Physical activity in aging: comparison among young, aged, and nonagenarian individuals

Inactivation of a non-canonical gp130 signaling arm attenuates chronic systemic inflammation and multimorbidity induced by a high-fat diet

Interleukin-6 (IL-6) is a major pro-inflammatory cytokine for which the levels in plasma demonstrate a robust correlation with age and body mass index (BMI) as part of the senescence-associated secretory phenotype. IL-6 cytokines also play a crucial role in metabolic homeostasis and regenerative processes, primarily via the canonical STAT3 pathway. Thus, selective modulation of IL-6 signaling may offer a unique opportunity for therapeutic interventions. Recently, we discovered that a non-canonical signaling pathway downstream of tyrosine (Y) 814 within the intracellular domain of gp130, the IL-6 co-receptor, is responsible for the recruitment and activation of SRC family of kinases (SFK). Mice with constitutive genetic inactivation of gp130 Y814 (F814 mice) show accelerated resolution of inflammatory response and superior regenerative outcomes in skin wound healing and posttraumatic models of osteoarthritis. The current study was designed to explore if selective genetic or pharmacological inhibition of the non-canonical gp130-Y814/SFK signaling reduces systemic chronic inflammation and multimorbidity in a high-fat diet (HFD)-induced model of accelerated aging. F814 mice showed significantly reduced inflammatory response to HFD in adipose and liver tissue, with significantly reduced levels of systemic inflammation compared to wild type mice. F814 mice were also protected from HFD-induced bone loss and cartilage degeneration. Pharmacological inhibition of gp130-Y814/SFK in mice on HFD mirrored the effects observed in F814 mice on HFD; furthermore, this pharmacological treatment also demonstrated a marked increase in physical activity levels and protective effects against inflammation-associated suppression of neurogenesis in the brain tissue compared to the control group. These findings suggest that selective inhibition of SFK signaling downstream of gp130 receptor represents a promising strategy to alleviate systemic chronic inflammation. Increased degenerative changes and tissue senescence are inevitable in obese and aged organisms, but we demonstrated that the systemic response and inflammation-associated multi-morbidity can be therapeutically mitigated.

Accelerometer-measured physical activity and sedentary behavior in nonagenarians: Associations with self-reported physical activity, anthropometric, sociodemographic, health and cognitive characteristics

BACKGROUND

Research on device-based physical activity in the oldest-old adults is scarce. We examined accelerometer-measured physical activity and sedentary behavior in nonagenarians. We also investigated how the accelerometer characteristics associate with nonagenarians' self-reported physical activity, anthropometric, sociodemographic, health and cognitive characteristics.

METHODS

Nonagenarians from a population-based cohort study (N = 38, mean age 91.2) used accelerometers during the waking hours for seven days. They also participated in a health survey and cognitive telephone interview. The Wald test and Pearson and polyserial correlations were used to analyze the data.

RESULTS

The participants' average day consisted of 2931 steps, 11 minutes of moderate-to-vigorous physical activity and 13.6 hours of sedentary time. Physical activity bouts less than 3 minutes per day and sedentary time bouts of 20-60 minutes per day were the most common. No sex differences were found. Many accelerometer-measured and self-reported physical activity characteristics correlated positively (correlations ≥0.34, p-values <0.05). The low levels of many accelerometer-measured physical activity characteristics associated with low education (correlations ≥0.25, p-values <0.05), dizziness (correlations ≤-0.42, p-values <0.01) and fear of falling (correlations ≤-0.45, p-values <0.01). Fear of falling was also associated with accelerometer-measured sedentary behavior characteristics (correlations -0.42 or ≥0.43).

CONCLUSIONS

Nonagenarians were mostly sedentary and low in physical activity, but individual variability existed. Accelerometer-measured and self-reported physical activity had a good consistency. Education, dizziness and fear of falling were consistently related to accelerometer-measured characteristics in nonagenarians.

Survival Analysis for Cohort of Bhopal Gas Disaster Victims during 1985-2015

Context

After the gas tragedy on the night of December 2/3, 1984, at Bhopal, the Indian Council of Medical Research (ICMR) started following up on four population cohorts with different levels of post-disaster mortality from December 3-6, 1984.

Aims

The present study was undertaken to estimate the survival time of the cohort, and investigate the risk of mortality based on exposure, gender, and median age.

Settings and Design

Survival analysis is generally used to evaluate factors associated with the time to an event of failure or death among any covered population.

Methods and Materials

To know the cause of death and mortality rate, a retrospective cohort analysis was conducted on the outcomes of 92,320 individuals with an exposed and non-exposed group from 1985 to 2015 in Bhopal, India.

Statistical Analysis Used

Basic survival analysis method, Kaplan-Meier method, and Cox proportional hazard regression model were used to analyze the mortality risk.

Results

During the past 30 years, the survivability was 87.25%, and the mortality rate was 7.2% for the cohort population of Bhopal gas survivors. Cox regression analysis showed that exposed, males, and individuals above 21 years (at the time of the disaster) were at higher risk of mortality from 1985 to 2015.

Conclusions

During the initial two phases, the mortality was higher in the exposed group, but over time, their survival turned out to be the same in both groups.

Physical Inactivity, Sedentary Behavior and Quality of Life in the Chilean Population: ENCAVI Results, 2015-2016

Regular physical activity (PA) is indicated to be one of the main healthy habits that allow populations to achieve a good quality of life (QoL); however, levels of physical inactivity (PI) and sedentary behavior (SB) have risen worldwide, with negative health effects. The aim of this study is to analyze PI and SB levels, as well as their association with QoL in the Chilean population. A secondary analysis was performed based on the database from the 2015-2016 National Quality of Life Survey (ENCAVI) in Chile, using the modules for sociodemographic characteristics, health, and PA. Contingency tables and logistic regressions were conducted to determine the association between PI (low-intensity PA, LIPA; low-moderate PA, LMPA), SB (P75), and QoL adjusted for sociodemographic variables. Approximately 84%, 83%, and 47% of the participants presented LIPA, LMPA, and moderate-high SB, respectively. Participants that presented high PI and SB had lower QoL scores than those who were more active (p < 0.05). We observe that, in people with PI (LIPA), there is a higher risk of a low QoL regarding mental and physical components (OR 1.941; OR 1.189, p < 0.001) among females (OR 1.473; OR 1.513, p < 0.001) and those of a low educational level (OR 2.170; OR 1.410 p < 0.001). People with PI (LMPA) increased their risk for a low QoL in regard to mental and physical components (OR 1.750; OR 1.458, p < 0.001) among females (OR 1.528; OR 1.507, p < 0.001) and those of a low educational level (OR 2.195; OR 1.402 p < 0.001). We observe that people with SB (P75) increased their risk of a low QoL concerning physical and mental components (OR 1.475; OR 1.257, p < 0.001) for those of the female gender (OR 1.615; OR 1.563, p < 0.001) and a low educational level (OR 2.248; OR 1.423 p < 0.001). High levels of PI in both intensities and SB impact QoL in the Chilean population. It is crucial to generate public policies for more PA, especially for females and those of lower educational levels.

