Physical exercise and health

Physical exercise and health
especially our cardiovascular system, is the result of an evolutionary process aimed at making it more resistant to the environment. The current knowledge of the physiology of different species shows that human beings developed their systems evolutionary, compared to reptiles, amphibians and even other mammals, to become much more resistant to lack of food or drink and prolonged physical activity1. However, the progressive increase in life expectancy and the significant changes in our lifestyle and diet over the past six decades have exposed the human species to threats for which it is neither prepared nor biologically adapted. Most of the conditions of this new life scenario are directly related to the development of risk factors and cardiovascular diseases, which have become the leading cause of death in the last century; This has led to the search for treatments that, in some cases, modify even some adaptive mechanisms that the human body developed evolutionary. On the contrary, the regular practice of physical exercise is an established recommendation for the treatment of the main modifiable cardiovascular risk factors, such as diabetes mellifluous, arterial hypertension and epidemically, as well as overweight, but it is one of the least implemented by both doctors and patients.

EPIDEMIOLOGY
The sedentary lifestyle is defined as one that does not meet the recommendations of a moderate intensity physical activity practice for a minimum of 30 min 5 days per week or of high intensity for a minimum of 20 min 3 days per week9. In recent decades there has been a slight decrease in the prevalence of sedentary people; Although different studies have shown somewhat divergent data, it could be considered that 20-40% of the population is sedentary, 10, 11, 12, 13. On the other hand, knowing the energy requirements is important to adjust the nutritional recommendations in an individualized way, but the measurement of energy consumption is difficult in daily practice; therefore, the objectives against sedentary lifestyle should be aimed at increasing physical activity until reaching, or even exceeding, the general recommendations.

Most people dedicate a very relevant portion of the day to their work, and this is usually an argument for not doing physical exercise. However, physical activity performed during work also provides protection against cardiovascular disease. In the middle of the last century it was already identified that the physical activity carried out during working hours determined the difference in the incidence of cardiovascular complications among the workers of the same company: the bus drivers had more acute myocardial infarction than the reviewers who climbed hundreds Sometimes the stairs of London double-decker bused, differences that were also observed among post office clerks and postmen or deliverymen. This difference in physical activity during work offered an important protection against cardiovascular diseases; However, with the changes that have occurred in recent decades, there has been a clear reduction in physical activity during working hours, 10, 11. This fact can be explained by the progressive automation and sophistication of the production of the factories, which has reduced the physical effort carried out by workers who have been relegated to tasks of surveillance of the machinery. From the point of view of cardiovascular prevention, this fact has been crucial, and currently the workers who do not perform office work have gone on to present a more unfavorable cardiovascular risk profile. In a large register of the workforce in Spain, it was observed that manual workers suffered more obesity, high blood pressure and metabolic syndrome than office workers and manageress.

SPORTS PROTECTIVE MECHANISMS
Physical exercise is defined as any bodily movement produced by the loco motor system by contraction and relaxation of the musculature that involves energy consumption. Said movement supposes an increase of the demand of oxygen and nutrients by the muscles in general. Muscular adaptation to exercise is the basis of training and it is known that it is mediated both by the adaptation and development of muscle fibers and by changes in their metabolism, mainly in mitochondria. It is a complex and not completely known process involving heterogeneous pathways such as calcimine receptors, parthenogenesis, genetic over expression, mitochondrial metabolic reprogramming and smoking synthesis.
It is a complex and not completely known process involving heterogeneous pathways such as calcimine receptors, parthenogenesis, genetic over expression, mitochondrial metabolic reprogramming and myokin synthesis from the muscle tissue itself. However, its effect is crucial not only in the muscles, since it has been related to the delay of aging due to stabilization of mitochondrial agglomerate.

