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Exercise training as a preventive tool for age-related disorders: a brief review

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REVIEW Exercise training as a preventive tool for age-related disorders: a brief review Emmanuel Gomes Ciolac Universidade Estadual Paulista - UNESP, Department of Physical Education, School of Sciences, Bauru/SP, Brazil. Aging populations are a worldwide phenomenon affecting both developed and developing countries. This issue raises serious concerns for both governments and the general population. Regular participation in physical activity and/or exercise training programs can minimize the physiological alterations that occur during aging and may contribute to improvements in health and well-being. The present review will discuss the role of regular exercise training in preventing age-related physiological decline and, consequently, associated chronic diseases. Compelling evidence that regular exercise and/or physical activity can improve quality of life, prevent or control the development of chronic disease and increase life expectancy is shown. In summary, regular exercise training and/or physical activity has an important influence on aging and may help to prevent agerelated disorders. KEYWORDS: Aging; Exercise Training; Cardiorespiratory Fitness; Muscular Capacity; Chronic Disease; Prevention. Ciolac EG. Exercise training as a preventive tool for age-related disorders: a brief review. Clinics. 2013;68(5):710-717. Received for publication on December 4, 2012; First review completed on December 29, 2012; Accepted for publication on January 18, 2013 E-mail: ciolac@fc.unesp.br & INTRODUCTION Aging populations are a worldwide phenomenon affecting both developed and developing countries. According to the Brazilian Geographic and Statistics Institute, there were 15 million elderly people in Brazil in the year 2000, which represented 8.6% of the Brazilian population, and this number is expected to increase to 30 million by the year 2030, which will represent 13% of the population (1). This population aging is a serious concern to both governments and the general population because aging changes the profile of a society and necessitates the adaptation of the entire sociopolitical system to a new reality of an increasing demand for geriatric services. This concern is justifiable because there is structural and functional deterioration of almost all physiological systems during aging, even in the absence of discernible disease, resulting in reduced independence and increased incidence and progression of chronic diseases in older adults (2,3). However, regular participation in physical activity and/ or exercise training programs can minimize the physiological alterations that occur during aging and may contribute to improvements in health and well-being (2,3). Numerous studies have shown that exercise training programs improve the muscle strength (4,5), balance (6,7), Copyright ß 2013 CLINICS – This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. No potential conflict of interest was reported. DOI: 10.6061/clinics/2013(05)20 cardiorespiratory fitness (4,8), metabolism (9), glucose tolerance (10), daily living activities (11) and psychological health (12) of elderly people, even those in their 80s or 90s (13,14). Accordingly, national and international agencies have recommended regular physical activity or exercise participation to promote older adult health and disease prevention (2,15,16). The purpose of the present review is to discuss the role of regular exercise training in preventing age-related physiological decline and associated chronic diseases. Exercise, functional decline and chronic disease risk Although aging is a multifactorial process that results from the interaction of the primary aging process with the effects of life style, genetics and chronic diseases, agerelated functional and structural decline occurs in most physiological systems (2). Cardiorespiratory and muscular capacity decline are two examples. In addition, cardiorespiratory capacity and muscular capacity are important determinants of exercise tolerance and functional capacity in older adults. The basal levels of these variables during middle age are predictors of future incapacity, chronic disease and mortality risk (2-5). The loss of muscle strength begins around the age of 30. This loss results from a muscle mass reduction that is associated with alterations in the percentage of intramuscular contractile tissue and a reduced capacity for muscular activation (sarcopenia). This issue has received increasing attention from the medical and scientific community in recent decades. It is well documented that the sarcopenia and loss of muscle strength that accompany aging reduce one’s ability to perform daily living activities and lower exercise tolerance. In addition, these factors have been 710 CLINICS 2013;68(5):710-717 Exercise Training and Aging Ciolac EG implicated in the development of osteopenia and its progression to osteoporosis and are risk factors for knee osteoarthritis (3). Moreover, age-related sarcopenia is also associated with