Age- and Sex-Specific Association Between Vegetation Cover and Mental Health Disorders: Bayesian Spatial Study

BACKGROUND

Despite growing evidence that reduced vegetation cover could be a putative risk factor for mental health disorders, the age- and the sex-specific association between vegetation and mental health disorder cases in urban areas is poorly understood. However, with rapid urbanization across the globe, there is an urgent need to study this association and understand the potential impact of vegetation loss on the mental well-being of urban residents.

OBJECTIVE

This study aims to analyze the spatial association between vegetation cover and the age- and sex-stratified mental health disorder cases in the neighborhoods of Toronto, Canada.

METHODS

We used remote sensing to detect urban vegetation and Bayesian spatial hierarchical modeling to analyze the relationship between vegetation cover and mental health disorder cases. Specifically, an Enhanced Vegetation Index was used to detect urban vegetation, and Bayesian Poisson lognormal models were implemented to study the association between vegetation and mental health disorder cases of males and females in the 0-19, 20-44, 45-64, and ≥65 years age groups, after controlling for marginalization and unmeasured (latent) spatial and nonspatial covariates at the neighborhood level.

RESULTS

The results suggest that even after adjusting for marginalization, there were significant age- and sex-specific effects of vegetation on the prevalence of mental health disorders in Toronto. Mental health disorders were negatively associated with the vegetation cover for males aged 0-19 years (-7.009; 95% CI -13.130 to -0.980) and for both males (-4.544; 95% CI -8.224 to -0.895) and females (-3.513; 95% CI -6.289 to -0.681) aged 20-44 years. However, for older adults in the 45-64 and ≥65 years age groups, only the marginalization covariates were significantly associated with mental health disorder cases. In addition, a substantial influence of the unmeasured (latent) and spatially structured covariates was detected in each model (relative contributions>0.7), suggesting that the variations in area-specific relative risk were mainly spatial in nature.

CONCLUSIONS

As significant and negative associations between vegetation and mental health disorder cases were found for young males and females, investments in urban greenery can help reduce the future burden of mental health disorders in Canada. The findings highlight the urgent need to understand the age-sex dynamics of the interaction between surrounding vegetation and urban dwellers and its subsequent impact on mental well-being.

Balance, physical conditioning, and health perception in elderly women submitted to a 32-week physical exercise program

Study aim: To assess the effects of a long-term physical exercise program on balance, physical conditioning, and health perception in elderly women.

Material and methods: The sample, 143 elderly women, were randomly assigned to an experimental group (EG; n = 71; age: 71.62 ± 4.96 years) and control group (CG; n = 72; age: 72.89 ± 5.40 years). The EG was submitted to a 32-week physical exercise program (3×/week, 60 min/session). Balance and physical conditioning were assessed through the 10-step in a straight-line test, the unipedal balance test (UBT), the timed up and go (TUG) test, and the 30-second chair stand test (30s CST). Health perception was evaluated by a questionnaire.

Results: Repeated measures ANOVA (2×3) revealed significant improvements (p < 0.05) in TUG and 30s CST in the EG from the pre- to the post-test and when compared to the CG in the post-test. There were significant increases (p < 0.05) in health perception, 10-step test, and UBT in the EG, and significant improvements (p < 0.05) in these EG variables when compared to the CG in the post-test.

Conclusions: Participating in the exercise program resulted in improvements in balance, muscle strength, agility, and health perception in the elderly of the present study.

Explaining the Unique Behavioral Characteristics of Elderly and Adults Based on Deep Learning

In modern society, the population has been aging as the lifespan has increased owing to the advancement in medical technologies. This could pose a threat to the economic system and, in serious cases, to the ethics regarding the socially-weak elderly. An analysis of the behavioral characteristics of the elderly and young adults based on their physical conditions enables silver robots to provide customized services for the elderly to counter aging society problems, laying the groundwork for improving elderly welfare systems and automating elderly care systems. Accordingly, skeleton sequences modeling the changes of the human body are converted into pose evolution images (PEIs), and a convolutional neural network (CNN) is trained to classify the elderly and young adults for a single behavior. Then, a heatmap, which is a contributed portion of the inputs, is obtained using a gradient-weighted class activation map (Grad-CAM) for the classified results, and a skeleton-heatmap is obtained through a series of processes for the ease of analysis. Finally, the behavioral characteristics are derived through the difference matching analysis between the domains based on the skeleton-heatmap and RGB video matching analysis. In this study, we present the analysis of the behavioral characteristics of the elderly and young adults based on cognitive science using deep learning and discuss the examples of the analysis. Therefore, we have used the ETRI-Activity3D dataset, which is the largest of its kind among the datasets that have classified the behaviors of young adults and the elderly.

Physical Activity and Sedentary Behavior at the End of the Human Lifespan

To objectively assess physical activity levels and sedentary behavior in a cohort of Spanish centenarians and their nonagenarian peers. Physical activity and sedentary behavior patterns were objectively measured by an ActiGraph GT3X accelerometer in centenarians (n = 18; 83% women; 100.8 ± 0.8 [100-103] years) and nonagenarians (n = 11; 91% women; 93.3 ± 2.5 [90-98] years). Centenarians showed less counts per minute (17.6 ± 7.1 vs. 46.1 ± 23.7, p = .003, d = 1.851) and steps per day (455 ± 237 vs. 1,249 ± 776, p = .007, d = 1.587) than nonagenarians. The daily number of sedentary breaks was also lower in the former (5.0 ± 1.5 vs. 6.7 ± 2.0, p = .019, d = 0.971). When observing time distribution, the most active day period in both groups was the morning, with a peak between 10:00 and 11:59. This data suggest that the decline in physical activity levels continues to worsen until the end of the human lifespan.

Regular Endurance Exercise Promotes Fission, Mitophagy, and Oxidative Phosphorylation in Human Skeletal Muscle Independently of Age

This study investigated whether regular endurance exercise maintains basal mitophagy and mitochondrial function during aging. Mitochondrial proteins and total mRNA were isolated from vastus lateralis biopsies (n = 33) of young sedentary (YS), old sedentary (OS), young active (YA), and old active (OA) men. Markers for mitophagy, fission, fusion, mitogenesis, and mitochondrial metabolism were assessed using qRT-PCR, Western blot, and immunofluorescence staining. Independently of age, fission protein Fis1 was higher in active vs. sedentary subjects (+80%; P < 0.05). Mitophagy protein PARKIN was more elevated in OA than in OS (+145%; P = 0.0026). mRNA expression of Beclin1 and Gabarap, involved in autophagosomes synthesis, were lower in OS compared to YS and OA (P < 0.05). Fusion and oxidative phosphorylation proteins were globally more elevated in the active groups (P < 0.05), while COx activity was only higher in OA than in OS (P = 0.032). Transcriptional regulation of mitogenesis did not vary with age or exercise. In conclusion, physically active lifestyle seems to participate in the maintenance of lifelong mitochondrial quality control by increasing fission and mitophagy.

