Relação entre força de preensão manual, funcionalidade e fragilidade física em pessoas idosas: revisão integrativa / Relación entre fuerza de agarre manual, funcionalidad y fragilidad física en ancianos: una revisión integradora / Relationship between handgrip strength, functionality, and physical frailty in elderly people: an integrative review

RESUMO Objetivo: analisar as publicações científicas sobre a relação entre força de preensão manual, funcionalidade e fragilidade física em pessoas idosas. Método: revisão integrativa realizada nas bases de dados PubMed, CINAHL, Web of Science e Portal BVS, no período amostral de janeiro de 2010 a novembro de 2021. Empregou-se o fluxograma do Preferred Reporting Items for Systematic Reviews and Meta-analyses para apresentar a seleção dos estudos, e o nível de evidência foi avaliado a partir do Oxford Centre for Evidence-Based Medicine e as referências gerenciadas no EndNote Web. Resultados: a busca inicial resultou em 211 estudos após a aplicação dos critérios de elegibilidade, sendo que 7 estudos constituíram a revisão integrativa. A força de preensão manual se revelou um importante indicador de força muscular e crucial para a funcionalidade das pessoas idosas. Quando associada a determinadas ocorrências clínicas, a força de preensão manual colabora para a redução da funcionalidade e dependência na realização das atividades de vida diária em idosos, com maior prejuízo entre aqueles com 75 anos ou mais, de forma mais significativa entre as mulheres. Conclusão: a relação entre a força de preensão reduzida e a diminuição da funcionalidade determina a condição de fragilidade física em pessoas idosas. Isso reforça a importância do investimento dos profissionais de Enfermagem em intervenções que viabilizem a manutenção da força muscular e da funcionalidade e a reversão da fragilidade física nesse segmento populacional.

RESUMEN Objetivo: analizar las publicaciones científicas sobre la relación entre la fuerza de agarre manual, la funcionalidad y la fragilidad física en ancianos. Método: revisión integradora realizada en las bases de datos PubMed, CINAHL, Web of Science y Portal BVS, desde enero de 2010 hasta noviembre de 2021. Se utilizó el diagrama de flujo de los Preferred Reporting Items for Systematic Reviews and Meta-analyses para presentar la selección de estudios, se evaluó el nivel de evidencia del Oxford Centre for Evidence-Based Medicine y se gestionaron las referencias en EndNote Web. Resultados: la búsqueda inicial dio lugar a 211 estudios, tras aplicar los criterios de elegibilidad, siete estudios constituyeron la revisión integradora. La fuerza de agarre de la mano resultó ser un indicador importante de la fuerza muscular y crucial para la funcionalidad de los ancianos. Cuando se asocia a determinadas circunstancias clínicas, la fuerza de la presión manual contribuye a la reducción de la funcionalidad y la dependencia en la realización de las actividades de la vida diaria en los individuos, con mayor prejuicio entre los que tienen 75 años o más y de forma más significativa entre las mujeres. Conclusión: la relación entre la fuerza de agarre reducida y la disminución de la funcionalidad determina la condición de fragilidad física en los ancianos. Esto refuerza la importancia de que los profesionales de Enfermería inviertan en intervenciones que permitan mantener la fuerza y la funcionalidad muscular y revertir la fragilidad física en este segmento de la población.

ABSTRACT Objective: to analyze scientific publications on the relationship between handgrip strength, functionality, and physical frailty in the elderly. Method: integrative review carried out in PubMed, CINAHL, Web of Science and VHL Portal databases, in the sample period from January 2010 to November 2021. The Preferred Reporting Items for Systematic Reviews and Meta-analyses flowchart was used to present the selection of studies, and the level of evidence was assessed from the Oxford Center for Evidence-Based Medicine and references managed in EndNote Web. Results: the initial search resulted in 211 studies after applying the eligibility criteria, with 7 studies constituting the integrative review. Handgrip strength proved to be an important indicator of muscle strength and crucial for the functionality of elderly people. When associated with certain clinical occurrences, handgrip strength contributes to the reduction of functionality and dependence in carrying out activities of daily living in the elderly, with greater impairment among those aged 75 years or older, more significantly among women. Conclusion: the relationship between reduced grip strength and decreased functionality determines the condition of physical frailty in elderly people. This reinforces the importance of investment by Nursing professionals in interventions that enable the maintenance of muscle strength and functionality and the reversal of physical frailty in this population segment.

