Effect of a physical activity promotion intervention based on the transtheoretical model on blood pressure in patients with hypertension attending primary care: a randomized controlled trial

Abstract

Background

Hypertension is a major public health concern, affecting an estimated 1.28 billion people worldwide. Although physical activity is a key component of non-pharmacological treatment, only a small proportion of adults achieve the recommended levels. This study aimed to assess the effect of a physical activity promotion intervention, that included a specific Exercise Program and grounded in the Transtheoretical Model, on blood pressure among patients with hypertension attending a primary care center in Aguascalientes, Mexico.

Methods

A randomized controlled trial was conducted with 440 patients aged 40 to 70 years diagnosed with hypertension. Participants were randomly assigned to either an intervention or control group. The intervention group had access to a six-month exercise program and attended six workshops, one per month. The first two workshops covered general recommendations on physical activity for adults, information on hypertension, and dietary guidelines for people with hypertension. The following four workshops focused on promoting physical activity using the Transtheoretical Model. The control group had usual care and attended the first two workshops. The primary outcomes were the differences in the changes between the groups in blood pressure levels, and in the proportion of blood pressure control. Blood pressure was measured at baseline and after six months. Participants were also asked about their stage of change and self-efficacy for exercising regularly, adherence to pharmacological treatment, and physical activity performed. The study was conducted between August 2022 and December 2023.

Results

Compared with the control group, the intervention group showed: (1) a greater change in blood pressure, with an average decrease of 3.9 mm Hg [95% CI: 0.87, 6.88] in systolic pressure and 3.2 mm Hg [95% CI: 1.2, 5.2] in diastolic pressure; (2) 14.8% [95% CI: 5.3, 24.3] more participants achieving controlled blood pressure; and (3) greater progression through the stages of readiness to adopt regular exercise.

Conclusions

This physical activity promotion intervention had positive effects on blood pressure levels, blood pressure control, and progression through the Transtheoretical Model stages of change. Primary care services should implement physical activity promotion programs as part of hypertension management.

Trial registration

ClinicalTrials.gov, ID NCT05680025. Registered on December 26, 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-026-03199-4.

Background

Hypertension affects approximately one-third of the adult population worldwide [1]. In Mexico, according to the 2023 National Health and Nutrition Survey (ENSANUT), 29.9% of adults aged 20 and older had hypertension, of whom 43% had not been diagnosed. Moreover, among those receiving pharmacological treatment, only 36.3% had their blood pressure (BP) under control [2]. Within the Mexican Social Security Institute (IMSS), which provides healthcare services to over half of the population, 7.48 million users have been diagnosed with hypertension [3]. In the state of Aguascalientes, where this study was conducted, 14.7% of adults are affected by hypertension [4].

The management of hypertension involves both pharmacological and non-pharmacological approaches. The main non-pharmacological interventions promote lifestyle modifications, including adherence to a healthy diet with limited sodium intake, weight reduction, regular physical activity (PA), moderation of alcohol consumption, and smoking cessation [2, 5–7]. According to data from the 2023 ENSANUT, most individuals with hypertension in Mexico do not adopt lifestyle changes. Among adults with hypertension, 52.1% reported taking no non-pharmacological measures to control their condition, and only 17.8% engaged in PA [2].

A systematic review on the pharmacological treatment of hypertension reported that a 5 mm Hg reduction in SBP can lower the risk of major cardiovascular events by approximately 10% [8]. The clinical practice guidelines on high blood pressure, suggest that even modest average reductions in blood pressure can result in meaningful benefits for the prevention of both incident and recurrent cardiovascular disease [9, 10].The beneficial effect of regular PA on BP has been observed in both normotensive individuals and those with hypertension, with a greater impact in the latter group [5, 11].Regular PA has been shown to reduce systolic blood pressure (SBP) by 5 to 17 mm Hg and diastolic blood pressure (DBP) by 2 to 10 mm Hg [5, 6, 11–14]. Several studies evaluating the effects of different types of exercise—aerobic, resistance, or isometric—on BP have reported positive outcomes for each type individually as well as for their combination [5, 6, 10, 11, 14, 15]. In addition, regular aerobic exercise has been shown to improve the structural, functional, and biochemical characteristics of the cardiovascular system [5, 10, 16]. Therefore, exercise is considered to play a key role in both the treatment of hypertension and the prevention of its complications.

However, adopting healthy lifestyle habits is challenging for both healthy adults and those with chronic conditions, as adults living with such conditions are generally less physically active [12]. Moreover, encouraging patients to engage in regular PA is also a challenge for healthcare providers [5, 12, 15]. This is due to a lack of professional training in this area, as well as limited institutional coordination to collaborate with other specialists qualified to design appropriate exercise programs and guide patients through the process of behavior change [12, 15, 17]. Interventions based solely on structured exercise programs have often failed to achieve lasting behavioral change. Therefore, interventions that combine motivational strategies with structured exercise programs have been studied in various populations [18]. Further research is needed to evaluate the health effects of such programs and to determine how they can be effectively implemented in primary healthcare settings, considering different populations and contexts [13, 18].

Research in psychology has developed models and theories to explain the processes involved in behavior change, such as adopting regular exercise habits. The Transtheoretical Model (TTM) is an integrative framework that combines processes and principles from multiple theories [19–21]. Marcus and other researchers have reviewed TTM applications to the initiation, adoption, and maintenance of regular exercise behavior According to the TTM, behavior change related to PA occurs through five stages of readiness for change, which reflect a person’s willingness and timeframe to modify behavior. An important attribute of these stages is that they encompass both behavior and behavioral intention. The stages of change for adopting regular exercise are: precontemplation, contemplation, preparation, action, and maintenance [20, 22, 23]. The first three stages are known as motivational stages, during which the behavior has not yet been adopted, while the last two—action and maintenance—are referred to as volitional stages, in which the desired behavior is practiced and sustained [20]. Another key construct of the TTM is self-efficacy, or confidence in one’s ability to make a behavioral change despite potential difficulties. Studies on this construct and its relationship with regular exercise behavior have found that self-efficacy scores tend to increase as individuals progress through the stages of change toward regular exercise [19–21, 23].