Mitochondrial Theory of Skeletal Muscle Ageing - New Facts, New Doubts

For many years, scientists have been pursuing research on skeletal muscle ageing both in humans and animals. Studies on animal models have extended our knowledge of this mechanism in humans. Most researchers agree that the major processes of muscle ageing occur in the mitochondria as the major energy production centres in muscle cells. It is believed that decisive changes occur at the enzymatic activity level as well as in protein synthesis and turnover ability. Deregulation of ion channels and oxidative stress also play significant roles. In particular, in recent years the free radical theory of ageing has undergone considerable modification; researchers are increasingly highlighting the partly positive effects of free radicals on processes occurring in cells. In addition, the influence of diet and physical activity on the rate of muscle cell ageing is widely debated as well as the possibility of delaying it through appropriate physical exercise and diet programmes. Numerous studies, especially those related to genetic processes, are still being conducted, and in the near future the findings could provide valuable information on muscle ageing. The results of ongoing research could answer the perennial question of whether and how we can influence the rate of ageing both in animals and humans.

Active Video Games for Improving Physical Performance Measures in Older People: A Meta-analysis

Background and Purpose:

Participation in regular physical activity is associated with better physical function in older people (>65 years); however, older people are the least active of all age groups. Exercise-based active video games (AVGs) offer an alternative to traditional exercise programs aimed at maintaining or enhancing physical performance measures in older people. This review systematically evaluated whether AVGs could improve measures of physical performance in older people. Secondary measures of safety, game appeal, and usability were also considered.

Methods:

Electronic databases were searched for randomized controlled trials published up to April 2015. Included were trials with 2 or more arms that evaluated the effect of AVGs on outcome measures of physical performance in older people.

Results:

Eighteen randomized controlled trials (n = 765) were included. Most trials limited inclusion to healthy community-dwelling older people. With the exception of 1 trial, all AVG programs were supervised. Using meta-analyses, AVGs were found to be more effective than conventional exercise (mean difference [MD], 4.33; 95% confidence intervals [CIs], 2.93-5.73) or no intervention (MD, 0.73; 95% CI, 0.17-1.29) for improving Berg Balance scores in community-dwelling older people. Active video games were also more effective than control for improving 30-second sit-to-stand scores (MD, 3.99; 95% CI, 1.92-6.05). No significant differences in Timed Up and Go scores were found when AVGs were compared with no intervention or with conventional exercise.

Conclusions:

Active video games can improve measures of mobility and balance in older people when used either on their own or as part of an exercise program. It is not yet clear whether AVGs are equally suitable for older people with significant cognitive impairments or balance or mobility limitations. Given the positive findings to date, consideration could be given to further development of age-appropriate AVGs for use by older people with balance or mobility limitations.

Body Composition, IGF1 Status, and Physical Functionality in Nonagenarians: Implications for Osteosarcopenia

OBJECTIVES

Body composition alterations occur during aging. The purpose of the present analysis was to explore the functional consequences of the overlap of sarcopenia and osteoporosis, and the potential role of insulin-like growth factor 1 (IGF1) in their development in the oldest old.

SETTING AND PARTICIPANTS

Eighty-seven nonagenarians from the Louisiana Healthy Aging Study were included.

MEASURES

The definition of sarcopenia was based on appendicular lean mass (ALM). Osteoporosis was diagnosed based on bone mineral density (BMD) T score. Four phenotypes were compared: (1) healthy body composition, that is, nonosteoporotic nonsarcopenic (CO, control group), (2) osteoporotic (O, low BMD T score), (3) sarcopenic (S, low ALM), and (4) osteosarcopenic (OS, low BMD T score and low ALM). Sex- and age-specific IGF1-Standard Deviation Scores (SDS) were calculated. The Continuous Scale-Physical Functional Performance (CS-PFP) test was performed.

RESULTS

In OS men, IGF1-SDS values (-0.61 ±0.37 vs -0.04 ± 0.52, P = .02) were lower than those in CO males (control group), whereas IGF1-SDS were similar in the 4 body composition phenotypes in women. In men only, ALM was positively associated with IGF1-SDS values (P = .01) independent of age and C-reactive protein concentration. Regarding bone health, we found no association between IGF1-SDS values and BMD. IGF1-SDS was not associated with functional performance (CS-PFP) in men and women.

CONCLUSIONS/IMPLICATIONS

IGF1 sensitivity in skeletal muscle and bone may differ by sex in the oldest old. IGF1 status did not appear to affect physical functionality. Determinants and clinical and functional characteristics of osteosarcopenia need to be further investigated in order to define conclusive diagnostic criteria.

Validity of objective methods for measuring sedentary behaviour in older adults: a systematic review

Background

The evidence showing the ill health effects of prolonged sedentary behaviour (SB) is growing. Most studies of SB in older adults have relied on self-report measures of SB. However, SB is difficult for older adults to recall and objective measures that combine accelerometry with inclinometry are now available for more accurately assessing SB. The aim of this systematic review was to assess the validity and reliability of these accelerometers for the assessment of SB in older adults.

Methods

EMBASE, PubMed and EBSCOhost databases were searched for articles published up to December 13, 2017. Articles were eligible if they: a) described reliability, calibration or validation studies of SB measurement in healthy, community-dwelling individuals, b) were published in English, Portuguese or Spanish, and c) were published or in press as journal articles in peer-reviewed journals.

Results

The review identified 15 studies in 17 papers. Of the included studies, 11 assessed the ActiGraph accelerometer. Of these, three examined reliability only, seven (in eight papers) examined validity only and one (in two papers) examined both. The strongest evidence from the studies reviewed is from studies that assessed the validity of the ActiGraph. These studies indicate that analysis of the data using 60-s epochs and a vertical magnitude cut-point < 200 cpm or using 30- or 60-s epochs with a machine learning algorithm provides the most valid estimates of SB. Non-wear algorithms of 90+ consecutive zeros is also suggested for the ActiGraph.

Conclusions

Few studies have examined the reliability and validity of accelerometers for measuring SB in older adults. Studies to date suggest that the criteria researchers use for classifying an epoch as sedentary instead of as non-wear time (e.g., the non-wear algorithm used) may need to be different for older adults than for younger adults. The required number of hours and days of wear for valid estimates of SB in older adults was not clear from studies to date. More older-adult-specific validation studies of accelerometers are needed, to inform future guidelines on the appropriate criteria to use for analysis of data from different accelerometer brands.

Trial registration

PROSPERO ID# CRD42017080754 registered December 12, 2017.

Electronic supplementary material

The online version of this article (10.1186/s12966-018-0749-2) contains supplementary material, which is available to authorized users.