Lower albumin levels are associated with frailty measures, trace elements, and an inflammation marker in a cross-sectional study in Tanushimaru

BACKGROUND@#There is little data on the association between the lower nutrition represented by serum albumin levels and related factors in a general population. The present study aimed to determine whether the albumin level positioned as some kind of biomarker with frailty measures, trace elements, and an inflammation marker.@*METHODS@#In 2018, we performed an epidemiological survey in 1368 subjects who resided in Tanushimaru, Japan, in which we examined the blood chemistry including albumin, trace elements, hormone levels, and carotid ultrasonography. Albumin levels were categorized into 4 groups (G1 [3.2-3.9 mg/dL], G2 [4.0-4.3 mg/dL], G3 [4.4-4.6 mg/dL], and G4 [4.7-5.3 mg/dL]). The participants underwent measurements of handgrip strength and were tested by asking to walk 5 m. Their cognitive functions were evaluated by the mini-mental state examination (MMSE).@*RESULTS@#Multiple stepwise regression analysis demonstrated that albumin levels were significantly and independently associated with age (inversely), systolic blood pressures, estimated glomerular filtration rate (eGFR), MMSE score, frailty measures (handgrip strength), an inflammation marker (high-sensitivity C-reactive protein), hormones (growth hormone (inversely) and insulin-like growth factor-1), and trace elements (calcium, magnesium, iron, and zinc), with a linear trend.@*CONCLUSIONS@#Lower albumin levels, even in the normal range, were found to be related factors of frailty measures, trace elements, and an inflammation marker in a general population.

Oxidative stress, telomere length, and frailty in an old age population

Abstract Background A global aging population requires focusing on the risk factors for unhealthy aging, preventive medicine, and chronic disease management. The identification of adverse health outcomes in older adults has been addressed by the characterization of frailty as a biological syndrome. In this field, oxidative stress and telomere length have been suggested as biomarkers of aging Objective The objective of the study was to study the association of oxidative stress, telomere length, and frailty in an old age population Methods We conducted a cross-sectional study based on 2015 data from 202 members of a cohort of older adults (n = 202; F/M gender ratio: 133/69; mean age: 69.89 ± 7.39 years). Reactive oxygen species were measured by dichlorofluorescein diacetate and lipid peroxidation by malondialdehyde. Telomere length was determined using quantitative polymerase chain reaction with SYBR Green Master Mix Results Statistical analysis showed an association between telomere length and frailty but no association between oxidative stress and telomere length or frailty Conclusions Telomere length could eventually be used as a marker to differentiate between healthy and unhealthy aging as expressed by frailty phenotype; oxidative stress seemed merely a biological process of aging.

Frailty-associated factors among Brazilian community-dwelling elderly people: longitudinal study

ABSTRACT BACKGROUND: Frailty among elderly people is associated with negative health outcomes. Through gaining better understanding of this syndrome over different time periods, healthcare actions that take predictive factors into consideration may be facilitated. OBJECTIVE: To identify factors associated with frailty syndrome among community-dwelling elderly people over a two-year follow-up. DESIGN AND SETTING: Longitudinal study on elderly people living in Uberaba (MG), Brazil. Methods: Elderly individuals were selected through multiple-stage conglomerate sampling from a national database. Participants were interviewed and evaluated in 2014 and again in 2016. Predictors were considered at the baseline, and frailty categories (frail, pre-frail or non-frail) at the follow-up. Frailty was identified based on the Fried criteria. Associations with socioeconomic factors, health status and physical performance were investigated using multinomial logistic regression. RESULTS: 353 individuals participated in both assessments. The final model showed that age over 80 years was predictive of both pre-frailty and frailty (odds ratio, OR 4.92; 95% confidence interval, CI: 1.57-15.38; OR 8.64; 95% CI: 2.05-36.35, respectively), while dependency regarding basic activities of daily living (OR 3.66; 95% CI: 1.22-11.02) and poor lower-limb physical performance (OR 7.87; 95% CI: 1.97-31.39) predicted frailty. A one-unit increased score for advanced activities of daily living decreased the frailty rate by 15% (OR 0.85; 95% CI: 0.74-0.99). CONCLUSION: Age over 80 years was predictive of pre-frailty and frailty, while dependency in basic activities of daily living and poor physical performance predicted frailty. A one-unit increased score for advanced activities of daily living decreased the frailty rate by 15%.

