Mancha3D Code: Multipurpose Advanced Nonideal MHD Code for High-Resolution Simulations in Astrophysics.

The Mancha3D code is a versatile tool for numerical simulations of magnetohydrodynamic (MHD) processes in solar/stellar atmospheres. The code includes nonideal physics derived from plasma partial ionization, a realistic equation of state and radiative transfer, which allows performing high-quality realistic simulations of magnetoconvection, as well as idealized simulations of particular processes, such as wave propagation, instabilities or energetic events. The paper summarizes the equations and methods used in the Mancha3D (Multifluid (-purpose -physics -dimensional) Advanced Non-ideal MHD Code for High resolution simulations in Astrophysics 3D) code. It also describes its numerical stability and parallel performance and efficiency. The code is based on a finite difference discretization and a memory-saving Runge-Kutta (RK) scheme. It handles nonideal effects through super-time-stepping and Hall diffusion schemes, and takes into account thermal conduction by solving an additional hyperbolic equation for the heat flux. The code is easily configurable to perform different kinds of simulations. Several examples of the code usage are given. It is demonstrated that splitting variables into equilibrium and perturbation parts is essential for simulations of wave propagation in a static background. A perfectly matched layer (PML) boundary condition built into the code greatly facilitates a nonreflective open boundary implementation. Spatial filtering is an important numerical remedy to eliminate grid-size perturbations enhancing the code stability. Parallel performance analysis reveals that the code is strongly memory bound, which is a natural consequence of the numerical techniques used, such as split variables and PML boundary conditions. Both strong and weak scalings show adequate performance up to several thousands of processors (CPUs).

The influence of thermal pressure gradients and ionization (im)balance on the ambipolar diffusion and charge-neutral drifts.

Solar partially ionized plasma is frequently modelled using single-fluid (1F) or two-fluid (2F) approaches. In the 1F case, charge-neutral interactions are often described through ambipolar diffusion, while the 2F model fully considers charge-neutral drifts. Here, we expand the definition of the ambipolar diffusion coefficient to include inelastic collisions (ion/rec) in two cases: a VAL3C one-dimensional model and a 2F simulation of the Rayleigh-Taylor instability (RTI) in a solar prominence thread based on [Lukin et al. 2024 Phil. Trans. R. Soc. A 382, 20230417. (doi:10.1098/rsta.2023.0417)]. On one side, we evaluate the relative importance of the inelastic contribution, compared to elastic and charge-exchange collisions. On the other side, we compare the contributions of ion/rec, thermal pressure, viscosity and magnetic forces to the charge-neutral drift velocity of the turbulent flow of the RTI. Our analysis reveals that the contribution of inelastic collisions to the ambipolar diffusion coefficient is negligible across the chromosphere, allowing the classical definition of this coefficient to be safely used in 1F modelling. However, in the transition region, the contribution of inelastic collisions can become as significant as that of elastic collisions. Furthermore, we ascertain that the thermal pressure force predominantly influences the charge-neutral drifts in the RTI model, surpassing the impact of the magnetic force. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

Criterion-related validity of self-report walking time from the EPIC questionnaire in older adults.

Tools for measuring walking time make use of objective and subjective methods. One subjective approach is to administer physical activity questionnaires (PAQ), mainly because they are inexpensive and easy to give to large groups. The European Prospective Investigation into Cancer and Nutrition (EPIC) study has a brief PAQ (EPIC-PAQ) and includes one question referencing walking time. The objective of this study was to assess the validity of the question about time spent walking included in the EPIC-PAQ. The sample included 200 older adults (113 women). To assess daily walking time, participants responded to the EPIC-PAQ in an interview and wore a portable gait analysis system and physical activity monitor for 48 consecutive hours in free-living condition. Results indicated that the mean of bias between the EPIC-PAQ and objetive measurement was -64.6 min/day. Also, the correlation was low compared to an objective measurement (rho = 0.196) and was positively correlated with the time spent at speeds below 2.5 mph but the correlation was low (slow walking rho = 0.154 and pace walking rho = 0.163). The EPIC-PAQ shows low correlations with the objective measurement of walking time, that suggests it may be inaccurate and affecting the estimate of the EPIC-PAQ's PA energy expenditure in this age group.

