1. Background
Nearly a billion people worldwide have high blood pressure (BP) and this number is anticipated to reach 1.56 billion by 2025 (1, 2). According to the seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high BP (JNC7), adoption of a healthy lifestyle is an inevitable part of the management of people with hypertension (HTN) and one component of this is regular aerobic physical activity (PA) such as fast walking (at least 30 minutes most days of the week) (3).One recent study found that only 14.1% of hypertensive patients engage in regular PA (4).
In reports on walking interventions, little attention has been given to the underlying theoretical basis of the program being tested (5). The lack of a theoretical basis in such interventions may lead to low commitment due to a lack of insight into the psychological difficulties of adopting the program (6). Theories that can identify the main factors that influence behavior and the relationships between these factors are useful in identifying the components upon which intervention should focus (7). One of the most common theoretical frameworks used for understanding health behaviour change is the trans-theoretical model (TTM) (8) which indicates that individuals engaging in a new behavior move through a series of stages of change (9). These stages include: pre-contemplation (inactive, no intention), contemplation (inactive and 6-month intention), preparation (irregularly active and intention), action (regularly active for less than 6 months) and maintenance (regularly active for more than 6 months) (10, 11). Processes of change are strategies that people use to progress through stages. There are five cognitive and five behavioural processes (12).
Studies that have tested the effectiveness of the TTM on exercise behaviour change in individuals with HTN have considered the construct of stages of change and self-efficacy rather than the processes of change (9, 13, 14). Chiang (2009) studied hypertensive persons based on stages of change and showed that a walking program had no significant effect on walking endurance (9). In an educational intervention by Bosworth (2008) in hypertensive patients for the purpose of promoting medication adherence and improving HTN-related health behaviours based on stages of change and a health decision model, 32% of the patients complied with the exercise module (13). In a study by Fort (2015), including an educational intervention for a healthy lifestyle based on stages of change and self-efficacy in hypertensive patients, no significant changes were observed with regard to self-efficacy and participation in PA (14).
2. Objectives
In light of the poor results obtained in the interventions mentioned above and because the integration of stages and processes of change can provide a beneficial guide for PA interventions (11), it would seem that adding the processes of change to PA interventions would be useful in increasing their effectiveness. Therefore, this study was designed to evaluate the effects of a TTM-based intervention on the PA of patients with HTN.
3. Methods
3.1. Trial Design
This was a concurrent parallel randomized clinical trial. Participants were individually randomized to parallel groups. Unit of randomization was patient. Study objectives were explained to each participant and informed written consent was obtained. The study was confirmed by the ethics committee of Tarbiat Modares University. This study is registered at www.irct.ir (No. IRCT2016061428463N1).
3.2. Participants
Inclusion criteria were that patients should be diagnosed with primary HTN; have a systolic BP of less than 170 mmHg; be taking at least one anti HTN medication; have completed at least 4th grade education, have no orthopedic limitations to walking; be cleared for moderate-intensity walking by a cardiologist; have a current PA level that is less than the criterion (30 minutes of fast walking five days a week); be in the stage of pre-contemplation, contemplation or preparation; and be ≤ 69 years of age. Exclusion criteria were diagnosis of cardiovascular disease, diabetes or depression; history of heart attack or stroke; and taking drugs for weight loss.
3.3. Setting and Locations Where the Data Were Collected
The study took place at the Shiraz healthy heart house in Shiraz, Iran, from January 2015 to March 2016. Individuals with HTN were selected by Purposive sampling from patients referred to the Shiraz healthy heart house. Healthy heart house is affiliated to the cardiovascular research center of Shiraz University of Medical Sciences and promotes population-based cardiovascular disease prevention activities. Shiraz is among the large cities in Iran, with a population of 1,460,445 (15) and an estimated HTN prevalence of 27.5% in adults 19 - 99 years in 2010 (16).
