A Compensatory Role of Physical Activity in the Association Between Sleep and Cognition.

We synthesize evidence investigating the hypothesis that greater engagement in physical activity (PA) may compensate for some of the negative cognitive consequences associated with poor sleep in older adults. Potential mechanistic pathways include glymphatic clearance, influences on depression, and other comorbidities. The evidence base is largely cross-sectional and observational, and further experimental studies are required.

Physical activity and brain amyloid beta: A longitudinal analysis of cognitively unimpaired older adults.

INTRODUCTION: The current study evaluated the relationship between habitual physical activity (PA) levels and brain amyloid beta (Aß) over 15 years in a cohort of cognitively unimpaired older adults. METHODS: PA and Aß measures were collected over multiple timepoints from 731 cognitively unimpaired older adults participating in the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Aging. Regression modeling examined cross-sectional and longitudinal relationships between PA and brain Aß. Moderation analyses examined apolipoprotein E (APOE) ε4 carriage impact on the PA-Aß relationship. RESULTS: PA was not associated with brain Aß at baseline (ß = -0.001, p = 0.72) or over time (ß = -0.26, p = 0.24). APOE ε4 status did not moderate the PA-Aß relationship over time (ß = 0.12, p = 0.73). Brain Aß levels did not predict PA trajectory (ß = -54.26, p = 0.59). DISCUSSION: Our study did not identify a relationship between habitual PA and brain Aß levels. HIGHLIGHTS: Physical activity levels did not predict brain amyloid beta (Aß) levels over time in cognitively unimpaired older adults (≥60 years of age). Apolipoprotein E (APOE) ε4 carrier status did not moderate the physical activity-brain Aß relationship over time. Physical activity trajectories were not impacted by brain Aß levels.

Longitudinal associations between exercise and biomarkers in autosomal dominant Alzheimer's disease.

INTRODUCTION: We investigated longitudinal associations between self-reported exercise and Alzheimer's disease (AD)-related biomarkers in individuals with autosomal dominant AD (ADAD) mutations. METHODS: Participants were 308 ADAD mutation carriers aged 39.7 ± 10.8 years from the Dominantly Inherited Alzheimer's Network. Weekly exercise volume was measured via questionnaire and associations with brain volume (magnetic resonance imaging), cerebrospinal fluid biomarkers, and brain amyloid beta (Aß) measured by positron emission tomography were investigated. RESULTS: Greater volume of weekly exercise at baseline was associated with slower accumulation of brain Aß at preclinical disease stages ß = -0.16 [-0.23 to -0.08], and a slower decline in multiple brain regions including hippocampal volume ß = 0.06 [0.03 to 0.08]. DISCUSSION: Exercise is associated with more favorable profiles of AD-related biomarkers in individuals with ADAD mutations. Exercise may have therapeutic potential for delaying the onset of AD; however, randomized controlled trials are vital to determine a causal relationship before a clinical recommendation of exercise is implemented. HIGHLIGHTS: Greater self-reported weekly exercise predicts slower declines in brain volume in autosomal dominant Alzheimer's disease (ADAD). Greater self-reported weekly exercise predicts slower accumulation of brain amyloid beta in ADAD. Associations varied depending on closeness to estimated symptom onset.

The influence of baseline sleep on exercise-induced cognitive change in cognitively unimpaired older adults: A randomised clinical trial.

OBJECTIVES: Observational studies consistently demonstrate that physical activity is associated with elevated cognitive function, however, there remains significant heterogeneity in cognitive outcomes from randomized exercise interventions. Individual variation in sleep behaviours may be a source of variability in the effectiveness of exercise-induced cognitive change, however this has not yet been investigated. The current study aimed to (1) investigate the influence of a 6-month exercise intervention on sleep, assessed pre- and post-intervention and, (2) investigate whether baseline sleep measures moderate exercise-induced cognitive changes. METHODS: We utilised data from the Intense Physical Activity and Cognition (IPAC) study (n = 89), a 6-month moderate intensity and high intensity exercise intervention, in cognitively unimpaired community-dwelling older adults aged 60-80 (68.76 ± 5.32). Exercise was supervised and completed on a stationary exercise bicycle, and cognitive function was measured using a comprehensive neuropsychological battery administered pre- and post-intervention. Sleep was measured using the Pittsburgh sleep quality index. There was no effect of the exercise intervention on any sleep outcomes from pre- to post-intervention. RESULTS: There was a significant moderating effect of baseline sleep efficiency on both episodic memory and global cognition within the moderate intensity exercise group, such that those with poorer sleep efficiency at baseline showed greater exercise-induced improvements in episodic memory. CONCLUSIONS: These results suggest that those with poorer sleep may have the greatest exercise-induced cognitive benefits and that baseline sleep behaviours may be an important source of heterogeneity in previous exercise interventions targeting cognitive outcomes.