Changes in objectively measured physical activity in adolescents with Down syndrome: the UP&DOWN longitudinal study.

BACKGROUND: It is a priority to understand that physical activity behaviour over time is a priority in Down syndrome population in order to design and promote succesfull interventions to maintain or increase levels of physical activity. We aimed to study 1 and 2-year changes in objectively measured physical activity among a relatively large sample of adolescents with Down syndrome. METHODS: This study comprised a total of 99 adolescents with Down syndrome (38 girls) aged from 11 to 20 years old at baseline. Participants with valid accelerometer data at baseline and at least one of the follow-up visits were included in the analysis. RESULTS: Overall, levels of physical activity observed in adolescents with Down syndrome declined from baseline to follow-ups, but these changes were not significant (all P > 0.05). Moderate-to-moderately high tracking of physical activity was observed in adolescents with Down syndrome (all P < 0.001). Youths who met physical activity guidelines at baseline demonstrated a greater decline in physical activity in 1 and 2-year changes (P < 0.05), although they were also more likely to meet physical activity guidelines at 1 and 2-year follow-ups (P < 0.05). CONCLUSIONS: Adolescents with Down syndrome do not change their levels of physical activity at 2-year follow-ups, but those who met physical activity guidelines presented stronger declines in physical activity over time.

The role of fatness on physical fitness in adolescents with and without Down syndrome: The UP&DOWN study.

BACKGROUND/OBJECTIVES: Adolescents with Down syndrome (DS) exhibit higher levels of fatness and low levels of physical fitness compared with those without DS. In adolescents without DS, fatness is tightly associated with physical fitness, but this association is unclear in adolescents with DS. The aim of this study was to examine the association between several markers of fatness and physical fitness in a relative large sample of adolescents with and without DS. SUBJECTS/METHODS: A total of 111 adolescents with DS (41 females) aged 11-20 years participated in this cross-sectional study. We also included a sex-matched control group (ratio 1:2) of 222 adolescents without DS aged 12-18 years, participating in the UP&DOWN Study. The Assessing Level of Physical Activity (ALPHA) health-related fitness test battery for adolescents was used to assess fatness and physical fitness. RESULTS: Our results show that fatness is not associated with low levels of physical fitness in adolescents with DS (that is, 3 of the 16 analyses identified differences in physical fitness variables by groups of fatness). In contrast, fatness, as expected, is associated with levels of physical fitness in adolescents without DS (that is, 13 of the 16 analyses identified differences in physical fitness variables by groups of fatness). CONCLUSIONS: The present finding contributes to new knowledge by suggesting that the role of fatness on physical fitness is different in adolescents with and without DS, and consequently, the poor levels of physical fitness in adolescents with DS may be due to the syndrome rather than the high prevalence of obesity from this population.

Influence of heat-labile serum components in the presence of OmpA on the outer membrane of Salmonella gallinarum.

Salmonella gallinarum is the causative agent of fowl typhoid. Being a Gram-negative bacteria, its outer membrane proteins (OMP) can be regulated by different microenvironments. S. gallinarum was cultured under the following conditions: nutrient broth (NB), NB supplemented with serum from specific pathogen-free birds (NBS) and NB with serum incubated at 56 °C prior to incubation with the bacteria (NBSD); OMP were subsequently extracted. Several changes were observed in the apparent expression of OMP, mainly a decrease in an OMP with a size of 30 kDa, approximately, under the NBS condition. In contrast, the same event was not observed in NB and NBSD when using one- and two-dimensional polyacrylamide gels (SDS-PAGE). Using the OMP with a size of 30 kDa, approximately, as antigen in indirect ELISA, we were able to differentiate serum from healthy and vaccinated birds, as well as birds infected with S. gallinarum and S. enteritidis. The amino-terminal of this protein was sequenced, showing 100 % identity with OmpA of S. typhimurium. Subsequently, we designed primers to amplify the gene by PCR. The partial sequence of the amplified gene showed 100 % identity with OmpA of S. gallinarum. (1) Heat-labile serum components influence the presence of OmpA in the OM of S. gallinarum; (2) by the way of ELISA, OmpA allows to specifically differentiate healthy from diseased birds.