3.4. Interventions
Thirty one patients in the experimental group (EG) were divided into 3 groups. A four-session training program totaling 8 hours was attended by the experimental participants. Meetings were held on a weekly basis. Commensurate with the constructs of processes of change appropriate content and teaching methods were used. For example, for self-reevaluation used from role playing. Examples of strategies used for each process of change is in Table 1 (8, 17). The first session discussed consciousness raising, dramatic relief and how to take a pulse. The second session was about self re-evaluation, environmental re-evaluation, social liberation, self-liberation. The third session presented helping relationships, counter-conditioning, reinforcement management and stimulus control. The fourth session determined the target heart rate of each person during exercise using the karvonen formula (18). Each subject was told their target heart rate and asked to take his/her pulse while walking to attain this value. Subjects were shown a video teaching fast walking and were instructed practically by an exercise coach. At least 30 minutes of fast walking at an intensity of 40% to 60% maximum heart rate was prescribed to the EG for at least 5 days a week for 6 months. During implementation, no additional intervention by researchers was provided to the control group (CG). After the training sessions, the members of the EG were followed up by phone and short message system once every two weeks for first 3 months and every month for the 3 next months.
| Processes of Change | Description | Examples of Strategies |
|---|---|---|
| Consciousness raising | Finding and learning new facts, ideas, and tips that support the healthy behavior change | give information about physical activity and its advantages and risks related to inactivity |
| Dramatic relief | Experiencing the negative emotions (fear, anxiety, worry) that go along with unhealthy behavioral risks | health risk feedback |
| Self re-evaluation | Realizing that the behavior change is an important part of one’s identity as a person | healthy role models |
| Environmental reevaluation | Realizing the negative impact of the unhealthy behavior reevaluation or the positive impact of the healthy behavior on one’s proximal social and/or physical | Empathy training |
| Social liberation | Realizing that the social norms are changing in the direction of supporting the healthy behavior change | Show alternative to the problematic behavior |
| Self liberation | Making a firm commitment to change | Technics of goal fixation, make plan about physical activity |
| Helping relationships | Seeking and using social support for the healthy behavior change | Education important others(spouse, Relative ,Friend, ,…) in the direction encourage and support of physical activity |
| Counterconditioning | Substitution of healthier alternative behaviors and cognitions for the unhealthy behavior | recognize the situation that lead to inactive and the different scenario that can be established to include physical activity |
| Reinforcement management | Increasing the rewards for the positive behavior change and decreasing the rewards of the unhealthy behavior | Make a reward list for each reached goal of physical activity |
| Stimulus control | Removing reminders or cues to engage in the unhealthy behavior and adding cues or reminders to engage in the healthy behavior | Give some photos or message that can motive doing physical activity |
Processes of Change, Description and Examples of Strategiesa
3.5. Outcomes
1- PA stages of change: PA stages of change was measured using stages of PA change questionnaire developed by Marcus et al. (19). Patients were asked to show which options best described their current level of PA (walking, biking, or playing ball for 30 minutes or more, 5 days a week) as active more than 6 months (maintenance), active less than 6 months (action), not active on a regular basis but occasionally engaged in activities and planning to start next month on a regular basis (preparation), not active but may start in the next 6 months (contemplation), not active and not planning to start in the next 6 months (pre-contemplation) (20). The validity and reliability of the questionnaire have been confirmed in Iran by Roozbahani (20). The PA stages of change were measured before, 3 and 6 months after intervention.
2- Processes of change: Processes of change were evaluated using a 40-item scale (19). The instrument assesses 10 processes of change (19). Processes of change are shown in Table 1 (8, 17). Participants responded to the questions on a scale ranging from 1 to 5 (never to repeatedly) A higher score shows more frequent use of processes of change to perform PA score range (1 - 5) (21). The validity and reliability of the questionnaire have been confirmed in Iran by Roozbahani (20). Processes of change was measured before, 3 and 6 months after intervention.
