1. CARDIOVASCULAR BENEFITS
According to Heckman and McKelvie (2008), life-long changes in cardiovascular function are not entirely due to age, but also to physical inactivity.
In recent decades, Spanish morbidity as a consequence of cardiovascular diseases has increased significantly.
The absence of regular physical exercise contributes to the early onset and progression of major cardiovascular diseases. Any increase in physical activity levels has positive effects on cardiovascular health at the same time that a sedentary lifestyle, such as that prevalent in Europe, is associated with a higher risk of cardiovascular diseases (Franco et al., 2005).
Following the consensus article of the American Heart Society (Thompson et al., 2003), we can highlight 3 fundamental roles of regular physical exercise on the cardiovascular system:
1. Prevents all cardiovascular disorders and diseases that have their origin in atherosclerosis.
2. Prevents and controls other risk factors associated with cardiovascular diseases, such as high levels of triglycerides and low-density lipoproteins (LDL cholesterol), low levels of high-density lipoproteins (HDL cholesterol), high blood pressure (HTN), diabetes and obesity.
3. Helps in the treatment and recovery of patients with already established cardiovascular diseases (HTN, heart failure or other heart diseases) or in the recovery phase (myocardial infarction, bypass, etc.).
Johnson, Bonow and Holly (2008) correlated the factors that they considered to have the greatest potential predictor of all-cause mortality (age, total testing time in the Bruce protocol, male gender, body mass index (BMI) and diabetes) with the mortality in a longitudinal multivariate analysis carried out with a sample of more than 2000 people with medium-high coronary risk. The results of this study showed an inversely significant correlation between high BMI or low aerobic capacity and mortality. In turn, the association between low aerobic capacity-mortality was greater than that established between high BMI-mortality, which gives greater predictive power for cardiovascular risk-mortality to the practice of physical exercise.
There are numerous studies that show the beneficial effects of exercise on physical recovery after a cardiovascular accident, with or without subsequent surgery. However, to date the effects on the population over 75 years of age had not been assessed. The study by Audelin, Savage and Ades (2008) has shown that this population group over 75 years of age shows similar benefits in physical functionality as younger heart patients. However, they are more reluctant to initiate physical activity, mainly as a result of the lack of intervention programs for adapted physical exercise in the elderly's own home.
Taking into account the scientific evidence, the inclusion of physical exercise programs at home supervised by professionals and aimed at the physical recovery of the elderly after these surgical interventions would be a necessary strategy on the part of health systems.
1.2. METABOLIC BENEFITS
According to a study carried out by Andreyeva, Michaud and Soest (2007) in 10 developed European countries, Spain has the highest prevalence of obesity in men (20.2%) and women (25.6%) over 50 years of age.
Longitudinal studies carried out with older people have confirmed a decrease in fat-free mass with increasing age (Dey et al., 2009, Fantin et al., 2007, Rossi et al., 2008). Fat mass, on the other hand, tends to increase in older people (Chen et al., 2008, Coin et al., 2008, Kyle et al., 2004, Kyle et al., 2006, Raguso et al., 2006) . These changes in body composition have very noticeable effects on different metabolic diseases, as explained below.
1.2.1. PREVENTION OF METABOLIC SYNDROME
The practice of about 30 minutes of daily physical exercise at moderate intensity, carried out even without changes in diet, has been shown to be effective in controlling and improving metabolic syndrome (Johnson et al., 2007).
1.2.2. REDUCTION OF INSULIN RESISTANCE
Modifications in the percentage of abdominal fat through aerobic exercise can delay insulin resistance caused by aging (Ryan, 2000). The insulin resistance observed in older people can be modified through physical exercise, which would increase insulin sensitivity and improve glycemic metabolism and thus prevent type II diabetes (Ryan, 2000, Samsa, 2007).
1.2.3 PREVENTION OF TYPE II DIABETES
With the aging of the population and increasing obesity rates, the prevalence of type II diabetes is increasing every day. In addition to traditional pharmacological therapy and dietary changes, physical activity plays a fundamental role in the control and management of type II diabetes in older people (Marquess, 2008).
The ability of older men and women to control their blood glucose levels through exercise has been highly demonstrated in scientific studies. Aerobic exercise is presented as the most effective therapy to reduce the risk of suffering from type II diabetes and improve the functional capacity of the elderly (Marquess, 2008). Strength training has also been shown to be effective in increasing energy requirements and insulin availability (Hakkinen et al., 2008).
1.3. PREVENTION OF OSTEOPOROSIS AND THE RISK OF FRACTURES
As age advances, the skeletal system undergoes structural modifications such as bone demineralization, which reduces the width of the vertebrae and deforms the length of the bones of the lower extremities (Sanchez et al., 2007).