Physical fitness as a mediator between objectively measured physical activity and clustered metabolic syndrome in children and adolescents: The UP&DOWN study.

BACKGROUND AND AIMS: The extent to which physical fitness (PF) attenuates or modifies the association between physical activity (PA) and clustered metabolic syndrome risk factors (CMetSRF) is controversial. We aimed: i) To examine the independent and combined association of objectively measured PA and PF with CMetSRF in children and adolescents; ii) To test the mediating effect of PF in the association of PA with CMetSRF. METHODS AND RESULTS: A total of 226 children and 256 adolescents participated. Levels of PA (light, moderate, vigorous and moderate-to-vigorous [MVPA]) and PF were measured by accelerometry and ALPHA battery, respectively. Cardiorespiratory and muscular fitness values were combined in a global PF variable. A CMetSRF was computed by assessing the following variables: waist circumference, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides and glucose. In children, the highest vigorous PA (ß = -0.193; P = 0.003) and MVPA (ß = -0.149; P = 0.025) were individually associated with lower CMetSRF, but these associations were not independent of global PF. In adolescents, the association of moderate (ß = -0.123; P = 0.046) and MVPA (ß = -0.147; P = 0.024) with CMetSRF was independent of PF. Among unfit adolescents, the higher time they spent in MVPA the lower CMetSRF levels were found (P = 0.032). CONCLUSIONS: The results are suggestive of a full mediation of global PF in the association of MVPA and vigorous PA with CMetSRF in children. In adolescents, the association of higher moderate and MVPA with lower CMetSRF was independent of levels of PF, and mediation analyses suggest only a partial mediation of global PF in the association of MVPA with CMetSRF.

Physical Activity, Sitting Time and Mortality in Older Adults with Diabetes.

The purpose of this study was to examine the independent and combined association of physical activity (PA) and sitting time (ST) with all-cause mortality in older adults with diabetes. A total of 611 individuals representative of the Spanish diabetic population aged ≥ 60 years. Participants were selected in 2000/2001 and were prospectively followed-up through 2011. PA and ST were self-reported at baseline. Study associations were summarized as hazard ratios (HR) and their 95% confidence interval (CI). During a mean follow-up of 8.3 years, 282 deaths occurred. The HR (95% CI) of mortality for very/moderately active individuals compared to those who were inactive/less active was 0.59 (0.45, 0.78). The association between ST and mortality was non-linear (P<0.001 in spline analysis), and mortality was increased only among individuals who reported a ST>8 h/day (HR=1.77, 95% CI 1.25, 2.52). The HR (95% CI) of mortality was 0.50 (0.32, 0.77) in participants who either were very/moderately active or had ST≤8 h/day, and 0.32 (0.20, 0.50) in those with both health behaviors, compared to those with none of these behaviors. In conclusion, among older adults with diabetes, high PA and less ST are independently and jointly associated with lower risk of all-cause mortality.

Combined influence of healthy diet and active lifestyle on cardiovascular disease risk factors in adolescents.