Analysis of Physical Activity Among Free-Living Nonagenarians From a Sardinian Longevous Population

Physical activity was identified as a major determinant of longevity. Using wearable accelerometers, we evaluated energy expenditure (EE), including resting- (REE) and total-energy expenditure (TEE), physical activity level (PAL), percentage of PAL ≥ 3 metabolic equivalent tasks (METs), number of steps, resting index (RI%) and sleep patterns in 44 free-living nonagenarians (27 men) residing in a Sardinian village famous for its longevous population. The average REE and TEE recorded were 1275 ± 163 kcal/day and 2284 ± 543 in the men and 952 ± 108 kcal/day and 1810 ± 302 in the women, respectively. The average PAL was 1.8, and the percentage of physical activity >3 METs was greater than 40%. A significant negative correlation (p < 0.05) between disability and PAL was found among the women. This study provides evidence that nonagenarians from the longevous population of Sardinia show excellent physical functionality indexes. Their longevity might result, at least in part, from their ability to stay physically fit during aging.

Surveying predictors of late-life longitudinal change in daily activity energy expenditure

Background

Total daily energy expenditure (TEE) is composed of resting metabolic rate (RMR), post-prandial thermogenesis and activity energy expenditure (AEE). Higher AEE is strongly associated with lower mortality and physical limitations among older adults, but factors that predict changes in AEE in septu and octogenarians are not clearly understood.

Objective

To identify factors associated with late-life longitudinal change in AEE.

Design

Energy expenditure was re-assessed in 83 participants (average age at baseline, 74.4±3.2 years)—an average of 7.5±0.54 years since the baseline measure. RMR was measured using indirect calorimetry and the thermic effect of meals was estimated at 10% of TEE. AEE was calculated as: TEE(0.9)-RMR. Participants were categorized into two groups according to the estimated day-to-day precision of the doubly-labeled water technique. Those who were within 10% or increased relative to their initial AEE measurement were categorized as having preserved AEE. Participants who declined greater than 10% of their initial measurement were categorized as having reduced AEE. A variety of socio-demographic, functional and mental factors, body composition, community and personal behaviors, blood measurements and health conditions were evaluated between groups at baseline and changes during follow-up.

Results

Daily AEE declined 106.61±293.25 kcal, which equated to a 14.63±40.57 kcal/d decrease per year. Fifty-nine percent (n = 49) preserved their AEE and 41% (n = 34) declined. Those who demonstrated a decline in AEE were older, had lower walking speed at baseline and showed a higher lean mass loss during follow up. Otherwise, groups were similar for socio-demographic characteristics, body composition, mental and physical function, health conditions and community and personal behaviors at baseline and change in these factors during follow-up.

Conclusions

This study demonstrates that AEE declines through the 8^th decade of life and is associated with age, lower walking speed at baseline and lean mass loss. Additionally, there are a significant number of individuals who appear to be resilient to these declines despite having health events that are expected to have a negative impact on their physical activity.

Relationship between objectively measured intensity of physical activity and self-reported enjoyment of physical activity

Physical activity is an important factor for the maintenance of health. Enjoyment of physical activity is essential to motivate persons to engage in sufficient physical activity. We examined whether self-reported enjoyment of PA is associated with objective measurement of the intensity of PA. A cardiovascular examination program was provided for individuals aged 40-75 years without a history of cardiovascular events in Greifswald, Germany between 2012 and 2013. Participants (n = 255) were asked to wear a three-axial accelerometer device (ActiGraph, GT3X +, Pensacola, Florida, USA) for 7 consecutive days. After wearing the device, the participants were asked to complete the 18-item self-administered physical activity enjoyment scale (PACES). Participants' (n = 200) daily minutes of moderate-to-vigorous physical activity (MVPA) and their enjoyment of PA were analysed in a linear regression approach. The mean age of the participants was 56.3 ± 9.7 years, 41.0% were male. The average MVPA duration was 44.4 ± 27.3 min per day. In the regression analysis, enjoyment of PA was positively associated with MVPA (β = 0.18, 95% CI (0.05; 0.31), p = 0.009), participants with higher enjoyment of PA showed higher MVPA. We found a positive association between MVPA and enjoyment of PA, although for male participants only. Between bouted MVPA and enjoyment of PA there was no significant relationship.

Muscle Characteristics and Substrate Energetics in Lifelong Endurance Athletes

PURPOSE

The goal of this study was to explore the effect of lifelong aerobic exercise (i.e., chronic training) on skeletal muscle substrate stores (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, and oxidative capacity (ox), in older endurance-trained master athletes (OA) compared with noncompetitive recreational younger (YA) athletes matched by frequency and mode of training.

METHODS

Thirteen OA (64.8 ± 4.9 yr) exercising 5 times per week or more were compared with 14 YA (27.8 ± 4.9 yr) males and females. IMTG, glycogen, fiber types, succinate dehydrogenase, and capillarization were measured by immunohistochemistry in vastus lateralis biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry before and after an insulin clamp and during a cycle ergometer graded maximal test.

RESULTS

V˙O2peak was lower in OA than YA. The OA had greater IMTG in all fiber types and lower glycogen stores than YA. This was reflected in greater proportion of type I and less type II fibers in OA. Type I fibers were similar in size, whereas type II fibers were smaller in OA compared with YA. Both groups had similar succinate dehydrogenase content. Numbers of capillaries per fiber were reduced in OA but with a higher number of capillaries per area. Metabolic flexibility and insulin sensitivity were similar in both groups. Exercise metabolic efficiency was higher in OA. At moderate exercise intensities, carbohydrate-ox was lower in OA but with similar Fat-ox.

CONCLUSIONS

Lifelong exercise is associated with higher IMTG content in all muscle fibers and higher metabolic efficiency during exercise that are not explained by differences in muscle fibers types and other muscle characteristics when comparing older with younger athletes matched by exercise mode and frequency.

Positive effects of 1-year football and strength training on mechanical muscle function and functional capacity in elderly men

PURPOSE

A decline in physical capacity takes place with increasing age that negatively affects overall physical function including work ability and the ability to perform typical activities of daily living (ADL). The overall aim of the present study was to determine the neuromuscular adaptations to long-term (1 year) football and strength training in older untrained adults, and to assess the concurrent effect on functional ADL capacity.

METHODS

Twenty-seven healthy elderly males (68.2 ± 3.2 years) were randomly assigned to 12 months of either recreational football training (FT: n = 10), strength training (ST: n = 9) or served as inactive controls (CON: n = 8). Recreational football training consisted of small-sided training sessions whereas strength training consisted of high intensity exercises targeting the lower extremity and upper body. Maximal thigh muscle strength and rate of force development (RFD) were assessed with isokinetic dynamometry, while postural balance and vertical jumping performance were evaluated using force plate analysis. Furthermore, functional ability was evaluated by stair-ascent and chair-rising testing.