3- Frequency and duration of walking: Frequency and duration of walking were measured using the international PA questionnaire (IPAQ) short form (22). The validity and reliability of the questionnaire have been confirmed in Iran by Moghadam (23). Frequency and duration of walking was measured before, 3 and 6 months after intervention.
4- Intensity of walking: Intensity of walking was measured using the Borg scale ranging from 6 (light effort) to 20 (fatigue) (24). The validity and reliability of the questionnaire have been confirmed in Iran by Parvari (24). Intensity of walking was measured before, 3 and 6 months after intervention.
3.6. Sample Size
According to Hashemi et al. study (25), at a 95% confidence interval and 90% power using the. Following formula (26) the sample size for the present study was determined to be 25 subjects for each group. Potential loss to follow-up was anticipated to be 20% per group, so 30 subjects were planned to be randomized to each group.
p1 = The proportion of people entered in the stage of action in EG.
p2 = The proportion of people entered the stage of action in CG
3.7. Randomization
Patients were randomly assigned following unrestricted randomization procedures (flip of the coin) to 1 of 2 EG or CG. Randomization was concealed in sequentially numbered, opaque, sealed and stapled envelopes. Investigators generated the random allocation sequence, enrolled participants and assigned participants to interventions.
3.8. Blinding
Investigators and patients (was not possible to blind participants given the nature of the intervention) that allocated to the EG were aware of the allocated arm, outcome assessors and data analysts were kept blinded to the allocation.
3.9. Statistical Methods
The data was analyzed using SPSS 22 software. Kolmogorov-Smirnov statistical test used for assess normal distribution of data. Data was analyzed using tests of chi-square, independent t-test, repeated measure and Mann-Whitney and freedman tests for non-parametric data. The results were considered significant at P < 0.05.
4. Results
This study was conducted on 60 patients with HTN (31 EG, 29 CG) without loss of participants. Table 2 shows the baseline characteristics of the EG and CG. Before intervention there was no significant difference between the EG and CG in the PA stages of change, processes of change, frequency, duration and intensity of walking (P > 0.05).
| Patient Characteristics | Experimental (n = 31) | Control (n = 29) | P Value |
|---|---|---|---|
| Age, y | 54.05 ± 7.01 | 53.75 ± 8.27 | 0.561 |
| Gender | 0.603 | ||
| Male | 12 (38.7) | 14 (48.3) | |
| Female | 19 (61.3) | 15 (51.7) | |
| Job | 0.683 | ||
| Laborer | 4 (12.9) | 4 (13.8) | |
| Employee | 0 (0) | 2 (6.9) | |
| Self-employment | 2 (6.5) | 2 (6.9) | |
| Housewife | 14 (45.2) | 12 (41.4) | |
| Retired | 11 (35.5) | 9 (31) | |
| Education | |||
| Under high school | 12 (38.7) | 15 (51.7) | 0.235 |
| High school | 9 (29) | 10 (34.5) | |
| College education | 10 (32.3) | 4 (13.8) | |
| Income ($ US) | 349.5 ± 204.51 | 291.52 ± 199.22 | 0.204 |
| Number of anti HTN drugs | 1.61 ± 0.72 | 1.47 ± 0.612 | 0.589 |
| Duration of consumption anti HTN drugs, y | 3.77 ± 2.21 | 5.89 ± 6.55 | 0.733 |
4.1. PA Stages of Change
At 3 and 6 months post-intervention, EG showed improvement in PA stages of change compared to CG (P < 0.001, Table 3). At 3 months post-intervention, in the EG, 87.1% patients (n = 27) and in the CG, 27.6% patients (n = 8) entered to the stage of action. At 6 months post-intervention, in the EG, 74.2% patients (n = 23) and in the CG, 13.8% patients (n = 4) entered the stage of action or maintenance (Table 3).