Investigating the Link between Later-Life Brain Volume and Cardiorespiratory Fitness after Mild Traumatic Brain Injury Exposure.

INTRODUCTION: Evidence suggests that maintaining a higher level of cardiorespiratory fitness (CRF) later in life can offer some protection against brain volume loss as we age. By contrast, mild traumatic brain injury (mTBI) could accelerate age-related cortical atrophy. The current study sought to examine whether variations in the CRF level modified the association between mTBI history and brain volumetric measures in a sample of older adults. METHODS: Seventy-nine community-dwelling older adults (mean age 68.7 ± 4.3 years, 54.4% female) were assessed for their mTBI history: 25 participants (32%) reported sustaining at least one lifetime mTBI. Participants also underwent a CRF assessment and magnetic resonance imaging (MRI) to obtain global and region-of-interest volumes. RESULTS: Analysis of covariance, controlling for age, sex, education, and apolipoprotein (APOE) ε4 allele carriage, revealed that participants with a history of mTBI had a significantly larger total mean grey matter volume (582.21 ± 12.46 cm3) in comparison to participants with no mTBI history (571.08 ± 17.21 cm3, p = 0.01 after correction for multiple comparisons). However, no differences between groups based on mTBI history were found for total white matter volume or in any other cortical or subcortical structures examined. A subsequent moderation analysis found that CRF was predominantly non-influential on the association between mTBI history and the MRI-quantified measures of brain volume. CONCLUSION: While unexpected, the findings suggest that a history of mTBI can lead to grey matter alterations in the ageing brain. However, concurrent variations in the CRF level did not influence the differences in brain volume found based on mTBI exposure status.

The relationship between objective physical activity and change in cognitive function.

INTRODUCTION: The current study investigated the association between objectively measured physical activity and cognition in older adults over approximately 8 years. METHODS: We utilized data from 199 cognitively unimpaired individuals from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study, aged ≥60. Actigraphy was used to measure physical activity (intensity, total activity, and energy expenditure) at baseline. Cognition was assessed using a comprehensive cognitive battery every 18-months. RESULTS: Higher baseline energy expenditure predicted better episodic recall memory and global cognition over the follow-up period (p = 0.031; p = 0.047, respectively). Those with higher physical activity intensity and greater total activity also had better global cognition over time (both p = 0.005). Finally, higher total physical activity predicted improved episodic recall memory over time (p = 0.022). DISCUSSION: These results suggest that physical activity can preserve cognition and that activity intensity may play an important role in this association. HIGHLIGHTS: Greater total physical activity predicts preserved episodic memory and global cognition. Moderate intensity physical activity (>3.7 metabolic equivalents of task [MET]) predicts preserved global cognition. Expending > 373 kilocalories per day may benefit episodic memory and global cognition.

The Effect of Self-Paced Exercise Intensity and Cardiorespiratory Fitness on Frontal Grey Matter Volume in Cognitively Normal Older Adults: A Randomised Controlled Trial.

