Frailty is a key concept in geriatric care; yet its definition and assessment remain debated. Since the early 2000s, two main models have emerged: the Fried frailty phenotype, focusing on physical deficits, and the Mitnitski frailty index, which incorporates broader health factors. These divergent approaches have led to over 50 frailty instruments, reflecting the absence of a unified framework. This review explores the content, weighting, and scoring methods of frailty instruments, identifying potential concerns derived from this. This review exposes the overlap of frailty with other constructs including function, disability, morbidity, and sarcopenia. Many instruments lack content validity, and detect highly heterogeneous samples within and between scales, all labeled under the “frail” tag. This poses challenges to interpreting instrument responsiveness. In addition, frailty should not be considered a clinical entity with a unique etiology. This review discusses how the broad nature of frailty conflicts with modern paradigms of individualization and precision. They may be useful in primary care, but lack the specificity for secondary care evaluations. This article also discusses how the predictive validity of frailty should be interpreted with caution. Finally, we summarize our findings and propose a new definition of frailty, highlighting the strengths and weaknesses of the construct. The identified inconsistencies should serve as a guide for refining the concept of frailty, both in research and in its application to geriatric care.

Background and Objectives: Exercise-induced hypoalgesia (EIH) is a topic of interest in the scientific community. This umbrella review aimed to analyze EIH research and compare it with public dissemination on X. Materials and Methods: We selected relevant EIH reviews that included a healthy population or patients with pain and studied exercise interventions. A systematic literature search was carried out in PubMed, Web of Science, SciELO, PEDro, and Google Scholar, employing the Population, Intervention, Comparison, and Outcome strategy. Data were extracted and summarized, and methodological quality was assessed with the Quality Assessment Scale for Systematic Reviews, and risk of bias with the Risk of Bias in Systematic Reviews tool. The Physical Activity Guidelines Advisor Committee was employed for evidence synthesis. Simultaneously, advanced X website searches gathered EIH-related content for analysis. Information from posts on X was qualitatively analyzed and contrasted with evidence in the literature. Results: We included nine systematic reviews and 17 narrative reviews. Systematic reviews presented high methodological quality. However, half had low risk of bias, while the other half presented high risk of bias. The EIH in healthy participants was controversial for some exercise modalities, such as aerobic exercise, and the influence of psychological variables. Modalities, such as isotonic resistance exercise, showed favorable effects on hypoalgesia. However, in patients with musculoskeletal pain, different exercise modalities did not generate EIH. X analysis unveiled a considerable representation of science-related content, although with prevalent misinterpretations of scientific evidence. Conclusions: EIH has been extensively studied, yet the certainty of evidence remains limited. While some exercise modalities demonstrate hypoalgesic effects in asymptomatic individuals, these effects remain unverified in patients with musculoskeletal pain. Moreover, the analysis of social media content highlights frequent misinterpretations of scientific evidence, particularly conflating hypoalgesia with analgesia. This underscores the need for more precise, evidence-based communication on social media platforms.

Introduction: Exercise-induced hypoalgesia is a phenomenon in which exercise bouts induce a reduction in pain sensitivity. Apnea training involves similar characteristics that could potentially induce hypoalgesia. Objectives: The objectives of this study are to explore the effect of apnea training on hypoalgesia; assess the correlation between conditioned pain modulation (CPM) response and apnea-induced hypoalgesia; and examine the association between hypoalgesia with hypoxemia, and heart rate (HR) during apnea. Methods: A randomized controlled trial was conducted comparing a walking protocol employing intermittent apnea compared with normal breathing in healthy volunteers. Hypoalgesia was tested with pressure pain thresholds (PPTs) and CPM. Oxygen saturation (SpO₂) and HR were also tested. Results: Relevant but not significant changes were detected in the thumb (MD = 0.678 kg/cm²), and tibialis (MD = 0.718 kg/cm²) in favor of the apnea group. No significant differences were detected in CPM. The apnea group presented lower SpO₂, but HR values similar to those of the control group during the intervention. Basal CPM and intrasession hypoxemia significantly correlated with the PPT response. However, HR did not correlate with the PPT response. Conclusions: The current results suggest a trend, though not statistically significant, toward an improvement in the PPT in favor of apnea training compared to normal breathing. Nevertheless, subjects who presented greater basal CPM and lower oxygen saturation during the session presented a greater PPT response, suggesting the possibility of mediators of response. Future investigations should clarify this phenomenon.