Several studies on health behavior change have implemented interventions based on the TTM to increase PA, improve adherence to specific diets, or enhance compliance with pharmacological treatment [24–28]. For instance, a study conducted among adult Latina women evaluated the effect of an intervention grounded in Social Cognitive Theory to promote greater PA and found a significant increase in mean weekly minutes of PA from baseline to the final assessment [27].

In a study by Chen in Beijing that included adult patients recently diagnosed with hypertension, the intervention was based on the TTM and consisted of motivational sessions to promote adherence to pharmacological treatment. The intervention group (IG) showed significantly greater progression through the stages of readiness to take prescribed medications compared with the control group (CG). In addition, BP decreased significantly in the IG compared with the CG [24].

Theory-based interventions to promote PA behavior change appear to be more effective than those without a defined theoretical foundation. Therefore, to achieve lasting lifestyle changes, interventions should not only include a structured program targeting the specific behavior to be modified but also be grounded in theories that address the psychosocial factors motivating or supporting individuals throughout the process of health behavior change [22, 29, 30].

The high prevalence of non-communicable chronic diseases and their impact on adult population health, as well as the strain they place on public health systems, underscore the need for research on effective preventive strategies. The objective of this study was to evaluate the effect of a PA promotion intervention, based on a structured exercise program and the TTM, on blood pressure among adults with hypertension attending primary care services at the Mexican Social Security Institute in Aguascalientes. We hypothesized that by the end of the study, the intervention group would show lower blood pressure levels and a higher proportion of blood pressure control compared with the control group.

Methods

Study design

The study was designed as a randomized controlled trial comparing a PA promotion intervention—based on a structured exercise program and the behavioral change theory of the TTM—with an active standard-of-care control group. Participants were randomly assigned to either the control or intervention group in a 1:1 ratio using a computer-generated randomization list prepared by an individual not involved in the trial.

Participants and setting

The participants in this study were adults aged 40 to 70 years with hypertension. All were patients at a primary care unit of the IMSS in Aguascalientes, Mexico. Hypertension was diagnosed by family physicians following the IMSS clinical practice guidelines, which are periodically updated [31, 32]. All participants received care at Family Medicine Unit No. 1, located in Aguascalientes. The unit has 162,000 affiliates and provides approximately 252,000 family medicine appointments per year; and around 15,300 of the patients receiving care there have been diagnosed with high blood pressure. The study was conducted between August 2022 and December 2023 and was approved by the Local Research Committee (registration No. 2021-101-054). All participants provided informed consent. The study is registered at ClinicalTrials.gov (https://clinicaltrials.gov/study/NCT05680025; on December 26, 2022).

Patients with hypertension were invited to participate by a nurse or public health professional while waiting for follow-up visits at the primary care unit. Individuals with medical conditions that contraindicated participation in an unsupervised exercise program—such as myocardial infarction, acute congestive heart failure, unstable angina—were excluded from the study [13]. Throughout the study, participants continued to receive standard care for hypertension at the IMSS.

Baseline and end-of-study measurements

At the beginning and end of the study, primary and secondary outcomes, as well as other variables of interest—sociodemographic, health, PA, and dietary characteristics—were measured by trained health personnel who were blinded to participants’ group assignments.

Primary outcome

The primary outcome was the change in BP (SBP, DBP, and BP control). BP was measured by nurses using a mercury sphygmomanometer (DuraShock Gold Series Aneroid, Welch Allyn) at baseline and post-intervention. Measurements were taken in the morning (between 7:00 and 9:00 a.m.) in a quiet environment. Participants were instructed to avoid coffee or other caffeinated beverages, physical activity, and smoking for at least 30 min before their appointment, and to remain silent during the measurement. BP was recorded after participants had rested for 5 min in a seated position, with their back supported, feet flat on the floor, and right arm at heart level (at a 45-degree angle), with the bottom of the cuff placed approximately 1″ above the bend of the elbow and using the appropriate cuff size. Three measurements were taken using the auscultatory method at 1- to 2-minute intervals, and the average of the last two readings was used for statistical analysis [6, 33, 34]. Uncontrolled BP was defined as systolic blood pressure ≥ 130 mm Hg and/or diastolic blood pressure ≥ 80 mm Hg [10].

Secondary outcome

The secondary outcome was the Transition through the stages of change of the TTM. Participants’ stage of readiness for change was assessed using a questionnaire.

This construct evaluates the participant’s perceived stage of readiness for behavioral change, determined through a question that integrates the intention to engage in regular exercise with the timeframe for initiation, or for those already active, the duration of participation [20]. The question begins by defining Regular Exercise as follows:

Regular exercise is any planned activity (e.g., brisk walking, aerobics, running, cycling, playing soccer, etc.) performed to improve physical fitness. This activity should be done 3 to 5 times per week for at least 30 min per session. Exercise does not need to be painful to be effective, but it should be performed at a level that increases your breathing rate and makes you sweat.

Based on this definition, participants were asked:

Do you exercise regularly?

1. No, and I do not intend to start within the next 6 months.

2. No, but I intend to start within the next 6 months.

3. No, but I intend to start within the next 30 days.

4. Yes, I have been doing so for less than 6 months.

5. Yes, I have been doing so for more than 6 months.

Each response corresponds to a stage of readiness for change in the following order: 1: Precontemplation, 2: Contemplation, 3: Preparation, 4: Action, and 5: Maintenance [20, 35].

Sociodemographic, Health, PA, and dietary characteristics of the study sample

Participants completed questionnaires that included items on sociodemographic characteristics, health status, adherence to pharmacological treatment, psychosocial factors, PA, and frequency of food consumption. Additionally, at the end of the study, a questionnaire was administered to assess changes in PA and eating habits over the previous six months.