| Variables | Baseline | P Valueb | 3 month Follow-Up | P Valueb | 6 month Follow-Up | P Valueb | |||
|---|---|---|---|---|---|---|---|---|---|
| Experimental | Control | Experimental | Control | Experimental | Control | ||||
| Pre-contemplation | 2 (6.5) | 5 (17.2) | 0.327 | 0 | 10 (34.5) | < 0.001 | 0 (0) | 4 (13.8) | < 0.001 |
| Contemplation | 7 (22.6) | 8 (27.6) | 1 (3.2) | 7 (24.1) | 1 (3.2) | 10 (34.5) | |||
| Preparation | 22 (71) | 16 (55.2) | 3 (9.7) | 4 (13.8) | 7 (22.6) | 11 (37.9) | |||
| Action | - | - | 27 (87.1) | 8 (27.6) | 10 (32.3) | 2 (6.9) | |||
| Maintenance | - | - | - | - | 13 (41.9) | 2 (6.9) | |||
Physical Activity Stages of Change in Experimental and Control Groupsa
4.2. Processes of Change
At 3 months post-intervention, the mean total scores for the cognitive and behavioral processes of consciousness raising, dramatic relief, self-re-evaluation, environmental re-evaluation, counter-conditioning, reinforcement management, self liberation and stimulus control differed significantly between the EG and CG (P < 0.05, Table 4). At 6 months post-intervention, the mean total scores for the behavioural and cognitive processes of consciousness raising, self-re-evaluation, environmental re-evaluation, counter-conditioning, helping relationships, reinforcement management and stimulus control differed significantly between the EG and CG (P < 0.05, Table 4).
| Parameter | 3-month Follow-Up | P Value | 6-month Follow-Up | P Value | ||
|---|---|---|---|---|---|---|
| Experimental | Control | Experimental | Control | |||
| Processes of change | 3.71 ± 0.76 | 3.14 ± 0.74 | 0.03 | 3.95 ± 0.59 | 3.46 ± 0.54 | 0.002 |
| Cognitive processes | 3.81 ± 0.72 | 3.30 ± 0.72 | 0.03 | 4.06 ± 0.50 | 3.54 ± 0.52 | < 0.001 |
| Consciousness raising | 3.76 ± 0.92 | 2.89 ± 0.98 | 0.002 | 3.90 ± 0.88 | 2.97 ± 0.95 | < 0.001 |
| Dramatic relief | 4.17 ± 0.95 | 3.53 ± 1 | 0.03 | 4.24 ± 0.75 | 3.87 ± 0.74 | 0.07 |
| Self re-evaluation | 4.34 ± 0.57 | 3.63 ± 0.86 | 0.002 | 4.52 ± 0.50 | 4.16 ± 0.50 | 0.01 |
| Environmental reevaluation | 3.81 ± 0.75 | 3.11 ± 0.97 | 0.006 | 4.12 ± 0.66 | 3.56 ± 0.75 | 0.005 |
| Social liberation | 3.25 ± 0.89 | 2.82 ± 0.98 | 0.141 | 3.52 ± 0.84 | 3.12 ± 0.88 | 0.08 |
| Behavioral processes | 3.65 ± 0.79 | 3 ± 0.91 | 0.01 | 3.85 ± 0.72 | 3.38 ± 0.64 | 0.01 |
| Counter conditioning | 3.80 ± 0.84 | 3.02 ± 0.95 | 0.006 | 4.08 ± 0.79 | 3.61 ± 0.81 | 0.03 |
| Helping relationships | 3.29 ± 1.08 | 2.78 ± 1.16 | 0.117 | 3.65 ± 1.13 | 3.03 ± 1.06 | 0.03 |
| Reinforcement management | 3.64 ± 1.04 | 3.06 ± 1.07 | 0.05 | 3.98 ± 0.85 | 3.53 ± 0.79 | 0.04 |
| Self liberation | 4.30 ± 0.66 | 3.49 ± 0.85 | < 0.001 | 4.11 ± 0.69 | 3.88 ± 0.59 | 0.18 |
| Stimulus control | 3.45 ± 1.06 | 2.59 ± 1.09 | 0.008 | 3.43 ± 1.02 | 2.86 ± 0.98 | 0.03 |
| Frequency of walking | 5.23 ± 1.56 | 2.71 ± 2.85 | < 0.001 | 5.03 ± 1.79 | 4.76 ± 2.28 | 0.63 |