Frailty syndrome in older adults from the community and long-term care institutions: an exploratory analysis / Síndrome da fragilidade em idosos da comunidade e de instituições de longa permanência: uma análise exploratória

OBJECTIVES: To investigate the association between Frailty syndrome, lipid profile, anthropometric variables, and the functional capacity of older adults; and to analyze an explanatory model of variables with higher predictive capacity for Frailty syndrome. METHODS: This cross-sectional study included 36 and 86 older adults residing in long-term care facilities and in their households, respectively. Anamnesis was followed by evaluation of anthropometric data, risk of falls, functional tests, and biochemical tests. Frailty syndrome was determined according to the criteria suggested by Fried et al. RESULTS: Geriatric patients classified as frail were older; had higher medication consumption; and presented lower performance in handgrip strength, sit-to-stand, and gait speed tests as compared to pre- and non-frail older adults. CONCLUSION: Gait speed and sit-to-stand tests were significant predictors of Frailty syndrome. Specifically, a good performance in these tests represents a protection factor against Frailty syndrome. Furthermore, gait speed performance was explained by age, handgrip strength performance, and frailty status, while sit-to-stand performance was explained by risk of falls and muscular strength.

OBJETIVOS: Investigar a associação entre síndrome da fragilidade, perfil lipídico, variáveis antropométricas e capacidade funcional de idosos; e analisar um modelo explicativo de variáveis com maior capacidade preditiva para síndrome da fragilidade. MÉTODOS: Este estudo transversal incluiu 36 e 86 idosos residentes em instituições de longa permanência e em suas residências, respectivamente. A anamnese foi seguida pela avaliação dos dados antropométricos, risco de quedas, testes funcionais e testes bioquímicos. A síndrome da fragilidade foi determinada de acordo com os critérios sugeridos por Fried et al. RESULTADOS: Os idosos classificados como frágeis eram mais idosos; tiveram maior consumo de medicação; e apresentaram menor desempenho nos testes de força de preensão palmar, levantar e sentar e velocidade da marcha quando comparados aos idosos pré e não frágeis. CONCLUSÕES: Os testes velocidade da marcha e levantar e sentar foram preditores significativos de síndrome da fragilidade. Especificamente, um bom desempenho nesses testes representa um fator de proteção contra a síndrome da fragilidade. Além disso, o desempenho da velocidade da marcha foi explicado pela idade, desempenho da força de preensão palmar e estado de fragilidade, enquanto o desempenho do levantar e sentar foi explicado pelo risco de quedas e força muscular.

Fragilidade em idosos no município de São Paulo: prevalência e fatores associados / Frailty in older adults in the city of São Paulo: Prevalence and associated factors