RESULTS

A total of nine, nine and seven participants from FT, ST and CON, respectively, were included in the analysis. Both exercise regimens led to substantial gains in functional ability, evidenced by 24 and 18 % reduced stair-ascent time, and 32 and 21 % increased chair-rising performance in FT and ST, respectively (all P < 0.05). Long-term strength training led to increased concentric (14 %; P < 0.01) and isometric (23 %; P < 0.001) quadriceps and isometric hamstring strength (44 %; P < 0.0001), whereas football training mainly resulted in enhanced hamstring strength (18 %, P < 0.05) and RFD (89 %, P < 0.0001).

CONCLUSIONS

Long-term (1 year) strength training led to increased quadriceps and hamstring strength, whereas the adaptations to football training mainly included enhanced strength and rapid force capacity of the hamstring muscles. Gains in functional ability were observed in response to both training regimens, evidenced by reduced stair-ascent time and increased chair-rising performance. Long-term football exercise and strength training both appear to be effective interventional strategies to improve factors of importance for ADL by counteracting the age-related decline in lower limb strength and functional capacity among old male adults. This could potentially be a way to improve work ability of senior workers.

Relating wrist accelerometry measures to disability in older adults

OBJECTIVE

This analysis assessed the extent to which: (1) wrist accelerometer measures were associated with difficulty performing specific activities of daily living and instrumental activities of daily living and (2) these measures contributed important information about disability beyond a typical self-reported vigorous activity frequency question.

METHODS

We used data from the National Social Life, Health and Aging Project (NSHAP) accelerometry sub-study (n=738). Activity was assessed using two wrist-accelerometer measures assessed over 3 days (routine activity expressed as mean count/15s epoch during wake time, and immobile time expressed as the proportion of wake time spent immobile), and self-reported average vigorous activity frequency. The association between routine activity, immobile time and difficulty performing fourteen activities of daily living (ADLs) and instrumental activities of daily living (IADLs) plus two summary measures (any ADL or IADL difficulty), was assessed using logistic regression models, with and without controlling for self-reported vigorous activity.

RESULTS

Self-reported activity was mildly correlated with routine activity (r=0.27) and immobile time (r=-0.21). Routine activity, immobile time, and self-reported vigorous activity were significantly associated with twelve, ten, and fourteen disability measures, respectively. After controlling for self-reported activity, significant associations remained between routine activity and eight disabilities, and immobile time and six disabilities.

CONCLUSION

Wrist accelerometry measures were associated with many ADL and IADL disabilities among older adults. Wrist acclerometry in older adults may be useful to help assess disability risks and set individualized physical activity targets.

Measuring active ageing among older adults in Singapore

Active Ageing is conceptualised to measure the extent to which older people remain actively engaged with life. However, there is no evidence that the concept of Active Ageing is actually associated with the activity levels of older persons. Influences of age, ethnicity and spirituality on Active Ageing are also unexplored. Using the Active Ageing Index (AAI), this study examines whether the level of Active Ageing predicted the actual activity level of 120 Singaporeans of Chinese, Malay and Indians ethnicities, aged 55–64 years old or 65 years and above. Spirituality, measured by the Spirituality Index of Well-Being, was added to the AAI, to see if the predictive power of AAI improved. Hierarchical multiple regression showed that the AAI alone (controlling for age) did not significantly predict the activity level of older persons. The predictive power of the AAI improved significantly with spirituality included. Two-way between-groups Analysis of Variance revealed main effects of age and ethnicity, with higher AAI in those aged 55–64 and in Indian-Singaporeans. These findings suggest that the theoretical construct of Active Ageing needs further examination to identify the domains that distinguish it from chronological age, and support broadening the construct by including spirituality in Active Ageing.

Chemotherapy Regimen in Nonagenarian Cancer Patients: A Bi-Institutional Experience

BACKGROUND

The elderly population in Western countries is growing and constitutes a public health issue. Concomitantly, age-related diseases such as cancer increase. There are few data on the efficacy, tolerability and toxicity of specific anticancer therapy in the very elderly patients; therefore, their management is not standardized.

METHODS

In this bi-institutional study, we reviewed medical records of patients who received or continued specific anticancer therapy beyond the age of 90 years. Geriatric assessment was not reported for our patients. Twelve patients were enrolled. Their general health condition was good, and half of them were living in elderly institutions. Ten patients had a solid tumor and 2 were treated for hematological malignancies. Most were diagnosed with a locally advanced or metastatic disease, and the goal of treatment was curative for only 1 patient. Six patients received chemotherapy as first-line treatment, 4 patients received targeted therapy and 2 received concomitant chemoradiation. Four patients received a second-line treatment.

RESULTS

Despite a significant reduction in treatment posology in half of the patients, 8 acute grade 3/4 toxicities were reported and 2 patients died of treatment-related septic shock. Median duration of first-line treatment was 3.2 months, and progression-free survival ranged from 18 to 311 days. Overall survival ranged from 18 days to 11 years.

CONCLUSION

Aging is a heterogeneous process, and management of elderly patients is a multidisciplinary approach. Geriatric assessment helps to identify older patients with a higher risk of morbidity/mortality and allows to assess the risks and benefits of specific anticancer therapy. The choice of treatment should be based primarily on the expected symptomatic benefit, and treatment should not compromise the quality of life.

Objective and subjective measurement of energy expenditure in older adults: a doubly labeled water study

BACKGROUND/OBJECTIVES

Objective and subjective measurement instruments have been used to estimate energy expenditure (EE) as alternatives to the doubly labeled water (DLW) methodology, but their relative validity for older adults remains uncertain. The purpose of this study was to validate an objective monitor (SenseWear Mini Armband) and a self-report instrument (7-Day Physical Activity Recall, 7D-PAR) relative to the DLW under free-living conditions in older adults.

SUBJECTS/METHODS

Twenty-nine older adults (60-78 years) each wore the Mini for 14 consecutive days and completed two 7D-PARs after each week. For each measurement method, activity EE (AEE) was calculated as total EE (TEE)—measured resting metabolic rate (RMR)—diet induced thermogenesis (10% of TEE). TEE and AEE from the Mini and 7D-PAR were each compared with values from the DLW.

RESULTS

Equivalence testing indicated that estimates of TEE from the Mini and the 7D-PAR were statistically equivalent to those measured with DLW; however, differences were evident for estimates of AEE. The Mini had smaller mean absolute percent error for TEE (8.0%) and AEE (28.4%) compared with the 7D-PAR (13.8 and 84.5%, respectively) and less systematic bias in the estimates.

CONCLUSIONS

The Mini and 7D-PAR provided reasonably valid estimates of TEE but large errors in estimating AEE. The Mini and 7D-PAR have the potential to accurately estimate TEE for older adults.