| Duration of walking | 45.33 ± 30.93 | 25.38 ± 36.13 | 0.001 | 42.20 ± 18.82 | 32.29 ± 30.43 | 0.01 |
| Intensity of walking | 13.66 ± 2.75 | 9.75 ± 3.40 | < 0.001 | 12.96 ± 2.02 | 11.66 ± 1.49 | 0.006 |
Table 5 indicated changes of processes of change over time (pre intervention, 3 month post intervention and 6 month post intervention) in the EG. Cognitive and behavioral processes, consciousness raising, environmental re-evaluation, social liberation, counter-conditioning, helping relationship, reinforcement management, self liberation and stimulus control differed significantly in over time in EG group (P < 0.05, Table 5). At 3 month post-intervention two processes of helping relationship and stimulus control and at 6 months post-intervention helping relationship and strengthening management had the most increase compared to before intervention. Table 6 indicated changes of processes of change over time in the CG. In the CG, significant difference was observed in behavioral processes, counter-conditioning and self liberation at 6 months post-intervention as compared with 3 month post intervention (Table 6).
| Parameter | Experimental | P Valueb | ||
|---|---|---|---|---|
| Baseline | 3-month Follow-Up | 6-month Follow-Up | ||
| Processes of change | 3.46 ± 0.62 | 3.94 ± 0.90 | 3.96 ± 0.63 | 0.001 |
| Cognitive processes | 3.66 ± 0.66 | 3.95 ± 0.70 | 4.08 ± 0.51 | 0.003 |
| Consciousness raising | 3.46 ± 1 | 3.81 ± 0.91 | 3.90 ± 0.93 | 0.04 |
| Dramatic relief | 4.19 ± 0.97 | 4.20 ± 0.89 | 4.29 ± 0.74 | 0.66 |
| Self re-evaluation | 4.18 ± 0.72 | 4.38 ± 0.61 | 4.50 ± 0.48 | 0.33 |
| Environmental reevaluation | 3.52 ± 0.92 | 3.93 ± 0.80 | 4.18 ± 0.65 | 0.01 |
| Social liberation | 2.90 ± 0.95 | 3.39 ± 0.85 | 3.53 ± 0.87 | 0.004 |
| Behavioral processes | 3.27 ± 0.64 | 3.93 ± 1.23 | 3.83 ± 0.80 | 0.002 |
| Counter conditioning | 3.65 ± 0.77 | 4.35 ± 2.23 | 4.22 ± 0.67 | 0.004 |
| Helping relationships | 2.72 ± 1.22 | 3.73 ± 2.47 | 3.62 ± 1.20 | 0.04 |
| Reinforcement management | 3.19 ± 0.90 | 3.70 ± 1.01 | 4.01 ± 0.88 | < 0.001 |
| Self liberation | 4 ± 0.82 | 4.32 ± 0.69 | 4.18 ± 0.67 | 0.05 |
| Stimulus control | 2.81 ± 1.02 | 3.54 ± 1.15 | 3.39 ± 1.09 | 0.005 |
| Frequency of walking | 4 ± 2.14 | 5.12 ± 1.67 | 5.20 ± 1.74 | 0.01 |
| Duration of walking | 40 ± 32.85 | 39.56 ± 25.44 | 42.60 ± 19.47 | 0.64 |
| Intensity of walking | 12.25 ± 2.62 | 13.88 ± 2.96 | 12.95 ± 2.11 | 0.05 |
Processes of Change ,Frequency, Duration and Intensity of Walking in Experimental Groupa
| Parameter | Control | P Valueb | ||
|---|---|---|---|---|
| Baseline | 3-month Follow-Up | 6-month Follow-Up | ||
| Processes of change | 3.32 ± 0.75 | 3.17 ± 0.88 | 3.41 ± 0.69 | 0.17 |
| Cognitive processes | 3.52 ± 0.71 | 3.44 ± 0.99 | 3.51 ± 0.67 | 0.89 |
| Consciousness raising | 3.25 ± 1.11 | 3.04 ± 0.92 | 2.92 ± 1.08 | 0.42 |
