The Intersection of Exercise and Health Sciences

1. Introduction

Exercise and health sciences intersect at various levels, from academic research through policy and program development, to practical implementation and evaluation. The power of exercise to prevent and reduce chronic diseases such as diabetes, high blood pressure, cancer and obesity is profound, and as the world’s population ages, the need for exercise and physical activity is growing.

Nevertheless, it has been difficult to harness this potential, particularly in less affluent communities. Exercise medicine is being pursued as an answer to bridging this gap 1.

Health promotion is both a rapidly expanding academic discipline and a source of new directions and professional opportunities. In health promotion research, examination of the determinants of health-enhancing behaviours is being augmented through the initiatives of community, national and international organizations committed to a broader health promotion agenda.

The organizations are taking action that addresses not only knowledge and skills for healthy living, but also the social, economic and environmental conditions conducive to healthy lifestyles. An important research agenda focuses on understanding how these wider influences affect the health of populations.

2. The Physiology of Exercise

The study of the physiology of exercise has garnered great interest in scientific arenas since the early 1950s. Individual tissues and organ systems respond to exercise appropriately and adaptively. Exercise can be a discrete increase or chronic training program on the complexity and volume of movement and will induce a spectrum of responses and adaptations in all physiological systems.

The initial changes in physiology can be rapid (<1 s) and transient during a single bout of exercise or may take years to develop if in response to intervention (i.e., training). Well known physiological adjustments to acute exercise include increased heart rate and ventilation, which can increase by 2–3 times in response to moderate intensity exercise.

Such adjustments act to guarantee that there is an effective and sustained supply of oxygen (and other nutrients) to active tissues and that the by-products of metabolism are swiftly removed 2. Importantly, the extent of each transient adjustment is also dependent on the type, intensity and duration of exercise performed as well as external environmental conditions. There is a complex and intricate network of communication amongst tissues and organs to maintain an effective response to exercise and therefore ensure homeostasis.

Physiological systems can initially respond to exercise in a highly dynamic and time-dependent manner. Responses occur in seconds (e.g., increased heart rate and ventilation) and can take several years to develop fully (e.g., reduction in resting blood pressure or increase in muscle size).

As outlined above, cardiovascular and pulmonary responses to a single bout of low intensity exercise more than double to meet the demands of an increased requirement for blood flow and oxygen delivery to the working muscles. The extent and form of adaptation to training depends on many factors, including the individual’s initial fitness or performance level, the age of the participant and their genetics. Adaptation in one physiological system will also influence the time course and extent of changes in other systems.

2.1. Cardiovascular Adaptations

Cardiovascular Adaptations. A topic of great interest is adaptations resulting from exercise. With the increase in physical activity, the heart, blood vessels and all components of the cardiovascular system respond in time to stimulate physiological adaptations. Understanding the mechanisms controlling these adaptations has a direct application in health.

Indeed, exercise has well-known beneficial effects, most notably on reducing cardiovascular disease 3. Long-term exercise leads to adaptations resulting in reduced cardiovascular workload whereas, with physical inactivity, cardiovascular function deteriorates. Physiological adaptations involve changes in heart structure, function and mass, and increased blood volume and redistribution accompanied with reoganization of peripheral vasculature.

The net effect is a reduced heart rate and increased stroke volume at rest and during exercise. Exercise-induced adaptations promote efficient transport and availability of substrates to active tissues. Alterations in autonomic balance at rest from a higher vagal tone, paralleled with reduced sympathetic activity, contribute to resting differences in cardiovascular function between the fit and the untrained.

Cardiovascular control during dynamic exercise is well understood through experimental models and human studies. Exercise training induces non-classical adaptations characterized by heart rate and stroke volume responses to moderate physical activity being independent of concomitant alterations in these two variables 4.

2.2. Muscular Adaptations: The Intersection of Exercise and Health Sciences

Various bodily systems are involved in maintaining homeostasis during exercise. Exercise is defined as an activity requiring physical or mental exertion that produces bodily or mental fatigue. Because of the physical demands imposed by exercise, the form and function of many bodily systems are either temporarily or permanently altered.

