Effects of Different Inspiratory Muscle Training Protocols on Exercise Capacity, Respiratory Muscle Strength, and Health-Related Quality of Life in Patients with Hypertension

Aim This study aimed to explore how varying inspiratory muscle training workloads affect exercise capacity, health-related quality of life (HrQoL), depression, peripheral and respiratory muscle strength, pulmonary function, dyspnea, fatigue, and physical activity levels in hypertension (HT) patients. Methods A randomized, controlled three-arm study. Forty-five patients (58.37 ± 8.53 y, 7F/38M) with HT received IMT (7 days/8 weeks) by POWERbreathe® Classic LR device and were randomized to control group (CG, 10% maximal inspiratory pressure (MIP), n: 15), low-load group (LLG, 30% MIP), and high-load group (HLG, %50 MIP). Exercise capacity, HrQoL, depression, peripheral and respiratory muscle strength, pulmonary function, fatigue, physical activity level, dyspnea, and sleep quality were evaluated before and after the training. Results Exercise capacity, physical functioning, peripheral muscle strength, and resting dyspnea were statistically significantly improved in HLG and LLG after the training compared to CG (p < 0.05). Similar improvements in perception of depression, fatigue, and sleep quality were seen within and between the groups (p > 0.05). Statistically significant differences were found within all the groups in terms of MIP and PEF values of respiratory functions (p < 0.05). The superior improvement in the physical activity level was found in the HLG (p < 0.05). Discussion. High-load IMT was particularly effective in increasing physical activity level, peripheral muscle strength, exercise capacity, and improved HrQoL. Low-load IMT was effective in reducing dyspnea and improving respiratory function. Device-guided breathing exercises decreased blood pressure, improved sleep quality, and strengthened respiratory muscles. IMT, an efficient method, is suggested for inclusion in rehabilitation programs due to its capacity to increase physical activity, exercise capacity, and peripheral muscle strength, enhance HrQoL and respiratory function, and alleviate dyspnea. Also, the efficacy of IMT should be investigated with different training protocols such as endurance IMT or functional IMT in HT patients.


Introduction
Hypertension, a prevalent chronic condition, afects over a billion individuals globally, elevating the risks of cardiovascular, cerebrovascular, and renal diseases.Its prevalence rises with age, resulting in substantial healthcare expenses [1].Increases in blood pressure above 115 mmHg (systolic) and 75 mmHg (diastolic) worsen the prognosis [2,3].A vigorous public awareness campaign is needed to alleviate the burden of HT and its complications.Besides medication, it is advised to consider the following: (1) decrease sodium intake, (2) prevent obesity and weight gain, (3) enhance physical activity, (4) raise disease awareness, and (5) better manage blood pressure while educating about HT and its multisystem complications [4].It is therefore not surprising that more attention is being paid to the role of nonpharmacological interventions.Lifestyle modifcations proven to lower blood pressure include quitting smoking, reducing salt intake, weight loss, increased physical activity, self-monitoring dietary changes, and adopting strategies to enhance adherence to a healthy lifestyle.[4].In addition, respiratory interventions have also been suggested to reduce BP.Inspiratory muscle training (IMT) is a respiratory training modality in which patients breathe against a load calculated from their maximum static inspiratory pressure.Among hypertensive patients who received inspiratory muscle training (IMT) at 30% of maximum inspiratory pressure (MIP) over 8 weeks, there was an observed decrease in systolic and diastolic blood pressure levels during the daytime (−7.9 and −5.5 mmHg, respectively).Additionally, this intervention led to reduced sympathetic modulation and increased parasympathetic modulation [5].Ferreira et al. showed that similar to aerobic training, IMT reduced sympathetic activity and improved endothelial function in controlled hypertensive patients after 12 weeks of training [6].Inspiratory muscle training has been shown to attenuate metaborefex in healthy subjects [7] and people with chronic heart failure [8].In healthy subjects, IMT increased exercise time on a bicycle ergometer by 14% [9]; a similar intervention has also been shown to alleviate quadriceps fatigue during exercise [10].Nagy et al. [11] found that exercise capacity was associated with depression, fatigue, and physical function.Research on the efcacy of breathing exercises for hypertensive patients highlights their ability to lessen stress, anxiety, and depressive symptoms, enhance wellbeing and sleep quality, and ofer general benefcial efects [12].However, there are few studies on the efectiveness of inspiratory muscle training in HT patients.In addition, the efective inspiratory workload to improve exercise capacity, HrQoL, and peripheral muscle strength of HT patients is unclear.In this study, we aimed to explore how varying inspiratory muscle training workloads afect exercise capacity, health-related quality of life (HrQoL), depression, peripheral and respiratory muscle strength, pulmonary function, dyspnea, fatigue, and physical activity levels in hypertension (HT) patients.

