In 2014, approximately 1.3 billion of adults worldwide, that were 18 years old and older, were overweight and 600 million were obese [1]. In many countries, being overweight or having obesity kills more people than being underweight [1]. In Mexico, 42% of men were overweight and 26.8% of men were obese, while 35.5% of women were overweight and 37.5% of women were obese [2]. Health risks related to overweight and obesity include cardiovascular diseases (leading cause of death in 2012), diabetes, musculoskeletal disorders and some cancers [1]. Exercise can help prevent, slow down the progression, or manage these diseases associated with overweight and obesity [3–8]. There are also several studies, including meta-analyses, that have found exercise interventions to be effective in reducing weight and body mass index in people with overweight or obesity [9–14].
Obesity and overweight are a public health problem in Mexico that needs to be attended to and it is important that this problem is dealt by analyzing and evaluating models that shape and change health behaviors. There are numerous psychosocial models that study and explain behavioral change in health. The World Health Organization (WHO) summarizes the most effective models and theories of health promotion and education that have been effective in practice including the Rational Model, Extended Parallel Process Model, Transtheoretical Model of Change, Theory of Planned Behavior, Activated Health Education Model, Social Cognitive Theory, Communication Theory, Diffusion of Innovation Theory, and the Health Belief Model [15]. These models and theories have been involved in the promotion of health behaviors by enabling people to increase control over and to improve their health [15]. From these models and theories, the Health Beliefs Model (HBM) has been shown to explain changes in people’s health behaviors [16], including exercise [17–20]. There are several studies that apply the HBM to physical activity [21–23], but physical activity and exercise are defined differently. Physical activity is “any bodily movement produced by skeletal muscles that results in energy expenditure… [and] in daily life can be categorized into occupational, sports, conditioning, household, or other activities” [24], and exercise is “a subset of physical activity that is planned, structured, and repetitive and has a final or an intermediate objective, the improvement of physical fitness” [24]. Nevertheless, some studies use the term physical activity and exercise interchangeably [24].
History of the health belief model
Over time people have been concerned about health. It is for this reason that professionals committed to this area have conducted research and interventions, and have also developed theories and models that explain health behaviors of individuals [16, 25]. In the 50s, in an effort to build a psychosocial model to explain behaviors related to health and prevention, the conceptual basis of the Health Belief Model [26–28] was formulated in collaboration with Mayhew Derryberry, creator of the Division of Behavior Studies in the Department of Public Health of the United States of America and of a group of four social psychologists: Godfrey Hochbaum, Stephen Kegeles, Hugh Leventhal and Irwin Rosenstock [16, 29].
The studies conducted by Hochbaum, in 1952, related to a prevention program against tuberculosis, were fundamental for the development of the HBM [30]. These studies observed more than 1200 adults in three American cities and their willingness to undergo X-ray examinations. They found that their willingness to undergo examinations was the product of individual beliefs of susceptibility to the disease and personal benefits of early detection [30]. The HBM was proposed, at first, to give an explanation and prediction of preventative behaviors and to know the reasons for people not going to medical examinations for early detection of diseases or simply to know their health status, among others preventive behaviors. The HBM began to arouse interest in different professionals from different countries in such a manner that by the 1970′s, the model began to be used in research and health interventions, and evidence in favor of the model began to be published [25]. In 1984, Janz and Becker [31] examined the HBM to account for its effectiveness in practice by reviewing 46 studies that included health behaviors like breast self-exams, vaccinations, exercise, physical activity, smoking, seat belt use, among others. Currently, the HBM is considered useful [25], and valid [29] as it is one of the most applied models in the promotion of health [32] and has been one of the most cited and used models to explain behaviors related to disease prevention, symptom responses, and diseases as well as other behaviors with health effects [16].
Factor structure of the health beliefs model
The HBM is based on three main assumptions: 1) the belief that a problem is extremely important to take it into account, 2) the perception of vulnerability because of that problem and, 3) the perception that the action taken will have, as result, a greater benefit compared with the personal cost produced. According to this model, the interaction of these assumptions stimulates the appearance of healthier behavior patterns that allow to prevent diseases and avoid risky situations [32]. The HBM is composed of two factors that explain health behaviors: the perception of health threat and the perception that specific health behavior can reduce or eradicate the threat [33].
The perception of health threat has three components (Fig. 1): 1) general health values, which refer to the interest and concern for one’s health, 2) personal beliefs about vulnerability and 3) beliefs about the severity and risk of the disorder. For example, people can change their behavior and start exercising if, 1) they are really concerned about their health, 2) they believe that by not exercising they can suffer from some illnesses and, 3) that suffering from those illnesses is very serious leading to a low quality of life or death [33].
The reduction or disappearance of the perceived threat by adopting a health behavior has two components: 1) whether or not the person thinks that such a measure will be effective and, 2) the belief that the benefits of carrying out the health behavior outweigh the costs. For example, a person who does not exercise, feels vulnerable about suffering from related illnesses, and maybe thinking about starting to exercise, may think that 1) exercising reduces the risk or illnesses, and 2) although it is hard to exercise, the ultimate benefit will be better than the potential harm to health, so the person will decide to modify their behavior [33].
The HBM has been applied and studied in several health behaviors [34] like tuberculosis treatment adherence [35], breast self-examination [36], osteoporosis prevention [37], cervical cancer screening [38], hepatitis A and B vaccination [39], Pap smear testing [40], Human Papilloma Virus vaccination [41], prostate cancer screening [42], colorectal cancer screening [43], high-risk sexual behaviors [44], physical activity [22, 23, 45], and exercise [17–20] among others with good results in explaining health behaviors.
There are several exercise studies using the HBM around the world where positive outcomes have been found. In a study done with a sample of 98 Jordanian myocardial infarction patients [17], with a mean age of 50 years (SD = 12.15), and 58% males, it was found that health motivation and perceived barriers had statistically significant correlations with exercise participation. A study with a sample of 132 Hong Kong adults [18], with a mean age of 49.3 years (SD = 9.46), and 59.8% female, found a statistically significant standardized beta, in a multiple regression analysis, between exercise and perceived barriers. In a different study with a sample of 57 participants from New York [19], with a mean age of 56 years (SD = 10.4) and 72% males, the HBM accounted for 29% of the variance of exercise attendance, and three HBM factors were associated with exercise attendance: perceived severity of coronary heart disease, perceived benefits of exercise, and special health practices. Currently there are no published articles that have studied exercise using the HBM in Mexico.
For this reason, the HBM will be used to explain exercise behavior in the Mexican population. Several articles that have studied the HBM design and use their own scales and for many of those studies the validation is not reported. There are some scales that have been validated, like the Champion’s Health Belief Model Scale for breast cancer [46], but a few studies use it. Exercise and physical activity studies, based on the HBM, have no validated scales used across studies, and most of them develop their own instruments without validating the scales. One of the studies used a scale, the HBM Questionnaire [47], but the original scale was designed for dieting and fasting and the study does not show the validation of the modified scale. Also, each factor was composed of only one item, when most of the other scales use more items per factor. There are no validated exercise scales based on the HBM in Spanish, so the purpose of this study was to develop and validate a scale by developing items, analyzing the factor structure, and analyzing the internal reliability of the factors. The validation of this scale will help researchers study exercise using the HBM in Mexico.