Quantitative measures of healthy aging and biological age

Numerous genetic and non-genetic factors contribute to aging. To facilitate the study of these factors, various descriptors of biological aging, including 'successful aging' and 'frailty', have been put forth as integrative functional measures of aging. A separate but related quantitative approach is the 'frailty index', which has been operationalized and frequently used. Various frailty indices have been constructed. Although based on different numbers and types of health variables, frailty indices possess several common properties that make them useful across different studies. We have been using a frailty index termed FI34 based on 34 health variables. Like other frailty indices, FI34 increases non-linearly with advancing age and is a better indicator of biological aging than chronological age. FI34 has a substantial genetic basis. Using FI34, we found elevated levels of resting metabolic rate linked to declining health in nonagenarians. Using FI34 as a quantitative phenotype, we have also found a genomic region on chromosome 12 that is associated with healthy aging and longevity.

Intensity of physical activity in the energy expenditure of older adults

This study examined the intensity of activity contributing to physical activity energy expenditure in older adults. In 57 men and women aged ≥ 65, total energy expenditure (TEE) was measured using doubly labeled water and resting metabolic rate was measured using indirect calorimetry to calculate a physical activity index (PAI). Sedentary time and physical activity of light and moderate to vigorous (mod/vig) intensity was measured using an accelerometer. The subjects were 75 ± 7 yrs (mean ± SD) of age and 79% female. Subjects spent 66 ± 8, 25 ± 5, and 9 ± 4% of monitor wear time in sedentary, light, and mod/vig activity per day, respectively. In a mixture regression model, both light (β = 29.6 [15.6-43.6, 95% CI]), p < .001) and mod/vig intensity activity (β = 28.7 [7.4-50.0, 95% CI]), p = .01) were strongly associated with PAI, suggesting that both light and mod/vig intensity activities are major determinants of their physical activity energy expenditure.

An elevation of resting metabolic rate with declining health in nonagenarians may be associated with decreased muscle mass and function in women and men, respectively

Previously, we showed that FI34, a frailty index based on 34 health and function ability variables, is heritable and a reliable phenotypic indicator of healthy aging. We have now examined the relationship between major components of energy expenditure and the FI34 in participants of the Louisiana Healthy Aging Study. Resting metabolic rate was associated with FI34, even after adjustment for fat-free mass, fat mass, age, sex, thyroid hormones, and insulin-like growth factor 1 levels, in multiple regression analyses. In contrast, there was no association between total daily energy expenditure and FI34. Circulating creatine phosphokinase, a clinical marker of muscle damage, was also significantly associated with FI34. However, these associations of resting metabolic rate with FI34 were restricted to the oldest old (≥90 years) and absent in younger age groups. In oldest old men, the association of FI34 with creatine phosphokinase persisted, whereas in the oldest old women, only the association with resting metabolic rate pertained with the appearance of an effect of body size and composition. These results point toward an increasing metabolic burden for the maintenance of homeodynamics as health declines in nonagenarians, and this has implications for contraction of metabolic reserve that may potentially accelerate the path to disability.

Accelerometry analysis of physical activity and sedentary behavior in older adults: a systematic review and data analysis

Accelerometers objectively monitor physical activity and sedentary patterns and are increasingly used in the research setting. It is important to maintain consistency in data analysis and reporting, therefore, we: (1) systematically identified studies using accelerometry (ActiGraph, Pensacola, FL, USA) to measure moderate-to-vigorous physical activity (MVPA) and sedentary time in older adults, and (2) based on the review findings, we used different cut-points obtained to analyze accelerometry data from a sample of community-dwelling older women. We identified 59 articles with cut-points ranging between 574 and 3,250 counts/min for MVPA and 50 and 500 counts/min for sedentary time. Using these cut-points and data from women (mean age, 70 years), the median MVPA minutes per day ranged between 4 and 80 min while percentage of sedentary time per day ranged between 62 % and 86 %. These data highlight (1) the importance of reporting detailed information on the analysis assumptions and (2) that results can differ greatly depending on analysis parameters.

Effect of Tai Chi versus walking on oxidative stress in Mexican older adults

It has recently been reported that the practice of Tai Chi reduces oxidative stress (OxS), but it is not clear whether walking or Tai Chi produces a greater antioxidant effect. The aim of the present study was to evaluate the effect of the practice of Tai Chi and walking on markers for OxS. We carried out a quasi-experimental study with 106 older adults between 60 and 74 years of age who were clinically healthy and divided into the following groups: (i) control group (n = 23), (ii) walking group (n = 43), and (iii) Tai Chi group (n = 31). We measured the levels of lipoperoxides (LPO), antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), and total antioxidant status (TAS) pre- and post-intervention in all subjects. The data were subjected to a covariant analysis. We found lower levels of LPO in the Tai Chi group compared with the walking group (Tai Chi, 0.261 ± 0.02; walking, 0.331 ± 0.02; control, 0.304 ± 0.023 µmol/L; P = 0.05). Likewise, we observed significantly higher SOD activity and lower OxS-score in the Tai Chi group (P < 0.05). Our findings suggest that the practice of Tai Chi produces a more effective antioxidant effect than walking.

Longitudinal change in energy expenditure and effects on energy requirements of the elderly

Background

Very little is known about the longitudinal changes in energy requirements in late life. The purposes of this study were to: (1) determine the energy requirements in late life and how they changed during a 7 year time-span, (2) determine whether changes in fat free mass (FFM) were related to changes in resting metabolic rate (RMR), and (3) determine the accuracy of predicted total energy expenditure (TEE) to measured TEE.

Methods

TEE was assessed via doubly labeled water (DLW) technique in older adults in both 1999 (n = 302; age: 74 ± 2.9 yrs) and again in 2006 (n = 87 age: 82 ± 3.1 yrs). RMR was measured with indirect calorimetry, and body composition was assessed with dual-energy x-ray absorptiometry.

Results

The energy requirements in the 9th decade of life were 2208 ± 376 kcal/d for men and 1814 ± 337 kcal/d for women. This was a significant decrease from the energy requirements in the 8th decade of life in men (2482 ± 476 kcal/d vs. 2208 ± 376 kcal/d) but not in women (1892 ± 271 kcal/d vs. 1814 ± 337 kcal/d). In addition to TEE, RMR, and activity EE (AEE) also decreased in men, but not women, while FFM decreased in both men and women. The changes in FFM were correlated with changes in RMR for men (r = 0.49, p < 0.05) but not for women (r = −0.08, ns). Measured TEE was similar to Dietary Reference Intake (DRI) predicted TEE for men (2208 ± 56 vs. 2305 ± 35 kcal/d) and women (1814 ± 42 vs. 1781 ± 20 kcal/d). However, measured TEE was different than the World Health Organization (WHO) predicted TEE in men (2208 ± 56 vs. 2915 ± 31 kcal/d (p < 0.05)) and women (1814 ± 42 vs. 2315 ± 21 kcal/d (p < 0.05)).

Conclusions

TEE, RMR and AEE decreased in men, but not women, from the 8th to 9th decade of life. The DRI equation to predict TEE was comparable to measured TEE, while the WHO equation over-predicted TEE in our elderly population.