The functional capacity and the amount of exercise correlate inversely with the development of cardiovascular risk factor's and, in addition, with long-term mortality from cardiovascular and neoplastic displeasure (). This fact is as striking as what was demonstrated by a comparative study of the long-term prognosis of a large sample of participants in the Tour de France compared to the general population, who observed that athletes had a 41% lower mortality, both by neoplasms (44%) as for cardiovascular diseases (33%) 21.
Effects on the cardiovascular system
Cardiovascular adaptations with training are mainly: a) increase in stroke volume; b) increase in the volume of cardiac cavities and parietal thicknesses; c) decreased heart rate at both rest and sub maximal intensity exercise, and d) improved myocardial perfusion.

Cardiac output increases during physical activity, because the two factors on which it depends increase: heart rate and stroke volume. During intense exercise, the stroke volume can double; although in untrained persons this increase is very little evident, in athletes in good shape it is considerable and continues to rise until reaching its maximum at levels of effort comprised between 50 and 60% of the maximum oxygen consumption. From this level of effort, the stroke volume stabilizes to very high exercise intensities.

Another functional adaptation related to the constant practice of physical exercise is that it causes an increase in the cardiac chambers, both in their volumes and in the parietal thicknesses; the first are the most important determinants for the increase in cardiac output. In athletes who perform aerobic endurance exercises, the first predominates, although after many years of training at high intensity, parietal hypertrophy also appears, while in those dedicated to the practice of isometric efforts and strength sports, very small changes occur in both the beat volume as in the parietal thickness.

Physical exercise, in turn, produces a reduction in heart rate at rest, and also becomes evident during physical exercise in trained individuals, when the preparation is performed at sub maximal intensities, a phenomenon directly related to the increase in beat volume. Among the mechanisms of bradycardia, it is first of all the regulation of the autonomic nervous system, by an increase in vagal tone, but also a decrease in the heart's own intrinsic frequency, variation in the sensitivity of the preceptors, the increase in volume systolic and, of course, the genetic conditions of each individual.

Another typical and beneficial adaptation that physical exercise causes is the improvement of the coronary circulation, which is due, among others, to the phenomenon of particularization, which consists of an increase in capillary density (number of capillaries per fibril) and is proportional to the Thickening of the myocardial wall, with the consequent increase in coronary blood flow. In addition, resistance training also increases the caliber of pericardial coronary vessel in order to maintain adequate perfusion for the greater myocardial mass. Apart from these changes related to parthenogenesis, functional adaptations also occur, such as greater relaxation of the small coronary arteries and / or production of nitric oxide from the coronary endothelial.

Athlete's heart
Regular training induces adaptive changes in the heart aimed at improving the performance of the cardiovascular system during exercise. This adaptation can lead to an increase in cardiac mass of up to 20% .However, by clearly identifying the possibility of heart disease specifically linked to exercise, such as arrhythmia or sudden death, there has been increased interest in this entity with three clear objectives: a) to know how cardiac adaptation to exercise can improve sports ability; b) to guide training to optimize cardiac adaptation, and c) to differentiate the normal cardiac adaptation from the pathological one. This last aspect is the one that has generated the greatest interest inside and outside the field of cardiology due to its important preventive and even legal implications.
As previously stated, the regular practice of physical exercise induces a morphological and electrical cardiac remodeling that supposes a physiological adaptation to the cardiac overload promoted with exercise, but, like so many other biological variables, it seems to have a "J-curve" distribution. », Since it has been identified that excessive remodeling, especially structural remodeling, is closely linked to the main serious cardiac diseases related to sports. Therefore, the great challenge for the professionals involved in the follow-up of athletes is to identify the moment in which cardiac adaptation to exercise begins to pose a risk. But, in addition, it is important to emphasize that poor cardiac adaptation to exercise only occurs in a small percentage of athlete. Therefore, the challenge for sports cardiology is to identify previously healthy people who suffer maladjustment heart disease during exercise and are at increased risk of a serious cardiac complication.

Cardiac Rehabilitation
Cardiac rehabilitation includes a series of coordinated and multidisciplinary interventions that aim to improve the functional capacity, both physical and psychological, of patients with a cardiovascular condition; In addition, it stabilizes and delays the evolution of its underlying disease, thereby improving its prognosis. Therefore, the main objectives of cardiac rehabilitation are to prevent the incapacity produced by cardiovascular diseases and new complications of atherosclerosis. In addition, it has been observed that patients achieve higher rates of smoking cessation and improve their eating habit's. Patients who are candidates for initiating cardiac rehabilitation programs are those who have suffered a myocardial infarction or have angina or heart failure.