OBJECTIVE: Exercise has been found to be important in maintaining neurocognitive health. However, the effect of exercise intensity level remains relatively underexplored. Thus, to test the hypothesis that self-paced high-intensity exercise and cardiorespiratory fitness (peak aerobic capacity; VO2peak) increase grey matter (GM) volume, we examined the effect of a 6-month exercise intervention on frontal lobe GM regions that support the executive functions in older adults. METHODS: Ninety-eight cognitively normal participants (age = 69.06 ± 5.2 years; n = 54 female) were randomised into either a self-paced high- or moderate-intensity cycle-based exercise intervention group, or a no-intervention control group. Participants underwent magnetic resonance imaging and fitness assessment pre-intervention, immediately post-intervention, and 12-months post-intervention. RESULTS: The intervention was found to increase fitness in the exercise groups, as compared with the control group (F = 9.88, p = <0.001). Changes in pre-to-post-intervention fitness were associated with increased volume in the right frontal lobe (ß = 0.29, p = 0.036, r = 0.27), right supplementary motor area (ß = 0.30, p = 0.031, r = 0.29), and both right (ß = 0.32, p = 0.034, r = 0.30) and left gyrus rectus (ß = 0.30, p = 0.037, r = 0.29) for intervention, but not control participants. No differences in volume were observed across groups. CONCLUSIONS: At an aggregate level, six months of self-paced high- or moderate-intensity exercise did not increase frontal GM volume. However, experimentally-induced changes in individual cardiorespiratory fitness was positively associated with frontal GM volume in our sample of older adults. These results provide evidence of individual variability in exercise-induced fitness on brain structure.

Cognitive Aging and the Promise of Physical Activity.

Is the field of cognitive aging irretrievably concerned with decline and deficits, or is it shifting to emphasize the hope of preservation and enhancement of cognitive function in late life? A fragment of an answer comes from research attempting to understand the reasons for individual variability in the extent and rate of cognitive decline. This body of work has created a sense of optimism based on evidence that there are some health behaviors that amplify cognitive performance or mitigate the rate of age-related cognitive decline. In this context, we discuss the role of physical activity on neurocognitive function in late adulthood and summarize how it can be conceptualized as a constructive approach both for the maintenance of cognitive function and as a therapeutic for enhancing or optimizing cognitive function in late life. In this way, physical activity research can be used to shape perceptions of cognitive aging.

Androgen receptor CAG repeat length as a moderator of the relationship between free testosterone levels and cognition.

Age-related decrease in testosterone levels is a potential risk factor for cognitive decline in older men. However, observational studies and clinical trials have reported inconsistent results on the effects of testosterone on individual cognitive domains. Null findings may be attributed to factors that studies have yet to consider. In particular, individual variations in polyglutamine (CAG) length in the androgen receptor (AR) gene could alter androgenic activity in brain regions associated with cognitive processes including memory and executive functions. However, the role of AR CAG repeat length as a moderator of the relationship between testosterone levels and cognition has not been investigated. Therefore, we aimed to examine the relationship between baseline calculated free testosterone (cFT) levels, change in cFT levels over 18 months and CAG repeat length on cognitive performance in memory, executive function, language, attention and processing speed domains. These relationships were examined in 304 cognitively normal older male participants of the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Ageing. In the attention and processing speed domain, a short CAG repeat length appears to exacerbate the effects of low baseline cFT levels that are also lower than expected at follow-up. These results highlight that individual variations in AR CAG repeat length should be considered in future studies and clinical trials that examine the complex relationship between testosterone and cognition.

A Randomized Controlled Trial of High-Intensity Exercise and Executive Functioning in Cognitively Normal Older Adults.

BACKGROUND: There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function. METHODS: Ninety-nine cognitively normal participants (age = 69.10 ± 5.2 years; n = 54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO2peak. RESULTS: First, the exercise intervention was found to increase cardiorespiratory fitness (VO2peak) in the intervention groups, in comparison to the control group (F =10.40, p≤0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis of change scores, cardiorespiratory fitness was found to associate positively with the executive function (EF) subdomains of Updating/Working Memory (ß = 0.37, p = 0.01, r = 0.34) and Verbal Generativity (ß = 0.30, p = 0.03, r = 0.28) for intervention, but not control participants. CONCLUSION: At the aggregate level, the authors failed to find evidence that 6-months of high-intensity aerobic exercise improves EF in older adults. However, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in Updating/ Working Memory and Verbal Generativity.