Daily physical activity assessment with accelerometers: new insights and validation studies

The field of application of accelerometry is diverse and ever expanding. Because by definition all physical activities lead to energy expenditure, the doubly labelled water (DLW) method as gold standard to assess total energy expenditure over longer periods of time is the method of choice to validate accelerometers in their ability to assess daily physical activities. The aim of this paper was to provide a systematic overview of all recent (2007-2011) accelerometer validation studies using DLW as the reference. The PubMed Central database was searched using the following keywords: doubly or double labelled or labeled water in combination with accelerometer, accelerometry, motion sensor, or activity monitor. Limits were set to include articles from 2007 to 2011, as earlier publications were covered in a previous review. In total, 38 articles were identified, of which 25 were selected to contain sufficient new data. Eighteen different accelerometers were validated. There was a large variability in accelerometer output and their validity to assess daily physical activity. Activity type recognition has great potential to improve the assessment of physical activity-related health outcomes. So far, there is little evidence that adding other physiological measures such as heart rate significantly improves the estimation of energy expenditure.

Skeletal muscle mitochondria and aging: a review

Aging is characterized by a progressive loss of muscle mass and muscle strength. Declines in skeletal muscle mitochondria are thought to play a primary role in this process. Mitochondria are the major producers of reactive oxygen species, which damage DNA, proteins, and lipids if not rapidly quenched. Animal and human studies typically show that skeletal muscle mitochondria are altered with aging, including increased mutations in mitochondrial DNA, decreased activity of some mitochondrial enzymes, altered respiration with reduced maximal capacity at least in sedentary individuals, and reduced total mitochondrial content with increased morphological changes. However, there has been much controversy over measurements of mitochondrial energy production, which may largely be explained by differences in approach and by whether physical activity is controlled for. These changes may in turn alter mitochondrial dynamics, such as fusion and fission rates, and mitochondrially induced apoptosis, which may also lead to net muscle fiber loss and age-related sarcopenia. Fortunately, strategies such as exercise and caloric restriction that reduce oxidative damage also improve mitochondrial function. While these strategies may not completely prevent the primary effects of aging, they may help to attenuate the rate of decline.

Physical inactivity in aging and dementia: a review of its relationship to pain

AIMS

The goal of this brief review is to address studies examining the relationship between physical inactivity and pain in aging and dementia.

BACKGROUND

A decrease in the level of physical activity is characteristic of older persons, both with and without dementia. Passive behaviour is often considered to be part of the apathy frequently observed in patients with dementia, although it could also be a sign of pain. Design.  Literature review. Method.  Searches were performed in PubMed and Embase. A total of 15 studies concerning the relationship between physical inactivity and pain in older persons with and without dementia were identified (older persons without dementia: 12; with dementia: 3).

RESULTS

In older persons without dementia, a positive relationship between physical inactivity and pain has been demonstrated. In older persons with dementia, pain may cause physical inactivity and physical inactivity may cause pain. Conclusions.  In older persons, a positive relationship between physical inactivity and pain was demonstrated. More specifically, pain may cause physical inactivity. In older persons with dementia pain may cause physical inactivity and vice versa.

RELEVANCE TO CLINICAL PRACTICE

Nurses' awareness of physical inactivity as an indication of pain in older persons with and without dementia may reduce the risk of underdiagnosis and subsequent undertreatment of pain.

Use of accelerometry to measure physical activity in adults and the elderly

OBJECTIVE

To review the use of accelerometry as an objective measure of physical activity in adults and elderly people.

METHODS

A systematic review of studies on the use of accelerometty as an objective measure to assess physical activity in adults were examined in PubMed Central, Web of Knowledge, EBSCO and Medline databases from March 29 to April 15, 2010. The following keywords were used: "accelerometry," "accelerometer," "physical activity," "PA," "patterns," "levels," "adults," "older adults," and "elderly," either alone or in combination using "AND" or "OR." The reference lists of the articles retrieved were examined to capture any other potentially relevant article. Of 899 studies initially identified, only 18 were fully reviewed, and their outcome measures abstracted and analyzed.

RESULTS

Eleven studies were conducted in North America (United States), five in Europe, one in Africa (Cameroon) and one in Australia. Very few enrolled older people, and only one study reported the season or time of year when data was collected. The articles selected had different methods, analyses, and results, which prevented comparison between studies.

CONCLUSIONS

There is a need to standardize study methods for data reporting to allow comparisons of results across studies and monitor changes in populations. These data can help design more adequate strategies for monitoring and promotion of physical activity.

Accelerometer use with children, older adults, and adults with functional limitations

Accurately assessing physical activity behavior in children, older adults, and adults with functional limitations is essential to further our understanding of determinants of physical activity behavior in these populations and to design, implement, and evaluate interventions designed to increase physical activity participation. Objective methods to assess physical activity behavior, owing to improvements in accuracy and precision over self-report measures, have become common in research and practice settings. This article reviews the current use of objective methods to assess physical activity in observational, determinant, and intervention studies for children, older adults, and adults with functional limitations. Important considerations are presented when adopting prediction algorithms developed on one population, and using in another population that is markedly different in age, health, and functional status. Best practices are presented, along with future recommendations for research to advance this area of scientific inquiry.

Functional independence, diagnostic groups, hospital stay, and modality of payment in three Croatian seaside inpatient rehabilitation centers

AIM

To determine patients' functional independence, diagnostic groups, duration of hospital stay, and modality of payment of rehabilitation in major special hospitals for rheumatology and medical rehabilitation on the Croatian seaside.

METHODS

In a cross-sectional study conducted from October 2006 until January 2009, we surveyed 400 patients treated at 3 special hospitals for medical rehabilitation. Their functional independence was assessed by modified Barthel index and they self-evaluated their health using the first item from the 36-Item Short-Form Health Survey questionnaire.

RESULTS

On admission, almost half of the patients (46%) were fully functionally independent, 33% were slightly dependent, while 21% were moderately or severely dependent. At the end of the hospitalization, significant predictors for the increase in Barthel index were longer hospital stay (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.06-1.22), diagnosis of post-procedural musculoskeletal disorders (OR, 4.84; 95% CI, 1.90-10.57), diagnosis of conditions following acute ischemic heart disease (OR, 9.71; 95% CI, 3.40-27.75), and lower Barthel index at admission (OR, 0.96; 95% CI, 0.94-0.97). Of the 97 patients with dorsopathy, 73 (75%) were fully functionally independent and 57 (59%) paid for the treatment either themselves or contributed substantially to the total cost.

CONCLUSION

Assessment of patients' functional status is important for the organization of inpatient rehabilitation. Patients with dorsopathy could be targeted as a population for medical tourism in rehabilitation medicine in order to maximize the use of rehabilitation hospitals.