To quantify physical activity, the Physical Activity and Sedentary Behaviour Questionnaire (PASB-Q) developed by the Canadian Society for Exercise Physiology was used [36]. The questionnaire asks participants: “How many days per week do you do moderate-intensity to vigorous-intensity aerobic physical activity (MVPA), and on average, how many minutes do you engage in exercise at this level?” The number of days per week was multiplied by the average minutes per day of MVPA to determine whether participants met physical activity recommendations. The PASB-Q also assesses the frequency of muscle-strengthening exercises performed per week [36].

Individuals’ confidence in their ability to engage in exercise despite potential obstacles, or self-efficacy, was measured using an 18-item questionnaire. An example item is: “I believe I can exercise even when I am feeling anxious or when I have too much work to do at home.” Responses were recorded on a 5-point Likert scale ranging from “Not at all confident” to “Completely confident” [35, 37].

Height and weight were measured, and body mass index (BMI) was calculated. Participants were also asked about the frequency of food consumption over the past seven days using a questionnaire designed for this study ( Supplementary Material 1), which included components or food groups from the Dietary Approaches to Stop Hypertension (DASH) diet [38].

Adherence to pharmacological treatment was evaluated using the Morisky scale, which distinguishes between unintentional non-adherence (e.g., forgetting to take medication) and intentional non-adherence (e.g., skipping medication due to side effects). The questionnaire includes eight items: seven questions with “Yes = 0” or “No = 1” response options, and one final question with a Likert-type response scale. Patients were classified as having low adherence if their total score was < 6, medium adherence if the score ranged from 6 to 7, and high adherence if the score was 8 [39].

Study overview

Description of the intervention

Exercise program

The exercise program, developed by a kinesiologist, was designed to help participants become physically active by the end of the six-month intervention. The program was divided into three levels, each lasting two months. Across the three levels, routines progressively increased in duration and intensity. The sessions included a predominant component of aerobic exercises and a component of muscle-resistance exercises, in accordance with WHO recommendations and PA guidelines.

In total, participants had access to 13 exercise videos: 4 routines for the first level, 4 for the second, and 5 for the third. Each video featured a routine lasting between 30 and 45 min. For some exercises, alternative variations were demonstrated, allowing participants to select the version best suited to their ability. Additionally, each level included a warm-up video lasting 5 to 10 min. For the cool-down, a yoga routine adapted for patients with high blood pressure was provided for the first two levels, and a stretching routine for the third level ( Supplementary Material 2).

All participants began at Level 1, as even those already meeting the physical activity recommendations for adults could benefit from the program’s progressive structure, improved physical conditioning, and instruction on proper exercise technique to help prevent injury.

Delivery of the exercise program via weekly whatsapp videos

Participants assigned to the IG received the following each week:

1. one video featuring the scheduled exercise routine(s) with the prescribed weekly frequency, and.

2. a text message reminding them to complete the routines, accompanied by a video showing examples of self-selected physical activities that could be performed once or twice a week, depending on their level.

Participants had access to 12 “PA self-select” videos with options such as walking, dancing, therapeutic yoga, and strength and flexibility routines. Each message also included a YouTube link to access the videos. The purpose of including “PA self-select” options was to help participants become independent from the program routines over time.

Before the delivery of videos and messages began, participants were asked to sign a data privacy policy form.

During the first workshop, participants assigned to the IG received materials containing the exercise program, which was explained in detail. The materials included a USB drive and a printed manual, with the exercise routines both stored on the USB and printed in the manual. Providing the material in multiple formats allowed each participant to choose the most convenient way to follow the program. At the beginning of Level 2, participants also received a kit with three resistance bands.

The following precautions were taken in designing the exercise program to ensure the safety of participants: Participants with medical conditions that could limit their participation in the MPA were excluded from the study. At the beginning of the exercise program, participants were shown a video explaining the Borg scale (from 0 to 10), a self-perceived scale of physical effort. Participants were informed that the exercise program was designed so that the perceived physical effort would be between 3 and 6 points on the 10-point Borg scale. For each number on the scale, participants were given examples of the sensations they might experience and the changes in their breathing and heart rate. At the beginning of each routine, participants were informed of the session’s goal and the expected self-perceived physical effort on the Borg scale. They were also advised to avoid exceeding that limit and to pay attention to any signs of extreme fatigue, such as shortness of breath, muscle pain or fatigue, and dizziness.

In addition, the training sessions were designed to be progressive in terms of both the difficulty of the exercises and the perceived physical effort. Participants were instructed to respect their own limits and take breaks when needed to avoid any incidents. The Exercise Program did not include exercises that could cause a sudden increase in blood pressure, such as exercises that use the Valsalva maneuver or sprinting.

Workshops for the intervention group

Participants assigned to the IG were invited to attend six workshops held over a six-month period, with one workshop conducted each month. Each session was carried out with a small group of 15–20 participants to encourage discussion and active participation.

In the first workshop, general PA recommendations for adults with or without chronic conditions were discussed, using a brochure distributed to each participant. The details of study participation were also explained during this session.

The second workshop covered information on hypertension—including its definition and risk factors—as well as dietary recommendations for individuals with hypertension based on the DASH diet, supported by an informational brochure.

The remaining four workshops focused on promoting regular exercise. The promotion strategy was based on Bandura’s Social Cognitive Theory [40]. In each workshop, participants’ progress was monitored using a monthly self-report form for completed exercise routines, and achievements were highlighted to encourage motivation. Group discussions were used to strengthen self-efficacy, emphasize the benefits of exercise as identified by participants, and explore possible solutions to perceived barriers or challenges.

The main goal of these workshops was to enhance motivation and adherence to the recommended exercise guidelines. This was achieved through discussions about the benefits of regular exercise for managing participants’ health conditions and identifying barriers and potential solutions to following the exercise program.

The planning and coordination of the workshops were carried out by an interdisciplinary team composed of psychologists trained in the TTM, a nutritionist, a family physician, a nurse, and public health professionals.