RESUMO: Introdução: Fragilidade é uma síndrome evitável e reversível caracterizada pelo declínio cumulativo dos sistemas fisiológicos, causando maior vulnerabilidade às condições adversas. Objetivos: Descrever a prevalência de fragilidade entre os idosos, analisar os fatores associados e a evolução da síndrome. Método: Estudo longitudinal que utilizou a base de dados do Estudo Saúde, Bem-Estar e Envelhecimento (SABE), nos anos de 2006 e 2010. A síndrome de fragilidade foi identificada por cinco componentes: perda de peso; fadiga; redução de força, de atividade física e de velocidade de caminhada. Os idosos foram classificados como "pré-frágeis" (1-2 componentes) e "frágeis" (3 ou +). Utilizou-se regressão multinomial múltipla hierárquica para análise dos fatores associados. Resultados: Do total de idosos (n = 1.399), 8,5% eram frágeis tendo como fatores associados idade, comprometimento funcional, declínio cognitivo, hospitalização e multimorbidade. Em quatro anos, tornaram-se frágeis 3,3% dos idosos não frágeis e 14,7% dos pré-frágeis. Conclusão: A identificação da prevalência e dos fatores associados à fragilidade pode ajudar a implementar intervenções adequadas precocemente, de modo a garantir melhorias na qualidade de vida dos idosos.

ABSTRACT: Introduction: Frailty is a preventable and reversible syndrome characterized by a cumulative decline of physiological systems, causing greater vulnerability to adverse conditions. Objective: To describe the prevalence of frailty among older adults and analyze its associated factors and progression. Method: This is a longitudinal study that used the Health, Well-being, and Aging Study (Saúde, Bem-Estar e Envelhecimento - SABE) database of 2006 and 2010. Five components identified the frailty syndrome: weight loss; fatigue; decreased strength, low physical activity, and reduced walking speed. Older adults were classified as "pre-frail" (1-2 components) and "frail" (3 or more). We used a hierarchical multiple multinomial regression to analyze associated factors. Results: Out of the total number of older adults (n = 1,399), 8.5% were frail, and the associated factors were age, functional impairment, cognitive decline, hospitalization, and multimorbidity. In four years, 3.3% of non-frail and 14.7% of pre-frail older adults became frail. Conclusion: Identifying the prevalence of frailty and its associated factors can help to implement adequate interventions early to improve the quality of life of older adults.

Factors associated with frailty in older adults: a longitudinal study / Fatores associados à fragilidade em idosos: estudo longitudinal

ABSTRACT OBJECTIVE To determine the demographic and health factors related to the frailty syndrome in older adults. METHODS This is a longitudinal quantitative study carried out with 262 older adults aged 65 years and older, of both sexes, living at home. Data collection was carried out in Period 1 between October 2007 and February 2008, and in Period 2 between July and December 2013. For data collection, we used the sociodemographic profile instrument, the Edmonton Frail Scale, the Mini-Mental State Examination, the number of falls in the last 12 months, the number of self-reported diseases and used drugs, the Functional Independence Measure, and the Lawton and Brody Scale. We used descriptive statistics for data analysis, in the comparison of the means between periods, the nonparametric Wilcoxon test, and the method of Generalized Estimating Equations, which is considered an extension of the Generalized Linear Models with p ≤ 0.05. RESULTS Of the 515 participants, 262 completed the follow-up, with a predominance of females, older individuals, and those who had no partner; there was an increase in frail older adults. In the Generalized Estimating Equations analysis, frailty score was related to sociodemographic (increase in age, no partner, and low education level) and health variables (more diseases, drugs, falls, and decrease in functional capacity). There was an association between the variables of age (older), marital status (no partner), and loss of functional capacity. CONCLUSIONS Frailty syndrome was associated with increasing age, having no partner, and decreased functional capacity over time, and investments are required to prevent this syndrome and promote quality in aging.