Energy expenditure in adults living in developing compared with industrialized countries: a meta-analysis of doubly labeled water studies

BACKGROUND

There is an assumption that people in developing countries have a higher total energy expenditure (TEE) and physical activity level (PAL) than do people in developed nations, but few objective data for this assertion exist.

OBJECTIVE

We conducted a meta-analysis of TEE and PAL by using data from countries that have a low or middle human development index (HDI) compared with those with a high HDI to better understand how energy-expenditure variables are associated with development status and population differences in body size.

DESIGN

We performed a literature search for studies in which energy expenditure was measured by using doubly labeled water. Mean data on age, weight, body mass index (BMI; in kg/m(2)), TEE, and PAL were extracted, and HDI status was assessed. Pooled estimates of the mean effect by sex were obtained, and the extent to which age, weight, HDI status, and year of publication explained heterogeneity was assessed.

RESULTS

A total of 98 studies (14 studies from low- or middle-HDI countries) that represented 183 cohorts and 4972 individuals were included. Mean (±SE) BMI was lower in countries with a low or middle HDI than in those with a high HDI for both men and women (22.7 ± 1.0 compared with 26.0 ± 0.7, respectively, in men and 24.3 ± 0.7 compared with 26.6 ± 0.4, respectively, in women). In meta-regression models, there was an inverse association of age (P < 0.001) and a positive association of weight (P < 0.001) with TEE for both sexes; there was an association of age only in men with PAL (P < 0.001). There was no association of HDI status with either TEE or PAL.

CONCLUSION

TEE adjusted for weight and age or PAL did not differ significantly between developing and industrialized countries, which calls into question the role of energy expenditure in the cause of obesity at the population level.

Obesity in the elderly: is faulty metabolism to blame?

The fastest growing segment of the US population, and that of other developed countries, is the oldest-old (aged >85 years). Many children born after the year 2000 in countries with the longest lived residents may live to see their 100th birthday. The combination of reduced mortality along with reduced fertility in developed countries is producing 'population aging', and the comorbidities associated with aging are becoming important public health issues. Age-associated obesity is one such important public health issue. Aging is associated with significant changes in body composition, including loss of skeletal muscle mass and increased visceral fat accumulation. The loss of muscle mass is accompanied by a disproportionate decline in muscle strength (up to three-times greater than the loss of mass), indicative of reduced muscle 'quality' or muscle dysfunctionality. Aging is characterized by markedly reduced physical activity and a drop in resting metabolic rate that is disproportionate to the loss of muscle mass, with a shift towards preferentially oxidizing carbohydrate at the expense of fat. A combination of these factors may act to increase muscular lipid infiltration and decrease insulin sensitivity; however, the cause and effect relationship remains undetermined. Changes in cellular energy (i.e., ATP) requirement owing to decreased ion channel activity, decreased protein synthesis or increased mitochondrial energy efficiency may underlie the decreased resting metabolic rate. Increasing energy demand through physical activity may alleviate some of the adverse metabolic changes that are associated with aging.

Energy expenditure and aging

The study of energy expenditure (EE) has deep roots in understanding aging and lifespan in all species. In humans, total EE decreases substantially in advanced age resulting from parallel changes in resting metabolic rate (RMR) and activity EE. For RMR, this reduction appears to be due to a reduction in organ mass and specific metabolic rates of individual tissues. However, these anatomical changes explain very little regarding the decline in activity EE, which is governed by both genetic and environmental sources. The biological control centers for activity EE are closely coupled with body mass fluctuations and seem to originate in the brain. Several candidate neuromodulators may be involved in the age-related reduction of activity EE that include: orexin, agouti-related proteins and dopaminergic pathways. Unfortunately, the existing body of research has primarily focused on how neuromodulators influence weight gain and only a few studies have been performed in aging models. Recent evidence suggests that activity EE has an important role in dictating lifespan and thus places emphasis on future research to uncover the underlying biological mechanisms. The study of EE continues to unlock clues to aging.

A stable isotope method for the simultaneous measurement of matrix synthesis and cell proliferation in articular cartilage in vivo

OBJECTIVE

Measurements of cell proliferation and matrix synthesis in cartilage explants have identified regulatory factors [e.g., interleukin-1 (IL-1)] that contribute to osteoarthritis and anabolic mediators [e.g., bone morphogenic protein-7 (BMP-7)] that may have therapeutic potential. The objective of this study was to develop a robust method for measuring cell proliferation and glycosaminoglycan synthesis in articular cartilage that could be applied in vivo.

METHODS

A stable isotope-mass spectrometry approach was validated by measuring the metabolic effects of IL-1 and BMP-7 in cultures of mature and immature bovine cartilage explants. The method was also applied in vivo to quantify physiologic turnover rates of matrix and cells in the articular cartilage of normal rats. Heavy water was administered to explants in the culture medium and to rats via drinking water, and cartilage was analyzed for labeling of chondroitin sulfate (CS), hyaluronic acid (HA) and DNA.

RESULTS

As expected, IL-1 inhibited the synthesis of DNA and CS in cartilage explants. However, IL-1 inhibited HA synthesis only in immature cartilage. Furthermore, BMP-7 was generally stimulatory, but immature cartilage was significantly more responsive than mature cartilage, particularly in terms of HA and DNA synthesis. In vivo, labeling of CS and DNA in normal rats for up to a year indicated half-lives of 22 and 862 days, respectively, in the joint.

CONCLUSIONS

We describe a method by which deuterium from heavy water is traced into multiple metabolites from a single cartilage specimen to profile its metabolic activity. This method was demonstrated in tissue culture and rodents but may have significant clinical applications.

Randomized controlled trial of the efficacy of aerobic exercise in reducing metabolic risk in healthy older people: The Hertfordshire Physical Activity Trial

BACKGROUND

While there are compelling observational data confirming that individuals who exercise are healthier, the efficacy of aerobic exercise interventions to reduce metabolic risk and improve insulin sensitivity in older people has not been fully elucidated. Furthermore, while low birth weight has been shown to predict adverse health outcomes later in life, its influence on the response to aerobic exercise is unknown. Our primary objective is to assess the efficacy of a fully supervised twelve week aerobic exercise intervention in reducing clustered metabolic risk in healthy older adults. A secondary objective is to determine the influence of low birth weight on the response to exercise in this group.

METHODS/DESIGN

We aim to recruit 100 participants born between 1931-1939, from the Hertfordshire Cohort Study and randomly assign them to no intervention or to 36 fully supervised one hour sessions on a cycle ergometer, over twelve weeks. Each participant will undergo detailed anthropometric and metabolic assessment pre- and post-intervention, including muscle biopsy, magnetic resonance imaging and spectroscopy, objective measurement of physical activity and sub-maximal fitness testing.

DISCUSSION

Given the extensive phenotypic characterization, this study will provide valuable insights into the mechanisms underlying the beneficial effects of aerobic exercise as well as the efficacy, feasibility and safety of such interventions in this age group.

TRIAL REGISTRATION

Current Controlled Trials: ISRCTN60986572.