halt or reverse cognitive decline are available. Behavioral interventions, such as physical exercise and Mindfulness-Based Stress Reduction, may reduce or reverse cognitive decline, but rigorously designed randomized controlled trials are needed to test the efficacy of such interventions. METHODS: Here, we describe the design of the Mindfulness, Education, and Exercise study, an 18-month randomized controlled trial that will assess the effect of two interventions-mindfulness training plus moderate-to-vigorous intensity exercise or moderate-to-vigorous intensity exercise alone-compared with a health education control group on cognitive function in older adults. An extensive battery of biobehavioral assessments will be used to understand the mechanisms of cognitive remediation, by using structural and resting state functional magnetic resonance imaging, insulin sensitivity, inflammation, and metabolic and behavioral assessments. RESULTS: We provide the results from a preliminary study (n = 29) of non-randomized pilot participants who received both the exercise and Mindfulness-Based Stress Reduction interventions. We also provide details on the recruitment and baseline characteristics of the randomized controlled trial sample (n = 585). CONCLUSION: When complete, the Mindfulness, Education, and Exercise study will inform the research community on the efficacy of these widely available interventions improve cognitive functioning in older adults.

The search for the ejecting chair: a mixed-methods analysis of tool use in a sedentary behavior intervention.

Research is needed on interventions targeting sedentary behavior with appropriate behavior-change tools. The current study used convergent sequential mixed methods (QUAN + qual) to explore tool use during a edentary behavior intervention. Data came from a two-arm randomized sedentary behavior pilot intervention. Participants used a number of intervention tools (e.g., prompts and standing desks). Separate mixed-effects regression models explored associations between change in number of tools and frequency of tool use with two intervention targets: change in sitting time and number of sit-to-stand transitions overtime. Qualitative data explored participants' attitudes towards intervention tools. There was a significant relationship between change in total tool use and sitting time after adjusting for number of tools (ß = -12.86, p = .02), demonstrating that a one-unit increase in tool use was associated with an almost 13 min reduction in sitting time. In contrast, there was a significant positive association between change in number of tools and sitting time after adjusting for frequency of tool use (ß = 63.70, p = .001), indicating that increasing the number of tools without increasing frequency of tool use was associated with more sitting time. Twenty-four semistructured interviews were coded and a thematic analysis revealed four themes related to tool use: (a) prompts to disrupt behavior; (b) tools matching the goal; (c) tools for sit-to-stand were ineffective; and (d) tool use evolved over time. Participants who honed in on effective tools were more successful in reducing sitting time. Tools for participants to increase sit-to-stand transitions were largely ineffective. This study is registered at clincialtrials.gov. Identifier: NCT02544867.

Validity of Cardiorespiratory Fitness Measured with Fitbit Compared to V˙O2max.

PURPOSE: Cardiorespiratory fitness (CRF), broadly defined as the body's ability to utilize oxygen, is a well-established prognostic marker of health, but it is not routinely measured. This may be due to the difficulty of acquiring high-quality CRF measures. The purpose of this study was to independently determine the validity of the Fitbit Charge 2's measure of CRF (Fitbit CRF). METHODS: Sixty-five healthy adults between the ages of 18 and 45 yr (55% female, 45% male) were recruited to undergo gold standard V˙O2max testing and wear a Fitbit Charge 2 continuously for 1 wk during which they were instructed to complete a qualifying outdoor run to derive the Fitbit CRF (units: mL·kg·min). This measure was compared with V˙O2max measures (units: mL·kg·min) epoched at 15 and 60 s. RESULTS: Bland-Altman analyses revealed that Fitbit CRF had a positive bias of 1.59 mL·kg·min compared with laboratory data epoched at 15 s and 0.30 mL·kg·min compared with data epoched at 60 s (n = 60). F statistics (2.09; 0.08) and P values (0.133; 0.926) from Bradley-Blackwood tests for the concordance of Fitbit CRF with 15- and 60-s laboratory data, respectively, support the null hypothesis of equal means and variances, indicating there is concordance between the two measures. Mean absolute percentage error was less than 10% for each comparison. CONCLUSIONS: The Fitbit Charge 2 provides an acceptable level of validity when measuring CRF in young, healthy, and fit adults who are able to run. Further research is required to determine if it is a potentially useful tool in clinical practice and epidemiological research to quantify, categorize, and longitudinally track risk for adverse outcomes.

Longitudinal Decline in Cardiorespiratory Fitness With Age Among Male Firefighters in San Diego, California, 2005-2015.

OBJECTIVES: To determine age-associated changes in cardiorespiratory fitness (CRF) among firefighters. METHODS: Male firefighters (n = 1169) underwent annual evaluations from 2005 to 2015 in San Diego, California. We assessed CRF, the ability to deliver and use oxygen, during a maximal graded exercise test and recorded it in metabolic equivalents (METs; 1 MET = 3.5 ml/kg/min). We investigated differences in baseline CRF among 10-year age groups and patterns of change over follow-up using cross-sectional and longitudinal analyses, respectively. RESULTS: Both analyses support an inverse relationship between CRF and age. Mean baseline CRF decreased from 15.7 ±1.7 to 11.7 ±1.9 METs in the younger than 30 years and 50 years and older age groups, respectively. There was no interaction between body fat and age in predicting CRF (Page × body fat = .09). Longitudinally, there was a nonlinear decrease in CRF, which differed across age groups: the youngest age group demonstrated the greatest decrease in CRF. CONCLUSIONS: Results support a negative, nonlinear association between age and CRF without modification by body fatness. Public Health Implications. Fire departments should recognize the health and safety risks of declining CRF and institutionalize programs to promote firefighter fitness.

Lessons Learned From a Feasibility Study Delivered in 2 WIC Sites to Promote Physical Activity Among Pregnant Latinas.

OBJECTIVE: To assess the feasibility, including demand for and acceptability of a physical activity (PA) intervention among pregnant Latinas recruited at the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). METHODS: Women <20 weeks gestation and self-reporting <150 minutes of PA/wk were recruited from 2 WIC locations in Southern California. The 9-wk, promotora-led intervention included 1-hour sessions and 2 walking groups/wk. RESULTS: WIC was supportive of recruitment, intervention, and evaluation activities. Of an estimated pool of 525 women at <20 wks gestation, 141 expressed interest, 108 were screened for eligibility, and 21 were enrolled. Of the 21 who enrolled, 12 completed the postintervention assessment (7 in the participant group and 5 in the nonparticipant group). CONCLUSIONS AND IMPLICATIONS: Demand and acceptability will need to be improved before this intervention can be considered feasible, potentially by extending eligibility and improving access to intervention.