RESUMO OBJETIVO Determinar os fatores demográficos e de saúde relacionados com a síndrome da fragilidade em idosos. MÉTODOS Estudo quantitativo longitudinal, realizado com 262 idosos acima de 65 anos de ambos os sexos, que vivem no domicílio. A coleta das informações no Tempo 1 foi realizada entre outubro de 2007 e fevereiro de 2008, e no Tempo 2 entre julho e dezembro de 2013. Para a coleta das informações, foi utilizado o instrumento do perfil sociodemográfico, a Edmonton Frail Scale, o Mini Exame do Estado Mental, o número de quedas nos últimos 12 meses, o número de doenças autorreferidas e medicamentos, a Medida de Independência Funcional e a Escala de Lawton e Brody. A estatística descritiva foi utilizada para a análise de dados, na comparação das médias entre ambos os tempos, o Teste não paramétrico de Wilcoxon e o método de Equações de Estimação Generalizadas, considerado uma extensão dos Modelos Lineares Generalizados com p ≤ 0,05. RESULTADOS Dos 515 participantes, 262 completaram o seguimento, com predomínio do sexo feminino, idosos mais velhos, sem companheiro(a); houve aumento de idosos frágeis. Na análise Equações de Estimação Generalizadas, o escore da fragilidade teve relação com as variáveis sociodemográficas (aumento da idade, estado civil sem companheiro(a) e baixa escolaridade), e de saúde (maior número de doenças, medicamentos, queda e diminuição da capacidade funcional). Verificou-se associação com as variáveis idade (mais velhos), o estado conjugal (não ter companheiro), e perda da capacidade funcional. CONCLUSÕES A síndrome da fragilidade esteve associada ao aumento da idade, estar sem companheiro(a) e diminuição da capacidade funcional ao longo do tempo, sendo necessários investimentos para a prevenção dessa síndrome e promoção de um envelhecimento de qualidade.

Physical frailty and fitness of older driver / Fragilidad física en ancianos y aptitud para dirigir un vehículo

Abstract Aim: to analyze the association between physical frailty and the results of fitness capacity exams for driving vehicles among elder Brazilians. Methods: this is a cross sectional study, performed in traffic medicine clinics of the city of Curitiba (Brazil). The data was collected through the physical frailty tests, the use of a structured questionnaire, and searches on the records of the Brazilian National Register of Qualified Drivers.To analyze the information, the authors used descriptive statistics and non-parametrical tests. Results: One hundred seventy two elderly people, of whom 56.4% pre-fragile and 43.6% non-fragile. 25.0% were considered fit for driving, 68.6% were considered fit, but with some restrictions, and 6.4% were placed as temporarily unfit for driving. There was no association between frailty condition and the final results for driving fitness (p= 0.8934). Physical frailty was significantly associated to the restrictions observed for those who were fit under restrictions (p= 0.0313), according to the weekly amount of kilometers traveled (p= 0.0222), and to car accidents occurred after the age of 60 (p= 0.0165). Conclusion: Physical frailty was significantly associated to the restrictions related to driving, reason to which makes important to manage frailty over this group of drivers. However, no association observed between physical frailty and the final result for driving vehicles.

Resumen Objetivo: Analizar la asociación entre la fragilidad física y los resultados del examen de aptitud para conducir un vehículo, en ancianos brasileños. Métodos: Estudio cuantitativo transversal, realizado en las clínicas de medicina de tráfico de Curitiba/PR (Brasil). Se recopilaron datos mediante pruebas de evaluación de la fragilidad física, aplicación de cuestionario estructurado y búsqueda en el formulario de Registro Nacional de Conductores Habilitados. Se utilizaron pruebas descriptivas y no paramétricas. Resultados: Ciento setenta y dos individuos de edad avanzada participaron en el estudio, de los cuales 56.4% fueron ancianos pre-frágiles y 43.6% no frágiles. Para conducir estaban aptos el 25.0% de los ancianos, 68.6% aptos con restricción y 6.4% no aptos temporarios. No hubo asociación entre la condición de fragilidad y los resultados finales para aptitud vehicular (p= 0.8934). La fragilidad física estuvo significativamente asociada a las restricciones impuestas para aptos con restricciones (p= 0.0313), al número de kilómetros conducidos semanalmente (p= 0.0222) y a los accidentes ocurridos después de los 60 años (p= 0.0165). Conclusiones: La fragilidad física estuvo significativamente asociada a las restricciones impuestas para aptos con restricciones, razón por la cual, es importante la gestión de la fragilidad en este grupo de conductores. Sin embargo no se observó una asociación entre la fragilidad física y el resultado final para conducir un vehículo.