Workshops for the control group

Participants in the CG were invited separately to attend two workshops, which were the same as the first two workshops offered to the IG. The first workshop covered general PA recommendations for adults, and the second addressed general information about hypertension and dietary recommendations for individuals with hypertension based on the DASH diet. Two brochures were used to guide group discussions on these topics. Additionally, during the first workshop, the details of participation in the study were explained.

Referral of control group participants to the social health care program

Participants in the CG were given a referral form for the IMSS Social Health Care Program, which is designed for users with chronic diseases. This program includes non-pharmacological treatment activities such as PA classes, psychology sessions, arts and crafts, and healthy eating courses. Alongside pharmacological treatment, these activities are part of the standard care that patients with hypertension should receive from the IMSS healthcare team. However, treating physicians do not always issue the referral, and patients who receive it may choose whether or not to enroll and participate in the program’s activities.

At the end of the study, after the final assessment, participants in the CG were granted access to the exercise program and all materials provided to the IG.

In summary, the intervention components by group are described in the following table:

Intervention group	Control group (usual care)
1. Baseline measurements.	1. Baseline measurements.
2. Delivery of the exercise program. Each week, two messages were sent via WhatsApp: (1) the routines scheduled for that week and the YouTube video link, and (2) a reminder.	2. Referral to the IMSS Social Health Care Program, a program for insured patients with chronic diseases. It offers a variety of courses and workshops, including recreational physical activity classes.
3. Attendance at six workshops: - Physical Activity Guide - DASH Diet (specific for patients with hypertension). - Four workshops on exercise promotion based on the TTM, addressing motivation, self-regulated learning, and self-efficacy.	3. Attendance at two workshops: - Physical Activity Guide - DASH Diet (specific for patients with hypertension)
4. Six-month follow-up measurements.	4. Six-month follow-up measurements.

Sample size

Sample size was calculated based on the following parameters: 80% power, 95% confidence level, a standard deviation of 12 mm Hg for SBP, and an estimated mean change in SBP of -5 mm Hg in the intervention group (IG) versus − 1.5 mm Hg in the control group (CG) [13, 41, 42]. Considering a potential 20% loss to follow-up, a total of 220 participants with hypertension was required for each study group.

Statistical analyses

Participant characteristics by assigned group were described using frequencies and percentages. Quantitative variables with a normal distribution were summarized using the mean and standard deviation, while those without a normal distribution were summarized using the median and the 25th and 75th percentiles. Baseline characteristics were compared between groups to verify that random assignment resulted in comparable groups. Depending on the distribution of the variables, Student’s t test, Mann-Whitney test, Fisher’s χ² test, or Pearson’s χ² test was used.

The effect of the intervention on the primary outcome—changes in systolic and diastolic BP and BP control—was evaluated. To compare mean systolic and diastolic BP within groups at baseline and at the end of the study, the paired t test was used. To assess differences between the means of change (difference-in-differences) in SBP and DBP between groups at the end of the study, Student’s t test was applied. The McNemar χ² test was used to compare changes in BP control within groups; and to evaluate between-groups differences in the proportion of participants with controlled BP at the end of the study, test of difference of proportions to independent samples was applied. Confidence intervals (CI) were computed at the 95% level.

To evaluate the secondary outcome—transitions in stages of change toward exercising—the proportions of participants in the different stages of readiness to exercise regularly were compared between groups at baseline and at the end of the study using the Pearson χ² test. For within-group comparisons of transitions in stages of readiness to change, the symmetry test was applied.

To determine whether other specific behavioral changes occurred, we examined changes in related behavioral variables such as self-efficacy, minutes per week of PA, exercise patterns, diet, and medication adherence. The self-efficacy score was rescaled to a range of 0 to 100 and analyzed both as a continuous variable and as a dichotomous variable, using a cutoff point of ≥ 75% and < 75%. To compare changes between groups, Student’s t test, Pearson’s χ² test, and the Mann-Whitney test were used. To compare changes within groups, the paired t test, McNemar’s χ² test, and the Wilcoxon signed-rank test were applied. All analyses were performed using STATA version 18 statistical software (StataCorp, College Station, TX).

Results

This study included 440 adults with hypertension who were patients at a primary care unit of the IMSS in Aguascalientes. A total of 219 participants were assigned to the IG and 221 to the CG. Between the baseline and final measurements, there was a 5.9% loss to follow-up in the IG (n = 13) and a 3.6% loss in the CG (n = 8). In the IG, 89.5% (n = 196) of participants received the intervention materials, including videos and the printed exercise program. Regarding workshop attendance, 85.4% (n = 187) of participants attended the first two workshops, and 87.7% (n = 192) attended the remaining four. In the CG, 84.2% (n = 186) attended the two planned workshops (Fig. 1).

Fig. 1.

Participant flow diagram

Baseline characteristics by group

Table 1 presents the sociodemographic and health characteristics of participants by assigned group (intervention or control). No significant differences were observed between groups at baseline. The mean age of participants was 56.5 ± 7.7 years in the IG and 57.3 ± 7.5 years in the CG. Women predominated in both groups, representing 84.5% of the IG and 87.3% of the CG. Most participants (approximately 65%) were married or in a common-law union. The most common education levels were primary and secondary school (35.2% and 41.2% for primary, 33.4% and 30.3% for secondary). Most participants reported being homemakers—49.3% in the IG and 56.2% in the CG (Table 1).

Table 1.

