Rodrigo Yáñez-Sepúlveda

Background: Slow gait, weak handgrip strength, and impaired balance are common functional deficits in aging populations that predict adverse health outcomes. Accurate, scalable prediction tools are needed for community-based screening in low-resource settings. Objectives: To benchmark nine machine learning (ML) classifiers for predicting the presence of ≥1 functional deficit using cardiometabolic and anthropometric predictors; to assess calibration, generalization, and clinical utility; to quantify the incremental value of these predictors over age and sex; and to characterize the stability of SHAP-based feature importance. Methods: We analyzed cross-sectional data from the Mexican Health and Aging Study 2012 (MHAS 2012) biomarker sub-study (N = 1961; mean age 61.9 ± 10.5 years; 59.8% women). The outcome was ≥1 of slow gait (<0.8 m/s), weak handgrip (EWGSOP2 sex-specific cut-points), or inability to sustain a 10-s one-leg stance (prevalence 78.7%). Twenty cardiometabolic and anthropometric predictors were used, excluding the functional measures used in outcome construction. Performance was estimated with nested, repeated stratified 10-fold cross-validation (5 × 10 outer folds; inner 5-fold hyperparameter tuning), with all preprocessing confined to training folds. Results: Logistic Regression (LR) achieved the highest discrimination (AUC-ROC 0.751, 95% CI 0.724–0.779), with good calibration (scaled Brier 0.125; calibration slope 0.96) and a small overfit gap (0.011); no classifier outperformed it (ET: AUC 0.745). An age–sex model alone reached AUC 0.734; all other predictors added ΔAUC = +0.018 (95% CI 0.004–0.031), almost entirely through anthropometry, whereas blood biomarkers and blood pressure added no measurable discrimination. SHAP identified age, sex, height, body weight, and BMI × Age as the most influential features; BMI ranked 12th of 20 (bootstrap 95% rank interval 8–20). Conclusions: Cardiometabolic and anthropometric predictors identify middle-aged and older Mexican people with ≥1 functional deficit with moderate accuracy (AUC ≈ 0.75), but most of the signal is carried by age, sex, and simple anthropometry. This reproducible, circularity- and leakage-free framework supports risk stratification rather than diagnosis, and requires external and temporal validation before clinical implementation.

Background: People who train outdoors accumulate higher ultraviolet doses than the general population, yet the instruments used to quantify their photoprotection were developed in high-latitude, English-speaking settings and are typically scored as undifferentiated summative indices whose internal structure is never examined. We aimed to test the internal structure of a Spanish-language sun-exposure and photoprotection questionnaire for physically active Latin American adults and to refine its item pool through a convergent principal component analysis (PCA) and k-means procedure. Methods: This is an instrumental cross-sectional study. Of 297 responses, 257 physically active adults from Costa Rica, Colombia, Mexico and Cuba (71.6% men) provided valid consent. The 14 items, which shared a five-point ordinal metric, were analyzed. Components were retained by parallel analysis (1000 random matrices) and rotated with varimax, and item-to-component assignment was corroborated by k-means clustering of the row-normalized loading vectors, with k fixed by the silhouette index. Sensitivity analyses used polychoric correlations, a common-factor model with oblique rotation and multiple imputation. Reliability used α, ordinal α and ω with 95% confidence intervals (CIs); structural replicability used 500 random split-halves and Tucker congruence coefficients. Results: Sampling adequacy was satisfactory (KMO = 0.71; Bartlett χ² (91) = 1041.1, p < 0.001). Kaiser, scree, and parallel analysis converged on four components (61.5% of variance). k-means selected k = 4 (silhouette = 0.731) and reproduced the PCA assignment exactly (adjusted Rand index = 1.00). Polychoric-based and common-factor solutions reproduced the same structure (Tucker φ ≥ 0.96). One hybrid item was removed (cross-loading 0.568/0.413; silhouette 0.252). The 13-item solution explained 62.5% of variance across four dimensions: pro-photoprotection attitude (α = 0.78, 95% CI 0.73–0.82; ω = 0.78), topical photoprotection and skin surveillance (α = 0.66, 95% CI 0.58–0.72; ω = 0.74), pro-tanning attitude (α = 0.79, 95% CI 0.74–0.83; ω = 0.82) and physical barriers and accessories (α = 0.65, 95% CI 0.56–0.72; ω = 0.71). Median congruence across split-halves ranged from 0.936 to 0.966. Inter-dimension correlations were low (ρ ≤ 0.24), and associations with sex, country, discipline, peer norms and perceived tanning desirability provided initial evidence of criterion validity. Conclusions: The 13-item instrument provides initial evidence of a four-dimensional structure, stable across random split-halves of a pooled multinational sample, that separates attitude from behavior and topical photoprotection from physical barriers. Content validity, confirmation in an independent sample, test–retest reliability and cross-country measurement invariance remain to be established before the instrument can be considered fully validated, and the behavioral dimensions are currently suitable for group-level rather than individual-level use.