reductions in the basal metabolic rate, fat oxidation, daily living physical activity and energy expenditure, which are associated with visceral and subcutaneous fat accumulation in older adults, resulting in an increased risk for obesity-related locomotor system diseases, as well as cardiovascular disease, dyslipidemia and insulin resistance (2,3,15,17). A schematic representation of the consequences of age-related muscular capacity reduction is shown in Figure 1. Older people are also less active than young people. Even if they have the same daily physical activity volume, the physical activity intensity performed by the elderly is always lower than is the activity performed by younger adults (2,3). This fact has important implications for the aging process and its consequences because the decline of many physiological variables with advancing age and the incidence of innumerous chronic diseases are increased with lower levels of physical activity. For example, the risk of developing and, consequently, dying from several chronic diseases (i.e., cardiovascular disease, type 2 diabetes, obesity and colon cancer), as well as developing musculoskeletal disorders (i.e., osteoporosis, osteoarthritis and sarcopenia) is lower in individuals with a higher physical fitness or greater daily physical activity levels (Figure 2) (2,15,17). It is important to note that currently, no lifestyle intervention (including physical activity) has been shown to affect the primary aging process (the aging process independent of behavioral factors). However, participation in regular physical exercise has been shown to increase life expectancy via its influence on the development of chronic diseases and the restoration, at least in part, of the functional capacity and physiological systems of previously sedentary older adults (2-5,15,17). In this context, avoiding a sedentary life style by performing any type or level of daily exercise is a prudent recommendation to follow as it will reduce the impact of aging on some physiological functions, reduce the risk of developing chronic disease and prevent premature mortality, regardless of age. Aerobic exercise, cardiorespiratory fitness and aging Cardiorespiratory fitness, also known as cardiopulmonary capacity, is an important factor influencing risk for cardiovascular and all-cause mortality in men and women (2,18). For example, it was shown that the risk of mortality for men with a cardiorespiratory fitness greater than or equal to 10 metabolic equivalents (METs) is 3 times lower than in men with a cardiorespiratory fitness of less than or equal to 4 METs, independent of any other risk factor (19). The same has been observed in women with a cardiorespiratory fitness of greater than or equal to 9 METs compared to women who have a cardiorespiratory fitness of less than or equal to 6 METs (20). Moreover, changes in cardiorespiratory fitness throughout life also alter the rate of mortality, even in individuals older than 70 (18). Two studies have analyzed the relative risk for cardiovascular and all-cause mortality in 9777 men aged 20 to 82 years. Two cardiopulmonary exercise tests, separated by a mean interval of 5 years, indicated a lower relative risk for mortality (cardiovascular and all-cause) in Figure 1 - Schematic representation of the consequences of sarcopenia associated with aging and the feedback from its consequences. Observe that most of the influences are bi-directional. Q indicates reduction; q indicates increase. 711 Exercise Training and Aging Ciolac EG CLINICS 2013;68(5):710-717 Figure 2 - Schematic representation of the manner in which exercise and/or physical activity may influence disease incidence and, consequently, mortality during aging. Observe that most influences are bi-directional, indicating that the presence of a risk factor or chronic diseases may alter the exercise/physical activity level, increasing the effects of sedentary behavior on disease and mortality. men with a high cardiorespiratory fitness in both tests than men with low cardiorespiratory fitness in both tests, whereas individuals who changed their cardiorespiratory fitness by the second test from low to high levels and viceversa displayed an intermediate relative risk for mortality (21,22). Similar results were found in a study that performed two cardiopulmonary exercise tests, with a mean interval of 8 years, in 867 older men who were 70 years old (23). A clinically important finding of these three studies was that the older men aged 70 to 82 years who improved their cardiorespiratory fitness from low to high levels reduced their mortality risk by approximately 50%, whereas the men who presented reduced cardiorespiratory fitness from high to low levels also had increased mortality risk by approximately 50% (18). During the primary aging process, there appears to be an inevitable cardiorespiratory fitness decline (after 25 years of age), which can be observed by the parallel decline in the maximum oxygen uptake (VO2MAX) in lifelong trained or untrained individuals. However, a mean difference of approximately 25–30 ml?kg?min21 in the VO2MAX between lifelong aerobically trained and untrained individuals (25 to 65 years of age) is observed, which is maintained as long as the physical training continues (18). In contrast, the secondary cardiorespiratory fitness aging process (caused by diseases and behavioral factors) appears to be reduced or accelerated following the adoption of a physically active or sedentary lifestyle, respectively. For example, young and middle-aged individuals who trained aerobically to maintain high levels of cardiorespiratory fitness or to participate in competitions demonstrated a lower VO2MAX decline compared to their untrained peers during a 20-year follow-up (24). Similar results were observed in a study indicating reduced VO2MAX decline in high– and moderate–intensity trained individuals (aerobic exercise) at a 20-year follow-up, whereas individuals who only participated in low–intensity physical training displayed an accelerated VO2MAX decline in the same period (25). Although a higher mortality rate is the most notable clinical consequence of low cardiorespiratory fitness and sedentary living, the lower cardiorespiratory fitness decline resulting from regular aerobic exercise throughout life has other important clinical implications that include the following: - A delay in the onset of physical frailty associated with low cardiorespiratory fitness – Subjects aged 60 to 70 years who have participated in lifelong aerobic exercise usually have a VO2MAX that is similar to 30year-old sedentary subjects (18). In this context, sedentary subjects may present cardiorespiratory frailty (VO2MAX,18 ml?kg?min21) before the subjects who have participated in lifelong aerobic exercise, which results in earlier physical dependency and fewer years with a good quality of life (26). - The maintenance of the functional capacity at adequate levels to maintain homeostasis in situations of physiological stress – Physiological stress situations that promote a marked increase in oxygen consumption, such as major surgeries, may not be tolerated by older subjects with poor cardiorespiratory fitness and may lead to otherwise avoidable morbidity and mortality (27). - Reduced risk of developing chronic diseases – Regular aerobic exercise/physical activity and high cardiorespiratory fitness are associated with a reduced incidence of several chronic diseases (i.e., cardiovascular diseases, type 2 diabetes and some types of cancer) (2,15), which may increase life expectancy (18). In this context, lifelong participation in aerobic exercise programs is an important strategy not only to increase life expectancy but also to extend the independent life span, 712 CLINICS 2013;68(5):710-717 Exercise Training and Aging Ciolac EG improve the quality of the years lived, reduce the risk of developing chronic diseases and reduce the morbidity and mortality risk in situations that promote marked physiological stress (i.e., major surgeries). Resistance exercise, muscular capacity and aging Muscular strength (the ability of a muscle group to generate force against a resistance) and power (the ability of a muscle group to generate force quickly or work per unit of time) are also important markers of morbidity and mortality. For example, a prospective study followed 8,762 men aged 20 to 80 years for approximately 18.9 years and revealed that there was an inverse association between muscular strength (measured by the supine and leg press exercise 1–repetition maximum [1–RM]) and cancer mortality, independent of any other risk factor, such as age, physical activity level, obesity, smoking, alcohol consumption, clinical conditions prior to follow-up, family history of cardiovascular disease or cardiorespiratory fitness (28). Confirming these data, a meta-analysis including more than 50,000 individuals indicated that the risk of death increased by 67% in subjects within the lower handgrip strength quartile, independent of age, gender and body mass index (29). Sarcopenia, the loss of muscle mass that accompanies aging, is associated with daily energy expenditure and bone mineral density reductions, which may have implications for the incidence of obesity, cardiovascular disease and osteoporosis (3). In addition to the greater susceptibility to disease, the muscular strength and power loss that results from sarcopenia may reduce exercise tolerance and the capacity to perform daily living activities. For example, a large number of subjects aged 55 years and older have difficulty walking 400 m or carrying 11 kg, and 57% of men and 70% of women in their 80s are unable to perform heavy housework (30), although simple activities may be performed (i.e., moderate walking, stair climbing and carrying objects). In addition, a higher heart rate, blood pressure and respiratory rate response, as well as early and general fatigue are observed (31). The reduced exercise tolerance leads older subjects to avoid these activities, resulting in a further reduction in the muscular capacity, which establishes a vicious cycle, thereby exacerbating the aging process. It is important to emphasize that women are more susceptible to the above mentioned consequences of sarcopenia because of their reduced muscle reserve due to differences in the production