Materials and Methods
HTpatients who were followed and treated in the Cardiology Department of Hatay Mustafa Kemal University Research and Application Hospital were included in the training program.We calculated that the study should include a total of 45 HT patients by taking into account the maximum inspiratory pressure (MIP) value of a similar study in the literature [5], with 80% power and 5% type 1 error and dropout from the study.
Te inclusion criteria are as follows: (1) Being in an age range of 18-79 years (2) Having a hypertension diagnosis (3) Being in a stable clinical status for the last month Te exclusion criteria are as follows: (1) Having neurological, orthopedic, and chronic respiratory diseases and active malignancy (2) Having unstable heart disease, NYHA (New York Heart Association) IV heart failure, or uncontrolled hypertension (3) Having acute infection (4) History of organ or bone marrow transplantation (5) Having a hemoglobin level <9 g/dL (6) Being pregnant or lactating Te study with protocol number 22/04/2021-17 was approved by the University's Clinical Research Ethics Committee.Te Declaration of Helsinki was followed in the conduct of this investigation.Before each participant took part, they all signed informed consent papers.

Study Protocol.
Te current study has three arms and is prospective, randomized, and controlled.Computer-based block randomization was used to allocate patients at random to the control group (CG, n: 15), low-load group (LLG, n: 15), or high-load group (HLG, n: 15).Individuals diagnosed with HT were evaluated at diferent times and included in the training program.CG performed IMT 10% of MIP, LLG 30%, and HLG 50% of MIP during seven days/week, with diferent loads of the respiratory muscle device for seven days/week for eight weeks.For eight weeks, groups received training for 30 minutes a day and seven days a week.Te diaphragm and rib cage muscles were strengthened during training by utilizing a pressure threshold-loading device (POWERbreathe VR Classic Low Resistance, IMT Technologies Ltd., Birmingham, UK), which is used to inhale against the same pressure load during each inhalation.Prior to training, patients were instructed to develop adequate breathing skills during a one-week familiarization period.Each group's participants underwent six sessions at home and one session under close supervision in the cardiology clinic (seven days/week).Troughout sessions, patients' vital signs were observed.Each patient received individual care during the program, with a focus on monitoring.Daily record charts were required and reviewed to emphasize training control.Regular calibration, follow-up, and device control occurred at specifed intervals.Patients were instructed not to alter their pressure loads.

Measured Parameters.
All groups underwent pre-and posttest evaluations at baseline and at the end of the 8th week.
Demographic, physical, and physiologic characteristics were recorded by asking the patients and from the patient fle.Exercise capacity was evaluated with the 6-minute walk test (6MWT).ATS (American Toracic Society) criteria were taken into consideration and the subjects rested for at least half an hour before starting the test.Participants walked briskly at their own walking pace for 6 minutes on a 30meter straight corridor.Te distance reached at the end of the test was recorded in meters [13].HrQoL was evaluated with SF-36V2.SF-36V2 has eight subparameters: "pain, physical functionality, general health perception, emotional role limitations, physical role limitations, social functionality, energy/fatigue, and mental health" [14].Te Hospital Anxiety and Depression Scale (HADS) was used to assess the depression.Te cut-of score of depression and anxiety subscales was 8 [15].Peripheral muscle strength and hand grip strength were evaluated with a portable dynamometer,