An Intense, But Ecologically Valid, Resistance Exercise Session Does Not Alter Growth Factors Associated With Cognitive Health.

The purpose of this investigation was to assess the acute changes in growth factors associated with cognitive health following two ecologically valid, intense resistance exercise sessions. Twenty-nine late-middle-aged adults performed one session of either (a) moderate-load resistance exercise or (b) high-load resistance exercise. Venous blood was collected prior to warm-up, immediately following exercise and 30 min following exercise. Serum was analyzed for brain-derived neurotrophic factor, insulin-like growth factor 1, and vascular endothelial growth factor. Session intensity was determined by blood lactate concentration and session rating of perceived exertion. Postexercise blood lactate was greater following moderate-load when compared with high-load resistance exercise. Subjective session intensity was rated higher by the session rating of perceived exertion following moderate-load when compared with high-load resistance exercise. No differences were observed in serum growth factor levels between groups. Ecologically valid and intense moderate-load or high-load exercise methods do not alter serum growth factor levels in late-middle-aged adults.

Subjective memory complaints predict baseline but not future cognitive function over three years: results from the Western Australia Memory Study.

ABSTRACTBackground:This study investigated the characteristics of subjective memory complaints (SMCs) and their association with current and future cognitive functions. METHODS: A cohort of 209 community-dwelling individuals without dementia aged 47-90 years old was recruited for this 3-year study. Participants underwent neuropsychological and clinical assessments annually. Participants were divided into SMCs and non-memory complainers (NMCs) using a single question at baseline and a memory complaints questionnaire following baseline, to evaluate differential patterns of complaints. In addition, comprehensive assessment of memory complaints was undertaken to evaluate whether severity and consistency of complaints differentially predicted cognitive function. RESULTS: SMC and NMC individuals were significantly different on various features of SMCs. Greater overall severity (but not consistency) of complaints was significantly associated with current and future cognitive functioning. CONCLUSIONS: SMC individuals present distinctive features of memory complaints as compared to NMCs. Further, the severity of complaints was a significant predictor of future cognition. However, SMC did not significantly predict change over time in this sample. These findings warrant further research into the specific features of SMCs that may portend subsequent neuropathological and cognitive changes when screening individuals at increased future risk of dementia.

Twelve weeks of resistance training does not influence peripheral levels of neurotrophic growth factors or homocysteine in healthy adults: a randomized-controlled trial.

INTRODUCTION: There is growing evidence for a preventative effect of resistance training on cognitive decline through physiological mechanisms; yet, the effect of resistance training on resting growth factors and homocysteine levels is incompletely understood. This study aimed to investigate the effect of intense resistance training, for 12 weeks, on changes in peripheral growth factors and homocysteine in late middle-aged adults. METHODS: 45 healthy adults were enrolled into the single-site parallel groups' randomized-controlled trial conducted at the Department of Exercise Science, Strength and Conditioning Laboratory, Murdoch University. Participants were allocated to the following conditions: (1) high-load resistance training (n = 14), or (2) moderate-load resistance training (n = 15) twice per week for 12 weeks; or (3) non-exercising control group (n = 16). Data were collected from September 2016 to December 2017. Fasted blood samples were collected at baseline and within 7 days of trial completion for the analysis of resting serum brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1, vascular endothelial growth factor, and plasma homocysteine levels. RESULTS: No differences in baseline to post-intervention change in serum growth factors or plasma homocysteine levels were observed between groups. A medium effect was calculated for BDNF change within the high-load condition alone (+ 12.9%, g = 0.54). CONCLUSIONS: High-load or moderate-load resistance training twice per week for 12 weeks has no effect on peripheral growth factors or homocysteine in healthy late middle-aged adults. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12616000690459.

Higher Cardiorespiratory Fitness Is Associated With Better Verbal Generativity in Community-Dwelling Older Adults.