In recent years, osteoporosis has become an increasing cause of morbidity and mortality in older women. Scientific evidence shows that osteoporosis is easier to prevent than to treat (Siegrist, 2008). The correct intake of nutrients and physical exercise (especially strength training or focused on micro-impacts) are the two keys to avoiding bone mineral loss. This type of exercise also promotes hormonal activation, improved gait parameters, proprioception, better balance and greater muscle strength even in a very elderly population with a high risk of fractures (Siegrist, 2008). An intervention program of 3 weekly sessions of moderate intensity with this type of exercise has been proven effective in older women (Park, Muto & Park, 2002).
With the aging of the population, a dramatic increase in the incidence of osteoporotic fractures is expected in the coming years. Together with pharmacological (Ytinger, 2003) and nutritional therapies, the practice of physical exercise has an important protective potential against the risk of this type of fractures. In the meta-analysis by Moayyeri, (2008), which analyzes and compares 13 longitudinal studies, it is concluded that through physical activity of moderate to vigorous intensity, the risk of suffering a hip fracture is reduced by 45% (95% CI , 31-56%) for men and 38% (95% CI, 31-44%) for women.
1.4. MUSCLE STRENGTHENING
Numerous studies have shown that handgrip strength reduces with increasing age (Araujo et al, 2008, Forrest, Zmuda and Cauley, 2007, Forrest, Zmuda and Cauley, 2005, Jansen et al., 2008). Strength reductions are greater in the lower limb than in the upper limb (Landers et al., 2001). Low muscle strength, both in the legs and in the handgrip, are strong and independent predictors of mortality in older people (Gale et al., 2007, Meter et al., 2002, Newman et al., 2006, Ruiz et al., 2008).
For Hunter, McCarthy and Bamman, (2004), the physical functionality and quality of life of the elderly are affected by reductions in strength, which in turn leads to a less active lifestyle. A physical exercise program where muscle strength is developed reduces the difficulty of the elderly in performing daily tasks, increases energy expenditure, reducing adipose tissue, and promotes voluntary and spontaneous participation in other expressions of physical activity. However, muscular strength work is favored when aerobic resistance is developed in parallel.
Muscle toning exercise not only promotes strength gains, it also has parallel benefits such as reducing the risk of falls, osteoporosis, diabetes and cardiovascular disease. Its inclusion within physical exercise programs for the elderly is a very attractive option, with additional benefits to those obtained with exclusively pharmacological treatment or with programs focused exclusively on aerobic activities (Phillips, 2007).
1.5. FALL PREVENTION
The damage caused by falls in the elderly is a problem for public health and one of the main causes of chronic pain, loss of physical functionality and, with it, personal independence, a cause of disability and even death. This problem is increasing in recent years, especially in those countries where the population is aging (Kannus et al., 2005).
Lack of balance is an important risk factor for falls and is affected by the progressive loss of sensorimotor function caused by increasing age. Deficits in proprioception, vision, vestibular sense, muscle function, and reaction time contribute to a balance disorder, causing falls to be common in older people (Sturnieks, George, & Lord, 2008). Balance disorders manifest in poor performance on tasks such as standing, bending, climbing stairs, walking, or responding to external perturbations (Sturnieks, George, & Lord, 2008).
Interventions based on balance and strength work have been shown to be effective in reducing the risk of falls (Howe et al., 2007). According to the review of more than 34 articles by Howe et al., (2007), to date, it is still not well defined which elements of the physical intervention are key and in what volume and intensity to achieve the most effective results in the improvement of the elderly's balance and decreased risk of falls. In the total of 2,883 participants included in these 34 studies, significant differences were always observed in those older people who carried out any type of physical intervention programs compared to those who only carried out daily physical activity. Those interventions that involved work on walking, balance, coordination and strength and that were developed with variety in the exercises, presented the best results in the balance tests used (Howe et al., 2007).
1.6. STRENGTHENING THE IMMUNE SYSTEM
Aging is associated with a deregulation of the immune system known as immunosenescence. This entails a series of cellular and molecular alterations that cause inadequate immune adaptation, increasing the incidence of infections and the risk of immune disorders such as autoimmunity, cancer or inflammatory diseases (Newlin, 2007, Senchina and Kohut, 2008).
In recent years, the practice of physical exercise by the elderly has been presented as an easy and effective strategy to combat immunosenescence. In the long term, regular and moderate exercise is associated with numerous benefits that include reducing the risk of contracting infections, increasing the effect of vaccines and improving aspects, both physical and psychosocial, related to daily life that help strengthen the immune system (improved physical functionality, decreased anxiety levels, improved self-esteem, etc.) (Senchina and Kohut, 2008).