Socio-demographic and health characteristics

Variables	Intervention group n= 219			Control group n= 221		P value
	n		%	n	%
Age (years) Mean ± SD a	56.5±7.7			57.3±7.5		0.278
Sexb
Male	34		15.5	28	12.7
Female	185		84.5	193	87.3	0.389
Marital Status b
Single	33		15.0	39	17.6
Married/Common-law union	142		64.9	147	66.6
Divorced/Separated	19		8.7	10	4.5
Widowed	25		11.4	25	11.3	0.338
Education Level b						0.181
Primary or less	77		35.2	91	41.2
Secondary	73		33.4	67	30.3
High school	39		17.8	24	10.8
Technical	15		6.8	21	9.5
University or higher	17		6.8	18	8.2
Occupation b
Employed	87		39.7	77	34.8
Homemaker	108		49.3	124	56.2
Retired	24		11.0	20	9.0	0.356
Systolic Blood Pressure (mmHg)Mean ± SDa	128.2±13.1			129.5±14.1		0.314
Diastolic Blood Pressure (mmHg)Mean ± SDa	81.6±8.6			81.0±8.0		0.400
Blood Pressure Control (<130/<80 mmHg)b
Yes	56	25.6		62	28.1
No	163	74.4		159	71.9	0.557
Adherence to Pharmacological Treatment for Hypertensionc
Low	88	40.2		94	42.5
Medium	127	58.0		124	56.1
High	4	1.8		3	1.4	0.794
Comorbiditiesb
Type 2 Diabetes	114	52.0		108	48.9
Hypothyroidism	25	11.4		26	11.8
Other	34	15.5		39	17.6
None	46	21.0		48	21.8	0.906
Smoking Statusb
Yes	31	14.2		24	10.9
No	188	85.8		197	89.1	0.296
Nutritional Status According to BMIb
Normal	22	10.0		25	11.4	0.848
Overweight	88	40.2		80	36.2
Obesity	109	49.8		116	52.4
Aerobic exercise (min/week), median (p25-p75)d	0 (0 – 120)			0 (0 – 120)		0.508
Meets the aerobic exercise recommendation (≥150 min/week)b
Yes	49	22.4		44	19.9
No	170	77.6		177	80.1	0.527
Meets the endurance exercise recommendation (≥2d/week)b
Yes	14	6.4		12	5.4
No	205	93.6		209	94.6	0.668

^aStudent´s t test

^bPearson´s χ² test 

^cFisher´s Exact test

^dMann-Whitney test

Baseline characteristics related to blood pressure and comorbidities

The mean SBP was 128.2 ± 13.1 mm Hg and the mean DBP was 81.6 ± 8.6 mm Hg in the IG, while in the CG, the means were 129.5 ± 14.1 mm Hg and 81.0 ± 8.0 mm Hg, respectively. A total of 25.6% of participants in the IG and 28.1% in the CG had controlled BP (< 130/<80 mm Hg) (Table 1). The mean duration of hypertension since diagnosis was 10 years in both groups.

The most common comorbidity was type 2 diabetes, reported by 52.0% of participants in the IG and 48.9% in the CG. Obesity was present in 49.8% of the IG and 52.4% of the CG, while only 10.0% of participants in the IG and 11.4% in the CG had a weight appropriate for their height. The percentage of smokers was 14.2% in the IG and 10.9% in the CG (Table 1).

Medium adherence to pharmacological treatment for hypertension control was the most common, observed in 58.0% of the IG and 56.1% of the CG. High adherence was the least frequent, reported by 1.8% of participants in the IG and 1.4% in the CG (Table 1).

Physical activity at baseline

The median and 25th to 75th percentile of minutes per week spent performing MVPA was 0 (0–120) in both the intervention and control groups. Compliance with the recommendation to engage in at least 150 min of MVPA per week was 22.4% in the IG and 19.9% in the CG. Regarding resistance exercise performed at least two days per week, 6.4% of participants in the IG and 5.4% in the CG met this recommendation (Table 1).

Primary outcome variables

Primary outcome

Difference in the means of change in SBP and DBP between groups

Both groups showed a reduction in mean systolic and diastolic blood pressure. In the IG, SBP decreased by 7.9 mm Hg [95% CI: 5.8–10.0], while in the CG, the reduction was 4.0 mm Hg [95% CI: 1.9–6.2]. The intervention effect on SBP corresponded to a reduction of 3.9 mm Hg [95% CI: 0.9–6.9]. DBP decreased by 5.9 mm Hg [95% CI: 4.4–7.4] in the IG and by 2.7 mm Hg [95% CI: 1.4–3.9] in the CG. The intervention effect on DBP was a reduction of 3.2 mm Hg [95% CI: 1.2–5.2] (Table 2).

Table 2.

Effectiveness of the intervention: differences between-groups in the means of change in SBP and DBP

Variables	Intervention groupn= 205		Control groupn= 213
	Baseline	Final	Baseline	Final
Systolic Blood Pressure change (mm Hg)
Mean ± SD	128.3±13.2	120.4±12.5	129.6±14.2	125.5±14.5
Within group difference
Mean [95% CI]	7.9 [5.8 – 10.0]		4.0 [1.9 – 6.2]
P valuea	<0.001		<0.001
Difference of the means of change in SBP between-groups [95% CI]	3.9 [0.9 – 6.9]
P valueb	0.012
Diastolic Blood Pressure change (mm Hg)
Mean ± SD	81.6 ±8.7	75.7±8.6	81.0±8.0	78.3±8.6
Within group difference
Mean [95% CI]	5.9 [4.4 – 7.4]		2.7 [1.4 – 3.9]
P value a	<0.001		<0.001
Difference of the means of change in DBP between- groups [95% CI]	3.2 [1.2 – 5.2]
P valueb	0.001

^aPaired t test 

^bStudent´s t test

At the end of the study, the percentage of participants with controlled BP was higher in the IG than in the CG: 56.6% [95% CI: 49.5–63.5] versus 41.8% [95% CI: 35.1–48.7], with a between-group difference of 14.8% [95% CI: 5.3–24.3] (Table 3).

Table 3.