Objectives: To examine the associations between physical activity duration and intensity, cardiorespiratory fitness, and executive function in older adults. Methods: Data from 99 cognitively normal adults (age = 69.10 ± 5.1 years; n = 54 females) were used in the current study. Physical activity (intensity and duration) was measured with the International Physical Activity Questionnaire, and fitness was measured by analysis of maximal aerobic capacity, VO2peak. Executive function was measured comprehensively, including measures of Shifting, Updating, Inhibition, Generativity, and Nonverbal Reasoning. Results: Higher levels of cardiorespiratory fitness were associated with better performance on Generativity (B = .55; 95% confidence interval [.15, .97]). No significant associations were found between self-reported physical activity intensity/duration and executive functions. Discussion: To our knowledge, this study is the first to identify an association between fitness and Generativity. Associations between physical activity duration and intensity and executive function requires further study, using objective physical activity measures and longitudinal observations.

Habitual exercise levels are associated with cerebral amyloid load in presymptomatic autosomal dominant Alzheimer's disease.

INTRODUCTION: The objective of this study was to evaluate the relationship between self-reported exercise levels and Alzheimer's disease (AD) biomarkers, in a cohort of autosomal dominant AD mutation carriers. METHODS: In 139 presymptomatic mutation carriers from the Dominantly Inherited Alzheimer Network, the relationship between self-reported exercise levels and brain amyloid load, cerebrospinal fluid (CSF) Aß42, and CSF tau levels was evaluated using linear regression. RESULTS: No differences in brain amyloid load, CSF Aß42, or CSF tau were observed between low and high exercise groups. Nevertheless, when examining only those already accumulating AD pathology (i.e., amyloid positive), low exercisers had higher mean levels of brain amyloid than high exercisers. Furthermore, the interaction between exercise and estimated years from expected symptom onset was a significant predictor of brain amyloid levels. DISCUSSION: Our findings indicate a relationship exists between self-reported exercise levels and brain amyloid in autosomal dominant AD mutation carriers.

Curcumin and cognition: a randomised, placebo-controlled, double-blind study of community-dwelling older adults.

Curcumin therapy in animals has produced positive cognitive and behavioural outcomes; results of human trials, however, have been inconsistent. In this study, we report the results of a 12-month, randomised, placebo-controlled, double-blind study that investigated the ability of a curcumin formulation to prevent cognitive decline in a population of community-dwelling older adults. Individuals (n 96) ingested either placebo or 1500 mg/d BiocurcumaxTM for 12 months. A battery of clinical and cognitive measures was administered at baseline and at the 6-month and 12-month follow-up assessments. A significant time×treatment group interaction was observed for the Montreal Cognitive Assessment (repeated-measures analysis; time×treatment; F=3·85, P<0·05). Subsequent analysis revealed that this association was driven by a decline in function of the placebo group at 6 months that was not observed in the curcumin treatment group. No differences were observed between the groups for all other clinical and cognitive measures. Our findings suggest that further longitudinal assessment is required to investigate changes in cognitive outcome measures, ideally in conjunction with biological markers of neurodegeneration.

Breast Reconstruction Post Mastectomy: Patient Satisfaction and Decision Making.

BACKGROUND: Although breast reconstruction has been shown to improve psychological, physical, and sexual well-being, Australia still has one of the lowest reconstruction rates among well-developed countries. This study explores both the quality-of-life benefits of reconstruction and the factors that influence patients' decisions of whether or not to undergo reconstruction. METHODS: This retrospective cohort study (296 consecutive mastectomy patients from 2000 to 2010) uses an internationally validated questionnaire (BREAST-Q) to evaluate patients' satisfaction with or without breast reconstruction. In addition, we analyzed factors that influence patients' decisions of whether to undergo reconstruction. RESULTS: Two hundred nineteen patients responded (74%) and of the 143 patients who elected to participate, 79 were in the "reconstruction group" and 64 in the "no-reconstruction group" post mastectomy. Patient demographics and cancer variables of the 2 groups were matched with the exception of age (reconstruction group 9.7 years younger: P < 0.01). The reconstruction group showed statistically significantly higher BREAST-Q scores with regard to satisfaction with the breast (P < 0.0001), psychological well-being (P = 0.0068), and sexual well-being (P = 0.0001). For the reconstruction group, the main reasons for undergoing reconstruction included improved self-image, more clothing choices, and the feeling of overcoming the cancer. One third of non-reconstructed patients still feared that reconstruction would mask cancer recurrence. CONCLUSION: Our study confirms the positive effects of breast reconstruction post mastectomy and identifies reasons that influence patients' decisions of whether to undergo reconstruction. Breast reconstruction should be seen as an integral part in the comprehensive care of women with breast cancer and an important health care priority in Australia.