Physical exercise is also an effective therapy for those elderly in whom pharmacological therapy has been unfeasible, ineffective or inappropriate. However, the mechanisms by which exercise strengthens the immune system have yet to be deciphered. Today, only based on the evidence, the increase in physical exercise programs aimed at the geriatric population would strengthen their immune system with a tendency to abnormalities and with it the hope and quality of life of the elderly (Newlin 2007, Senchina and Kohut, 2008).
1.7. PREVENTIVE EFFECT AGAINST CERTAIN TYPES OF CANCER AND RECOVERY FROM THE SAME
About 80% of cancers are diagnosed in people over 60 years of age (Courneya and Harvinen, 2007). Longitudinal studies have studied the relationship between regular physical exercise and a lower incidence of certain types of cancers, especially breast, pancreas and colon (Nelson et al., 2008, Slattery and Potter, 2002).
However, in the older population, where the evolution of cancer is slow, the benefits of physical exercise as a therapy to help recover and physically and mentally overcome the disease become more important (Luctkar-Flude et al., 2007, Schmitz , 2005, Visovsky and Dvorak 2005).
Fatigue is the most prevalent symptom associated with cancer symptoms and its treatment. Sometimes, this state of fatigue persists years after treatment. If left untreated, this fatigue can cause reductions in the person's physical functionality and quality of life, interfering with adherence to cancer treatment (Luctkar-Flude et al., 2007). Among all therapies, the practice of physical exercise presents the strongest and most contrasted scientific evidence as an intervention to reduce fatigue levels and, thereby, maintain and improve the physical function and quality of life of the elderly (Luctkar-Flude et al. ., 2007).
The review by Courneya and Harvinen (2007) on the relationship between exercise, age and cancer shows that few studies have assessed the practice of exercise in older cancer survivors. However, for people who have overcome cancer at over 60 years of age, the following conclusions are drawn: a) similar benefits of practicing physical exercise, b) less participation in physical exercise programs, c) they do not present greater difficulty of adherence to physical exercise programs, and d) have different determinants and motivations for practice. Therefore, it would once again be important to include public physical exercise programs oriented and adapted to this population group.
1.8. IMPROVEMENTS IN COGNITIVE FUNCTION
Physical exercise increases and preserves the cognitive function of the elderly (Blain et al., 2000, Brisswalter, Collardeau and René, 2002, Cassilhas et al., 2007, Lautenschlager et al., 2008).
Since the beginning of the 20th century, cognitive function has been studied with contradictory results and without reaching agreements about the recommended type and intensity of exercise (Brisswalter, Collardeau and René, 2002). Currently, some aspects are clear: a) a decrease in the level of attention has been detected after cessation of sports practice, b) an increase in decision-making capacity has been observed after an incremental test as a consequence of the secretion of adrenaline, c) nutritional factors have an important role (correct intake of liquids and carbohydrates), but not a decisive one.
In the review by Angevaren et al., (2008), carried out with those studies carried out in people over 55 years of age where the effects of aerobic physical exercise programs on cardiovascular and cognitive parameters were assessed, it was concluded that as long as there were improvements in around 14% of VO2max, there were parallel improvements in cognitive capacity. The main effects on cognitive function were found in motor function and attention to sound stimuli. These authors concluded that a greater number of studies are necessary to determine which components of aerobic training are related to cognitive function and which type of exercise is most appropriate for its improvement.
Although it has been the most studied, aerobic exercise is not the only one that can cause cognitive improvements in the elderly; strength work could also prevent cognitive deterioration through mechanisms involved in said training, such as increasing of sensitivity to insulin, growth factor 1 or homocysteine (Liu-Ambrose and Donalson, 2009). For this reason, for these same authors, emphasis should be placed on both aerobic and strength exercise, because strength exercise significantly participates in promoting greater physical functionality, with its consequent psychological benefits (Liu-Ambrose and Donalson, 2009).
In recent years, studies have been carried out seeking to determine if physical exercise could prevent the risk of Alzheimer's. In the study by Lautenschlager et al., (2008), a 6-month physical exercise program improved the results obtained on the Alzheimer's Cognitive Function Assessment Scale (ADAS-Cog). Furthermore, these improvements were maintained during an 18-month follow-up period.
Appropriate physical exercise programs aimed at improving cognitive function would be one of the most successful prescriptions in the prevention of cognitive degeneration in adult and elderly populations at risk (Williamson et al., 2009).
