Functional Control of Stance in Older Adults

Exercise Testing and Training Strategies for Healthy and Frail Elderly

BackgroundLung cancer patients have low survival rates resulting in over 131,000 deaths in the US in 2021. Muscle health decline from sarcopenia and cachexia increases the risk of death among patients with lung cancer. Though muscle mass is often used for sarcopenia diagnosis and non‐tissue specific weight loss is typically used for cachexia diagnosis, both conditions have no consensus definitions. Therefore, the need for quantitative biomarkers that reflect muscle health changes due to aging and weight loss is critical to mitigate sarcopenia and cachexia. We propose using highly accurate MRI‐based proton density fat fraction (PDFF) as a reference measure of muscle health to develop bedside ultrasound measures as biomarkers of muscle health. We hypothesized that PDFF is associated with ultrasound‐based echointensity (EI) and shear wave elastography (SWE), and that all three modalities are sensitive to muscle health differences between healthy young, healthy older, and older adults undergoing treatment for lung cancer.MethodsWe compared muscle health operationalized as myosteatosis in the mid‐thigh of the rectus femoris using ultrasound‐based brightness‐mode for EI, ultrasound‐based SWE for tissue elasticity, and MRI‐based PDFF for percent fat, which was the reference measure. We compared the 3 measures among young healthy (n=10), older healthy (n=10), and older adults with non‐small cell lung cancer (n=10) in a cross‐sectional pilot study. We also compared non‐myosteatosis measures including subcutaneous adipose tissue thickness and rectus femoris thickness via ultrasound, whole‐leg cross‐sectional area via MRI, and BMI between groups and between myosteatosis measures. We used ANOVAs with Tukey post‐hoc comparisons to assess muscle health between groups and Pearson correlations to determine muscle health measure associations between imaging modalities.ResultsWe found young healthy adults had significantly lower PDFF than older healthy adults and older adults with lung cancer (0.33% vs 2.83% vs 2.93%, respectively; p=0.001). Young adults also had significantly lower EI than older healthy adults, but not older adults with cancer (48.58 vs 81.81 vs 75.35; p=0.008). When comparing between measures, PDFF was highly associated with EI (r=0.62, p<0.001) and moderately inversely associated with SWE (r=‐0.41, p=0.025) but not BMI, rectus femoris thickness, or rectus femoris cross‐sectional area.ConclusionPDFF was sensitive to myosteatosis differences between young and both older adult groups. EI was less sensitive to myosteatosis differences between groups, yet EI was highly associated with PDFF unlike BMI. Our results suggest that the ultrasound measures could serve to determine muscle health at the bedside and are more sensitive to muscle health differences than BMI, which could improve interventions for cachexia and patient outcomes.