of anabolic hormones, which causes the muscular capacity threshold necessary to affect the functional capacity to be crossed at least 10 years earlier than in men (31). In contrast to what happens with the age-associated cardiorespiratory fitness reduction, the consequences of sarcopenia (loss of muscle, strength, power and endurance) are generally not mitigated by regular aerobic exercise throughout life. However, muscular stress promoted by regular resistance training has been shown to prevent, or at least to reduce, the loss of muscle mass during aging. A pioneering study analyzing knee extensor muscle function and morphology of young and older adults demonstrated that older runners and swimmers (at least 10 years of regular practice in the modality) had a muscle mass (crosssectional area and fiber type proportion) and strength that was similar to older sedentary adults and lower than in young sedentary adults, whereas subjects practicing resistance training for at least 10 years had levels that were similar to those of sedentary men who were 40 to 50 years younger (32). It has also been shown that the capacity to improve muscular strength and mass are preserved in previously sedentary older subjects. Elderly individuals practicing resistance training have shown muscle strength improvements of up to 150% (4,5,26). Improvements of 10% to 30% in the muscle fiber cross-sectional area have also been observed in older subjects following 3 to 6 months of resistance training (3,26). In addition to the preserved capacity to improve muscle mass and strength, older adults appear to be able to similarly adapt to a resistance training workload, even better than do young adults (4,5,33). In studies by our group, sedentary young and older men or women performing the same resistance training program displayed similar increases in muscle strength and resistance training workload progression (4,5), whereas aerobically trained older men (senior runners) displayed greater increases in resistance training workload progression than did sedentary young men (Figure 3) (5). The preserved capacity to improve muscle strength and to adapt to a resistance training workload has been demonstrated even in older subjects enfocar la importancia de la producción mediática de los niños en su descubrimiento del mundo, sobre todo utilizando el periódico escolar y la imprenta. Asimismo las asociaciones de profesores trabajaron en esta línea e incluso la enseñanza católica se comprometió desde los años sesenta realizando trabajos originales en el marco de la corriente del Lenguaje Total. Páginas 43-48 45 Comunicar, 28, 2007 En el ámbito de los medios, también desde el principio del siglo XX hay ciertas corrientes de conexión. Pero es a lo largo de los años sesenta cuando se constituyeron asociaciones de periodistas apasionados por sus funciones de mediadores, que fomentaron la importancia ciudadana de los medios como algo cercano a los jóvenes, a los profesores y a las familias. Así se crearon la APIJ (Asociación de Prensa Información para la Juventud), la ARPEJ (Asociación Regional de Prensa y Enseñanza para la Juventud), el CIPE (Comité Interprofesional para la Prensa en la Escuela) o la APE (Asociación de Prensa y Enseñanza), todas ellas para la prensa escrita Estas asociaciones fueron precedidas por movimientos surgidos en mayo de 1968, como el CREPAC que, utilizando películas realizadas por periodistas conocidos, aclaraba temas que habían sido manipulados por una televisión demasiado próxima al poder político y realizaba encuentros con grupos de telespectadores. cipio del siglo XX, y nos han legado textos fundadores muy preciados, importantes trabajos de campo y muchos logros educativos y pedagógicos. La educación en medios ha tenido carácter de oficialidad de múltiples maneras, aunque nunca como una enseñanza global. Así la campaña «Operación Joven Telespectador Activo» (JTA), lanzada al final de los años setenta y financiada de manera interministerial para hacer reflexionar sobre las prácticas televisuales de los jóvenes, la creación del CLEMI (Centro de Educación y Medios de Comunicación) en el seno del Ministerio de Educación Nacional en 1983, la creación de la optativa «Cine-audiovisual» en los bachilleratos de humanidades de los institutos en 1984 (primer bachillerato en 1989) y múltiples referencias a la educación de la imagen, de la prensa, de Internet. La forma más visible y rápida de evaluar el lugar de la educación en medios es valorar el lugar que se le ha reservado en los libros de texto del sistema educa- 2. Construir la educación en los medios sin nombrarla El lugar que ocupa la edu- La denominación «educación en medios», que debería cación en los medios es muy ambiguo, aunque las cosas están cambiando recientemente. entenderse como un concepto integrador que reagrupase todos los medios presentes y futuros, es a menudo percibida En principio, en Francia, co- por los «tradicionalistas de la cultura» como una tendencia mo en muchos otros países, la educación en los medios no es hacia la masificación y la pérdida de la calidad. una disciplina escolar a tiempo completo, sino que se ha ido conformado progresivamente a