| Dramatic relief | 3.62 ± 1.01 | 3.33 ± 1.09 | 3.75 ± 0.79 | 0.87 |
| Self re-evaluation | 4.10 ± 0.89 | 4.55 ± 2.92 | 4.12 ± 0.56 | 0.55 |
| Environmental reevaluation | 3.72 ± 1.02 | 3.32 ± 1.11 | 3.63 ± 0.99 | 0.24 |
| Social liberation | 2.92 ± 1.09 | 2.84 ± 1.17 | 3.11 ± 1.12 | 0.59 |
| Behavioral processes | 3.12 ± 0.85 | 2.90 ± 0.83 | 3.31 ± 0.81 | 0.01 |
| Counter conditioning | 3.64 ± 0.97 | 2.98 ± 0.92 | 3.58 ± 1.05 | 0.02 |
| Helping relationships | 2.41 ± 1.19 | 2.42 ± 1.11 | 2.78 ± 1.33 | 0.16 |
| Reinforcement management | 2.95 ± 1.02 | 3.10 ± 1.06 | 3.35 ± 0.95 | 0.17 |
| Self liberation | 3.80 ± 0.90 | 3.46 ± 0.79 | 3.98 ± 0.69 | 0.01 |
| Stimulus control | 2.78 ± 1.17 | 2.52 ± 1.08 | 2.86 ± 1.08 | 0.35 |
| Frequency of walking | 3.74 ± 2.44 | 2.47 ± 2.96 | 4.31 ± 2.40 | 0.03 |
| Duration of walking | 37.35 ± 36.14 | 30.58 ± 39.12 | 31.47 ± 34.94 | 0.49 |
| Intensity of walking | 11.28 ± 2.67 | 9.61 ± 3.44 | 11.55 ± 1.61 | 0.06 |
Processes of Change and Frequency, Duration and Intensity of Walking in Control Groupa
4.3. Frequency and Duration of Walking
At 3 months post-intervention, frequency of walking differed significantly between the EG and CG (P < 0.001, Table 4). At 6 months post-intervention, frequency of walking did not differ significantly between the EG and CG (P = 0.63, Table 4). At 3 and 6 months post-intervention, duration of walking differed significantly between the EG and CG (Table 4). In the EG, frequency of walking was significantly different over time (P = 0.01, Table 5). In the CG, frequency of walking significantly differed at 6 months post-intervention compared to 3 months post intervention (P = 0.03, Table 6).
4.4. Intensity of Walking
At 3 and 6 months post-intervention, Intensity of walking differed significantly between the EG and CG (P < 0.05, Table 4). In the EG, intensity of walking was significantly different at over time (P = 0.05, Table 5). In the CG, Intensity of walking were not significantly different over time (P = 0.06, Table 6).
5. Discussion
The present study tested the effect of an intervention program based on TTM in patients with HTN. In the present study, progress in the stages of change was considered one of the criteria for success in intervention. At 3 and 6 months post-intervention, the EG showed improvement in PA stages of change compared to CG. Studies of Mutrie (27), Woods (11), Plow (21) about trans-theoretical-based intervention on physical activity reported similar results. At 3 months post-intervention 87.1% of the EG and at 6 months post-intervention 74.2% of the EG regularly active (action or maintenance). These amounts in CG was 27.6% and 13.8% respectively. In the study of Daley (28), stage specific intervention in hypertensive women, 4 weeks after the intervention %85 women proceeded to or stayed in the action or maintenance stages of change that is consistent with this study.