Introduction: Greater heat-related health risks are a direct consequence of global warming. These risks are precipitated by physiological heat strain, specifically an increase in core temperature and heart rate, and sweating-induced dehydration. Older adults face greater heat-related heath risks, especially amongst those living with chronic health conditions. To our knowledge, limited research has explored the effect of health status on physiological strain of older adults during environmental heat exposure. Objectives: The objective of this study is to compare physiological heat strain between healthy older adults, older adults with risk factors for chronic diseases, and older adults living with chronic disease during exposure to a hot and humid environment with short bouts of light exercise to simulate activities of daily living. We hypothesized that physiological heat strain would be greatest for adults living with chronic disease, followed by those living with risk factors compared to healthy older adults. Methods: Seven healthy older adults (60-74 years, 5 females), 23 adults living with ≥1 risk factor according to the harmonized definition of metabolic syndrome (61-88 years, 6 females), and 10 older adults living with ≥1 non-communicable chronic disease (61-84 years, 2 females) were exposed to a 38°C environment with 60% humidity in an environmental chamber for 4 hours. To induce energy expenditure associated with activities of daily living (~3.5 METs), participants performed 10 minutes of light exercise (treadmill walking or cycling) every hour. Participants could drink water served at 15°C ad libitum. Rectal temperature and heart rate were measured continuously. Dehydration was calculated as the difference between pre- and post-exposure nude body mass (post-void) relative to pre-exposure nude body mass. Data are presented as mean ± standard deviation. Results: During the 4 hours of heat exposure, rectal temperature increased by 0.4 ± 0.3°C in healthy older adults, 0.5 ± 0.3°C in those living with at least 1 risk factor, and by 0.5 ± 0.4°C in older adults living with chronic disease. Heart rate increased by 11 ± 6 bpm in healthy older adults, 15 ± 7 bpm in those living with at least 1 risk factor, and by 9 ± 4 bpm in older adults living with chronic disease. Dehydration was 0.3 ± 1.0% in healthy older adults, 0.7 ± 0.8% in those living with at least 1 risk factor, and 0.8 ± 0.7% in older adults living with chronic disease. Conclusion: During exposure to hot/humid heat that integrates light exercise to simulate activities of daily living, these preliminary results suggest that thermal and cardiac strain do not differ markedly as a function of health status amongst older adults. However, older adults living with at last 1 risk factor or those living with chronic disease seem to experience greater dehydration. The clinical consequences of these differences remains to be determined. Canadian Institutes of Health Research This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction: Understanding determinants of community mobility disability is critical for developing interventions aimed at preventing or delaying disability in older adults. In an effort to understand these determinants, capturing and measuring community mobility has become a key factor. The objectives of this paper are to present and illustrate the signal processing workflow and outcomes that can be extracted from an activity and community mobility measurement approach based on GPS and accelerometer sensor data and 2) to explore the construct validity of the proposed measurement approach using data collected from healthy older adults in free-living conditions.Methods: Personal, functional impairment and environmental variables were obtained by self-report questionnaires in 75 healthy community-living older adults (mean age = 66 ± 7 years old) living on the island of Montreal, QC, Canada. Participants wore, for 14 days during waking hours on the hip, a data logger incorporating a GPS receiver with a 3-axis accelerometer. Time at home ratio (THR), Trips out (TO), Destinations (D), Maximal distance of destinations (MDD), Active time ratio (ATR), Steps (S), Distance in a vehicle (DV), Time in a vehicle (TV), Distance on foot (DF), Time on foot (TF), Ellipse area (EA), and Ellipse maximum distance (EMD) were extracted from the recordings.Results: After applying quality control criteria, the original data set was reduced from 75 to 54 participants (28% attrition). Results from the remaining sample show that under free-living conditions in healthy older adults, location, activity and community mobility outcomes vary across individuals and certain personal variables (age, income, living situation, professional status, vehicle access) have potential mitigating effects on these outcomes. There was a significant (yet small) relationship (rho < 0.40) between self-reported life space and MDD, DV, EA, and EMD.Conclusion: Wearability and usability of the devices used to capture free-living community mobility impact participant compliance and the quality of the data. The construct validity of the proposed approach appears promising but requires further studies directed at populations with mobility impairments.

The evaluation of walking footwear on postural stability in healthy older adults: An exploratory study

The aging brain is characterized by altered dopamine signaling. The amino acid tyrosine, a catecholamine precursor, is known to improve cognitive performance in young adults, especially during high environmental demands. Tyrosine administration might also affect catecholamine transmission in the aging brain, thereby improving cognitive functioning. In healthy older adults, impairments have been demonstrated in two forms of response inhibition: reactive inhibition (outright stopping) and proactive inhibition (anticipatory response slowing) under high information load. However, no study has directly compared the effects of a catecholamine precursor on reactive and load-dependent proactive inhibition. In this study we explored the effects of tyrosine on reactive and proactive response inhibition and signal in dopaminergically innervated fronto-striatal regions. Depending on age, tyrosine might lead to beneficial or detrimental neurocognitive effects. We aimed to address these hypotheses in 24 healthy older human adults (aged 61–72 years) using fMRI in a double blind, counterbalanced, placebo-controlled, within-subject design. Across the group, tyrosine did not alter reactive or proactive inhibition behaviorally but did increase fronto-parietal proactive inhibition-related activation. When taking age into account, tyrosine affected proactive inhibition both behaviorally and neurally. Specifically, increasing age was associated with a greater detrimental effect of tyrosine compared with placebo on proactive slowing. Moreover, with increasing age, tyrosine decreased fronto-striatal and parietal proactive signal, which correlated positively with tyrosine’s effects on proactive slowing. Concluding, tyrosine negatively affected proactive response slowing and associated fronto-striatal activation in an age-dependent manner, highlighting the importance of catecholamines, perhaps particularly dopamine, for proactive response inhibition in older adults.