Qualidade de vida e síndrome da fragilidade em idosos / Quality of life and frailty syndrome in the elderly

A síndrome da fragilidade surge no cenário do crescente número de idosos na população mundial, acometendo esses indivíduos, agravando suas condições de vida e saúde. Considerando que essa síndrome é multifatorial e multidimensional, que atinge idosos que vivem em diversas realidades, esta pesquisa buscou verificar a percepção de qualidade de vida de idosos residentes na comunidade e em Instituições de Longa Permanência, diante de sua condição de fragilidade. Por meio de um estudo epidemiológico descritivo do tipo transversal, com abordagem quantitativa, foram entrevistados 136 idosos, sendo metade deles residentes da comunidade, e a outra metade, residentes de Instituições de Longa Permanência para Idosos - ILPIs. Para o cálculo adotou-se nível de significância de 5% e poder do teste de 80% para se demonstrar uma correlação mínima de 0,35 são necessários 68 sujeitos para cada tipo de residência. Utilizou-se a Escala de Fragilidade de Edmonton (EFS) para identificar a presença de fragilidade e os questionários Whoqol Bref e Old para mensurar a percepção de qualidade de vida. Foi observado uma diferença notória entre o número de idosos frágeis moradores da comunidade (16,2%) e os residentes de ILPIs (51,5%), com significância estatística (p<0,001). A percepção de qualidade de vida também é melhor entre os domiciliados nos dois questionários, com destaque para os domínios relações sociais, meio ambiente e morte e morrer. O domínio autonomia apresentou a pior percepção, sobretudo entre os idosos institucionalizados. Entre os idosos frágeis estão as piores percepções de qualidade de vida na maioria dos domínios, para ambos os questionários. Os resultados mostram que a condição de fragilidade piora a qualidade de vida dos idosos e não são apenas os domínios relacionados à saúde física e mental que prejudicam a qualidade de vida. Fatores relacionados à intimidade, autonomia e relações sociais também se mostram associados à piora da percepção de qualidade de vida para as duas realidades, sobretudo para os institucionalizados. Assim, identifica-se que distinguir idosos frágeis de não frágeis é fundamental para a assertiva intervenção de saúde física ou mental.(AU)

The fragility syndrome appears in the scenario of the growing number of elderly people in the world population, affecting these individuals, aggravating their living conditions and health. Considering that this syndrome is multifactorial and multidimensional, reaching elderly people living in different realities, this research sought to verify the perception of quality of life of elderly residents in the community and in Long Stay Institutions, given their fragility condition. A descriptive epidemiological study of the transversal type, with a quantitative approach, interviewed 136 elderly people, half of whom were residents of the community; and the other half, residents of Long Stay Institutions for the Elderly (ILPIs). For the calculation, a significance level of 5% and 80% test power were used to demonstrate a minimum correlation of 0.35, 68 subjects were required for each type of residence. The Fragility Scale of Edmonton (EFS) was used to identify the presence of fragility and the Whoqol Bref and Old questionnaires to measure the perception of quality of life. A noticeable difference was observed between the number of fragile elderly in the community (16.2%) and the residents of ILPIs (51.5%), with statistical significance (p <0.001). The perception of quality of life is also better among those domiciled in the two questionnaires, especially in the areas of "social relations", "environment" and "death and dying". The domain "autonomy" presented the worst perception, especially among the institutionalized elderly. Among the fragile elderly are the worst perceptions of quality of life in most domains, for both questionnaires. The results show that the fragility condition worsens the quality of life of the elderly and it is not only the domains related to the physical and mental health that impairs the quality of life. Factors related to intimacy, autonomy and social relations are also associated with the deterioration of the perception of quality of life for both realities, especially for the institutionalized ones. Thus, it is identified that distinguishing fragile elderly from non-fragile individuals is fundamental for assertive physical or mental health intervention.(AU)

Biomecánica de las fracturas por stress / Biomechanical features of stress fractures