Effectiveness of the intervention: difference in the proportion of participants with Controlled Blood Pressure (<130/<80 mm Hg)

	Intervention groupn=205		Control Groupn=213
	Baseline	Post-intervention	Baseline	Post-intervention
Percentage of participants with controlled BP	25.8	56.6	28.6	41.8
Within-group difference, % [95% CI]	30.7 [21.5 – 40.0]		13.1 [3.9 – 22.4]
P value a	<0.001		0.004
Between-groups difference, % [95% CI]	14.8 [5.3 – 24.3]
P value b	0.002

^aMcNemar’s Χ2 test

^bTest difference between proportions for two independent samples

Effectiveness of the intervention on transitions in stages of readiness for change

At baseline, most participants in both the IG (63.0%) and the CG (61.1%) perceived themselves to be in the motivational stages of readiness for change—that is, stages in which individuals are not yet engaging in regular exercise (precontemplation, contemplation, and preparation). In the IG, 6.3% were in precontemplation, 29.8% in contemplation, and 25.8% in preparation. In the CG, the corresponding proportions were 6.1%, 36.2%, and 18.8%.

In the volitional stages—those in which participants reported engaging in regular physical activity—37.0% of participants in the IG and 39.0% in the CG were represented. Specifically, in the IG, 9.8% were in the action stage and 28.3% in the maintenance stage, while in the CG, 15.0% were in action and 23.9% in maintenance.

At the final measurement, notable shifts were observed. In the IG, 72.2% of participants perceived themselves to be in the volitional stages, compared with 47.4% in the CG. Specifically, 22.4% and 49.8% of the IG were in the action and maintenance stages, respectively, versus 17.8% and 29.6% in the CG. A statistically significant transition between stages was identified within both groups, and a significant difference in readiness stages was observed between groups at the end of the study (Fig. 2).

Fig. 2.

Stages of Readiness to Change Within and Between Groups

Between-group comparison at baseline: p = 0.150; at final measurement: p = 0.000 (Pearson’s χ² test). Within-group comparison: IG, p < 0.001; CG, p = 0.026 (symmetry test)

To identify which specific behavior changes contributed to improvements in systolic and diastolic blood pressure, BP control, and stages of change, we examined related variables such as self-efficacy for regular exercise, PA, exercise patterns, adherence to drug treatment, and diet.

Regarding self-efficacy for engaging in regular exercise, no differences were observed between groups. At the end of the study, the mean self-efficacy score was 52.4 ± 20.6% in the IG and 50.2 ± 19.1% in the CG. A significant between-group difference was found in the minutes per week dedicated to aerobic physical activity. The median and 25th–75th percentiles were 20 (0–120) minutes/week in the IG and 0 (0–80) in the CG. A difference was also observed in the percentage of participants performing resistance exercises at least two days per week: 24.9% in the IG versus 10.3% in the CG (Table 4).

Table 4.

Self-Efficacy and Compliance with the Exercise Recommendations at the Beginning and End of the Study

Variables	Intervention Group n=205		Control Group n=213		Between groups at EofS, p value
	Baseline n (%)	Final n (%)	Baseline n (%)	Final n (%)
Self-Efficacy *
Mean ± SD	53.1±18.1	52.4±20.6	50.3±19.6	50.2±19.1	0.236 b
Within group, p value a	0.592		0.947
Self-Efficacy
≥ 75%	22 (10.7)	26 (12.7)	22 (10.3)	22 (10.3)
< 75%	183 (89.3)	179 (87.3)	191 (89.7)	191 (89.7)	0.450 d
Within group, p value c	0.493		1.000
Aerobic exercise (min/week)
Median (p25-p75)	0 (0 – 120)	20 (0 – 120)	0 (0 – 120)	0 (0 – 80)	0.002 f
Within group, p value e	0.724		0.011
Meets the aerobic exercise recommendation (≥150 min/week)
Yes	47 (22.9)	47 (22.9)	42 (19.7)	39 (18.3)
No	158 (77.1)	158 (77.1)	171 (80.3)	174 (81.7)	0.243 d
Within group, p value c	1.000		0.647
Meets the endurance exercise recommendation (≥2d/week)
Yes	14 (6.8)	51 (24.9)	12 (5.6)	22 (10.3)
No	191 (93.2)	154 (75.1)	201 (94.4)	191 (89.7)	0.000 d
Within group, p value c	0.000		0.059

* Scale variable, values 0-100%, EofS: End of Study

^a Paired t-test, ^b Student´s t test, ^c McNemar´s χ² test, ^d Pearson´s χ² test

^e Wilcoxon signed-rank test, ^f Mann-Whitney test

In addition, 54.4% of participants in the IG reported making changes to their exercise habits. The most frequent change was the incorporation of the exercise routines proposed in the intervention (56.4%), followed by an increase in the amount or intensity of PA (21.8%). In contrast, only 18.4% of participants in the CG reported any changes in their PA. Among these, the most common changes were increasing the amount or intensity of exercise (34.2%) and exercising more frequently (29.0%). However, 23.7% of CG participants who reported a change stated that it involved doing less exercise due to musculoskeletal soreness, compared with only 1.8% in the IG. The proportion of participants who made changes in PA, as well as the types of changes reported, differed significantly between groups (Table 5).

Table 5.

Changes in Physical Activity

Type of Change	Intervention group111 (54.4%)		Control group38 (18.4%)		P value a
	n	%	n	%
Exercise study routines	62	56.4	0	0.0
Increased (amount and/or intensity)	24	21.8	13	34.2
Walking	11	10.0	5	13.2
Exercised more	8	7.3	11	29.0
Exercised less	2	1.8	9	23.7
Other	3	2.7	0	0.0	0.000

^a Fisher´s exact test

Of the participants in the control group who received a referral to the IMSS Social Health Care Program for patients with chronic diseases, only 11 attended the courses. No differences were found between groups in adherence to pharmacological treatment for hypertension. At the final measurement, according to the Morisky adherence scale, 35.7% of participants in the IG were classified as having low adherence, 62.0% as medium, and 2.3% as high. In the CG, the corresponding proportions were 41.8%, 56.8%, and 1.4%.

Regarding dietary changes, 44.4% of participants in the IG and 40.4% in the CG reported making modifications. The main changes in both groups included reducing soda intake, eating fewer cereals and salty snacks, and adding less salt or sugar to meals. These differences were not statistically significant between groups.