To investigate the combined influence of diet quality and physical activity on cardiovascular disease (CVD) risk factors in adolescents, adolescents (n = 1513; 12.5-17.5 years) participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence study were studied. Dietary intake was registered using a 24-h recall and a diet quality index was calculated. Physical activity was assessed by accelerometry. Lifestyle groups were computed as: healthy diet and active, unhealthy diet but active, healthy diet but inactive, and unhealthy diet and inactive. CVD risk factor measurements included cardiorespiratory fitness, adiposity indicators, blood lipid profile, blood pressure, and insulin resistance. A CVD risk score was computed. The healthy diet and active group had a healthier cardiorespiratory profile, fat mass index (FMI), triglycerides, and high-density lipoprotein cholesterol (HDL-C) levels and total cholesterol (TC)/HDL-C ratio (all P ≤ 0.05). Overall, active adolescents showed higher cardiorespiratory fitness, lower FMI, TC/HDL-C ratio, and homeostasis model assessment index and healthier blood pressure than their inactive peers with either healthy or unhealthy diet (all P ≤ 0.05). Healthy diet and active group had healthier CVD risk score compared with the inactive groups (all P ≤ 0.02). Thus, a combination of healthy diet and active lifestyle is associated with decreased CVD risk in adolescents. Moreover, an active lifestyle may reduce the adverse consequences of an unhealthy diet.

Physical activity attenuates the negative effect of low birth weight on leptin levels in European adolescents; the HELENA study.

We examined whether physical activity (PA) influences the association between birth weight and serum leptin in adolescents. The study comprised a total of 538 adolescents (315 girls), aged 12.5-17.49 years, born at term (≥ 37 weeks of gestation). We measured serum leptin levels and time engaged in moderate-vigorous PA (MVPA) by accelerometry. There was an interaction effect between birth weight and meeting the PA recommendations (60 min/day MVPA) on leptin levels in girls (P = 0.023) but not in boys (P = 0.809). Birth weight was negatively associated with leptin levels in girls not meeting the PA recommendations (i.e. more than 60 min/day of MVPA) (ß = -0.096, P = 0.009), whereas no significant association was observed in those meeting the PA recommendations (ß = -0.061, P = 0.433). In conclusion, meeting the PA recommendations may attenuate the negative effect of low birth weight on serum leptin levels in European female adolescents.

Sedentary behaviour and clustered metabolic risk in adolescents: the HELENA study.

BACKGROUND AND AIMS: Although sedentary behaviours are linked with mortality for cardiovascular reasons, it is not clear whether they are negatively related with cardio-metabolic risk factors. The aim was to examine the association between time engaged in television (TV) viewing or playing with videogames and a clustered cardio-metabolic risk in adolescents. METHODS AND RESULTS: Sedentary behaviours and physical activity were assessed in 769 adolescents (376 boys, aged 12.5-17.5 years) from the HELENA-CSS study. We measured systolic blood pressure, HOMA index, triglycerides, TC/HDL-c, VO2max and the sum of four skinfolds, and a clustered metabolic risk index was computed. A multilevel regression model (by Poisson) was performed to calculate the prevalence ratio of having a clustered metabolic risk. In boys, playing >4 h/day with videogames (weekend) and moderate to vigorous PA (MVPA) was associated with cardio-metabolic risk after adjustment for age, maternal education and MVPA. In contrast, TV viewing was not associated with the presence of cardio-metabolic risk. CONCLUSION: In boys, playing with videogames may impair cardio-metabolic health during the adolescence. Adolescents should be encouraged to increase their participation in physical activity of at least moderate intensity to obtain a more favourable risk factor profile.

Identification of antimicrobial resistance genes in intestinal content from Coyote (Canis latrans).

Antibiotic resistance has become a global public health concern in the last few years. Given the widespread rate of recurrence, increasing attention is being turned toward environmental pathways that potentially contribute to antibiotic resistance genes (ARGs) dissemination outside the clinical realm. In this study, a metagenome analysis of intestinal virus-like particle fraction (VLPs) from a wild coyote ( Canis latrans) revealed for the first time, multiple ARGs, such as B-lactamases and multidrug efflux pumps. Description of ARGs presence in natural environments is critical to understand the emergence of resistant strains.