Frontoparietal function and underlying structure reflect capacity for motor skill acquisition during healthy aging

Recently, subclinical aspiration has been identified in approximately 30% of community-dwelling older adults. Given that the tongue is a key component of the safe swallow, we hypothesized healthy older adults who aspirate will generate less tongue strength than adults who do not aspirate. Furthermore, as muscle weakness may reflect a global effect of aging, we further investigated whether tongue strength is correlated with handgrip strength. We assessed 78 healthy community-dwelling older adults (M = 77.3 years, SD = 7.26) for aspiration status (37% aspirators) via flexible endoscopic evaluation of swallowing. Maximal isometric anterior and posterior tongue strength, anterior and posterior swallowing tongue strength, and maximum handgrip strength were measured. Isometric tongue strength was significantly lower in aspirators versus nonaspirators (p = .03) at both the anterior (463 vs 548 mmHg, respectively) and posterior lingual locations (285 vs 370 mmHg, respectively). Likewise, swallowing tongue strength was significantly lower in aspirators versus nonaspirators at both the anterior (270 vs 317 mmHg, respectively) and posterior lingual locations (220 vs 267 mmHg, respectively). There was no difference between aspirators and nonaspirators' handgrip strength (p > .05), although handgrip strength was correlated with posterior tongue strength (r = .34, p = .005). Lower anterior and posterior isometric and swallowing tongue strength were dependent on aspiration status. Lower lingual strength in healthy adults may predispose them to aspiration. The correlation between tongue and handgrip strength is consistent with the hypothesis that impaired oropharyngeal strength reflects global age-related declines in muscle strength.

BackgroundDiminished control of standing balance, traditionally indicated by greater postural sway magnitude and speed, is associated with falls in older adults. Tai Chi (TC) is a multisystem intervention that reduces fall risk, yet its impact on sway measures vary considerably. We hypothesized that TC improves the integrated function of multiple control systems influencing balance, quantifiable by the multi-scale “complexity” of postural sway fluctuations.ObjectivesTo evaluate both traditional and complexity-based measures of sway to characterize the short- and potential long-term effects of TC training on postural control and the relationships between sway measures and physical function in healthy older adults.MethodsA cross-sectional comparison of standing postural sway in healthy TC-naïve and TC-expert (24.5±12 yrs experience) adults. TC-naïve participants then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Postural sway was assessed before and after the training during standing on a force-plate with eyes-open (EO) and eyes-closed (EC). Anterior-posterior (AP) and medio-lateral (ML) sway speed, magnitude, and complexity (quantified by multiscale entropy) were calculated. Single-legged standing time and Timed-Up–and-Go tests characterized physical function.ResultsAt baseline, compared to TC-naïve adults (n = 60, age 64.5±7.5 yrs), TC-experts (n = 27, age 62.8±7.5 yrs) exhibited greater complexity of sway in the AP EC (P = 0.023), ML EO (P<0.001), and ML EC (P<0.001) conditions. Traditional measures of sway speed and magnitude were not significantly lower among TC-experts. Intention-to-treat analyses indicated no significant effects of short-term TC training; however, increases in AP EC and ML EC complexity amongst those randomized to TC were positively correlated with practice hours (P = 0.044, P = 0.018). Long- and short-term TC training were positively associated with physical function.ConclusionMultiscale entropy offers a complementary approach to traditional COP measures for characterizing sway during quiet standing, and may be more sensitive to the effects of TC in healthy adults.Trial RegistrationClinicalTrials.gov NCT01340365

Effects of aerobic exercise on executive function of healthy middle-aged and older adults: A systematic review and meta-analysis

Implicit learning theories suggest that we update syntactic knowledge based on prior experience (e.g., Chang et al., 2006). To determine the limits of the extent to which implicit learning can influence syntactic processing, we investigated whether structural priming effects persist up to 1 month postexposure, and whether they persist less long in healthy older (compared to younger) adults. We conducted a longitudinal experiment with three sessions: Session A, Session B (1 week after A), and Session C (4 weeks after B). For young adults, we found passive priming effects to persist and accumulate across sessions (1 week and 4 weeks). However, for older adults the effects persisted for 1 week but not 4. This suggests that for young adults, who unlike older adults experience no age-related decline in implicit memory, the limit to the duration of structural priming persistence is longer than 4 weeks. In a second longitudinal experiment with two sessions 1 week apart we found that priming in Session A affected syntactic processing in a different, independent task in Session B, both for young and older adults. Experiment 2 suggests that implicit persistence of the learned syntax is not limited to a specific context or task. Together, our findings give insight into how structural priming can contribute to language change throughout the life span, showing that implicit learning is a pervasive and robust mechanism that contributes to syntactic processing. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