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International Journal of Clinical Practice and the values obtained were recorded in Newton (N)/kgf/ Pascal.Peripheral muscle strength was measured seated, employing a hand-held dynamometer (J-Tech Power Track Commander, Baltimore, MD, USA).Tis device, known for its portability and cost-efectiveness, serves as an alternative to isokinetic machines and ofers greater sensitivity in detecting changes in muscle strength compared to manual muscle tests [16][17][18].Respiratory muscle strength "maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP)" was calculated with a portable, electronic mouth pressure measuring device.Te best of the measurements was recorded for analysis [19].Te pulmonary function test was measured with a portable spirometer (Spirobank II ® Moggiolino, Rome, Italy).Te best of 3 technically acceptable maneuvers with 95% agreement was selected and recorded [20].Te Fatigue Severity Scale used for fatigue assessment was scored between 9 and 63.A score of 36 or higher indicates severe fatigue [21].Physical activity level was measured with the International Physical Activity Questionnaire (IPAQ).Te international validity and reliability studies of this questionnaire were performed by Craig et al. [22].In this questionnaire, which provides information about the time spent in sitting, walking, moderately vigorous activities, and vigorous activities, the criterion for evaluating all activities is that each activity is performed for at least 10 minutes at a time.A score is obtained as "MET-minutes/week" by multiplying minutes, days, and MET values (multiples of resting oxygen consumption) [22].Dyspnea was recorded using the Modifed Medical Research Council (mMRC) Dyspnea and Borg Dyspnea Scales.Patients rate their level of dyspnea at rest and/or when exercising on a subjective measure called the Modifed Borg Scale (MBS), which ranges from 0 to 10. Te lowest score of 0 indicates "none" and the highest score of 10 indicates "very severe" dyspnea.Te mMRC is a scale used to assess breathlessness during activities of daily living.Patients select the statement that best describes their perceived shortness of breath from among 5 statements about shortness of breath.Scoring is performed on a 0-4 scale [23,24].Te Pittsburgh Sleep Quality Index (PSQI) was developed by Buysse et al. [25].Te PSQI, which evaluates sleep quality during the last month, includes a total of 24 questions.Te total score has a value between 0 and 21.A total score higher than 5 indicates poor sleep quality [25].

Statistical Analysis.
All statistical analyses were performed using SPSS version 26.Te Shapiro-Wilk test was used to assess the normality of the data.According to the data normality, continuous variables are expressed as mean and standard deviation (SD)/median (IQR), and categorical variables are expressed as number and percentage (%).Oneway ANOVA and the Kruskal-Wallis test were used to compare the three groups' baseline characteristics.By controlling for any changes in baseline variables, we applied the ANCOVA (analysis of covariance) test to determine diferences in exercise capacity, HrQoL, peripheral and respiratory muscle strength, anxiety and depression, fatigue, sleep quality, dyspnea, and resting blood pressure between groups.For the purpose of using ANCOVA, all presumptions (normally distributed, homogeneous, homogeneity of regression slope, random independent samples, and linearity) have been confrmed.Each outcome measure's baseline values were used as covariates.Calculations were made for post hoc comparisons using the Bonferroni test (syntax).A p value <0.05 was considered statistically signifcant.Te remaining study groups' pairwise comparisons and between-group efects were the main topics of the secondary analysis.Intention-to-treat analysis was performed for missing data.By assessing individuals based on their originally assigned groups, the intention-to-treat (ITT) approach allows for impartial conclusions about intervention efectiveness.Its adherence to randomization safeguards its advantages, setting it apart from alternative analysis methods [26].Te ITTanalysis facilitates comparing individuals in both the experimental and control groups based on their random assignment to these groups [27].

Results
Eighty patients in total had their eligibility for the inclusion criterion checked.Tree groups of 45 patients each were randomly assigned.35 patients in total were excluded, and 43 patients successfully fnished the course.Figure 1 displays the withdrawal's justifcations.Tere were no adverse efects.Te patients' prescriptions were not modifed during the training.
Sociodemographic and clinical characteristics of individuals diagnosed with HT are shown in Table 1.Tere was no statistically signifcant diference between the groups in terms of age (p > 0.05).Te rate of males was higher than females within the groups and the proportion of males and females was similar between the groups.Physical activity status was similar in all three groups and more than half did not engage in physical activity.
Te results of the efect of IMT on respiratory parameters in individuals with HT are shown in Table 2. Te results of MIP before and after training were statistically increased within the groups (p < 0.05).Te efect of IMT between the groups was statistically similar for MIP and MEP (p > 0.05).MEP values were statistically increased after the training within LLG and HLG (p < 0.05).∆MIP diference was 12.81 cmH 2 O (p � 0.290) between the control and LLG, 18.63 cmH 2 O (p � 0.056) between the control group and HLG, and 5.819 cmH 2 O (p � 0.999) between HLG and LLG.Medium efects were found in MIP after the training between the groups (ES � 0.570).