The first units of cardiac rehabilitation were founded in the late sixties, and their results coincide in the effectiveness to achieve the goal of reducing mortality by around 25% . In cardiac rehabilitation there have been great advances in recent years, and has gone from continuous work at low programmed intensities and controlled to the development of complex training programs that include, in addition to aerobic exercise, workloads at intervals (combinations of high and low intensity) and training strengthen. This is due not only to the fact that these types of exercise have been shown to be useful in improving cardiac function, but also because the physiology of these patients is better known every day, and this has revealed that functional limitation that they suffer is not only a problem of the heart, but is also conditioned by many peripheral factor's. In addition, work to improve the functional capacity of a patient with heart disease should never end, so these programs should serve as a basis and support to acquire the habit of regularly doing physical exercise.

Effects outside the cardiovascular system
In spite of the physiological adaptations produced, it is very important to remember that the most important positive effects of physical activity do not occur only in the cardiovascular area, but also other beneficial psychological, sociological and certain disease effects are obtained. Therefore, activity and physical exercise are of great importance for the treatment and prevention of cardiovascular disease risk factors, but for practically all of the population.

One of the most direct effects of physical exercise is to decrease insulin resistance, since muscle tissue increases its capacity for glucose uptake. Regular physical activity decreases the risk of diabetes mellifluous type 238 and, once established, helps control blood glucose levels and even, in some cases, reduces the need for anti diabetic drugs and / or insulin. Regular physical exercise, even at moderate intensities, decreases insulin resistance of peripheral tissues, improves glucose uptake by skeletal muscle and glycogen metabolism, decreases postprandial hyperglycemia and helps reduce body weight, everything which translates into beneficial effects for the control of glucose and the decrease of hemoglobin in an intermediate term. In the classic Diabetes Prevention Program study, patients included in the treatment arm based on the modification of their diet and lifestyle had the lowest incidence of diabetes mellifluous at follow-up.
Interestingly, the main difference between the patients in this treatment arm and the placebo or misinform arms was that the former performed up to 4 times more weekly hours of physical exercise.

It is necessary to take into account that high dynamic component exercise programs prevent high blood pressure and lower blood pressure in both nonsensitive adults and those with high blood pressure. This effect is more marked in hypertensive patients, with an average reduction of 6-7 mm Hg in systolic and diastolic pressures, compared to 3 mm Hg in nonsensitive patienter. Regular training reduces sympathetic activity at rest, but also decreases the plasma concentration of chatelaines (at rest and in sub maximal exercise) and produces modifications in renal homeostasis (decrease in renal vascular resistance), all of which contribute to the reduction of blood pressure

It is essential to remember the fundamental role of physical training, especially if combined with hypo caloric diet, in the prevention and treatment of overweight and obesity. The continuous practice of physical activity helps to reduce body weight, preferably the fat percentage, and modifies many of the metabolic alterations underlying the development of cardiovascular risk factors. At the same time, a reduction in inflammatory markers such as C-reactive protein has been shown in people who are overweight or obese.

The improvement of the lipid profile is another of the great benefits of the usual performance of physical exercise, since it is one of the few effective strategies to increase the serum concentration of high density protein cholesterol, 42. Therefore, exercise Continuous physical has a broad beneficial effect on the body, the cardiovascular system and risk factors.

Finally, it has also been shown that physical exercise has important effects on the central nervous system. An interesting observation is that its effects occur in all stages of life, since they improve the learning capacity of adolescents, but it also has beneficial effects in adult diseases, such as depression, Parkinson's and Alzheimer.

For all these reasons, the frequent and constant practice of physical exercise should be recommended to the entire population in order to ensure the improvement of the quality of life of the individual and also their physical, psychological and social health. Likewise, it must be taken into account that in some cases some supervision of physical exercise must be carried out, both for the intensity and for the individual characteristics of each person.