INTRODUCTION Extreme heat is associated with a greater risk of cardiovascular mortality in older adults (≥60 years). However, the pathophysiology that links extreme heat and cardiovascular mortality remains unknown. One possibility is that myocardial oxygen requirements during heat exposure cannot be met by sufficient increased in myocardial blood flow (MBF) thereby predisposing to ischemia. However, the extent to which MBF increases during heat exposure, and whether age alters this increase, is unknown. The objective of this study was to test the hypothesis that passive heat exposure increases MBF and that this increase is attenuated in healthy older adults. METHODS MBF was measured during passive heat exposure (water‐perfused suit) in 15 young (27 years, range: 24‐30) and 14 older (68 years, range: 64‐72) healthy adults with 82‐Rubidium positron emission tomography. Four MBF measurements were performed: prior to heat exposure (baseline) and at an increase in rectal temperature of 0.5°C, 1.0°C, and 1.5°C. Heart rate (ECG) and blood pressure (automated auscultation) were also measured to calculate rate pressure product (RPP; heart rate x systolic blood pressure). MBF reserve (MFR) was calculated by dividing the MBF at 1.5°C by baseline MBF. RESULTS Baseline MBF was 0.76 ± 0.19 mL/min/g in young adults and 0.88 ± 0.21 mL/min/g in older adults (p=0.14). MBF increased similarly in both groups during heat exposure (interaction, p=0.31). Nonetheless, older adults displayed a lower MFR at an increase in rectal temperature of 1.5°C (young: 2.3 ± 0.7 vs. older: 1.8 ± 0.4, p=0.03). The lower MFR in older adults was paralleled by an attenuated increase in RPP during passive heating (at + 1.5°C, young: 6.8 ± 1.7vs. older: 3.6 ± 2.2 bpm·mmHg·10 3 , p&lt;0.01), due to a blunted increase in heart rate (young: 50 ± 12vs. older: 34 ± 14 bpm, p&lt;0.01). When the change in MBF was plotted against the change in RPP, the slope of the regression lines did not differ between young (0.11 [95% CI; 0.07, 0.15]) and older (0.08 [95% CI; 0.04, 0.11] mL/g/min/ bpm·mmHg·10 3 ,p=0.24) adults. CONCLUSION These results show that passive heat exposure roughly doubles MBF in healthy young and older adults. Furthermore, the results demonstrate that the increase in MBF during passive heat exposure is not altered by age and is proportional to the increase in RPP.

Motor performance and cognitive function both decline with aging. Older adults for example are usually less steady for a constant-force task than young adults when performing low-intensity contractions with limb muscles. Healthy older adults can also show varying degrees of cognitive decline, particularly in executive function skills. It is not known, however, whether age-related changes in steadiness of low-force tasks and cognitive function are independent of one another. In this study, we determined if executive function skills in aging are associated with the steadiness during a low-force muscle contraction performed with and without the imposition of a cognitive challenge. We recruited 60 older adults (60–85 years old, 34 women, 26 men) and 48 young adults (19–30 years old, 24 women, 24 men) to perform elbow flexor muscle contractions at 5% of maximal voluntary contraction (MVC) force in the presence and absence of a difficult mental-math task (counting backward by 13 from a four-digit number). Force steadiness was quantified as the coefficient of variation (CV) of force and executive function was estimated with the Trail-making Test part A and B. The cognitive challenge increased the CV of force (i.e., decreased force steadiness) with greater changes in older adults than young adults (5.2 vs. 1.3%, respectively, cognitive challenge × age: P < 0.001). Older adults were 35% slower in both parts A and B of the Trail-making Test (P < 0.001), and to eliminate the effects of age and education on this variable, all further analyses were performed with the age-corrected z-scores for each individual using established normative values. Hierarchical regression models indicated that decreased force steadiness during a cognitive challenge trial was in part, explained by the performance in the Trail-making Test part A and B in older (r = 0.53 and 0.50, respectively, P < 0.05), but not in young adults (P > 0.05). Thus, healthy community-dwelling older adults, who have poorer executive function skills, exhibit reduced force steadiness during tasks when also required to perform a high cognitive demand task, and are likely at risk of reduced capacity to perform daily activities that involve cognitively challenging motor tasks.