International Journal of Clinical Practice
A statistically signifcant improvement was observed across all groups in the PEF (%) results (p < 0.05).
Table 3 displays how IMT afects HT patients' peripheral muscular strength, exercise capacity, HrQoL, depression, anxiety, sleep quality, and level of physical activity.Te increase in pre-and post-training values in LLG and HLG was statistically signifcantly diferent for quadriceps muscle strength, hand grip strength, and 6MWT distance.Te efect of training was statistically signifcant with an increase in the right-hand grip strength and 6MWT distance (p < 0.05).∆ 6MWT diference was 21.68 m between CG and LLG (p� 0.018) and 23.17 m (p� 0.012) between CG and HLG.Tere was no statistically signifcant diference between LLG and HLG in ∆ 6MWT (∆ � 1.48 m, p � 0.865), but a medium efect (ES � 0.716) was found between the groups in ∆ 6MWT after the training.Physical function and pain pretest and posttest results of SF-36 subparameters were signifcantly diferent in LLG and HLG.Social functioning and emotional role difculty scores of SF-36 were signifcantly diferent within HLG compared to the pretraining.Te vitality and emotional well-being scores of SF-36 were statistically signifcantly improved only within LLG.Te efect of training was statistically signifcant in right-hand grip strength, 6MWT distance, and physical function parameter of SF-36 (p < 0.05).Depression, anxiety, fatigue, and sleep quality results were statistically similar within and between groups (p > 0.05).Fatigue levels were similar between the groups after the training.Te perception of fatigue was similar within CG and HLG compared to the pretraining, whereas the decrease in the perception of fatigue was statistically diferent within LLG.Te increase in physical activity was signifcant between the groups and the highest increase was found in the high-intensity training group.IMT decreased resting blood pressure, resting dyspnea perception, and improved sleep quality.

Discussion
Tis frst comprehensive study was aimed to investigate the efects of diferent IMTs applied for 8 weeks on exercise capacity, HrQoL, depression, peripheral and respiratory muscle strength, respiratory function, fatigue, and physical     [30,31].More recent research has confrmed the impact of inspiratory muscles on functional capacity [30] by demonstrating a substantial correlation between MIP and peak VO2 in individuals with acute myocardial infarction and heart failure [32].HT is one of the increasingly common risk factors globally.Inspiratory muscle weakness has been found in HT patients and this also afects exercise capacity [33].Studies on the exercise capacity effectiveness of respiratory exercises, one of the alternative treatments of hypertension, have been increasing recently.Ublosakka-Jones et al. [34] found that respiratory exercise training given at low load (MIP 25%) for 8 weeks was efective on arm endurance capacity.In another study examining the efects of respiratory muscle endurance training on performance capacity in normotensive elderly patients, respiratory muscle endurance training applied for 5 weeks caused an increase in performance [35].Inspiratory muscle training applied at 30% of MIP in pulmonary hypertension patients was not diferent from the training given at the lowest load of the device in terms of 6MWT results [36].A similar therapeutic efect was declared on inspiratory muscle strength in COPD patients who performed threshold IMT and resistive IMTat an intensity of 60% of MIP, but resistive IMT was more efective than threshold IMT in improving exercise capacity, inspiratory muscle strength, HrQoL, and degree of dyspnea [37].