Temporary or short-term adjustments are often referred to as responses and may involve several bodily systems, including the muscular, cardiovascular, respiratory, endocrine, and thermoregulatory systems. These changes boost the performance of bodily systems and improve exercise performance during, immediately following, or soon after the cessation of exercise.

Permanent or long-term changes that occur as a result of repeated or chronic exercise participation are referred to as adaptations 4. Exercise pushes the body to the limit and tests the maximal capabilities of its bodily systems. Some responses and adaptations are obvious, such as increased perspiration and a higher heart rate, but some are not, such as biochemical changes within the cells of the working muscle and various organ systems.

Furthermore, it can be considered whether exercise produces positive effects, negative effects, or both on the form or function of bodily systems. On the one hand, exercise can provide positive effects such as improved health and well-being and reduced risks of disease and premature death. On the other hand, elevated fatigue and stress may negatively affect health 5.

Herein, the various responses and adaptations that occur with acute and chronic exercise participation are presented, beginning with those involved in the circulatory, respiratory, and muscular systems. This article focuses on the responses and adaptations associated with endurance-type exercise, high-intensity resistance-type exercise, and habitual and regular physical activity and exercise participation.

3. The Role of Nutrition in Exercise

Exercise performance and good health are positively influenced by appropriate nutrition. Proper nutrition is critically important for improvement of athletic performance, conditioning, and recovery from fatigue after exercise 6 , as well as avoidance of injury due to physical activity. These points are especially crucial for elite athletes who take part in international competitions.

Athletes need to eat a well-balanced diet, but there are several nutritional factors which are difficult to obtain from a normal diet since athletes generally require more nutrients than the recommended daily allowances. For example, vitamins with antioxidant effects, some amino acids, essential fatty acids, creatine and carnosine are recommended for athletes but cannot be obtained from diet alone as they are not or are only minimally synthesized in the body.

Such nutrients are in high demand by athletes and their increased level becomes essential for improving athletic performance or homeostasis disturbed by exercise. In order to compensate for these issues, many nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields. In addition, some natural food components have been found to exert physiological effects that can be useful for improving athletic performance and/or avoiding the disturbance of homeostasis by strenuous exercise.

Recent advances in molecular biology and biochemistry have provided insights into the mechanisms underlying the physiological effects of food components. Consequently, food components with physiological actions have recently been called “functional foods” and their relative effects on exercise have been scientifically investigated.

Intense exercise induces numerous physiological responses to maintain the metabolic homeostasis of trained skeletal muscle during and after exercise, such as increased energy metabolism, augmented oxygen delivery, and enhanced catecholamine-dependent hormonal and sympathetic nervous functions.

These physiological responses are beneficial for health, although inappropriate levels of exercise or lack of nutritional support can induce fatigue and overtraining 7. Proper nutrition is essential for maintaining metabolic homeostasis during long-term and strenuous exercise training. However, the effects of regular exercise on the physiological functions of nutrients and the homeostatic regulation of their metabolism in the body have not yet been fully elucidated.

Topics such as the structural and functional distinction of enterocytes in the small intestine and the physiological responses of the macro- and micronutrients to exercise are discussed in this article to allow for a better understanding of the unique actions of exercise and training on nutrient metabolism.

3.1. Macronutrients and Micronutrients

Ingested nutrients are broadly classified as macronutrients (e.g., carbohydrates, fats, proteins) and micronutrients (e.g., vitamins and minerals). In view of exercise, there are specific roles for each of the macronutrients. Metabolism of carbohydrates and fats provides the energy needed for exercise, while protein may serve a supplementary role as energy substrate and, more importantly, as a nitrogen source for synthesis of new tissues.

Micronutrients play essential roles in various physiological processes associated with exercise. Vitamins and minerals participate in energy metabolism in skeletal muscle, and many of them have antioxidant properties. In addition, there is evidence that some enzymes related to exercise have vitamin coenzymes 6.