One of the main health-related worries for older adults is becoming dependent. Even healthy older adults may worry about becoming dependent, generating guilt feelings due to the anticipation of future needs that others must solve. The guilt associated with self-perception as a burden has not been studied in older adults, and there is no instrument available to measure these feelings. To adapt the Self-Perceived Burden Scale (SPBS; Cousineau et al., 2003) for the assessment of feelings of guilt for perceiving oneself as a burden for the family in older adults without explicit functional or cognitive impairment. Participants were 298 older adults living independently in the community. Participants completed the assessment protocol, which included measures of guilt associated with self-perception as a burden, depressive and anxious symptomatology, self-perceived burden, and sociodemographic information. Results from exploratory, parallel and confirmatory factor analyses suggest that the scale, named Guilt associated with Self-Perception as a Burden Scale (G-SPBS), has a unidimensional structure, explaining 57.04% of the variance of guilt. Good reliability was found (Cronbach's alpha = .94). The results revealed significant (p < .01) positive associations with depressive and anxious symptomatology. These findings suggest that the G-SPBS shows good psychometric properties which endorse its use with healthy community older adults. Also, guilt associated with perceiving oneself as a burden seems to be a relevant variable that can contribute to improving our understanding of psychological distress in older adults.

Event Abstract Back to Event Individual Differences in Right Dorsolateral Prefrontal Cortex Volumes, Whole Brain Activity and Memory Performance in Healthy Young and Older Adults Y. Czechowska1, C L Grady1, 2, R. Languay1, J C Pruessner1, M N Rajah1* and L. Valiquette1 1 McGill University, Douglas Mental Health University Institute, Canada 2 University of Toronto, Rotman Research Institute at Baycrest, Canada We conducted an fMRI study on 25 young and 26 older healthy adults and reported deficits in right dorsolateral PFC (DLPFC) activity that were linked to context memory reductions deficits in older adults (Rajah et al 2010). To extend this result we conducted semi-automatic volume segmentation of left and right DLFPC in this cohort and found a near significant (p = .055) group-by-hemispheric difference in DLPFC volume, due to older adults exhibiting smaller right versus left DLPFC volumes compared to young adults. To determine if this age-difference in right DLPFC volume was linked with changes in right DLPFC structure-function associations, we conducted a multivariate partial least squares (ST-PLS) seed analysis, using right DLPFC volumes and accuracy scores. One significant effect (p<.001) was indentified, which reflected group differences in the network of brain regions activated in association with correct context retrieval and larger right DLPFC volumes. In young adults improved retrieval accuracy and larger right DLPFC volumes was associated with increased bilateral DLPFC activity and right hippocampal activity. In contrast, in older adults retrieval accuracy and larger right DLPFC volumes was associated with increased activity in left, but not right, DLPFC, bilateral ventrolateral PFC and caudate. This supports the argument that age-related deficits in context memory retrieval may be due to changes in right DLPFC structure, function and its structure-function associations with the retrieval network, including right hippocampus. Conference: The 20th Annual Rotman Research Institute Conference, The frontal lobes, Toronto, Canada, 22 Mar - 26 Mar, 2010. Presentation Type: Poster Presentation Topic: Cognitive Neuroscience Citation: Czechowska Y, Grady C, Languay R, Pruessner J, Rajah M and Valiquette L (2010). Individual Differences in Right Dorsolateral Prefrontal Cortex Volumes, Whole Brain Activity and Memory Performance in Healthy Young and Older Adults. Conference Abstract: The 20th Annual Rotman Research Institute Conference, The frontal lobes. doi: 10.3389/conf.fnins.2010.14.00116 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Jun 2010; Published Online: 30 Jun 2010. * Correspondence: M N Rajah, McGill University, Douglas Mental Health University Institute, Montreal, QC, Canada, maria.rajah@mcgill.ca Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Y. Czechowska C L Grady R. Languay J C Pruessner M N Rajah L. Valiquette Google Y. Czechowska C L Grady R. Languay J C Pruessner M N Rajah L. Valiquette Google Scholar Y. Czechowska C L Grady R. Languay J C Pruessner M N Rajah L. Valiquette PubMed Y. Czechowska C L Grady R. Languay J C Pruessner M N Rajah L. Valiquette Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.