4.2.
Health-Related Quality of Life.HrQoL of individuals with hypertension is slightly worse than normotensive individuals [39].Aerobic exercises have positive efects on HrQoL.It was found that pulmonary rehabilitation applied for 10 weeks improved HrQoL and increased exercise capacity in individuals with pulmonary hypertension [40].In another study, IMT increased exercise capacity and MIP in pulmonary hypertension, but there was insufcient information on its efect on HrQoL and fatigue.In a previous study examining the efect of breathing exercises combined with relaxation exercises on cardiovascular risk factors, it was found that relaxation training combined with breathing exercises improved HrQoL [41].Tere are no studies in the literature examining the efect of IMT on HrQoL in hypertensive patients.In our study, it was observed that IMT caused an improvement in HrQoL, especially on the physical function parameter.Te observed signifcant enhancement in the PF parameter of the quality of life questionnaire within the training groups possibly contributed to a reduction in perceived exertional dyspnea during daily physical activities, indicating a treatment efect.A previous study has consistently demonstrated that IMT diminishes exertional dyspnea in both healthy and patient populations [42].Tis could be attributed to enhancements in peripheral and respiratory muscle strengths, thereby augmenting the overall performance of these muscle groups, a notion supported by studies [42,43].Tese studies illustrate that low-intensity IMT bolsters respiratory muscle strength and functionality across diverse patient groups, encompassing heart failure [44] hemodialysis patients [45], individuals with metabolic syndrome [43], and those with atrial fbrillation [46].Furthermore, an increase in physical activity tolerance post-IMT might ofer an additional rationale for the observed improvement in HrQoL in the present study.

Depression.
Respiratory exercises impact physiological mechanisms connected to respiration, emotion, and cognition via the autonomic nervous system.Tese exercises reduce sympathetic nervous system activity while enhancing parasympathetic nervous system activity, which is linked to cardiac vagal tone.Consequently, these exercises infuence emotions, emotional regulation, psychological adaptation, reactivity, expression, and empathic responses.By utilizing this mechanism, conditions such as depression can potentially beneft from breathing exercises [47,48].Breathing control has been shown to be benefcial in lowering blood pressure in HT patients [49].It is not known whether qigong 8 International Journal of Clinical Practice reduces blood pressure by this mechanism, but qigong has been shown to improve respiratory efciency for oxygen uptake and carbon dioxide production [50].According to another study in adults aged eighteen years and older, diaphragmatic breathing can reduce stress as measured by physiological biomarkers as well as psychological self-report instruments.Given the benefts of diaphragmatic breathing on stress reduction, further research is needed to continue to build the evidence base for this self-administered, low-cost, nonpharmacological intervention.In our study, deviceassisted respiratory exercises performed with or without a certain workload yielded similar results in the perception of depression in HT patients.However, the highest decrease in depression perception was in the LLG and HLG.It is recommended to further investigate the efects of respiratory muscle endurance training on depression in HT patients.

Peripheral and Respiratory Strength.
According to a study examining the respiratory-sympathetic connection in relation to hypertension, the respiratory and circulatory systems are both involved in the delivery of oxygen and removal of carbon dioxide from tissues in the body, and any alteration in this connection is expected to lead to cardiovascular consequences.Indeed, studies on this connection have suggested that an increase in respiratory modulation of sympathetic vasoconstrictor drive may contribute to the development of hypertension and that this increased respiratorysympathetic connection may be responsible for the occurrence of HT in humans [51,52].As part of this connection, we found that IMT increased both respiratory muscle strength and quadriceps muscle strength.Te clinical signifcance of these fndings may increase the efectiveness of respiratory muscle training in HT.IMT suggests that the reduction in respiratory rate reduces blood pressure through positive modulation of cardiovascular refexes.Tis training applies an external resistance to the respiratory muscles and has shown benefcial training efects in patients with cardiovascular disease, especially in patients with chronic heart failure [38].However, there are very few studies on the efectiveness of IMT on hypertension.According to Ferreira et al. [5], who investigated the efect of 8 weeks of inspiratory muscle training on blood pressure and respiratory muscle strength in HT, there was a signifcant increase in inspiratory muscle strength in the IMT group (82.