Insufficient micronutrient intake can negatively affect exercise performance, growth, and development. It has been reported that deficiency of one or more micronutrient(s) is common among children in many developing countries, and such deficiency has been associated with impaired physical fitness.

Micronutrient deficiency can lead to stunted growth. In studies with rats, zinc deficiency has been shown to negatively affect running endurance. Despite such evidence, few studies have examined the relationships between the specific micronutrient intake and physical performance in human populations 8.

3.2. Hydration and Performance

Hydration is an integral yet often neglected aspect of exercise 9. Both the exercise itself and the environment in which it is performed play an important role in fluid loss and associated impairment. Etiological factors, exercise-induced responses, and adjustments required to optimize hydration status and consequently exercise performance are the focus of this section.

There are two likely means by which exercise may affect hydration status 10. The first relates to an increased rate of fluid loss due to sweating, which oftentimes exceeds voluntary fluid intake. The second concerns the site of focus of fluid loss and redistribution in the body, with blood plasma and ultimately total body water being diverted to perfuse the skin and transport heat to the periphery for dissipation. These adjustments result in reduced fluid available to perfuse working muscle, which can initiate fatigue and compromise performance.

4. Exercise Prescription and Programming

Understanding the principles of exercise prescription, supports the development of exercise programming that promotes safe and effective participation in exercise for a variety of purposes (e.g. health benefits, injury rehabilitation, sports performance improvement). Exercise prescription involves the selection of individual exercise program components including frequency (number of exercise sessions per week); intensity (difficulty of the exercise task); duration (length of each exercise session); and type (specific exercises or modes of exercise to be performed).

Furthermore, once an exercise program has been implemented, attention needs to be given to how, and when, the exercise program should be progressed (i.e. overload); and how alternatives can be incorporated to avoid monotony and ensure continued involvement in exercise (i.e. variation). Understanding how to tailor exercise programming for different populations (e.g. those with chronic illnesses, older adults) is also required 11.

Many individuals and populations are subject to specific risks and/or have particular physiological adaptations that they would like to achieve through exercise programming. As a result, knowledge and skills regarding which exercise components to include in exercise programming for these groups, how best to enhance or mitigate an exercise program’s effects, and understandings of how exercise programming may be different, and why this is the case, is required.

Exercise is an effective medicine for chronic disease and health promotion practice. Exercise is a powerful intervention, a medicine for modern health problems that might be key players to fight the most urgent healthcare and economic challenges of the society throughout the world. Innovative models for integrating Exercise Sports Medicine in everyday medicine are needed. Near and fast results are achievable by adopting non-pharmacological therapy in patients approaching primary care 12.

Also Read: Muscle Activation Technique Exercises

5. Special Populations in Exercise and Health Sciences

The effects of exercise on health may be considered from a number of different perspectives and apparently endless combinations of variables, including forces impinging on the system, the effects of exercise on many different physical systems with what appear to be completely different physiological functions as well as their mere sum total, and all conceivable subpopulations of the “healthy” and “diseased” 13.

Although the theoretical understanding of race, sex, age, and genetic appropriateness of exercise is essentially non-existent, a large number of studies are published that within the context of obviously inappropriate exercise “prescribe” programs for groups of “others.” Regardless of literally hundreds of economically devastating failures of exercise programs, particularly in the health-related area, this interest appears insatiable 14.

Exercise is known to produce a large spectrum of changes in all systems, and a vast literature attests to its profound effects on many organ systems. There are compelling evidence and examples of the profound effects of exercise on the body, thus predicting disastrous effects on health for apparently all diseases or conditions deleterious to one or many physical systems (and their end-organ effects).

Thus, exercise may affect the damage processes directly (gangrene) or indirectly, e.g., the dysregulation of exercise-induced homeostasis (e.g., more systemic effects of altered secretion levels of hormones, energetic substances, ventilation, etc.) producing down-stream effects on organs and tissues likewise regulated (autonomic nervous system).

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