Cerebral palsy generates an elevated burden on both patients and health-care systems. Cost-effective therapies such as action observation therapy (AOT), have been proposed to enhance motor performance in these patients. Objective: This systematic review with meta-analysis aimed to evaluate the effectiveness of AOT in children and adolescents with CP and describe its prescription parameters. Results: Fourteen studies involving a total of 393 patients with CP were included. Most studies presented some concerns on risk of bias. Meta-analyses compared AOT to placebo (no motor content) observation and found inconclusive results for the following: unilateral upper limb function (g = 0.565; 95% CI −0.174, 1.305), assisting hand function during bimanual activities (g = 0.200; 95% CI −0.742, 1.143), manual function daily activities (g = −0.022; 95% CI −3.134, 3.090), and hand grip strength (MD (kg) = 1.175; 95% CI −0.280, 2.630). Meta-analysis comparing AOT and physical therapy also yielded inconclusive findings for standing (g = 0.363; 95% CI −5.172, 5.898), as well as the combined dimension of walking, standing, and jumping (g = 0.798; 95% CI −8.821, 10.417) within gross motor function. Conclusions: Current evidence is imprecise and does not support definitive conclusions regarding the effectiveness of AOT over placebo observation, or over physical therapy, on functional outcomes including upper limb, hand, and lower limb functioning parameters. Current findings prevent recommending AOT for its employment in clinical practice. Further evidence is required to draw precise conclusions.

To reduce the risk of syncope, trained breath-hold divers (BHDs) use a specialized breathing technique after surfacing called “hook breathing” (HB). It consists of a full inspiration followed by a Valsalva-like maneuver and with subsequent exhalation performed against resistance to generate continuous positive airway pressure during exhalation. This study analyzed the influence of HB on oxygen saturation recovery after a −40 m depth apnea dive in trained BHDs. Thirteen BHDs performed two dives to −40 m at different days, one followed by HB after a dive and the other using usual breathing (UB). To detect signs of lung edema, ultrasound B-line measurements were conducted before, 10 min after the dive, and within 1 h after the dive. To detect oxygen saturation recovery, pulse oximetry was recorded before and immediately after surfacing. Both groups exhibited significant increases in SpO₂ over time (UB: F (2.25, 24.7) = 22.1, p < 0.001, ηg2 = 0.612; HB: F (2.11, 23.2) = 29.0, p < 0.001, ηg2 = 0.688). Significant differences in SpO₂ were observed between the HB and UB groups at 30–45 s post-apnea, with higher SpO₂ values in the HB group; between 1.64 and 5.08% of SpO₂ in favor of the HB intervention. Four participants showed ultrasound B-lines within ten minutes post-dive. After a 40 m apnea dive, the results revealed significant SpO₂ recovery from 30 s to 45 s, with the HB recovering more rapidly. No differences were found at earlier (10–25 s) or later time points (50–60 s).

La fragilidad es uno de los términos más ampliamente discutidos en la literatura científica relacionada con el envejecimiento. Introducido inicialmente a principios de los años 2000, este concepto ha tenido un alto impacto en la comunidad científica. Diferentes grupos de investigación han propuesto diversos modelos de fragilidad, generando a una divergencia conceptual que persiste hasta hoy. Esta divergencia ha resultado en más de 51 instrumentos diferentes para medir la fragilidad, reflejando la complejidad del constructo. Sin embargo, esta diversidad también destaca la falta de consenso sobre la definición de fragilidad. La literatura científica sobre fragilidad se ha centrado predominantemente en definiciones conceptuales y operativas, a menudo descuidando una base teórica coherente. Esta omisión ha llevado a la proliferación de herramientas de evaluación heterogéneas, muchas de las cuales carecen de una adecuada validez de contenido. La ausencia de una definición teórica unificada ha complicado el desarrollo y la validación de estas herramientas, planteando dudas sobre su capacidad para medir con precisión el constructo de fragilidad. Además, la heterogeneidad entre las escalas complica la clasificación e identificación de un perfil homogéneo de pacientes, conllevando posibles inconsistencias en la toma de decisiones clínicas. A pesar de estas limitaciones, las herramientas de evaluación de fragilidad han mostrado asociaciones prospectivas con eventos relacionados con el deterioro de la salud, tales como mortalidad, hospitalización, institucionalización y discapacidad. Futuras investigaciones deberían revisar la capacidad predictiva de estas escalas, enfatizando la relevancia, plausibilidad, validez y fiabilidad del proceso de medición de los items incluidos en las escalas. Para avanzar en nuestra comprensión y estrategias de cuidado para los adultos mayores frágiles, es necesario un nuevo paradigma que enfatice el desarrollo de un marco teórico unificado para la fragilidad. Este marco debería proporcionar una base coherente para la investigación y la práctica clínica, delinear los límites de la fragilidad con otros constructos y guiar el desarrollo de herramientas de evaluación válidas y fiables.