través de experiencias y reflexiones teóricas que han tivo en Francia. Una inmersión sistemática nos permi- permitido implantar interesantes actividades de carác- te constatar que los textos oficiales acogen numerosos ter puntual. Se ha ganado poco a poco el reconoci- ejemplos, citas, sin delimitarla con precisión. miento de la institución educativa y la comunidad es- colar. Podemos decir que ha conquistado un «lugar», 3. ¿Por qué la escuela ha necesitado casi un siglo en el ámbito de la enseñanza transversal entre las dis- para oficilializar lo que cotidianamente se hacía en ciplinas existentes. ella? Sin embargo, la escuela no está sola en esta aspi- Primero, porque las prácticas de educación en me- ración, porque el trabajo en medios es valorado igual- dios han existido antes de ser nombradas así. Recor- mente por el Ministerio de Cultura (campañas de foto- demos que no fue hasta 1973 cuando aparece este grafía, la llamada «Operación Escuelas», presencia de término y que su definición se debe a los expertos del colegios e institutos en el cine ), así como el Minis- Consejo Internacional del Cine y de la Televisión, que terio de la Juventud y Deportes que ha emprendido en el seno de la UNESCO, definen de esta forma: numerosas iniciativas. «Por educación en medios conviene entender el estu- Así, esta presencia de la educación en los medios dio, la enseñanza, el aprendizaje de los medios moder- no ha sido oficial. ¡La educación de los medios no apa- nos de comunicación y de expresión que forman parte rece oficialmente como tal en los textos de la escuela de un dominio específico y autónomo de conocimien- francesa hasta 2006! tos en la teoría y la práctica pedagógicas, a diferencia Este hecho no nos puede dejar de sorprender ya de su utilización como auxiliar para la enseñanza y el que las experiencias se han multiplicado desde el prin- aprendizaje en otros dominios de conocimientos tales Páginas 43-48 46 Comunicar, 28, 2007 como los de matemáticas, ciencias y geografía». A pe- mente en todas las asignaturas. Incluso los nuevos cu- sar de que esta definición ha servido para otorgarle un rrículos de materias científicas en 2006 para los alum- reconocimiento real, los debates sobre lo que abarca y nos de 11 a 18 años hacen referencia a la necesidad no, no están totalmente extinguidos. de trabajar sobre la información científica y técnica y En segundo lugar, porque si bien a la escuela fran- el uso de las imágenes que nacen de ella. cesa le gusta la innovación, después duda mucho en Desde junio de 2006, aparece oficialmente el tér- reflejar y sancionar estas prácticas innovadoras en sus mino «educación en medios» al publicar el Ministerio textos oficiales. Nos encontramos con una tradición de Educación los nuevos contenidos mínimos y las sólidamente fundada sobre una transmisión de conoci- competencias que deben adquirir los jóvenes al salir mientos muy estructurados, organizados en disciplinas del sistema educativo. escolares que se dedican la mayor parte a transmitir Este documento pretende averiguar cuáles son los conocimientos teóricos. La pedagogía es a menudo se- conocimientos y las competencias indispensables que cundaria, aunque los profesores disfrutan de una ver- deben dominar para terminar con éxito su escolaridad, dadera libertad pedagógica en sus clases. El trabajo seguir su formación y construir su futuro personal y crítico sobre los medios que estaba aún en elaboración profesional. Siete competencias diferentes han sido te- necesitaba este empuje para hacerse oficial. nidas en cuenta y en cada una de ellas, el trabajo con Aunque el trabajo de educación en los medios no los medios es reconocido frecuentemente. Para citar esté reconocido como disciplina, no está ausente de un ejemplo, la competencia sobre el dominio de la len- gua francesa definen las capa- cidades para expresarse oral- La metodología elaborada en el marco de la educación en mente que pueden adquirirse con la utilización de la radio e, medios parece incluso permitir la inclinación de la sociedad incluso, se propone fomentar de la información hacia una sociedad del conocimiento, como defiende la UNESCO. En Francia, se necesitaría unir el interés por la lectura a través de la lectura de la prensa. La educación en los medios las fuerzas dispersas en función de los soportes mediáticos y orientarse más hacia la educación en medios que al dominio adquiere pleno derecho y entidad en la sección sexta titulada «competencias sociales y cívi- técnico de los aparatos. cas» que indica que «los alum- nos deberán ser capaces de juz- gar y tendrán espíritu crítico, lo que supone ser educados en los las programaciones oficiales, ya que, a lo largo de un medios y tener conciencia de su lugar y de su influencia estudio de los textos, los documentalistas del CLEMI en la sociedad». han podido señalar más de una centena de referencias a la educación de los medios en el seno de disciplinas 4. Un entorno positivo como el francés, la historia, la geografía, las lenguas, Si nos atenemos a las cifras, el panorama de la las artes plásticas : trabajos sobre las portadas de educación en medios es muy positivo. 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