Background The source of dietary protein has been linked to cognitive outcomes; however, evidence on the association between isocaloric substitution of protein sources and academic performance in adolescents is limited. This study examined whether replacing animal-based protein with plant-based protein was associated with academic performance in adolescents. Methods This secondary analysis used data from the Eating Healthy and Daily Life Activities (EHDLA) study (n = 769; 55.5% girls; 12–17 years). Dietary intake was assessed using the 45-item food-frequency questionnaire. Academic performance was evaluated using grade point average and specific subjects (i.e., language, maths, and foreign language). Isocaloric substitution models were applied to estimate the association of replacing animal-based with plant-based protein, adjusting for relevant sociodemographic, lifestyle, and anthropometric factors. Robust linear regression was used. Results Replacing animal- with plant-based protein was consistently associated with higher academic performance across all outcomes (all p < 0.001). Substituting 5% of total energy intake was associated with higher grade point average and subject-specific scores. These associations were primarily driven by replacing protein from red/processed meat and certain fish with plant-based sources. Conclusions Isocaloric substitution of animal-based protein with plant-based protein was associated with better academic performance in adolescents, highlighting the potential importance of protein source in dietary patterns related to educational outcomes. Impact Replacing animal-based protein with plant-based protein is associated with better overall and subject-specific academic performance in adolescents. This is the first study to apply an isocaloric substitution approach to examine the association between protein source (plant vs. animal) and academic performance in adolescents. Dietary patterns with a higher contribution of red and processed meat protein (relative to plant protein) were associated with less favorable academic outcomes. These findings highlight the importance of protein quality within dietary patterns and may inform nutrition-based strategies to support academic achievement during adolescence.

Background/Objectives: The 24 h movement behavior (24HMB) framework integrates moderate-to-vigorous physical activity (MVPA), recreational screen time, and sleep. Sociodemographic correlates of simultaneous guideline adherence among European adolescents remain poorly understood. We aimed to estimate 24HMB compliance with each guideline and their combination, identify sociodemographic correlates, and compare accelerometry- and questionnaire-based sleep models. Methods: Cross-sectional data from 444 Spanish adolescents aged 12–17 years in the Eating Healthy and Daily Life Activities (EHDLA) study, conducted in a single semi-rural municipality in the Region of Murcia, were analyzed. MVPA and sleep were measured by ActiGraph wGT3X-BT accelerometry (valid days ranged from 1 to 6); sleep and screen time were also self-reported. Firth’s penalized logistic regression was applied uniformly across binary outcomes to provide a consistent estimation framework, with primary inference based on uncorrected p-values and Benjamini–Hochberg false discovery rate (FDR) correction reported for transparency. Results: In the subsample with complete screen-time data (n = 403; 51.6% female; median age 14 years), compliance was 26.1% (MVPA), 20.3% (screen time), and 36.7%/40.2% (accelerometry-derived sleep period time/questionnaire self-reported time in bed); only 3.5–4.0% met all three guidelines simultaneously. Female sex was associated with lower MVPA (odds ratio, OR = 0.51) and screen time (OR = 0.44) compliance (both FDR-corroborated). Caucasian ethnicity was unexpectedly associated with lower MVPA compliance (OR = 0.29) in the primary complete-case analysis. Older age was associated with lower screen-time compliance (OR = 0.45; both FDR-corroborated). No predictor was significant for accelerometry-derived sleep period time compliance, and questionnaire self-reported time in bed associations did not survive FDR correction. Conclusions: Concurrent adherence to 24HMB guidelines is critically low and socially patterned. Female sex was an FDR-corroborated correlate of lower MVPA and screen-time compliance. The Caucasian ethnicity association with MVPA was specific to the primary complete-case analysis and attenuated under stricter wear-time criteria. Sleep compliance estimates and their sociodemographic correlates differed by assessment method. Future 24HMB surveillance should use validated, standardized, and clearly reported protocols, and cross-study comparisons should account for methodological differences in sleep assessment.