Discussion

The results of this study suggest that a six-month exercise promotion intervention, based on a specific exercise program and guided by a behavior change theory—the TTM—enabled participants in the IG to lower systolic and diastolic BP, improve BP control, and achieve greater progression through the stages of change compared with the usual-care group.

Participants in the IG showed a greater reduction in mean systolic and diastolic blood pressure compared with the CG. The effect of the intervention was a reduction of 3.9 mm Hg [95% CI: 0.9–6.9] in SBP and 3.2 mm Hg [95% CI: 1.2–5.2] in DBP. Moreover, BP control was 14.8% [95% CI: 5.3–24.3] higher in the IG than in the CG.

The IG also showed significantly greater stage transitions in readiness to engage in regular exercise. In the IG, the proportion of participants in the motivational stages decreased from 63% at baseline to 28% at the end of the intervention, while those in the volitional stages (action and maintenance) increased from 37% to 72%. In the CG, the proportion in motivational stages decreased from 61% to 53%, and those in volitional stages increased from 39% to 47%.

These findings are consistent with previous research demonstrating positive effects on BP and hypertension control through lifestyle interventions grounded in health behavior change theories and models. The literature emphasizes that adopting and maintaining regular physical activity is the central challenge to achieving lasting health benefits [18]. Interventions based solely on structured exercise programs often fail to produce sustained behavior change or long-term exercise adherence. Therefore, programs that combine motivational components with structured exercise routines—such as the one implemented in this study—have been shown to be more effective in promoting and maintaining regular physical activity [7, 11, 18, 24, 28, 43–47].

In the study by Rodríguez et al., patients with uncontrolled hypertension in the United States were assigned to three groups: a behavioral intervention adapted to the TTM with personalized telephone counseling, a non-personalized health education group with general counseling, and a usual-care group. The intervention lasted six months, followed by six months of observation without intervention. Both intervention groups achieved better blood pressure control compared with the usual-care group. At 12 months, the odds of BP control were 1.84 times higher (95% CI: 1.28–2.67) in the behavioral stage-matched intervention group and 1.48 times higher (95% CI: 1.02–2.14) in the non-tailored health education group compared with the usual-care group. A significant reduction in SBP was observed only in the behavioral stage-matched group, with a decrease of 2.58 mm Hg (95% CI: 0.27–5.33) compared with the usual-care group [28].

In a randomized clinical trial conducted in Pakistan with 240 participants with hypertension, a three-month multicomponent intervention—including medication adjustments, adherence monitoring, a sodium-restricted diet, and physical activity—led to a significant reduction in SBP and improved BP control in the intervention group compared with the controls [44].

Similarly, in a longitudinal study conducted in Turkey with 133 adults attending primary care, all diagnosed with hypertension and presenting with overweight or obesity, a six-month intervention based on the TTM was implemented to promote both PA and healthy eating. The intervention resulted in reductions in SBP, plasma glucose, triglycerides, and body weight [48].

The results of these studies, together with our findings, consistently show that educational interventions targeting key components of hypertension management—such as PA, diet, and medication adherence—can lead to improvements in blood pressure levels and BP control. These outcomes can be achieved through both stage-matched and non-stage-matched approaches [28, 29].

In our study, changes were observed in the stages of readiness to engage in regular exercise, with the IG showing significantly greater stage transitions compared with the CG. In a non-randomized feasibility study involving Malaysian adults, a PA promotion intervention based on the TTM was implemented. Weekly 90-minute aerobic sessions were conducted for six months, accompanied by monthly motivational talks during follow-up. The results showed significant differences in stage transitions regarding participants’ readiness for change. In the experimental group, 64% were in the motivational stages and 36% in the volitional stages at baseline; by the end of the intervention, these figures shifted to 28% and 72%, respectively. In contrast, no significant changes were observed in the CG [29]. These findings align with those of our study, suggesting that PA promotion interventions framed within the TTM can foster favorable transitions between stages of change, reflecting a shift toward the adoption and maintenance of regular exercise—even when the intervention is not tailored to participants’ initial stage of change.

At the end of our study, 23.0% of participants in the IG and 18.3% in the CG met the recommendation of engaging in aerobic PA for at least 150–300 min per week. At the final measurement, the weekly minutes of aerobic exercise differed between groups, with the IG reporting higher levels of activity. However, total weekly exercise time in both groups remained below the recommended level. Additionally, 24.9% of participants in the IG and 10.3% in the CG met the recommendation for muscle-resistance exercise (≥ 2 days per week).

Nevertheless, even without achieving the recommended 150–300 min per week of MVPA, small increases in PA have been associated with beneficial effects on BP levels and BP control [13, 14, 29, 41, 44, 49]. In an observational study conducted among Japanese adults with hypertension, greater reductions in BP were observed among those who engaged in 61 to 90 min of aerobic exercise per week compared with those who exercised only 30 min per week. However, increasing exercise duration beyond 91 min per week did not yield additional significant reductions in BP levels [44]. It is possible that non–face-to-face PA interventions—such as the one in our study, which used video materials for participants to follow the proposed exercise program—are less likely to produce large increases in exercise duration (minutes per week) compared with more direct and personalized approaches [29, 44]. The main advantage of using videos with exercise routines for PA promotion is the broader reach and lower cost, which facilitate large-scale implementation. However, future research could evaluate the intervention by inviting participants to meet to exercise following the videos, possibly with the participation of an instructor to facilitate and motivate them to follow the Exercise Program.