Respiratory Function.
Studies showing the efect of hypertension on the lungs are limited and contradictory.Some investigators show a decrease in pulmonary function parameters in hypertensive patients [53].Te alleged pathophysiology was the occurrence of edema of the lung secondary to left ventricular failure with high sustained blood pressure and reduced elasticity of the pulmonary parenchyma [53,54].In contrast, some other researchers have concluded that hypertension has no efect on the pulmonary function; instead antihypertensive drugs have the above efect [55].In our study, 8-week IMT showed similar diferences between the groups in terms of pulmonary function.However, in the pretest-posttest intragroup comparison, FVC was diferent within the group in the LLG and HLG, and the PEF % value was diferent within all groups.Increasing respiratory muscle strength in HT patients may have improved respiratory functions as a result of a decreased diaphragmatic fatigue with respiratory metaborefex activation.In addition, expiratory muscle strength is related to PEF values and the increase in PEF values might result from the improvement of respiratory muscle strength [56][57][58].Te metaborefex efect of IMT may have improved respiratory functions in HT patients by afecting oxygenation.In order to prove the efectiveness of IMT on pulmonary function, more long-term training is needed.
4.6.Fatigue.Te relationship between functional parameters such as lung mechanics, chest kinematics, metabolism, peripheral and respiratory muscle function, and exercise tolerance level remains a controversial issue.An increase in energy output required by an external stimulation results in fatigue, which is described as a disturbance of internal balance.Along with fatigue, physical performance declines as a result of a rise in the actual or perceived difculty of a task or activity, as well as the muscles' inability to maintain the desired level of strength during exercises.Physical activity that results in the buildup of specifc metabolites in muscle fbers or insufcient motor control in the motor cortex would be the stimulus for weariness [59].Although it has been previously shown in other diseases that inspiratory muscle training can improve exercise tolerance in hypertensive patients, the degree to which each of the parameters mentioned above contributes to this change remains unclear [36,60].In our study, fatigue perception decreased statistically only within LLG.IMT led to an increase in both peripheral and respiratory muscle strength and increased exercise capacity in the groups, which may have led to a decrease in the perceived fatigue level.It is recommended to further investigate the relationship between fatigue level and respiratory exercises in hypertensive patients.Dyspnea is a common symptom afecting up to 25% of patients seen in the ambulatory setting.It can be caused by many diferent underlying conditions and is sometimes a manifestation of a life-threatening disease.Problems with the cardiovascular system, such as hypertension, are a pathogenesis of dyspnea [63].Patients with pulmonary hypertension (PH) frequently experience the debilitating feeling of dyspnea, particularly exertional dyspnea.While ignoring the role of respiratory control, the etiology of dyspnea in these patients has been linked to cardiovascular factors and specifc anomalies of the respiratory system during exercise [64].Hossein Pour et al. [65] found that weekly home-based IMT was efective and safe in reducing dyspnea and fatigue and improving the New York Heart Association's functional classifcation.According to Saglam et al. [66], IMT provides signifcant improvements in respiratory muscle strength and exercise capacity, resulting in reduced dyspnea during activities of daily living and less fatigue in patients with PAH (pulmonary arterial hypertension).Similar to the literature, current study's fnding showed that low-load IMT and high-load IMT could decrease dyspnea perception in HT.
In patients with hypertension, systolic blood pressure should be reduced to <140 mmHg and diastolic pressure to <90 mmHg and blood pressure should be around 130-139/ 80-85 mmHg [67].Recent data from SPRINT recommend lowering blood pressure below 120/85 mmHg, but it is also expressed in the guideline recommendations to keep in mind that changes may not occur in the near future [68].Although it is uncontrollable and frequently goes unnoticed, breathing is a crucial part of maintaining cardiovascular homeostasis.Respiratory training allows for the practice and improvement of respiration, which is characterized by diaphragmatic motions.Slow breathing lowers blood pressure and increases barorefex sensitivity, according to an acute controlled breathing program with 6 cycles per minute compared to spontaneous breathing.After adopting slower breathing patterns, blood pressure decreases primarily due to autonomic and refex mechanisms.Reducing respiratory cycles causes the lungs to expand more.In order to prevent lung overinfation, this mechanical change stimulates the Hering-Breuer refex and pulmonary stretch receptors.Tis acts as an input to the medulla, which is a crucial area for cardiopulmonary refexes and where data produced by arterial baroreceptors is gathered and consolidated.Tus, as required by the refex mechanism, a vagal-mediated response is triggered in the presence of an acute rise in blood pressure and/or lung expansion.Tis response causes systemic vasodilation with a reduction in cardiac chronotropic and inotropic activities as well as a reduction in vascular peripheral resistance, which ultimately lowers blood pressure [69].IMT decreases resting heart rate and blood pressure with the metaborefex efect.According to a metaanalysis and review examining the efects of IMT on the cardiovascular system, this training was found to be particularly efective on heart rate and diastolic blood pressure [30].According to a recently published study, IMTapplied at high intensity (MIP 75%) reduced SBP by 9 ± 6 mmHg and DBP by 4 ± 4 mmHg.IMT-associated reductions in SBP and DBP occurred at week 2 of training (−4 ± 8 mmHg and −3 ± 6 mmHg, respectively) and persisted throughout the following 6-week intervention.Consistent with the literature, both low-load IMT and high-load IMT lowered blood pressure for 8 weeks.It is recommended that respiratory muscle training and breathing exercises be added to treatment programs as an alternative therapy, especially in patients with HT risk factors or diagnosed with HT.
Tere are a limited number of studies evaluating the efectiveness of breathing exercises on sleep quality.According to a meta-analysis study reviewing the efects of IMT in individuals with sleep apnea syndrome, IMT improved sleep quality, MIP, and respiratory functions [70].Similar to the literature, eight-week IMT improved sleep quality in all groups, while the efect of training was similar.In conclusion, breathing exercises may have improved sleep quality through relaxation efects.
Comparing the efects of diferent IMT loads in HT patients, especially showing the efects on physical and psychological symptoms, and being performed only in patients with a diagnosis of HT (no comorbidities) are the strengths of the study.To evaluate exercise capacity with CPET, not examining the changes in cardiac functions in patients, and not showing the cost-efectiveness of IMT are the limitations of the study.International Journal of Clinical Practice