At 3 and six months post-intervention, a significant difference was observed between the EG and CG in behavioural and cognitive processes. This result is consistent with studies of Moeini (29) and Van Sluijs (30) with the purpose of evaluating trans-theoretical based intervention on PA in under investigation patients. In study of Pirzade (31) on 141 patients with metabolic syndrome also 6 months after intervention significant difference were seen in the processes of change between the EG and CG. These findings showed that intervention was effective in increasing use of the processes of change.
At 3 months post-intervention, walking increased significantly in the EG compared to the CG. Jalilian’s (32) study with purpose of investigating the effect of physical activity, stage-matched intervention on 50 diabetic patients showed that intervention group performed significantly more regular physical activity than CG. At 6 months post-intervention, walking increased in EG compared to the CG but not significantly. Study of Gong (33) about efficacy of behavioral intervention (KM2H2) by trans-theoretical model among hypertensive patients indicated that actual physical activity levels were significantly higher for intervention participants than for the control participants at 6 months post intervention. In the study of Pirzade (31) with the purpose of evaluating trans theoretical model to promote physical activities among 141 women with metabolic syndrome, walking increased in case group compared to the CG at 6 months post intervention. Reason of increased physical activity in studies of Gong and Pirzade compared to the current study can attributed to Gong’s study including patients that were in all stages of change (pre contemplation, contemplation, preparation, action and maintenance) and in Pirzade’s study included patients that were in stages of contemplation and preparation and action at pre intervention. Whereas this study entered patients that were in pre-action stages (pre-contemplation, contemplation and preparation) in which it was hard motivating patients compared to action stages. Of course at 6 months post-intervention; frequency, duration and intensity of walking in EG (5.03, 42.20, 12.96, respectively) compared with CG (4.76, 32.29, 11.66, respectively) indicated that EG reached the purpose of intervention (30 minutes of fast walking at least 5 days a week for 6 months). This situation shows that with regard to the existence of obstacles and competitive conditions against exercise, continuation of educational measures or reinforcing communication seems necessary.
In the EG a significant increase was observed in the use of the 8 the processes of change over time. In the EG 3 month post-intervention, two processes of helping relationship and stimulus control and 6 months post-intervention, helping relationship and strengthening management had the most increase compared to before intervention. Helping relationship and stimulus control and strengthening management are behavioral processes. According to findings of Plotnikoff (34) and Sullum (35), the role of behavioural processes in predicting the transfer of individuals during the stages of change is more obvious than in the cognitive processes. Findings in studies of Griffin-Blake (36) and Prapavessis (37) is indicative of the great effect the use of behavioral processes in action and maintenance stages. Since in 6 months post-intervention a significant proportion of the EG were in the action or maintenance stages, increased use of these two behavioral processes is justifiable.
In the CG, frequency of walking, behavioral processes, counter-conditioning and self liberation were significantly higher at 6 months post-intervention compared to 3 months post intervention. In Eakin study, The Logan Healthy Living Program, a significant improvement in PA in the CG occurred (38). A recent systematic review also indicated that in nearly 30% of PA interventions, a significant improvement in PA was observed in the CG (39). In studies of Mostafavi (7) and Moeini (40) significant difference was also observed in processes of change in CG at post intervention compared with pre intervention that was consistent with this study. Reasons of CG improvements in this study could be: 1. the effects of measurement (when measurement is sufficient to produce a change in behavior in the absence of a formal intervention). 2. education that about the prevention of cardiovascular diseases and specifically doing PA occurred frequently in recent years by media. CG could be affected by this education.
The limitation of this study was the use of self-reported PA data. By providing explanations and using effective communication, we attempted to gain the confidence of the participants and keep the amount of biased self-reporting to a minimum. This study included several strengths: 1) This is the first study that tested the effect of the processes of change on the PA of patients with HTN; and 2) Valid and reliable questionnaires were used to assess the impact of the intervention on the determinants of PA.
The present study showed that TTM-based intervention effectively increased the PA stages of change, processes of change and walking. So use of TTM-based interventions can be suggested for increased commitment to PA in hypertensive patients.