However, our intervention combined this virtual modality with an in-person component: the workshops. Both groups attended two workshops—one with information on hypertension and dietary recommendations for patients with hypertension and another on recommended physical activity for adults—while the IG participated in four additional workshops specifically focused on promoting PA. This combination of strategies can enhance adherence and engagement, partially compensating for the limitations of purely virtual interventions. In this study, in both groups, more than 84% of participants attended the workshops. Participants were encouraged to follow the exercise program during the workshops. However, we do not have an exact measure of the proportion of participants in the IG who watched and followed the exercise videos. This is because the exercise program was delivered to participants through different formats: a USB drive, a printed manual, and a link to the videos sent via WhatsApp messages. These different modes of access to the Exercise Program were used due to the wide age range of participants (40–70 years) and their varying levels of ability and access to electronic media. However, at the end of the study, we did not ask participants which medium they used to perform the exercise routines. This information would have been important for planning future studies and for implementing a similar program. Nevertheless, when asked about changes in their exercise habits over the past 6 months, 54.4% of participants in the IG reported having made changes, compared with 18.4% in the CG.

The participants were encouraged to follow the program during the workshops. However, at the end of the study, we did not ask participants about the medium they used to perform the exercise routines. This would have provided important information for planning future studies and implementing a similar program. However, we asked about changes in their exercise habits over the past 6 months, 54.4% of the IG participants reported having made changes, compared to 18.4% of the CG.

In our study, in which participants were recruited from a primary care medical unit during follow-up visits for hypertension management, 86% of participants were women. Several studies have reported that men tend to use healthcare services less frequently than women [5, 50]. In a systematic review of PA interventions—randomized controlled trials conducted among Hispanic adults in the United States—11 of the 21 included studies involved only women, and in none of the remaining 10 studies did male participants exceed 36% [33]. However, because men are at high risk for cardiovascular diseases, it is essential to develop targeted strategies to encourage their participation in preventive health activities, self-care, and the adoption of healthy lifestyles.

This trial has several important strengths. One of them is its design—a randomized controlled trial—which allows the results to be interpreted as causal effects of the intervention. Moreover, the study achieved a low rate of loss to follow-up, reducing the likelihood of bias and strengthening the validity of the findings.

Another strength is that the exercise program was specifically designed for patients with hypertension, taking into account that they often have comorbidities such as overweight or obesity. Consequently, the execution techniques of certain exercises were adapted to these conditions to facilitate participants’ ability to perform the routines as intended.

One limitation of this study is that the exercise program was not tailored to the stage of readiness for change in which participants perceived themselves at baseline. It was assumed—based on findings from previous studies and supported by our baseline data—that most participants were not engaging in regular physical, and they could benefit from the program’s progressive structure, improved physical conditioning, and instruction on proper exercise technique to help prevent injury, that combining both aerobic and strength/resistance exercises. Therefore, all participants began the program at the same level, regardless of their initial stage of change.

Finally, although the physical activity promotion workshops were grounded in the TTM—encouraging reflection on the perceived benefits of exercise, addressing barriers, and reinforcing progress through positive motivation—they were not stage-matched due to logistical constraints. This lack of alignment between the intervention and participants’ self-perceived stage of readiness for change may have limited its potential to maximize engagement and progress. However, as noted in other studies where interventions were not stage-matched, positive effects on BP have nonetheless been observed.

Our findings should be interpreted in light of the study’s setting and design. The participants in this study were patients with hypertension receiving care at the IMSS in a single primary care center in the city of Aguascalientes, which may limit the generalizability of the results to other regions or contexts. The sample represents Mexican adults with hypertension living in an urban environment—primarily women aged 40 to 70 years, receiving primary care, and frequently presenting comorbidities such as type 2 diabetes and obesity. Therefore, the results may be generalizable to other healthcare contexts with similar populations and conditions, particularly in Latin American countries with comparable healthcare systems and epidemiological profiles.

Conclusions

The results of this study are consistent with previous research showing positive effects of PA promotion interventions framed within behavior change theories and models, such as the TTM. This study demonstrated greater reductions in mean systolic and diastolic blood pressure, a higher percentage of patients with controlled BP, and greater progression through the stages of readiness for change in the IG compared with the CG.

Increasing PA through a structured exercise program is recommended for adults with hypertension. Such programs should be implemented at the primary level of healthcare and guided by behavior change theories to promote the adoption and maintenance of regular exercise. Further research is needed to support the large-scale implementation of these strategies in broader healthcare programs.

Abbreviations

ENSANUT

National Health and Nutrition Survey

BP

Blood Pressure

IMSS

Mexican Social Security Institute

PA

Physical Activity

SBP

Systolic Blood Pressure

DBP

Diastolic Blood Pressure

TTM

Transtheoretical Model

IG

Intervention group

CG

Control group

PASB-Q

Physical Activity and Sedentary Behavior Questionnaire

MVPA

Moderate or vigorous physical activity

MPA

Moderate physical activity

BMI

Body Mass Index

DASH

Dietary Approaches to Stop Hypertension

CI

Confidence Interval

Authors’ contributions

P-L J, DX, T-D L, A-G CI, and P-A CA conceptualized the study, contributed to methodology, data curation, and writing of the original draft, as well as to writing—review and editing. Muñoz S contributed to formal analysis and writing—review and editing. P-A CA, P-L J, and DX contributed to project administration and funding acquisition. MS, M-A G, and V-G J contributed to study conceptualization, methodology, and writing—review and editing. All authors read and approved the final manuscript.

Funding

This research was funded by the Health Research Coordination of the Mexican Social Security Institute, Grant: 2023 Funding Call: Priority Health Topics, Vulnerable Populations, and Emerging Topics.

Jannett Padilla-López (CVU 509249) received a scholarship from the National Council for the Humanities, Science and Technology (CONAHCYT) and from the Mexican Social Security Institute through the Research Training Support Program.

Data availability

All data generated or analyzed during this study are included in this published article [Supplementary Material 3, 4].

Declarations

Ethics approval and consent to participate

The study received approval from the Local Research Committee in Aguascalientes of the Mexican Social Security Institute (Registration No. R-101-2021-054, dated November 12, 2021). The research was conducted in full compliance with the Declaration of Helsinki. All procedures involving human participants adhered to the ethical standards outlined in the Declaration of Helsinki and applicable national regulations. Informed consent was obtained from all individuals prior to their participation in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.