Background/Objectives: Multimorbidity is usually attributed to ageing and health behaviours; social and environmental exposures are rarely quantified in the same model. We estimated how much of the predictive attribution for chronic condition burden, beyond age, falls to social, environmental, and behavioural domains. Methods: We analysed 16,590 respondents aged ≥15 years in the 2023–2024 Chilean National Quality of Life and Health Survey, counting 19 physician-diagnosed chronic conditions. After removing age with design-weighted splines, we modelled the residual count on 151 upstream determinants with 17 supervised algorithms, using survey weights and disjoint sampling units for training and testing. SHapley Additive exPlanations (SHAP) values were aggregated into pre-specified domains, summed, and averaged per variable. Results: Among 12,070 complete cases, weighted multimorbidity prevalence was 40.1%; age alone explained 23.2% of variance. The random forest used for attribution reached test R² = 0.117 (95% confidence interval 0.091–0.138), leaving 88.3% of residual variation unexplained. Predictive attribution was highest for social isolation and support (23.1%), neighbourhood environment (20.9%), and socio-economic position (20.3%), whereas health behaviours received 12.0% and the lowest attribution per variable of any substantive domain. Each of these domains exceeded health behaviours with age modelled directly, with size-normalised or grouped attribution, with reweighting for exclusion, and without mental health diagnoses in the count; among adults aged 15–44 years, however, health behaviours received the largest summed attribution (20.9%). Conclusions: After accounting for age, social isolation, neighbourhood conditions, and material deprivation received greater predictive attribution within the final model than health behaviours did, whereas behaviours led among younger adults, suggesting age-specific pathways into multimorbidity. Attribution is not a causal estimate; most variation remained unexplained, and reverse causation cannot be excluded. Nevertheless, the ordering questions behaviour-centred framings of prevention, and these domains warrant evaluation as prevention targets in longitudinal and intervention studies.

Background: Population ageing requires community-based strategies supporting functional capacity, psychological well-being, and participation among older adults. Objective: To analyze the changes following a community-based motor education program grounded in Chilean folk dances in physical function, psychological well-being, and subjective participation experiences among older adults. Methods: A sequential explanatory mixed-methods design included a single-group pre–post quantitative phase and a qualitative phase. Physical function was assessed using the Short Physical Performance Battery (SPPB), Timed Up and Go (TUG), and single-leg stance tests. Psychological outcomes included the SF-12, life satisfaction, self-efficacy, and perceived social support. The 9-week intervention comprised two 90-min sessions weekly. Sixty-four older adults were recruited: 58 completed pre–post assessments and 17 joined a focus group. Quantitative changes were examined using the Wilcoxon signed-rank test, and qualitative data were analyzed thematically. Results: Mean age was 72.1 years, and 89.7% were women. Significant improvements were observed in SPPB scores (p = 0.003), dominant single-leg stance (p < 0.001), non-dominant single-leg stance (p < 0.001), SF-12 Mental Component (p < 0.001), self-efficacy (p = 0.010), and perceived social support (p < 0.001). No significant changes were found in TUG, the SF-12 Physical Component, or life satisfaction. Qualitative findings emphasized the instructor’s role, reduced embarrassment and fear of ridicule, and stronger social bonds. Conclusions: Participation was associated with improvements in physical and psychological outcomes, supporting culturally adapted folk dance-based motor education as a feasible strategy for active and healthy ageing.