Se define como estrés (stress) tanto la fuerza que una carga externa ejerce sobre un cuerpo sólido como la fuerza reactiva que acompaña a la primera (Ley de Newton), por unidad de área imaginaria transversal a su dirección. Las cargas internas reactivas inducen deformaciones proporcionales del cuerpo. La resistencia del cuerpo a deformarse se llama rigidez. La deformación puede resquebrajar el cuerpo y, eventualmente, producir una fractura por confluencia de trazos. La resistencia del cuerpo a separarse en fragmentos por esa causa se llama tenacidad. La resistencia del cuerpo a la fractura es proporcional al stress que puede soportar sin separarse en fragmentos por deformación (no hay fractura sin deformación y sin stress previo). El stress máximo que un cuerpo puede soportar sin fracturarse resulta de una combinación de ambas propiedades: rigidez y tenacidad, cada una con distintos determinantes biológicos. Una o varias deformaciones del cuerpo pueden provocarle resquebrajaduras sin fracturarlo. La acumulación de resquebrajaduras determina la "fatiga" del material constitutivo del cuerpo, que reduce su rigidez, tenacidad y resistencia a la fractura para la próxima ocasión ("fragilidad por fatiga"). En el caso de los huesos, en general, los términos stress y fatiga tienen las connotaciones amplias referidas, respecto de todas las fracturas posibles. La fatiga predispone a fracturas a cargas bajas, que se denominan (correctamente) "fracturas por fatiga" y también (incorrectamente) "fracturas por stress", para distinguirlas de las que ocurren corrientemente, sin resquebrajaduras previas al trauma, que se denominan (incorrectamente) "fracturas por fragilidad, o por insuficiencia". En realidad, todas las fracturas se producen por stress y por fragilidad o insuficiencia (en conjunto); pero la distinción grosera entre fracturas "por fatiga, o por stress", por un lado, y "por fragilidad" o "por insuficiencia", por otro, aceptando las amplias connotaciones referidas antes, tiene valor en la práctica clínica. Este artículo intenta explicar esas particularidades biomecánicas y describir las distintas condiciones que predisponen a las fracturas "por fatiga o por stress" en la clínica, distinguiéndolas de las fracturas "por fragilidad o por insuficiencia" (manteniendo estas denominaciones) y detallando las características de interés directo para su diagnóstico y tratamiento. (AU)

The term "stress" expresses the force exerted by an external load on a solid body and the accompanying, opposed force (Newton's Law), expressed per unit of an imaginary area perpendicular to the loading direction. The internal loads generated this way deform (strain) proportionally the body's structure. The resistance of the body to strain expresses its stiffness. Critical strain magnitudes may induce micro-fractures (microdamage), the confluence of which may fracture the body. The body's resistance to separation into fragments determines its toughness. Hence, the body's resistance to fracture is proportional to the stress the body can support (or give back) while it is not fractured by the loadinduced strain (no stress, no strain -> no fracture). Therefore, the maximal stress the body can stand prior to fracture is determined by a combination of both, its stiffness and its toughness; and each of those properties is differently determined biologically. One or more deformations of the body may induce some microdamage but not a fracture. Microdamage accumulation determines the fatigue of the material constitutive of the body and reduces body's toughness, leading to a "fatigue-induced fragility". In case of bones, in general, both stress and fatigue have the referred, wide connotations, regarding any kind of fractures. In particular, bone fatigue predisposes to low-stress fractures, which are named (correctly) "fatigue fractures" and also misnamed "stress fractures", to distinguish them from the current fractures that occur without any excess of microdamage, that are named (wrongly) "fragility" or "insufficiency" fractures. In fact, all fractures result from all stress and fragility or insufficiency as a whole; however, the gross distinction between "fatigue or stress fractures", on one side, and "fragility or insufficiency fractures", on the other, accepting the wide connotations of the corresponding terminology, is relevant to clinical practice. This article aims to explain the above biomechanical features and describe the different instances that predispose to "fatigue or stress fractures" in clinical practice, as a different entity from "insufficiency or fragility fractures" (maintaining this nomenclature), and describe their relevant features to their diagnosis and therapy. (AU)