Conclusion
To the best of our knowledge, this is the frst study that compared the diferent loads of IMT in HT patients.Highload IMT was particularly efective in increasing physical activity level, peripheral muscle strength, exercise capacity, and improved HrQoL.Low-load IMT was efective in reducing dyspnea and improving respiratory function.Deviceguided breathing exercises when performed with load (%30 MIP and %50 MIP) or without workload (%10 MIP) decreased blood pressure, improved sleep quality, and strengthened respiratory muscles.It may be useful to take into account the efects of these diferent workloads when designing exercise programs for HT patients.Also, the effcacy of inspiratory muscle training should be investigated with diferent training protocols such as endurance IMT or functional IMT in HT patients.

Figure 1 :
Figure 1: CONSORT fow diagram of the study.

Table 1 :
Demographic, physical, and physiologic characteristics of HT patients.

Table 2 :
Te results of the efect of IMT on respiratory parameters in individuals with HT.

Table 3 :
Comparisons of peripheral muscle strength, exercise capacity, HrQoL, depression, anxiety, sleep quality, physical activity status, dyspnea, and blood pressure within and between .68 m) and HLG (23.17 m) was statistically signifcant after the training.Te diference between the LLG and HLG was 1.48.Te efect of training was statistically signifcant and medium efective (ES � 0.716) in exercise capacity.It seems that a workload applied to the inspiratory muscles for 8 weeks, whether low or high intensity, may increase exercise capacity.
(21]larly efective on exercise capacity, peripheral muscle strength, respiratory muscle strength, and physical activity level in pacemaker patients with HT[38].Contrary to the literature, in our study, a signifcant increase was found in the low-load intensity (MIP 30%) and high-load intensity (MIP 50%) groups compared to the control group (at the lowest load of the device).∆6MWT distance between CG and LLG(21 7 ± 28.8 vs. 121.5 ± 21.8 cmH 2 O) and this increase was not detected in the placebo-IMT group (93.3 ± 25.3 vs. 106.1 ± 25.3 cmH 2 O).Similar to this study, the diference in In our study, more than half of the HT patients were inactive at baseline.At the end of 8 weeks, the physical activity level increased in the LLG and HLG.Te efect of training was also observed in the changes in physical International Journal of Clinical Practice activity levels.Terefore, since high-intensity training seems to increase physical activity more, it is recommended to add this workload to exercise programs for patients with HT.