Studies demonstrated that exercise is medicine and necessary for health (American College of Sports Medicine, 2014; Dishman et al., 2013; Lavie et al., 2013; Ross et al., 2016). In fitness clubs, members predominantly exercise for health benefits (Baart de la Faille et al., 2012). The International, Health, Racquet and Sportsclub Association (IHRSA, 2016), estimated that 151 million individuals exercise in 187.000 fitness clubs worldwide. Towards exercising in a fitness club, Middelkamp et al. (2016) distinguish three kinds of behavior: attendance behavior (this occurs when an individual enters the facility), program attendance (an individual attends a specific program), and finally exercise behavior (the individual needs to exercise towards certain standards or minimums in terms of frequency, duration and intensity). Research on attendance and exercise behavior in fitness clubs is limited (Middelkamp and Steenbergen, 2015), but preliminary studies indicated low amounts of exercise sessions in fitness clubs with an average of 1.1 session per month over a 24-month period for a sample of 259.000 ex-members. Only 10% demonstrated regular exercise behavior for six consecutive months and 2.3% never relapsed in two years (Middelkamp et al., 2016). These frequencies will hardly impact health (ACSM, 2014; Dishman et al., 2013). Other studies reported low attendance figures as well, mainly for the first 36 weeks (Annesi et al., 2011; Annesi, 2003).
The transtheoretical model of behavior change (TTM) is frequently used to systematically describe and understand a wide range of health behaviors and changes therein, such as smoking cessation, safer sex, quitting cocaine, or the adoption and maintenance of exercise (Prochaska and DiClemente, 1983; Prochaska et al., 1994). Although interventions demonstrated that physical activity and exercise are necessary for health (American College of Sports Medicine, 2014; Dishman et al., 2013), studies on different populations (USA and Europe) showed that less than 5% of adults exercise the minimum amount to impact health (Cavill et al., 2006; Garber et al., 2011). Furthermore, research indicated that 50% of the exercisers drop-out in the first six months (Berger et al., 2002). To study exercise behavior, the TTM is often applied for an in-depth understanding of the development of this specific behavior and its change over time (Buckworth et al., 2013; Reed, 2001). In various populations and settings, the existence of significant relationships between the TTM and exercise behavior have been demonstrated (Fallon et al., 2005; Marshall and Biddle, 2001; Spencer et al., 2006). The current model describes four key constructs; 1. stages of change; 2. decisional balance; 3. self-efficacy; and 4. processes of change. The stages of change are the organizing construct of the TTM and hypothesize that individuals move cyclically through the stages with periods of progression and relapse. The stages of change contain five main stages (Dishman et al., 2010) to cease an unhealthy (like smoking) or adopt a healthy behavior (like exercise), or six stages if the termination/relapse stage is also included (Cardinal, 1998; Fallon et al. 2005; Prochaska and Marcus, 1994;). The stages are summarized in Table 1.
The decisional balance is the second construct of the TTM and contains two main scales of pros and cons for changing behavior (Janis and Mann, 1977). There are four dimensions for pros: useful benefits for the self; useful benefits for others; self-approval; approval of others. There are also four dimensions for cons: useful losses for the self; useful losses for others; self-disapproval; disapproval of others. The pros and cons are important for influencing persons in an early stage (pre-contemplation preparation) to the action stage (Velicer et al., 1998). The third construct is self-efficacy (Bandura, 1997), which involves the degree of confidence a person has that he or she will not engage in a problem behavior in tempting situations. In short, self-efficacy is a person's belief in capabilities to overcome personal, social and environmental barriers to exercise. There are two important aspects that will influence the confidence to adopt and maintain exercise behavior. The first is efficacy expectations; one's belief about their own competence. The second is outcome expectations; one's belief in regards to the perceived results or outcomes of exercise. According to self-efficacy theory, human behavior is strongly influenced by self-regulation, for example by options to self-set (choose) exercise activities and self-set exercise goals (Bandura, 1991). A high level of (perceived) self-efficacy makes it more likely that an individual will initiate and maintain the behavior. Temptation to not exercise describes urges to engage in a specific habit for example remaining sedentary. It is conceptually related to self-efficacy. Dishman et al. (2010) reported that construct validity of temptation has been supported by significantly lower levels of temptation in the later stages but question whether temptation predicts physical activity independently of barrier self-efficacy. The fourth construct measures ten processes of change, divided in five experimental or cognitive processes and five behavioral processes. The five cognitive processes are: consciousness raising; dramatic relief; environmental reevaluation; self-reevaluation and social liberation. The five behavioral processes are: counter conditioning; helping relationship; reinforcement management; self-liberation and stimulus control (Dishman et al., 2010; Prochaska and DiClemente, 1983; Reed, 2001).
The TTM supposes to be an integrative model (Velicer et al., 1998) meaning that individual constructs are related. This contains primarily the relationship of decisional balance, self-efficacy, temptation and processes of change with the stages of change. Prochaska et al. (1994) studied twelve problem behaviors and ordered the usage of pros and cons to the stages of change participants claimed to be in. The outcomes showed that pros and cons develop over time over the stages of change, and variations per problem behavior were observed. Concerning processes of change, Prochaska and DiClemente (1983) indicated that self-changers are using the fewest processes of change during precontemplation and emphasize consciousness raising at contemplation. They emphasized self-reevaluation in contemplation and action stage, and reported increased usage of self-liberation, helping relationships, plus reinforcement management in the action and maintenance stage. Velicer et al. (1998) mentioned that the cognitive processes are mostly used in the early stages, and the behavioral processes in the later stages of change. Dishman et al. (2010) reported contrary results; people appear to use both cognitive and behavioral processes while they attempt to increase or maintain their physical activity. The integrative nature of the TTM has also been applied to self-efficacy and temptations. Based on theory, self-efficacy mainly starts to increase at preparation and remains stable in action and maintenance stage. Temptation decreases in the preparation, action and maintenance stage (Velicer et al. 1998; Dishman et al. 2010). A schematic overview of the relationship between stage and self-efficacy, temptation, pros and cons for a healthy behavior such as exercise, is demonstrated in Figure 1, based on Velicer et al. (1998).
Spencer et al. (2006) reviewed 150 studies that applied the TTM to exercise behavior, of which 38 interventions, 70 population studies, and 42 validation studies. From the intervention studies, 32 stage-matched programs were reviewed, plus 6 non-stage matched, with 29 using self-report exercise measures. 25 studies were shown to be successful in motivating participants towards higher stages and increased amounts of exercise. Although the applicability of the TTM to exercise behavior seems promising, the current state of literature is inconclusive. For example, Dishman et al. (2009) concluded that the TTM failed to predict change in regular physical activity in a multiethnic cohort. Fallon et al. (2005) and Spencer et al. (2006), reported that TTM studies have important limitations: lack of diverse and representative participants; lack of...