What does being healthy mean? For some it is the simple avoidance of disease, but it is also more than that. Health has been defined as a human condition possessing social, psychological, and physical dimensions. Positive health is associated with a capacity to enjoy life and withstand challenges. Negative health is associated with morbidity (incidence of disease) and premature mortality (34). The highest quality of life includes mental alertness and curios- ity, positive emotional feelings, meaningful relationships with others, awareness and involvement in societal striv- ings, recognition of the broader forces of life, and the physi- cal capacity to accomplish personal goals with vigor. These aspects of positive health are interrelated; a high level of accomplishment in one area enhances the other areas, and, conversely, a low level of function in any area restricts the accomplishments possible in other areas. Although physi- cal activity plays a major role in the physical dimension, it also contributes to learning, relationships, and a sense of human limitations within the broader perspective. An optimal quality of life requires individuals to strive, grow, and develop, though they may never achieve the highest level of positive health. What are the risks or challenges to our health and well being?
Factors Affecting Health and Disease
The five leading causes of death in the United States in 2007 were cardiovascular diseases (CVD) (31.0%), can- cers (23.2%), chronic lower-respiratory diseases (5.3%), accidents (5.1%), and Alzheimer’s disease (3.1%) (35). Although infectious diseases are not in the top five, we are warned each year to make sure that our flu shots and other vaccinations are up to date in order to prevent a problem from occurring. Most of the top five leading causes of death are chronic degenerative diseases whose onset can be delayed or prevented. Risk factors associated with chronic diseases can be divided into three categories (see figure 1.2) (38).
Inherited or Biological Factors
These factors include the following:
• Age—older adults have more chronic diseases than younger people.
• Gender—men develop CVD at an earlier age than women, but women experience more strokes than men (6).
• Race—African Americans develop about 30% more heart disease than non-Hispanic white Americans (36).
• Susceptibility to disease—several diseases have a genetic component that increases the potential for having them.
People can achieve health and fitness goals up to their genetic potential, but it is not possible to establish the relative portion of a person’s health that is determined by heredity. Although heredity influences physical activity, fitness, and health (27), most people can lead healthy or unhealthy lives regardless of their genetic makeup. Thus, genetic background neither dooms a person to poor health nor guarantees good health.
We are born not only with fixed genetic potentials but also into environments that affect our development. An environment includes physical factors (e.g., climate, water, altitude, pollution), socioeconomic factors (e.g., income, housing, education, workplace characteristics), and family (e.g., parental values, divorce, extended family, friends) that affect our opportunities to be active, level of fitness, and health status. Some elements, such as our nutrition or the air we breathe and water we drink, affect us directly. Other elements, such as the values and behaviors of people we admire, influence our lifestyles indirectly. We can control certain aspects of our environments; for instance, we choose many of the mental and physical activities we undertake. However, our past and current environments affect us in various ways. For example, some children have inadequate food because of their environment and cannot think about other aspects of health until that basic need is fulfilled.
We have discussed the leading causes of death, but what are the actual causes of death? The list of behaviors in figure 1.2 helps answer that question. That smoking is at the top of the list should be no surprise given its connection to both lung cancer and CVD. In fact, it is the number one actual cause of death, accounting for 18% of all deaths (23, 24). The existence of smoking-cessation programs and laws to restrict areas in which one can smoke speak to the serious- ness with which our society takes that risk to health. The number two actual cause of death is poor diet and physical inactivity (15.2%), with alcohol consumption coming in at number three (3.5%). The emphasis on healthy eating at work and school and the creation of new parks and bike trails to enhance opportunities to be physically active are examples of responses to these actual causes of death. Figure 1.3 shows that healthy eating and physical activity affect a large number of factors that influence health and disease. Clearly, your ability to help establish and reinforce the behaviors of healthy eating and physical activity in the people you serve during your professional life will do much to improve their health and well-being. (See chapter 5 for information on nutrition and chapter 23 for steps to help clients change their behaviors.) This chapter introduces the role that physical activity and fitness play in a healthy lifestyle. However, before we begin, we need to review a few terms that will be important in the following sections of this chapter.
We will introduce you to key terms as we move through the chapters of the text; however, we need to begin here in order to facilitate your understanding of the various parts of an exercise prescription or physical activity recom- mendation (9, 33, 34).
• Physical activity is defined as any bodily move- ment produced by skeletal muscle that results in energy expenditure (e.g., it is associated with occu- pation, leisure time, household chores, and sport).
• Exercise is a subset of physical activity that is planned, structured, and repetitive and has the objective of improving or maintaining physical fitness.
• Physical fitness refers to a set of health- or skill- related attributes that can be measured by specific tests.
• Health-related fitness refers to muscular strength and endurance, CRF, flexibility, and body composi- tion (relative leanness).
• Skill-related (performance-related) fitness refers to agility, balance, coordination, speed, power, and reaction time that are linked to games, sport, dance, and so on.
• Exercise intensity describes the rate of work (i.e., how much energy is being expended per minute) and the degree of effort required to carry out the task. The rate of work is the absolute intensity and can be expressed in a number of ways: kilocalories (kcal) of energy produced per min (kcal ∙ min−1), milliliters of oxygen consumed per kilogram of body weight per minute (ml ∙ kg−1 ∙ min−1), or metabolic equivalents (METs), where one MET is taken as resting metabolic rate and is equal to 3.5 ml ∙ kg−1 ∙ min−1. Walking at 3 mi ∙ hr−1 (4.8 km ∙ hr−1) requires 3.3 METs (11.5 ml ∙ kg−1 ∙ min−1), and jogging at 6 mi ∙ hr−1 (9.7 km ∙ hr−1) requires 10 METs (35 ml ∙ kg−1 ∙ min−1). You will see more on this in chapter 6.
• Relative intensity describes the degree of effort required to expend that energy and is influenced by maximal aerobic power or cardiovascular fitness (V.O2 max). Relative intensity can be expressed as a percentage of V.O2 max or a percentage of maximal heart rate (HRmax). You will see more on this in chapter 11.
• Moderate intensity refers to an absolute intensity of 3 to 5.9 METs and a relative intensity of 40% to 59% V.O2max or 64% to 76% HRmax.
• Vigorous intensity refers to an absolute intensity of 6 or more METs and a relative intensity of 60% to 84% V.O2max or 77% to 93% HRmax.
• Frequency refers to the number of days per week physical activity is done. Duration refers to the amount of time a physical activity is done.
• Volume refers to the total amount of energy expended or work accomplished in an activity, and it is equal to the product of the absolute intensity, frequency, and time. For example, a person expend- ing 5 kcal ∙ min−1 for 20 min on 3 days ∙ wk−1 will have an exercise volume of 300 kcal ∙ wk−1 (5 kcal ∙ min−1 × 20 min ∙ day−1 × 3 days ∙ wk−1). The volume can also be expressed using the MET scale: A 10 MET activity done 3 days ∙ wk−1 for 20 min ∙ day−1 generates a volume of 600 MET-min ∙ wk−1 (10 METs × 3 days ∙ wk−1 × 20 min ∙ day−1).