Background and Objectives: Dual-energy X-ray absorptiometry (DXA) provides areal bone mineral density (BMD) and T-scores but does not fully characterize image texture. This study examined the relationship between lumbar T-score and DXA-derived Shannon entropy, a first-order descriptor of image-intensity heterogeneity, and whether entropy differed across densitometric categories in older adults. Materials and Methods: This cross-sectional study included 271 community-dwelling adults aged ≥60 years who underwent lumbar DXA. Regions of interest from L1–L4 were segmented, gray levels were quantized to 8 bits, and entropy was calculated for each evaluable vertebra and averaged at the participant level. Pearson correlation, one-way ANOVA with Tukey post hoc testing, effect sizes, tertile-based discordance analysis, and multiple linear regression were applied. Results: T-score and entropy showed a weak positive correlation (r = 0.203; R² = 0.04; p < 0.001). Entropy differed across densitometric categories (F = 9.04; p < 0.001; η² = 0.063). Values were similar in the normal and osteopenic groups (2.151 ± 0.063 vs. 2.150 ± 0.063), whereas the osteoporosis group showed lower entropy (2.111 ± 0.076; p < 0.001). Low entropy was also observed in 27.5% of participants with normal BMD and 29.0% with osteopenia. After adjustment for age, sex, and BMI, T-score was not independently associated with entropy (p = 0.127). Conclusions: DXA-derived Shannon entropy showed limited correspondence with lumbar T-score and lower values in osteoporosis. It should be interpreted as a descriptor of DXA image-intensity heterogeneity, not as a direct measure of trabecular microarchitecture. Further validation is required before clinical application.

Background/Objectives: University students are at a critical stage for establishing healthy lifestyle habits, yet little is known about their adherence to integrated 24 h movement guidelines that include physical activity, sedentary behavior, and sleep. We examined the proportion of students meeting the Canadian 24 h movement guidelines and associated factors among first-year students at a single Spanish university (UNILIFE-M). Methods: This cross-sectional analysis included 671 first-year students from Universidad Loyola Andalucía (Spain) participating in the UNIversity Students’ LIFEstyle Behaviours and Mental Health (UNILIFE-M) study. Combined guideline adherence used complete cases (n = 646). Behaviors were assessed with the Spanish Physical Activity Scale 2.1 (PAS-2.1S). Adherence required ≥150 min/week of moderate-to-vigorous physical activity, ≤8 h/day of total sedentary time including ≤3 h/day of recreational screen time (both sedentary criteria required), and 7–9 h/night of sleep. Multivariable logistic regression estimated adjusted odds ratios (complete cases on covariates, n = 644). Results: Overall, 137/646 students (21.2%) met all three guidelines, while 54 (8.4%) met none. Male sex was associated with higher odds of adherence (adjusted odds ratio [aOR] = 1.65; 95% confidence interval [95% CI] 1.10 to 2.47), and a lifetime mental health diagnosis was associated with lower odds (aOR = 0.28; 95% CI 0.08 to 0.72). Age > 18 years (aOR = 0.64; 95% CI 0.39 to 1.03) and non-health sciences enrollment (aOR = 0.69; 95% CI 0.46 to 1.03) showed borderline associations that were not robust across sensitivity analyses. Conclusions: In this single-university first-year sample, adherence to the 24 h movement guidelines was relatively low. Associations should be interpreted as cross-sectional correlates, not causal determinants.

The 2024 Copa América brought together the ten CONMEBOL national teams, yet no peer-reviewed study has analysed differences in performance among individual CONMEBOL teams using StatsBomb event data from this tournament. This exploratory study aimed to characterise the offensive and defensive profiles of the CONMEBOL teams and to describe their association with advancement to the quarterfinals, with particular attention to Chile. To ensure a comparable competitive window across teams, the analysis was restricted to the 24 group-stage matches, and penalty-shootout events were excluded. Event data were obtained from StatsBomb Open Data (competition_id = 223; CC BY-SA 4.0), from which expected goals (xG), passes per defensive action (PPDA), pass completion, and passing-network metrics (density and reciprocity) were computed at match level and averaged per team. Given the small sample (n = 10 CONMEBOL teams), between-group comparisons used the Mann–Whitney U test, prioritising effect sizes (r) and bootstrapped 95% confidence intervals over the significance dichotomy. With teams classified by their actual progression (six qualified, four eliminated), xG per match and xG per shot differed significantly between groups (both U = 24, p = 0.010, r = 0.82), whereas pressing (PPDA), pass completion, and passing-network metrics did not. Because with ten teams, the smallest attainable two-sided p is 0.010, findings are interpreted jointly with effect sizes and confidence intervals. Chile recorded the third-lowest xG per match of the bloc (0.54) and was the only team without goals across three matches, with a PPDA (35.86) and a share of shots from inside the box (59.1%) close to the bloc mean. These exploratory, descriptive findings indicate that Chile’s weak offensive output coincided with its elimination; the design does not permit causal inference or the identification of generalisable discriminators.