Associations of physical activity and fitness with adipocytokines in adolescents: the AFINOS Study.

BACKGROUND AND AIMS: Adipocytokines may have a key role in the development of atherosclerosis and type 2 diabetes. The purpose of this study was to examine the independent and joint associations of physical activity (PA), cardiorespiratory fitness (CRF) and muscular fitness (MF) with adiponectin and leptin in adolescents. METHODS AND RESULTS: A sample of 198 adolescents (96 girls), aged 13-17-year, was selected. Participants completed anthropometric measurements (height, weight, and waist circumference) and percentage of body fat (%BF) was estimated by bioelectrical impedance. PA was measured by accelerometer for 7-day. The 20-m shuttle-run test was used to assess CRF and two MF tests (handgrip strength and standing broad jump) were used to create an MF score. A cluster score of health status (0-3 risks) was created. Serum adiponectin and plasma leptin were also determined. Regression analyses controlling for age, sex, pubertal status and waist circumference showed that PA was not significantly associated with adiponectin and vigorous PA showed a significant inverse association with leptin. Both CRF and MF were significantly and inversely associated with adiponectin and leptin. Further analyses revealed that the 'healthy' group (0 risks) had significantly lower adiponectin and leptin than 'medium-healthy' (1 risk) and 'unhealthy' (2-3 risks) status groups. CONCLUSIONS: PA, CRF and MF are inversely and jointly associated with adiponectin and leptin concentrations in adolescents.

[Multidisciplinary unit specialized in the treatment of diabetic foot: Evaluation and results]. / Unidad multidisciplinar especializada en el tratamiento del pie diabético: evaluación y resultados.

INTRODUCTION: In this study the evaluation of the care process of the diabetic foot will be carried out after the implementation of an intra-hospital clinical pathway and a multidisciplinary consultation. OBJECTIVES: Evaluate the influence on factors related to the care, amputations, and rehabilitation of the amputee patient. METHODOLOGY: Retrospective study, in which the comparison of three periods has been made. First (3years): Before the implantation of the pathway. Second (5years): After the implementation of the pathway. Third (10years): After the implementation of the consultation. RESULTS: A specialized consultation in diabetic foot care contributes to a reduction in femoral and minor amputations. The assessment and treatment by rehabilitation of patients undergoing major amputation has been optimized. CONCLUSION: The implantation of the pathway and consultation contributes to the preservation of the lower limb. However, the incidence remains high, suggesting that diabetic foot care remains suboptimal.

Associations of physical activity with muscular fitness in adolescents.

The aim of this study was to examine the associations between objectively assessed physical activity (PA) and muscular fitness (MF) in adolescents, and to determine whether only resistance training exercise is associated with the increase of MF. A sample of 211 Spanish adolescents (105 girls) wore the ActiGraph monitor for 7 days. Participants also completed a fitness evaluation including three MF tests (handgrip strength, a 60-s abdominal test and a standing broad jump), a cardiorespiratory fitness assessment and anthropometric measures. A standardized MF score was computed using the three muscular tests. Adolescent participation in resistance training was self-reported. Linear regression showed that only vigorous PA was significantly (P=0.041) and positively (ß=0.133) associated with MF after adjustment by gender, age, pubertal status, BMI, and cardiorespiratory fitness. Significant differences in MF were found between youth in the lowest and upper tertiles of vigorous PA. Moreover, adolescents who were involved in resistance training had significantly higher MF scores compared with youth in low and medium tertiles of vigorous PA, but no significant differences were found when compared with non-lifters from the highest tertile of vigorous PA (P=0.356). These findings suggest that vigorous activity may be associated with indicators of MF in adolescents.

Participation of interferon type I during canine parvovirus infection.