Predicting Alzheimer disease with ß-amyloid imaging: results from the Australian imaging, biomarkers, and lifestyle study of ageing.

OBJECTIVE: Biomarkers for Alzheimer disease (AD) can detect the disease pathology in asymptomatic subjects and individuals with mild cognitive impairment (MCI), but their cognitive prognosis remains uncertain. We aimed to determine the prognostic value of ß-amyloid imaging, alone and in combination with memory performance, hippocampal atrophy, and apolipoprotein E ε4 status in nondemented, older individuals. METHODS: A total of 183 healthy individuals (age = 72.0 ± 7.26 years) and 87 participants with MCI (age = 73.7 ± 8.27) in the Australian Imaging, Biomarkers, and Lifestyle study of ageing were studied. Clinical reclassification was performed after 3 years, blind to biomarker findings. ß-Amyloid imaging was considered positive if the (11) C-Pittsburgh compound B cortical to reference ratio was ≥1.5. RESULTS: Thirteen percent of healthy persons progressed (15 to MCI, 8 to dementia), and 59% of the MCI cohort progressed to probable AD. Multivariate analysis showed ß-amyloid imaging as the single variable most strongly associated with progression. Of combinations, subtle memory impairment (Z score = -0.5 to -1.5) with a positive amyloid scan was most strongly associated with progression in healthy individuals (odds ratio [OR] = 16, 95% confidence interval [CI] = 3.7-68; positive predictive value [PPV] = 50%, 95% CI = 19-81; negative predictive value [NPV] = 94%, 95% CI = 88-98). Almost all amnestic MCI subjects (Z score ≤ -1.5) with a positive amyloid scan developed AD (OR = ∞; PPV = 86%, 95% CI = 72-95; NPV = 100%, 95% CI = 80-100). Hippocampal atrophy and ε4 status did not add further predictive value. INTERPRETATION: Subtle memory impairment with a positive ß-amyloid scan identifies healthy individuals at high risk for MCI or AD. Clearly amnestic patients with a positive amyloid scan have prodromal AD and a poor prognosis for dementia within 3 years.

Estimating cardiorespiratory fitness in older adults using the international physical activity questionnaire.

Introduction: Non-exercise estimates of cardiorespiratory fitness hold great utility for epidemiological research and clinical practice. Older adults may yield the greatest benefit from fitness estimates due to limited capacity to undergo strenuous maximal exercise testing, however, few of the previously developed non-exercise equations are suitable for use in older adults. Thus, the current study developed a non-exercise equation for estimating cardiorespiratory fitness in older adults derived from the widely used International Physical Activity Questionnaire (IPAQ). Methods: This study was a secondary analysis of baseline data from a randomized controlled trial. Participants were community-dwelling, cognitively unimpaired older adults aged 60-80 years (n = 92). They completed the IPAQ and underwent maximal exercise testing on a cycle ergometer. Stepwise linear regression was used to determine the equation in a randomly selected, sex-balanced, derivation subset of participants (n = 60), and subsequently validated using a second subset of participants (n = 32). Results: The final equation included age, sex, body mass index and leisure time activity from the IPAQ and explained 61% and 55% of the variance in the derivation and validation groups, respectively (standard error of estimates = 3.9, 4.0). Seventy-seven and 81% of the sample fell within ±1SD (5.96 and 6.28 ml·kg-1·min-1) of measured VO2peak for the derivation and validation subgroups. The current equation showed better performance compared to equations from Wier et al. (2006), Jackson et al. (1990), and Schembre & Riebe (2011), although it is acknowledged previous equations were developed for different populations. Conclusions: Using non-exercise, easily accessible measures can yield acceptable estimates of cardiorespiratory fitness in older adults, which should be further validated in other samples and examined in relation to public health outcomes.