Canine parvovirus (CPV) is a single-stranded DNA virus that causes severe and fatal gastrointestinal diseases in dogs. CPV has developed several strategies to evade innate immune response mediated by type I interferons (IFN-I) to achieve a successful infection. The aim of this work was to evaluate the capability of CVP-2c to evade the IFN-I mediated response in infected cells. To establish the role of this response, the gene expression of interferon ß (IFNß), IFIT1, IFIT3, MAVS, and STING were estimated in MDCK cells infected with CPV-2c. Viral replication and gene expression was evaluated by quantitative PCR, also, a treatment with IFN-I (interferon omega) was included to confirm the role of IFN-I during CPV infection. The results revealed that CPV-2c infection stimulates the expression of IFNß moderately, in these cells. Due to low IFNß induction, the IFIT1 and IFIT3 expression were also low, and therefore CPV-2c was able to replicate in these cells. However, when the cells were treated with exogenous IFN-I, the IFNß expression was higher, leading to an increased gene expression of IFIT1 and IFIT3, responsible for antiviral control. The overexpression of these proteins reduced the expression of NS1 and VP2 viral genes and hence viral replication. MAVS and STING expression on infected cells showed a mild increase compared to IFNß, suggesting that the viral infection could partially modify its expression. All results obtained in this study showed that during CPV-2c infection in MDCK cells, the IFNß expression was altered since this cytokine is one of the most critical factors for the control and inhibition of viral replication.

Evaluation of intracellular survival of Campylobacter fetus subsp. fetus in bovine endometrial cells by qPCR.

BACKGROUND: Campylobacter fetus subsp. fetus is the causal agent of sporadic abortion and infertility in bovines that produces economic losses in livestock. AIMS: This study evaluates the capability of C. fetus subsp. fetus to invade and survive in bovine endometrial epithelial cells and attempts to describe a pathogenic mechanism of this microorganism. METHODS: Primary culture of bovine endometrial epithelial cells was challenged with C. fetus subsp. fetus. Intracellular bacteria, represented by the number of genomic copies (g.c.) were quantified at 0, 2, 4, 10, and 24 hours post-infection (h.p.i.), by quantitative polymerase chain reaction (qPCR). The presence of intracellular bacteria was evaluated by immunofluorescence and immunohistochemistry. RESULTS: The results showed that only viable C. fetus subsp. fetus could invade endometrial cells. The g.c. number in assays with viable C. fetus subsp. fetus reached an average value of 656 g.c., remained constant until 4 h.p.i., then decreased to 100 g.c, at 24 h.p.i. In assays with non-viable microorganisms, the average value of g.c. was less than 1 g.c. and never changed. The intracellular presence of this bacteria was confirmed at 2 h.p.i. by immunofluorescence and immunohistochemistry. CONCLUSION: The results suggest that only C. fetus subsp. fetus viable can invade bovine endometrial epithelial cells but will not replicate in them, indicating that the endometrial cells do not represent a replication niche for this pathogen. Nonetheless, this invasion capability suggests that this type of cell could be employed by the pathogen to spread to other tissues.

Associations of physical activity, cardiorespiratory fitness and fatness with low-grade inflammation in adolescents: the AFINOS Study.

OBJECTIVE: To examine the independent associations of objectively measured physical activity (PA), cardiorespiratory fitness (CRF) and fatness with low-grade inflammatory markers in adolescents. DESIGN: Cross-sectional study in Spain. SUBJECTS: A sample of 192 adolescents aged 13-17 years. MEASUREMENTS: PA was assessed with an accelerometer for 7 days. A 20-m shuttle-run test was used to assess CRF. Skinfold thicknesses at six sites and WCs were measured. BMI was calculated from measured height and weight. C-reactive protein (CRP), interleukin-6 (IL-6) and complement factors C3 and C4 were assayed. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated from glucose and insulin. Regression analysis adjusted for potential confounders and HOMA-IR was used to determine the associations between PA, CRF and fatness with low-grade inflammatory markers. RESULTS: Total PA, vigorous PA and MVPA were positively associated with CRF (r=0.25-0.48), whereas vigorous PA was negatively associated with skinfolds (r=-0.27). CRF was inversely associated with fatness, (r=-0.30 to -0.48). CRF and fatness were inversely and positively associated with HOMA-IR (r=-0.16 and 0.21, respectively). PA variables were not independently associated with inflammatory markers. CRF and fatness were inversely and positively associated with CRP, C3 and C4, respectively. Only body fat explained a relevant amount of the variance of the model in CRP (4%) and C4 (19%), whereas CRP and body fat jointly explained the variance in C3 (25%). All these observations were independent of HOMA-IR. CONCLUSIONS: These findings support the key role of CRF and fatness on low-grade inflammation, as well as the possible indirect role of habitual PA through CRF and body fat in adolescents.

Role of cardiorespiratory fitness on the association between physical activity and abdominal fat content in adolescents: the HELENA study.

We examined the role of cardiorespiratory fitness (CRF) on the association between physical activity (PA) and abdominal fat content in adolescents. Abdominal fat content was measured by waist circumference, waist-to-height ratio and dual energy X-ray absorptiometry (DXA) at 3 regions (R1, R2, and R3). PA and CRF were assessed by accelerometry and the 20 m-shuttle run test, respectively. Vigorous PA was inversely associated with waist circumference and waist-to-height ratio (ß from -0.149 to -0.197; p<0.05). In both CRF groups (i. e., low and high), vigorous and moderate-to-vigorous PA (also average PA in the low CRF group) were inversely associated with abdominal fat (i. e., R1, R2 and R3; ß from -0.146 to -0.244; p<0.05). This association did not differ according to CRF group (P for interaction >0.05), yet the percentage of variance in abdominal fat content, when assessed by DXA, explained by PA was slightly higher in adolescents with low CRF (3-8%) compared to those with high CRF (2-4%). The findings indicate that there is not a clear interaction effect of CRF in the association between PA and abdominal fat in adolescents, yet slightly stronger association was observed in the low fit group.

Associations of Frailty and Physical Function with a Daily Activities Measured by a Pattern-Recognition Activity Monitor: An Isotemporal Substitution Analysis in the IMPACT65+ Study.

OBJECTIVES: The aims of this study were (i) to examine the independent associations of the time spent in daily activities measured by multi-sensor pattern-recognition with frailty and physical functioning (PF); and (ii) to analyze how relocating time between these daily activities is associated with frailty and PF in a sample of older adults. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: The study sample consists of 436 (287 women) high-functioning community-dwelling older adults, aged 65 to 92 years, who participated in the IMPACT65+ Study. MEASUREMENTS: Frailty was calculated as a continuous measure; based on the five widely recognized Fried's criteria. PF was assessed using the SF-12 questionnaire. The time in daily activities was assessed by the Intelligent Device for Energy expenditure and Activity (IDEEA). Independent associations of daily activities with frailty and PF were examined using linear regression models adjusting for potential confounders. The isotemporal substitution models for estimate the effect of replacing time in one activity with the same amount of time in another activity while holding wake time constant. RESULTS: Time spent lying was directly associated, while time in walk at average and brisk pace was inversely associated with frailty. The independent associations for PF were similar to lying, walk at average pace and walk at brisk pace. Isotemporal substitution analyses revealed a clear beneficial effect of hypothetically replacing 30 min/day of sedentary behaviors or light physical activity by the same amount of moderate-to-vigorous physical activity for frailty and PF. CONCLUSION: This is the first study examining the activity-specific and isotemporal association of daily activities with frailty and PF in older adults. Isotemporal substitution analyses showed that replacing sedentary behaviors (lie, recline, passive sit) by light-intensity activities (active sit, stand and walk at slow pace), as well as light-intensity activities by activities at MVPA such as walk at brisk pace, may produce theoretical improvements in frailty and PF. These findings are important for the development of effective interventions focused on reducing age-related frailty and declines in PF.